| trhoppe | 02-28-2005 01:12 PM |
Correct me if I'm wrong Joel, but last year, you were still getting a lot of rear wheel lift even w/o a rear bar correct?
-Tom
-Tom
| Scooby South | 02-28-2005 01:34 PM |
My thoughts:
a Prepped STi and a Prepped WRX are different...their are similarities...but the way the power is...with the Diffs make things react differently...
what is a good setup on a WRX...doesn't mean its going to be optimum on a STi...It will work but I think there's alot more to learn on a STi ...One reason I am leaving the Stock bars alone for the time being...I think the coilovers will hopefully let the suspension work...so we will see...
I don't think you can compare a STi and WRX on the same level....The Diffs alone make a HUGE difference in Grip... where the WRX open Diff is limiited in its ability....
the Geometry is slightly different....as well as the Unsprung weight. The aluminum Control arms, the Steering Rack, The aluminum Trailing arms, are all a little different for a Baseline WRX....Personally...I think a STi could win an any class given the right components and driver....A Stock, ESP, STu, SM, Etc...
Call me stupid...but I think the Diffs have a HUGE advantage over WRX...wheel lift and all...Because in an STi...the Front Diff is pulling also...so to say that wheel lift costs time...maybe...But I think its negligable compared to a WRX..because of the open front diff unit on it...We all know tricks from our previous cars...RS, WRX Etc..Heck even from an 04 to an 05 STi is so different I don't even think you can compare those 2...similar yes...but the same no...The steering rack is different on the 05...the front Helical LS is different....
All I am saying is what seems to work on a 02-05 WRX is different than even a 04 Sti much less an 05 with different components from the factory...
there are similarities....but different...
Bill
a Prepped STi and a Prepped WRX are different...their are similarities...but the way the power is...with the Diffs make things react differently...
what is a good setup on a WRX...doesn't mean its going to be optimum on a STi...It will work but I think there's alot more to learn on a STi ...One reason I am leaving the Stock bars alone for the time being...I think the coilovers will hopefully let the suspension work...so we will see...
I don't think you can compare a STi and WRX on the same level....The Diffs alone make a HUGE difference in Grip... where the WRX open Diff is limiited in its ability....
the Geometry is slightly different....as well as the Unsprung weight. The aluminum Control arms, the Steering Rack, The aluminum Trailing arms, are all a little different for a Baseline WRX....Personally...I think a STi could win an any class given the right components and driver....A Stock, ESP, STu, SM, Etc...
Call me stupid...but I think the Diffs have a HUGE advantage over WRX...wheel lift and all...Because in an STi...the Front Diff is pulling also...so to say that wheel lift costs time...maybe...But I think its negligable compared to a WRX..because of the open front diff unit on it...We all know tricks from our previous cars...RS, WRX Etc..Heck even from an 04 to an 05 STi is so different I don't even think you can compare those 2...similar yes...but the same no...The steering rack is different on the 05...the front Helical LS is different....
All I am saying is what seems to work on a 02-05 WRX is different than even a 04 Sti much less an 05 with different components from the factory...
there are similarities....but different...
Bill
| Scooby South | 02-28-2005 01:50 PM |
one other thing....Isn't most of the ESP competition RWD???? which means to me that Those folks have similar traction issues that makes them 1 WD...correct??? unless they have a locking rear diff...but I have seen a Cobra Lift the inside tire as well...
I Still have 3 Wheels driving...the fronts and the outside Rear...which gives me a 66% increase in traction over my competition..;)
Bill
I Still have 3 Wheels driving...the fronts and the outside Rear...which gives me a 66% increase in traction over my competition..;)
Bill
| zzyzx | 02-28-2005 01:54 PM |
[QUOTE=Scooby South]there are similarities....but different...[/QUOTE]
Based on first-hand experience I disagree with most of what you've posted. All Imprezas are more similar than they are different. The biggest factor that changes the handling behavior of an Impreza is the amount grip levels reached. Grippy concrete is the worst-case scenario for us in an Impreza chassis and hence why many of us look forward to Nats switching over the Heartland Park asphault in the near future...
- Steve
Based on first-hand experience I disagree with most of what you've posted. All Imprezas are more similar than they are different. The biggest factor that changes the handling behavior of an Impreza is the amount grip levels reached. Grippy concrete is the worst-case scenario for us in an Impreza chassis and hence why many of us look forward to Nats switching over the Heartland Park asphault in the near future...
- Steve
| zzyzx | 02-28-2005 01:57 PM |
[QUOTE=Scooby South]I Still have 3 Wheels driving...the fronts and the outside Rear...which gives me a 66% increase in traction over my competition..;)
Bill[/QUOTE]
... having to keep 4 wheels on the ground to get all power to the tarmac where it belongs means your [b]twice[/b] as likely to loose power than a FWD or RWD setup.
Bill[/QUOTE]
... having to keep 4 wheels on the ground to get all power to the tarmac where it belongs means your [b]twice[/b] as likely to loose power than a FWD or RWD setup.
| KC | 02-28-2005 02:05 PM |
zzyzx.. but with the wrx/rs, power gets transferred to the lifted wheels via open diffs.
No open diffs on an STi means power goes to the gripping wheels for the most part.
I agree, you'll never reach a point where you'll keep all four wheeels (STi or not) on Topeka concrete. Heck, even with my rates, I was lifting the rear wheel on my wagon in Topeka.
Just look to where you can LIMIT it, or when the wheel connects again, you can make use of the power in a turn.
Also, since this is auto-x... you're not going to be on full power before the apex that often... so really... see what you can do to get that wheel down just before or at the apex so when you're powering away, you have full contact.
That's my philosophy anyway.
--kC
No open diffs on an STi means power goes to the gripping wheels for the most part.
I agree, you'll never reach a point where you'll keep all four wheeels (STi or not) on Topeka concrete. Heck, even with my rates, I was lifting the rear wheel on my wagon in Topeka.
Just look to where you can LIMIT it, or when the wheel connects again, you can make use of the power in a turn.
Also, since this is auto-x... you're not going to be on full power before the apex that often... so really... see what you can do to get that wheel down just before or at the apex so when you're powering away, you have full contact.
That's my philosophy anyway.
--kC
| zzyzx | 02-28-2005 02:12 PM |
[QUOTE=KC]zzyzx.. but with the wrx/rs, power gets transferred to the lifted wheels via open diffs.
No open diffs on an STi means power goes to the gripping wheels for the most part.
[/QUOTE]
In theory. In practice the STi loses just as much power out that wheel in the air than any other Impreza. It's worse, in fact, because the additional power the STi has to spin that wheel will generally unsettle the car once it comes back down and makes contact with the ground.
I'm not sure eactly how the rear diff in the STi works, but it seems to react more like a torque multiplier (e.g. Quaife), then a clutch-pack type diff. That's to say X * 0 = 0.
I'm sure others will confirm this.
- Steve
No open diffs on an STi means power goes to the gripping wheels for the most part.
[/QUOTE]
In theory. In practice the STi loses just as much power out that wheel in the air than any other Impreza. It's worse, in fact, because the additional power the STi has to spin that wheel will generally unsettle the car once it comes back down and makes contact with the ground.
I'm not sure eactly how the rear diff in the STi works, but it seems to react more like a torque multiplier (e.g. Quaife), then a clutch-pack type diff. That's to say X * 0 = 0.
I'm sure others will confirm this.
- Steve
| trhoppe | 02-28-2005 02:25 PM |
Thats why a clutch-pack diff needs to go in the car for a serious autox build ;)
-Tom
-Tom
| Draken | 02-28-2005 02:27 PM |
Steve,
I actually don't agree with you on this. In several STS/STX/DSP 2.5 RSs I've raced, i delt with wheel spin through open diffs. Plain and simple, power getting spun away on a lifted wheel.
With my ESP STi, i never noticed the wheel lifted in terms of wasted power, wheel spin etc. However, I did experience interesting jerking motions with the big tires during hard acceleration. This was coming off corners, on throttle, when the inside rear would touch down. Yes, the car had reactions due to a wheel being lifted, but it was completely different feeling than any other Subie I've driven.
And i still dont agree that an Impreza is an Impreza. And, as Tom mentioned, having no rear bar will not cause the rear tire to stay on the ground. Quite a bit of it has to do with the rear rebound valving.
my rear lifted, no rear bar:
[img]http://www.subrew.com/tmp/nats4.JPG[/img]
frotn shot...rear tire touching...just threw it on here to show i don't have massive body roll:
[img]http://www.subrew.com/tmp/nats1.JPG[/img]
Chris H.
I actually don't agree with you on this. In several STS/STX/DSP 2.5 RSs I've raced, i delt with wheel spin through open diffs. Plain and simple, power getting spun away on a lifted wheel.
With my ESP STi, i never noticed the wheel lifted in terms of wasted power, wheel spin etc. However, I did experience interesting jerking motions with the big tires during hard acceleration. This was coming off corners, on throttle, when the inside rear would touch down. Yes, the car had reactions due to a wheel being lifted, but it was completely different feeling than any other Subie I've driven.
And i still dont agree that an Impreza is an Impreza. And, as Tom mentioned, having no rear bar will not cause the rear tire to stay on the ground. Quite a bit of it has to do with the rear rebound valving.
my rear lifted, no rear bar:
[img]http://www.subrew.com/tmp/nats4.JPG[/img]
frotn shot...rear tire touching...just threw it on here to show i don't have massive body roll:
[img]http://www.subrew.com/tmp/nats1.JPG[/img]
Chris H.
| zzyzx | 02-28-2005 02:52 PM |
An Impreza is basically a FWD chassis with a 60/40 weight split. This is why we're all talking about rear wheel lift and not front wheel lift (e.g. BMW). The physics are basically the same. And no, you'll never eliminate rear wheel lift because an Impreza is an Impreza... If you took a FWD L and ran it in E-Prepared, it'll look like every other FWD Honda tricycle out there at Forbes.
The STi "feels different" because you have a computer trying to figure out what to do and making corrections on the fly. That doesn't change the underlying chassis dynamics, however.
As to rear rebound damping, well, zero isn't going to keep that wheel on the ground, either.
The STi "feels different" because you have a computer trying to figure out what to do and making corrections on the fly. That doesn't change the underlying chassis dynamics, however.
As to rear rebound damping, well, zero isn't going to keep that wheel on the ground, either.
| Draken | 02-28-2005 03:11 PM |
perhaps it isn't a question of the rebound keeping the rear tire on the ground, but a matter of insufficient rear droop.
And yes, i understand what you are saying. But i still dont entirely agree with it. I had front wheel spin on my g-stock 2.5RS i ran nationally in 2002. With and without big front bars, proper shocks etc. Completely different animal, imo, compared to an STi. Even a few DSP RSs i've driven, and STX WRXs. As witnessed by a few comments from other ESP STi guys, i have a huntch that they will be setup more like Camaros, then a FWD Civic.
Chris H.
And yes, i understand what you are saying. But i still dont entirely agree with it. I had front wheel spin on my g-stock 2.5RS i ran nationally in 2002. With and without big front bars, proper shocks etc. Completely different animal, imo, compared to an STi. Even a few DSP RSs i've driven, and STX WRXs. As witnessed by a few comments from other ESP STi guys, i have a huntch that they will be setup more like Camaros, then a FWD Civic.
Chris H.
| zzyzx | 02-28-2005 03:22 PM |
[QUOTE=Draken]perhaps it isn't a question of the rebound keeping the rear tire on the ground, but a matter of insufficient rear droop.
[/quote]
I would agree that there are coilovers with insufficient rear droop out there. However, the set I designed have more rear droop than stock (... a LOT). Even with the lowest rebound setting (see pic above), the rear would still come off the ground. This is mostly do to the fact that things are happening so quickly.
[QUOTE=Draken]
And yes, i understand what you are saying. But i still dont entirely agree with it. I had front wheel spin on my g-stock 2.5RS i ran nationally in 2002. With and without big front bars, proper shocks etc. Completely different animal, imo, compared to an STi. Even a few DSP RSs i've driven, and STX WRXs. As witnessed by a few comments from other ESP STi guys, i have a huntch that they will be setup more like Camaros, then a FWD Civic.
[/QUOTE]
I have a Quaife in the front (RS), Phil has a Quaife F, Kaaz R on his WRX. We still fight the same underlying issues. Sure, my RS will pull around a corner better than one with an open diff. I guess since we're talking DSP/ESP/SM, I don't look at, say, an STi as different than a WRX since the parts in question are legal to swap out in these classes. Certainly changing the diffs will change the character of the car somewhat, but doesn't change the underlying (common to all...) issues.
It'll be interesting to see what people come up with this year. Setup like Camaros? That's an interesting thought. What are you seeing that makes you say that?
- Steve
[/quote]
I would agree that there are coilovers with insufficient rear droop out there. However, the set I designed have more rear droop than stock (... a LOT). Even with the lowest rebound setting (see pic above), the rear would still come off the ground. This is mostly do to the fact that things are happening so quickly.
[QUOTE=Draken]
And yes, i understand what you are saying. But i still dont entirely agree with it. I had front wheel spin on my g-stock 2.5RS i ran nationally in 2002. With and without big front bars, proper shocks etc. Completely different animal, imo, compared to an STi. Even a few DSP RSs i've driven, and STX WRXs. As witnessed by a few comments from other ESP STi guys, i have a huntch that they will be setup more like Camaros, then a FWD Civic.
[/QUOTE]
I have a Quaife in the front (RS), Phil has a Quaife F, Kaaz R on his WRX. We still fight the same underlying issues. Sure, my RS will pull around a corner better than one with an open diff. I guess since we're talking DSP/ESP/SM, I don't look at, say, an STi as different than a WRX since the parts in question are legal to swap out in these classes. Certainly changing the diffs will change the character of the car somewhat, but doesn't change the underlying (common to all...) issues.
It'll be interesting to see what people come up with this year. Setup like Camaros? That's an interesting thought. What are you seeing that makes you say that?
- Steve
| dwx | 02-28-2005 03:56 PM |
If it's any consolation, the EVO guys have the same exact problems. The suspension and weight layout are almost the same in both cars and they suffer from the same issues.
I'm hoping my car comes in underweight this year so I can ballast it somewhat, but I doubt that's going to happen.
I'm using a Cusco 1-way 6MT diff in the front this year, as opposed to the Suretrac diff. The Suretrac diff didn't seem to do a whole lot for me last year, I think it's too weak to handle the power. The amount of front wheelspin I'd get when I wanted to was amazing, and it wasn't both front wheels spinning. The Cusco is a mechanical diff that acts like a clutch-type diff. I figure it will work well or it will explode under the power. :)
I'm hoping my car comes in underweight this year so I can ballast it somewhat, but I doubt that's going to happen.
I'm using a Cusco 1-way 6MT diff in the front this year, as opposed to the Suretrac diff. The Suretrac diff didn't seem to do a whole lot for me last year, I think it's too weak to handle the power. The amount of front wheelspin I'd get when I wanted to was amazing, and it wasn't both front wheels spinning. The Cusco is a mechanical diff that acts like a clutch-type diff. I figure it will work well or it will explode under the power. :)
| Scooby South | 02-28-2005 04:04 PM |
[QUOTE=Draken]Steve,
I actually don't agree with you on this. In several STS/STX/DSP 2.5 RSs I've raced, i delt with wheel spin through open diffs. Plain and simple, power getting spun away on a lifted wheel.
With my ESP STi, i never noticed the wheel lifted in terms of wasted power, wheel spin etc. However, I did experience interesting jerking motions with the big tires during hard acceleration. This was coming off corners, on throttle, when the inside rear would touch down. Yes, the car had reactions due to a wheel being lifted, but it was completely different feeling than any other Subie I've driven.
And i still dont agree that an Impreza is an Impreza. And, as Tom mentioned, having no rear bar will not cause the rear tire to stay on the ground. Quite a bit of it has to do with the rear rebound valving.
my rear lifted, no rear bar:
[img]http://www.subrew.com/tmp/nats4.JPG[/img]
frotn shot...rear tire touching...just threw it on here to show i don't have massive body roll:
[img]http://www.subrew.com/tmp/nats1.JPG[/img]
Chris H.[/QUOTE]
Exactly what I am saying...
To say one setup is superior over another on a 05 STi...is NOT proven...
Theres so much more developmental stuff that I am looking at...
[QUOTE=zzyzx]In theory. In practice the STi loses just as much power out that wheel in the air than any other Impreza. It's worse, in fact, because the additional power the STi has to spin that wheel will generally unsettle the car once it comes back down and makes contact with the ground.
I'm not sure eactly how the rear diff in the STi works, but it seems to react more like a torque multiplier (e.g. Quaife), then a clutch-pack type diff. That's to say X * 0 = 0.
I'm sure others will confirm this.
- Steve[/QUOTE]
This is where I differ on this...With the diff set in Auto...its providing power to the front end as well...being able to "PULL" you along....
Its a great argument....Thats why I don't think theres much if any time left out there for lifting a wheel...It might "Feel" better to the driver....but the dynamics of the DCCD Say the car is still working...Is it working Effectivily??? I don't know...but its still working...
As for Spinning the tires....One reason the STi feels squirrely is because of the power transfer....and the DIFFS working like they should... Thats my theory...To me...thats the Best Traction Device from Fuji that they offer...short of some Traction Control device...like a BMW or Vette has...
Unless you have a Full on Rally Suspension...With lots of travel and droop...you gonna get wheel lift....The WRC Car has Wheel lift...Yes I know much more complicated diffs than what we are talking about ...but...I just don't think your gonna get "ALL" the wheel lift out of a car...and have it handle like it should...
Bill
I actually don't agree with you on this. In several STS/STX/DSP 2.5 RSs I've raced, i delt with wheel spin through open diffs. Plain and simple, power getting spun away on a lifted wheel.
With my ESP STi, i never noticed the wheel lifted in terms of wasted power, wheel spin etc. However, I did experience interesting jerking motions with the big tires during hard acceleration. This was coming off corners, on throttle, when the inside rear would touch down. Yes, the car had reactions due to a wheel being lifted, but it was completely different feeling than any other Subie I've driven.
And i still dont agree that an Impreza is an Impreza. And, as Tom mentioned, having no rear bar will not cause the rear tire to stay on the ground. Quite a bit of it has to do with the rear rebound valving.
my rear lifted, no rear bar:
[img]http://www.subrew.com/tmp/nats4.JPG[/img]
frotn shot...rear tire touching...just threw it on here to show i don't have massive body roll:
[img]http://www.subrew.com/tmp/nats1.JPG[/img]
Chris H.[/QUOTE]
Exactly what I am saying...
To say one setup is superior over another on a 05 STi...is NOT proven...
Theres so much more developmental stuff that I am looking at...
[QUOTE=zzyzx]In theory. In practice the STi loses just as much power out that wheel in the air than any other Impreza. It's worse, in fact, because the additional power the STi has to spin that wheel will generally unsettle the car once it comes back down and makes contact with the ground.
I'm not sure eactly how the rear diff in the STi works, but it seems to react more like a torque multiplier (e.g. Quaife), then a clutch-pack type diff. That's to say X * 0 = 0.
I'm sure others will confirm this.
- Steve[/QUOTE]
This is where I differ on this...With the diff set in Auto...its providing power to the front end as well...being able to "PULL" you along....
Its a great argument....Thats why I don't think theres much if any time left out there for lifting a wheel...It might "Feel" better to the driver....but the dynamics of the DCCD Say the car is still working...Is it working Effectivily??? I don't know...but its still working...
As for Spinning the tires....One reason the STi feels squirrely is because of the power transfer....and the DIFFS working like they should... Thats my theory...To me...thats the Best Traction Device from Fuji that they offer...short of some Traction Control device...like a BMW or Vette has...
Unless you have a Full on Rally Suspension...With lots of travel and droop...you gonna get wheel lift....The WRC Car has Wheel lift...Yes I know much more complicated diffs than what we are talking about ...but...I just don't think your gonna get "ALL" the wheel lift out of a car...and have it handle like it should...
Bill
| DrBiggly | 03-01-2005 12:34 AM |
It seems as though the general concensus is that wheel lift (under hard cornering circumstances) is impossible to eliminate, but is also detrimental to time on course.
The balance would be just like anything else in the suspension; trade one area for another. Better handling overall yet a minimal loss in time from the wheel lift vs. more droop travel and insufficient handling in other areas.
A suspension is nothing more than a series of tradeoffs. The key is finding what one is willing to trade and what one is not willing to trade. Only then can one find the sweet spot. :)
The balance would be just like anything else in the suspension; trade one area for another. Better handling overall yet a minimal loss in time from the wheel lift vs. more droop travel and insufficient handling in other areas.
A suspension is nothing more than a series of tradeoffs. The key is finding what one is willing to trade and what one is not willing to trade. Only then can one find the sweet spot. :)
| makofoto | 03-01-2005 02:36 AM |
I don't get what the big deal is about inside rear wheel lift ... since it occurs at corner entry ... and by the time you are on the power ... that wheel is back down again ... ? What am I missing ...
Also, doesn't a stiff rear bar help put weight on the inside front tire ... something WRX's w/o LSD's want ...
Also, doesn't a stiff rear bar help put weight on the inside front tire ... something WRX's w/o LSD's want ...
| Storm | 03-01-2005 03:04 AM |
[QUOTE=makofoto]I don't get what the big deal is about inside rear wheel lift ... since it occurs at corner entry ... and by the time you are on the power ... that wheel is back down again ... ? What am I missing ...
Also, doesn't a stiff rear bar help put weight on the inside front tire ... something WRX's w/o LSD's want ...[/QUOTE]I can assure you that we're on the power before the wheel comes back down.
Jay Storm
Also, doesn't a stiff rear bar help put weight on the inside front tire ... something WRX's w/o LSD's want ...[/QUOTE]I can assure you that we're on the power before the wheel comes back down.
Jay Storm
| Skibum4444 | 03-01-2005 03:55 AM |
I've been running ESP in a street tire class, non SCCA; in a weak STX car. Anyway theres a Evo in this link shows a little of what you've been talking about. [URL=http://homepage.mac.com/alandahl/PhotoAlbum24.html]http://homepage.mac.com/alandahl/PhotoAlbum24.html[/URL]
| afpdl | 03-01-2005 04:56 AM |
[QUOTE=makofoto]I don't get what the big deal is about inside rear wheel lift ... since it occurs at corner entry ... and by the time you are on the power ... that wheel is back down again ... ? What am I missing ...
Also, doesn't a stiff rear bar help put weight on the inside front tire ... something WRX's w/o LSD's want ...[/QUOTE]
Ive experiance wheel lift bad enough to make me think my clutch was slipping. The rpms were going up but I wasnt going anywhere untill the wheel came back down. And when it comes down it jerks the car, and makes all kinds of noises I would rather never hear come out of my car. And that was just on azenis with r-comps the problem would be way worse.
Also, doesn't a stiff rear bar help put weight on the inside front tire ... something WRX's w/o LSD's want ...[/QUOTE]
Ive experiance wheel lift bad enough to make me think my clutch was slipping. The rpms were going up but I wasnt going anywhere untill the wheel came back down. And when it comes down it jerks the car, and makes all kinds of noises I would rather never hear come out of my car. And that was just on azenis with r-comps the problem would be way worse.
| KC | 03-01-2005 07:30 AM |
Have you guys thought of working on the opposite end of the car with higher spring rates in the front? Look at the pics of STis/EVOs lifting the rear wheels, the front loaded corner is buried in the wheel well.
Well if you take a piece of wood, put your finger under it dead square in the middle and you push down on one corner, what happens to the other corner? It lifts.
[Napolean Dynamite]If you increase the front stiffness, the rear won't lift as high, right? Gosh![/Napolean Dynamite] ;)
--kC
Well if you take a piece of wood, put your finger under it dead square in the middle and you push down on one corner, what happens to the other corner? It lifts.
[Napolean Dynamite]If you increase the front stiffness, the rear won't lift as high, right? Gosh![/Napolean Dynamite] ;)
--kC
| trhoppe | 03-01-2005 08:05 AM |
Thats what Joel is doing with a 32mm hollow front bar. its 44% stiffer then the 27mm Whiteline bar according to his calculations. The thing is, there has to be a point of diminishing returns. Where is that with swaybar size? I bet we will find out by the end of the year ;) Also, once you go too big on teh bar, you will get inside front wheel lift, which is worse mmkay.
-Tom
-Tom
| wrx2.0 555 | 03-01-2005 08:24 AM |
[QUOTE=trhoppe]Thats what Joel is doing with a 32mm hollow front bar. its 44% stiffer then the 27mm Whiteline bar according to his calculations. The thing is, there has to be a point of diminishing returns. Where is that with swaybar size? I bet we will find out by the end of the year ;) Also, once you go too big on teh bar, you will get inside front wheel lift, which is worse mmkay.
-Tom[/QUOTE]
Not the same as:
[QUOTE=KC]Have you guys thought of working on the opposite end of the car with higher spring rates in the front?[/QUOTE]
-Tom[/QUOTE]
Not the same as:
[QUOTE=KC]Have you guys thought of working on the opposite end of the car with higher spring rates in the front?[/QUOTE]
| Scooby South | 03-01-2005 08:34 AM |
I plan to experiment with the springs...for that reason....then if it needs it...I will start messing with the bars....Its all about Weight transfer....I am not a physicist but it seems that springs are the first things the suspension will encounter, then transfering the dynamics to the sway bars....so if the springs are stiffer...then bars become less of factor...IMO...there is going to be a happy median here somewhere....to me...BIG BARS are compensating for weaker springs....the initial weight transfer is what gets the suspension unsettled anyway....(going to hot in maybe, or Abrupt weight transfer)
You can debate it all day...I just don't see how your gonna fix it without getting another problem somewhere else...
I understand that on certain courses..the inside wheel lift issue is upsetting the balance of the transition...causing a big clunk in the rear end....maybe hurting the rear diff and/or axles...I still think the DCCD is the only way to control it...or at least understand it a bit better....Playing with diff would make it less suseptable to the abrupt impact of the wheel making contact with the ground again...
I am actually considering Progressive rate springs on my coilovers .....more on that later..
Bill
You can debate it all day...I just don't see how your gonna fix it without getting another problem somewhere else...
I understand that on certain courses..the inside wheel lift issue is upsetting the balance of the transition...causing a big clunk in the rear end....maybe hurting the rear diff and/or axles...I still think the DCCD is the only way to control it...or at least understand it a bit better....Playing with diff would make it less suseptable to the abrupt impact of the wheel making contact with the ground again...
I am actually considering Progressive rate springs on my coilovers .....more on that later..
Bill
| Draken | 03-01-2005 09:28 AM |
I'm going to be upgrading front anti-roll bars first, then screwing with springs if need be. My STi is still kinda my fair weather daily driver ;) I'm in agreement with the mods that Joel/Hoppe is suggesting....its just that I'm not going to be running ESP nationally this year, so I won't be going quite so extreme. I only ran nationals for vacation..threw the hoosiers in the back seat and drove out to meet up with friends.
KC: I've got a touch too much body roll, imo, and want to help reduce that so i can bring the ride height down a bit. However..i don't think i had as much body rool as other STis/Evos i watched running. IMO..my rear wheel lifting is caused by the Tein's fairly hi rebound valving, and somewhat limited droop travel. I'm not going for extreme changes, just a few small ones to improve what i think is a good package already. Maybe not ESP class winning good, but good for my uses.
[img]http://www.subrew.com/tmp/nats3.JPG[/img]
Chris H.
KC: I've got a touch too much body roll, imo, and want to help reduce that so i can bring the ride height down a bit. However..i don't think i had as much body rool as other STis/Evos i watched running. IMO..my rear wheel lifting is caused by the Tein's fairly hi rebound valving, and somewhat limited droop travel. I'm not going for extreme changes, just a few small ones to improve what i think is a good package already. Maybe not ESP class winning good, but good for my uses.
[img]http://www.subrew.com/tmp/nats3.JPG[/img]
Chris H.
| zzyzx | 03-01-2005 11:17 AM |
[QUOTE=KC]Have you guys thought of working on the opposite end of the car with higher spring rates in the front?[/QUOTE]
Sure. Until the car doesn't turn anymore. :)
But then there's lift. As you'll note in my pic above, there isn't much body roll - the inside of the car is lifting off the tarmac because there's so much grip.
- Steve
Sure. Until the car doesn't turn anymore. :)
But then there's lift. As you'll note in my pic above, there isn't much body roll - the inside of the car is lifting off the tarmac because there's so much grip.
- Steve
| AUTOwrXER | 03-01-2005 12:43 PM |
[QUOTE=trhoppe]Correct me if I'm wrong Joel, but last year, you were still getting a lot of rear wheel lift even w/o a rear bar correct?
-Tom[/QUOTE]
We were getting quite a bit. I was also running no front bar or stock 20mm. The addition of the large front bar should help balance the load across the rear this year.
-Tom[/QUOTE]
We were getting quite a bit. I was also running no front bar or stock 20mm. The addition of the large front bar should help balance the load across the rear this year.
| AUTOwrXER | 03-01-2005 12:50 PM |
[QUOTE=KC]No open diffs on an STi means power goes to the gripping wheels for the most part.[/QUOTE]
But torque sensing diff types go open with a wheel in the air. I know the rear operates this way, and I believe the front does as well.
But torque sensing diff types go open with a wheel in the air. I know the rear operates this way, and I believe the front does as well.
| dwx | 03-01-2005 12:55 PM |
I'm using the GC8 chassis this year and I'm hoping the weight of the 6MT in that chassis will help keep it a little more stable , but it's not going to really change the weight balance tremendously over the 5MT, it's only a couple inches longer. I'm going to widen the track a little bit over its stock configuration as well, and the wheels are two inches wider than the ones I ran last year. Here is a picture Tom took of my car at Oscoda last year, which is pretty grippy concrete. The only other picture he had in his gallery of a car with the inside rear up was an ESP DSM, but I know other cars were doing it as well.
[img]http://my.execpc.com/~pbedard/oscoda1.jpg[/img]
[img]http://my.execpc.com/~pbedard/oscoda1.jpg[/img]
| AUTOwrXER | 03-01-2005 12:55 PM |
[QUOTE=zzyzx]I have a Quaife in the front (RS), Phil has a Quaife F, Kaaz R on his WRX. We still fight the same underlying issues. Sure, my RS will pull around a corner better than one with an open diff. I guess since we're talking DSP/ESP/SM, I don't look at, say, an STi as different than a WRX since the parts in question are legal to swap out in these classes. Certainly changing the diffs will change the character of the car somewhat, but doesn't change the underlying (common to all...) issues.
- Steve[/QUOTE]
Isn't a Quaife just a gear-driven torque sensing type? If so, it will still go open with the inside wheel in the air. They work like magic on FWD cars that don't have issues lifting a driven wheel, but I don't think they are the answer here.
- Steve[/QUOTE]
Isn't a Quaife just a gear-driven torque sensing type? If so, it will still go open with the inside wheel in the air. They work like magic on FWD cars that don't have issues lifting a driven wheel, but I don't think they are the answer here.
| AUTOwrXER | 03-01-2005 12:59 PM |
[QUOTE=Storm]I can assure you that we're on the power before the wheel comes back down.
Jay Storm[/QUOTE]
True. It's worse if you LFB.
Jay Storm[/QUOTE]
True. It's worse if you LFB.
| dwx | 03-01-2005 01:00 PM |
Yeah that's why he didn't mention using a Quaife in the rear. :)
Different conversation I think, didn't really pertain to the tire lifting in the air one. I just mentioned it "helping" in the sense that I wasn't overpowering my inside rear wheel when it came back down on the ground. I think the rear LSD in the STI is very good, 100x better than the viscous one in the WRX, which just isn't effective at all with a lot of power.
Different conversation I think, didn't really pertain to the tire lifting in the air one. I just mentioned it "helping" in the sense that I wasn't overpowering my inside rear wheel when it came back down on the ground. I think the rear LSD in the STI is very good, 100x better than the viscous one in the WRX, which just isn't effective at all with a lot of power.
| AUTOwrXER | 03-01-2005 01:01 PM |
[QUOTE=trhoppe]Thats what Joel is doing with a 32mm hollow front bar. its 44% stiffer then the 27mm Whiteline bar according to his calculations. The thing is, there has to be a point of diminishing returns. Where is that with swaybar size? I bet we will find out by the end of the year ;) Also, once you go too big on teh bar, you will get inside front wheel lift, which is worse mmkay.
-Tom[/QUOTE]
True, though the effects of the front lift are an unknown right now. I plan to use a rear power bias, so IMO it will be less. Building the front diff may be the next project after the other stuff though...
-Tom[/QUOTE]
True, though the effects of the front lift are an unknown right now. I plan to use a rear power bias, so IMO it will be less. Building the front diff may be the next project after the other stuff though...
| AUTOwrXER | 03-01-2005 01:07 PM |
[QUOTE=dwx]Yeah that's why he didn't mention using a Quaife in the rear. :)
Different conversation I think, didn't really pertain to the tire lifting in the air one. I just mentioned it "helping" in the sense that I wasn't overpowering my inside rear wheel when it came back down on the ground. I think the rear LSD in the STI is very good, 100x better than the viscous one in the WRX, which just isn't effective at all with a lot of power.[/QUOTE]
Wheel lift is wheel lift. He's pulling the front wheel too, as noted in the pic. I very well maybe also after the FSB. I know Stemler is in the Evo. If I am correct about the design of the Quaife, the issue will still exist with the wheel in the air. I was thinking a clutch-type up front would be better (just as in the rear) when lift is an issue.
Different conversation I think, didn't really pertain to the tire lifting in the air one. I just mentioned it "helping" in the sense that I wasn't overpowering my inside rear wheel when it came back down on the ground. I think the rear LSD in the STI is very good, 100x better than the viscous one in the WRX, which just isn't effective at all with a lot of power.[/QUOTE]
Wheel lift is wheel lift. He's pulling the front wheel too, as noted in the pic. I very well maybe also after the FSB. I know Stemler is in the Evo. If I am correct about the design of the Quaife, the issue will still exist with the wheel in the air. I was thinking a clutch-type up front would be better (just as in the rear) when lift is an issue.
| zzyzx | 03-01-2005 01:17 PM |
[quote]
Isn't a Quaife just a gear-driven torque sensing type? If so, it will still go open with the inside wheel in the air.
[/quote]
Correct.
The pic of my car above is, thankfully, more the exception than the rule. Getting the front inside that high off the ground is rare. It's more the case that it just gets unloaded a bit and given power and no diff, will spin the inside tire. The tricky issue with the front diff is you don't want something that induces understeer when off the throttle.
Make no mistake, a Quaife in the front is a great thing in an Impreza. The rear diff is more problematic.
Isn't a Quaife just a gear-driven torque sensing type? If so, it will still go open with the inside wheel in the air.
[/quote]
Correct.
The pic of my car above is, thankfully, more the exception than the rule. Getting the front inside that high off the ground is rare. It's more the case that it just gets unloaded a bit and given power and no diff, will spin the inside tire. The tricky issue with the front diff is you don't want something that induces understeer when off the throttle.
Make no mistake, a Quaife in the front is a great thing in an Impreza. The rear diff is more problematic.
| AUTOwrXER | 03-01-2005 02:50 PM |
My understanding is that the 2005 STi has a device very similar to a Quaife in the front from the factory, while the 2004 is more like the Suretrac rear.
| dwx | 03-01-2005 03:06 PM |
They are both torsen diffs and both like the Quaife, I think the mechanical helical LSD in the 05 just reacts faster than the suretrac diff. I thought the USDM STI had a plated rear diff already, and didn't use the Suretrac rear diff.
In Japan the helical front lsd is an option on the STI, it still comes with the Suretrac as standard.
In Japan the helical front lsd is an option on the STI, it still comes with the Suretrac as standard.
| Scooby South | 03-01-2005 03:12 PM |
[QUOTE=AUTOwrXER]My understanding is that the 2005 STi has a device very similar to a Quaife in the front from the factory, while the 2004 is more like the Suretrac rear.[/QUOTE]
Thats my thinking too...
Doing some Research on the DCCD....hopefully It will answer some of these questions...Besides the torque split...It does some other things ....as I am sure you guys are aware...
more later
Bill
Thats my thinking too...
Doing some Research on the DCCD....hopefully It will answer some of these questions...Besides the torque split...It does some other things ....as I am sure you guys are aware...
more later
Bill
| Got Pink? | 03-01-2005 03:35 PM |
Is there a consensus to leave it in Auto mode so that it can do all these things and not be limited to a single setting? I have ran both all the way back and in auto mode and it tends to understeer with stock suspension on auto in the dry but really helps with wet conditions to keep it under control. Doesn't the 05 include a yaw rate sensor to help it react more intellgently to weight transfer?
| dowroa | 03-01-2005 04:45 PM |
[QUOTE=Got Pink?]Is there a consensus to leave it in Auto mode so that it can do all these things and not be limited to a single setting? I have ran both all the way back and in auto mode and it tends to understeer with stock suspension on auto in the dry but really helps with wet conditions to keep it under control. Doesn't the 05 include a yaw rate sensor to help it react more intellgently to weight transfer?[/QUOTE]
My limited response to this will be that I saw a great increase in lateral grip and predictability with the car in auto vs DCCD 1-click from open.
Last year running a BONE Stock STi, I would say 1-click from open was ideal due to all the understeer. This year, with a locally prepped STU/ESP STi, I would say auto is *definitely* the best. In terms of being able to dynamically change the center diff, I believe it is going to be your best option when running at higher levels of Asphalt grip.
The '05 STi does include yaw rate sensor for the DCCD to help it better manage its torque split.
To answer [b]Fred[/b], I think with a good driver, and STi will be a car you need to drive fast and clean with. However, if you are a n00b, it takes some getting used to having that extra power (as opposed ot an unprepped WRX).
Lots of 3rd and 4th gear. Man, do I ever love having torque downlow. No more 1st gear.. unless the local Miata guys design the course again ;) :)
- dow
My limited response to this will be that I saw a great increase in lateral grip and predictability with the car in auto vs DCCD 1-click from open.
Last year running a BONE Stock STi, I would say 1-click from open was ideal due to all the understeer. This year, with a locally prepped STU/ESP STi, I would say auto is *definitely* the best. In terms of being able to dynamically change the center diff, I believe it is going to be your best option when running at higher levels of Asphalt grip.
The '05 STi does include yaw rate sensor for the DCCD to help it better manage its torque split.
To answer [b]Fred[/b], I think with a good driver, and STi will be a car you need to drive fast and clean with. However, if you are a n00b, it takes some getting used to having that extra power (as opposed ot an unprepped WRX).
Lots of 3rd and 4th gear. Man, do I ever love having torque downlow. No more 1st gear.. unless the local Miata guys design the course again ;) :)
- dow
| Storm | 03-01-2005 06:32 PM |
[QUOTE=zzyzx]Correct.
The pic of my car above is, thankfully, more the exception than the rule. Getting the front inside that high off the ground is rare. It's more the case that it just gets unloaded a bit and given power and no diff, will spin the inside tire. The tricky issue with the front diff is you don't want something that induces understeer when off the throttle.
Make no mistake, a Quaife in the front is a great thing in an Impreza. The rear diff is more problematic.[/QUOTE]Do you recall if that pic is after a bump or other element that upset the car? It's tough to tell if the surface is smooth entering that turn....afterall, it is Forbes Field.... My point being that looking at front wheel lift in that pic may not mean as much as keeping the rear planted.
At what point do we look at the placement of weight in the car as it is now contributing to the lifting of wheels at either end? I'm thinking that more droop is just an excuse to let the car roll more....but that may be wrong.
Jay Storm
The pic of my car above is, thankfully, more the exception than the rule. Getting the front inside that high off the ground is rare. It's more the case that it just gets unloaded a bit and given power and no diff, will spin the inside tire. The tricky issue with the front diff is you don't want something that induces understeer when off the throttle.
Make no mistake, a Quaife in the front is a great thing in an Impreza. The rear diff is more problematic.[/QUOTE]Do you recall if that pic is after a bump or other element that upset the car? It's tough to tell if the surface is smooth entering that turn....afterall, it is Forbes Field.... My point being that looking at front wheel lift in that pic may not mean as much as keeping the rear planted.
At what point do we look at the placement of weight in the car as it is now contributing to the lifting of wheels at either end? I'm thinking that more droop is just an excuse to let the car roll more....but that may be wrong.
Jay Storm
| AUTOwrXER | 03-01-2005 08:58 PM |
[QUOTE=dowroa]My limited response to this will be that I saw a great increase in lateral grip and predictability with the car in auto vs DCCD 1-click from open.
Last year running a BONE Stock STi, I would say 1-click from open was ideal due to all the understeer. This year, with a locally prepped STU/ESP STi, I would say auto is *definitely* the best. In terms of being able to dynamically change the center diff, I believe it is going to be your best option when running at higher levels of Asphalt grip.
The '05 STi does include yaw rate sensor for the DCCD to help it better manage its torque split.
To answer [b]Fred[/b], I think with a good driver, and STi will be a car you need to drive fast and clean with. However, if you are a n00b, it takes some getting used to having that extra power (as opposed ot an unprepped WRX).
Lots of 3rd and 4th gear. Man, do I ever love having torque downlow. No more 1st gear.. unless the local Miata guys design the course again ;) :)
- dow[/QUOTE]
Out of curiosity, how much testing have you done on big R-compounds? My experience has been very different than what you describe. Also, how could the diff setting result in a "great increase in lateral grip"?
Last year running a BONE Stock STi, I would say 1-click from open was ideal due to all the understeer. This year, with a locally prepped STU/ESP STi, I would say auto is *definitely* the best. In terms of being able to dynamically change the center diff, I believe it is going to be your best option when running at higher levels of Asphalt grip.
The '05 STi does include yaw rate sensor for the DCCD to help it better manage its torque split.
To answer [b]Fred[/b], I think with a good driver, and STi will be a car you need to drive fast and clean with. However, if you are a n00b, it takes some getting used to having that extra power (as opposed ot an unprepped WRX).
Lots of 3rd and 4th gear. Man, do I ever love having torque downlow. No more 1st gear.. unless the local Miata guys design the course again ;) :)
- dow[/QUOTE]
Out of curiosity, how much testing have you done on big R-compounds? My experience has been very different than what you describe. Also, how could the diff setting result in a "great increase in lateral grip"?
| dowroa | 03-01-2005 09:07 PM |
[QUOTE=AUTOwrXER]Out of curiosity, how much testing have you done on big R-compounds? My experience has been very different than what you describe. Also, how could the diff setting result in a "great increase in lateral grip"?[/QUOTE]
Ah, so this is why I probably should not have entered into this converation, so I will more than likely bow out now with the following statement:
- I run RE070s and Azenis with an STU setup but class ESP b/c the drivers run there.
- Increasing my cars potential for lateral grip and helping my camber curve with a 'real' alignment and 26mm bars on everything else otherwise stock 'felt' like it allowed my car to react better, where as completely stock, the DCCD in auto was a pain and enduced more understeer with my driving style.
From my experience, auto DCCD did not work for me in a terrible stock setup and I had to leave it close to open to add more rear rotation. Now, with the car at a more balanced setup, auto DCCD allows me to make more use of the power/grip that is there.
For me, setting up the car 'correctly' allowed me to take advantage of teh DCCD in auto rather than having it feel like it was a hinderance to me.
That is all, and I bow out now due to lack of a good 'national' setup.
- dow
Ah, so this is why I probably should not have entered into this converation, so I will more than likely bow out now with the following statement:
- I run RE070s and Azenis with an STU setup but class ESP b/c the drivers run there.
- Increasing my cars potential for lateral grip and helping my camber curve with a 'real' alignment and 26mm bars on everything else otherwise stock 'felt' like it allowed my car to react better, where as completely stock, the DCCD in auto was a pain and enduced more understeer with my driving style.
From my experience, auto DCCD did not work for me in a terrible stock setup and I had to leave it close to open to add more rear rotation. Now, with the car at a more balanced setup, auto DCCD allows me to make more use of the power/grip that is there.
For me, setting up the car 'correctly' allowed me to take advantage of teh DCCD in auto rather than having it feel like it was a hinderance to me.
That is all, and I bow out now due to lack of a good 'national' setup.
- dow
| Draken | 03-01-2005 09:15 PM |
I run auto mode. Didn't like how it felt in manual mode, on any setting. For both my 225 070 and 275 Hoosiers.
Chris H.
Chris H.
| Scooby South | 03-01-2005 11:00 PM |
Found a few excerps from the NET
[quote]The WRX STi's performance-oriented symmetrical full-time All-Wheel Drive system features a Subaru-exclusive Driver Controlled Centre Differential (DCCD). Controlled by a small dial within easy reach, DCCD allows drivers to control torque distribution between the front and rear wheels - giving you the freedom to choose a variety of ratios, from the neutrality of a 50/50 split to a performance-oriented, 35/65 front/rear split. DCCD also features an automatic mode which chooses an optimal torque split to provide the utmost in performance and traction. Used in concert with a new-for-2005 helical-type limited-slip front differential, a mechanical-type limited-slip rear differential as well as a new-for-2005 yaw-rate sensor, DCCD provides enhanced traction and control, enabling drivers to remain confident in a variety of challenging road conditions.
Or leave DCCD in its auto mode, where it is said to redistribute power automatically as needed to any wheel.[/quote]
[URL=http://forums.sidc.co.uk/messageview.cfm?catid=18&threadid=21199&STARTPAGE=1]Nice thread on DCCD[/URL]
[URL=http://www.canadiandriver.com/articles/jk/031210.htm]Another nice link on DCCD[/URL]
more:
[quote]During hard cornering, DCCD begins to lock the differential, bringing the power split closer to 50/50. Subaru says the system allows aggressive drivers to maximize handling in corners while maintaining good control. For extra handling "tunability," there's a unique, center-console thumbwheel that allows the driver to manually choose how much torque is split between the front and rear by selecting from among six levels of center-differential locking. Want to get jiggy with the back end? Dial the thumbwheel all the way back, and the tail swings like it belongs to Jennifer Lopez.
Second, STi has Subaru's excellent new Suretrac limited-slip front differential, a faster-acting gearless unit that responds to torque differences between the front wheels to increase traction and reduce understeer.
All that sounds like a long-winded way to get stability control. But DCCD, Suretrac and the new Super Sport ABS work in tandem to give driving enthusiasts a performance edge that Subaru says isn't available from brake-activated stability control systems.
The auto mode maximises grip without over-stressing the driver. It also has a reaction you feel in your back, when the DCCD sends a tad extra power to the front to scramble out of a corner.
However, on the new 2005 Impreza WRX STi, the system is further upgraded by the fitment of a yaw-rate sensor and new front helical limited-slip differential.
The new front LSD is quicker-acting than the previous type and improves steering stability when cornering near the limit. It also improves the car�s steering behaviour on slippery surfaces with less side-to-side tug.
Meanwhile, the yaw rate sensor enhances the balance between straight-line stability and turn-in.
The car, of course, continues to employ Subaru�s much-admired symmetrical, full-time all-wheel drive system with a rear LSD.[/quote]
Just some things I found....
Bill
[quote]The WRX STi's performance-oriented symmetrical full-time All-Wheel Drive system features a Subaru-exclusive Driver Controlled Centre Differential (DCCD). Controlled by a small dial within easy reach, DCCD allows drivers to control torque distribution between the front and rear wheels - giving you the freedom to choose a variety of ratios, from the neutrality of a 50/50 split to a performance-oriented, 35/65 front/rear split. DCCD also features an automatic mode which chooses an optimal torque split to provide the utmost in performance and traction. Used in concert with a new-for-2005 helical-type limited-slip front differential, a mechanical-type limited-slip rear differential as well as a new-for-2005 yaw-rate sensor, DCCD provides enhanced traction and control, enabling drivers to remain confident in a variety of challenging road conditions.
Or leave DCCD in its auto mode, where it is said to redistribute power automatically as needed to any wheel.[/quote]
[URL=http://forums.sidc.co.uk/messageview.cfm?catid=18&threadid=21199&STARTPAGE=1]Nice thread on DCCD[/URL]
[URL=http://www.canadiandriver.com/articles/jk/031210.htm]Another nice link on DCCD[/URL]
more:
[quote]During hard cornering, DCCD begins to lock the differential, bringing the power split closer to 50/50. Subaru says the system allows aggressive drivers to maximize handling in corners while maintaining good control. For extra handling "tunability," there's a unique, center-console thumbwheel that allows the driver to manually choose how much torque is split between the front and rear by selecting from among six levels of center-differential locking. Want to get jiggy with the back end? Dial the thumbwheel all the way back, and the tail swings like it belongs to Jennifer Lopez.
Second, STi has Subaru's excellent new Suretrac limited-slip front differential, a faster-acting gearless unit that responds to torque differences between the front wheels to increase traction and reduce understeer.
All that sounds like a long-winded way to get stability control. But DCCD, Suretrac and the new Super Sport ABS work in tandem to give driving enthusiasts a performance edge that Subaru says isn't available from brake-activated stability control systems.
The auto mode maximises grip without over-stressing the driver. It also has a reaction you feel in your back, when the DCCD sends a tad extra power to the front to scramble out of a corner.
However, on the new 2005 Impreza WRX STi, the system is further upgraded by the fitment of a yaw-rate sensor and new front helical limited-slip differential.
The new front LSD is quicker-acting than the previous type and improves steering stability when cornering near the limit. It also improves the car�s steering behaviour on slippery surfaces with less side-to-side tug.
Meanwhile, the yaw rate sensor enhances the balance between straight-line stability and turn-in.
The car, of course, continues to employ Subaru�s much-admired symmetrical, full-time all-wheel drive system with a rear LSD.[/quote]
Just some things I found....
Bill
| afpdl | 03-01-2005 11:43 PM |
The dccd works by changing the lock ration depending on inputs of lateral/longintudinal gs and the yaw rate on the 05s the 04s just had a g sensor in that location.
nhulr (sp) has posted a link showing the graph and how it acts around a corner, basically the diff opens up on corner entry to get the car to rotate and progressivly locks up towards corner exit to put the power down.
Found the graph
[img]http://www.subaru-sti.co.jp/spec_c_RA/02/04/01/imgs/p3.gif[/img]
There was one in english for the 04s at least but I cant find it.
nhulr (sp) has posted a link showing the graph and how it acts around a corner, basically the diff opens up on corner entry to get the car to rotate and progressivly locks up towards corner exit to put the power down.
Found the graph
[img]http://www.subaru-sti.co.jp/spec_c_RA/02/04/01/imgs/p3.gif[/img]
There was one in english for the 04s at least but I cant find it.
| zzyzx | 03-01-2005 11:52 PM |
[QUOTE=Storm]Do you recall if that pic is after a bump or other element that upset the car? It's tough to tell if the surface is smooth entering that turn....afterall, it is Forbes Field.... My point being that looking at front wheel lift in that pic may not mean as much as keeping the rear planted.
[/quote]
Good point, Jay. I don't remember exactly where this was. I can say that this was my co-driver and the pics I bought from digital race photography of the both of us demonstrated that he was the only one doing this. I think I was driving smoother than he was.
I would agree that front wheel lift - totally off the ground like the pic - is much less a factor than rear wheel lift.
On the South course last year, the finish section was particularly hairy. I saw many an CS MR2 Spyder get up on two wheels coming around the shallow bend towards the finish lights. I think just about anybody on Rs got pretty light through there. On one run, my co-driver bicycled through there in my RS and the crowd got a good look at the underside of my car.
[QUOTE=Storm]
I'm thinking that more droop is just an excuse to let the car roll more....but that may be wrong.
[/QUOTE]
Think basic physics. The answer is simple, really. Droop rate is a function of rebound damping + unsprung mass. Roll rate acts against droop rate and if roll rate is greater than droop rate then you have wheels in the air. Roll rate could be due to body roll or lift. Now, apply 1.5Gs in a quick transition situation, convert to roll rate and I think it becomes clear that roll rate can easily overcome droop rate. Other than controlling unwanted oscillation, I think droop rate (rebound damping) should not be relied on to counter roll rate. In other words, you don't want any more rebound damping than it necessary to counteract "bounce".
- Steve
[/quote]
Good point, Jay. I don't remember exactly where this was. I can say that this was my co-driver and the pics I bought from digital race photography of the both of us demonstrated that he was the only one doing this. I think I was driving smoother than he was.
I would agree that front wheel lift - totally off the ground like the pic - is much less a factor than rear wheel lift.
On the South course last year, the finish section was particularly hairy. I saw many an CS MR2 Spyder get up on two wheels coming around the shallow bend towards the finish lights. I think just about anybody on Rs got pretty light through there. On one run, my co-driver bicycled through there in my RS and the crowd got a good look at the underside of my car.
[QUOTE=Storm]
I'm thinking that more droop is just an excuse to let the car roll more....but that may be wrong.
[/QUOTE]
Think basic physics. The answer is simple, really. Droop rate is a function of rebound damping + unsprung mass. Roll rate acts against droop rate and if roll rate is greater than droop rate then you have wheels in the air. Roll rate could be due to body roll or lift. Now, apply 1.5Gs in a quick transition situation, convert to roll rate and I think it becomes clear that roll rate can easily overcome droop rate. Other than controlling unwanted oscillation, I think droop rate (rebound damping) should not be relied on to counter roll rate. In other words, you don't want any more rebound damping than it necessary to counteract "bounce".
- Steve
| zzyzx | 03-02-2005 12:04 AM |
[QUOTE=Draken]perhaps it isn't a question of the rebound keeping the rear tire on the ground, but a matter of insufficient rear droop.
[/QUOTE]
Here's a pic of rear droop travel in my setup:
[img]http://zzyzxmotorsports.com/pics/coilovers/rear-droop-travel.jpg[/img]
Certainly rally-car like rear droop tavel. If this isn't enough droop, then, well droop isn't the problem to begin with. :)
- Steve
[/QUOTE]
Here's a pic of rear droop travel in my setup:
[img]http://zzyzxmotorsports.com/pics/coilovers/rear-droop-travel.jpg[/img]
Certainly rally-car like rear droop tavel. If this isn't enough droop, then, well droop isn't the problem to begin with. :)
- Steve
| Scooby South | 03-02-2005 07:23 AM |
[URL=http://wallace.as.arizona.edu/~cgroppi/DCCD_FAQ/DCCD_FAQ.html]Really Good Read[/URL]
| Scooby South | 03-02-2005 08:00 AM |
[QUOTE=zzyzx]Here's a pic of rear droop travel in my setup:
[img]http://zzyzxmotorsports.com/pics/coilovers/rear-droop-travel.jpg[/img]
Certainly rally-car like rear droop tavel. If this isn't enough droop, then, well droop isn't the problem to begin with. :)
- Steve[/QUOTE]
I agree with you on the Droop....its the dynamics of the suspension and weight transfer..
Bill
[img]http://zzyzxmotorsports.com/pics/coilovers/rear-droop-travel.jpg[/img]
Certainly rally-car like rear droop tavel. If this isn't enough droop, then, well droop isn't the problem to begin with. :)
- Steve[/QUOTE]
I agree with you on the Droop....its the dynamics of the suspension and weight transfer..
Bill
| ratt_finkel | 03-02-2005 01:49 PM |
[QUOTE=zzyzx]Here's a pic of rear droop travel in my setup:
[img]CRAZY TIRE PIC[/img]
Certainly rally-car like rear droop tavel. If this isn't enough droop, then, well droop isn't the problem to begin with. :)
- Steve[/QUOTE]
Jeebus Steve, I had no clue the tires were that large :eek:
Are you running a 16x8?
[img]CRAZY TIRE PIC[/img]
Certainly rally-car like rear droop tavel. If this isn't enough droop, then, well droop isn't the problem to begin with. :)
- Steve[/QUOTE]
Jeebus Steve, I had no clue the tires were that large :eek:
Are you running a 16x8?
| Got Pink? | 03-02-2005 03:15 PM |
I think you could get those Kosei K1's in 16x8.5 from tire rack by special order? They have 16x7.5 normally. Those are some seriously big tires for an RS.
| zzyzx | 03-02-2005 03:20 PM |
Yes, they're the Kosei 16x8.5. They have the blanks which they then have machined for the 5x100 bolt pattern and hub center. The ones I have are +37 offset. They also have +17 and +27 in this size. It can take about 6 weeks to get them if they don't already have them in stock.
- Steve
- Steve
| xjohnx | 03-02-2005 03:37 PM |
Here's a pic of my STi doing the infamous wheel lift this past weekend. It's suspension is currently stock, save for alignment (-1 deg camber front, 0 toe in the rear), and 17x8 rotas with 225 falkens. I understand this situation isn't totally avoidable, but does anyone have any tips to what i can do to help reduce it's occurence?
[img]http://www.itsalwaysgoodbye.com/lift.jpg[/img]
[img]http://www.itsalwaysgoodbye.com/lift.jpg[/img]
| trhoppe | 03-02-2005 03:47 PM |
[quote]I understand this situation isn't totally avoidable, but does anyone have any tips to what i can do to help reduce it's occurence?[/quote]
:confused: Thats what we've been talking about for the last two pages :)
-Tom
:confused: Thats what we've been talking about for the last two pages :)
-Tom
| xjohnx | 03-02-2005 03:56 PM |
[QUOTE=trhoppe]:confused: Thats what we've been talking about for the last two pages :)
-Tom[/QUOTE]
I know, but it seems y'all were talking more from a dedicated auto-x/fully prepped car standpoint, i don't plan on putting uberstiff springs on my car or anything like that. Would a FSB help? If i missed something in the past couple pages please excuse me, i'm a little out of it today from all this cold medicine.
-Tom[/QUOTE]
I know, but it seems y'all were talking more from a dedicated auto-x/fully prepped car standpoint, i don't plan on putting uberstiff springs on my car or anything like that. Would a FSB help? If i missed something in the past couple pages please excuse me, i'm a little out of it today from all this cold medicine.
| afpdl | 03-02-2005 04:00 PM |
Yours really isnt bad enough to have to find a solution. That is just happening on turn in, are you noticing the negative effects while driving or would you not know you were lifting a wheel without having someone outside the car tell you/take a pic?
| xjohnx | 03-02-2005 04:39 PM |
[QUOTE=afpdl]Yours really isnt bad enough to have to find a solution. That is just happening on turn in, are you noticing the negative effects while driving or would you not know you were lifting a wheel without having someone outside the car tell you/take a pic?[/QUOTE]
On the session after that one it did it three times, car just revved freely, felt like the clutch was pushed in, so yeah, it's happening enough to warrant some kind of attention.
On the session after that one it did it three times, car just revved freely, felt like the clutch was pushed in, so yeah, it's happening enough to warrant some kind of attention.
| AUTOwrXER | 03-02-2005 04:40 PM |
FSB will help
| xjohnx | 03-02-2005 04:44 PM |
[QUOTE=AUTOwrXER]FSB will help[/QUOTE]
Thanks. Should i go with whitelines 27mm, or the 24? this will be a daily driven car, and run only on street tires for autox.
Thanks. Should i go with whitelines 27mm, or the 24? this will be a daily driven car, and run only on street tires for autox.
| trhoppe | 03-02-2005 04:46 PM |
With no other mods, go with the BSF33XZ.
-Tom
-Tom
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