| Rallycarperson | 08-04-2004 11:44 AM |
What Swaybars to Use In Rally...??
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Whats up,
Ive heard that swaybars limit independant suspension travel. Someone took me for a spin on a rough gravel road with a Cusco 23mm rear swaybar(set in the middle setting), and it was just tooo stiff. Seemed like we bottomed-out all the time! What do the Big Boys use in ProRally...and how can they deal with the stiffness?? thanks.
-Mark
[url="http://www.MAPmotors.com"]www.MAPmotors.com[/url]
Ive heard that swaybars limit independant suspension travel. Someone took me for a spin on a rough gravel road with a Cusco 23mm rear swaybar(set in the middle setting), and it was just tooo stiff. Seemed like we bottomed-out all the time! What do the Big Boys use in ProRally...and how can they deal with the stiffness?? thanks.
-Mark
[url="http://www.MAPmotors.com"]www.MAPmotors.com[/url]
| Subie Gal | 08-04-2004 11:49 AM |
a lot of them remove their sway bars entirely
creates a completely independent set up
i have a 20front 20rear setup on my rally car
completely neutral setup, works well for my driving style.
[img]http://www.subiegal.com/images/rallies/treeline04/subie_gal_jamie_thomas5.jpg[/img]
Jamie
[url]www.subiegal.com[/url]
creates a completely independent set up
i have a 20front 20rear setup on my rally car
completely neutral setup, works well for my driving style.
[img]http://www.subiegal.com/images/rallies/treeline04/subie_gal_jamie_thomas5.jpg[/img]
Jamie
[url]www.subiegal.com[/url]
| rallykeith | 08-04-2004 11:58 AM |
In snow no sway bars seems to be the way to go. Having less sway bar allows the weight to transfer a little more and get the tire to bit into the surface. Stock on our car seems to do well.
Keith
Keith
| zzyzx | 08-04-2004 12:01 PM |
None. Ever. Tarmac, dirt or snow. :)
| Rallycarperson | 08-04-2004 12:52 PM |
Thanks everyone! Subie Gal, where did you get your 20mm swaybars? Also, this maybe noob, but what mm swaybars come stock on a WRX? Thanks.
-Mark
[url="http://www.MAPmotors.com"]www.MAPmotors.com[/url]
-Mark
[url="http://www.MAPmotors.com"]www.MAPmotors.com[/url]
| Subie Gal | 08-04-2004 12:55 PM |
depends on what wrx and what year
my car came stock with 20front/17rear
i purchased a 20mm sedan rear (from subaru) and swapped it on
i decided to keep my sways as i had learned to drive the car with them in place
and had adjusted to them well. but i was suffering massive understeer...
after adding the 20mm rear, car is now very neutral and much easier to handle.
Jamie
my car came stock with 20front/17rear
i purchased a 20mm sedan rear (from subaru) and swapped it on
i decided to keep my sways as i had learned to drive the car with them in place
and had adjusted to them well. but i was suffering massive understeer...
after adding the 20mm rear, car is now very neutral and much easier to handle.
Jamie
| rallynutdon | 08-04-2004 01:21 PM |
Don't understand your bottoming out. Bottoming out as I know it would have nothing to do with sway bars but would be struts/springs. My 96 Impreza with WRX drive train I've been stage rallying stock 96 sway bars for 4 years. Don't really see a need to change them. It handles well, not too stiff, but no loose problems either.
| Rallycarperson | 08-04-2004 03:39 PM |
[QUOTE=rallynutdon]Don't understand your bottoming out. Bottoming out as I know it would have nothing to do with sway bars but would be struts/springs. My 96 Impreza with WRX drive train I've been stage rallying stock 96 sway bars for 4 years. Don't really see a need to change them. It handles well, not too stiff, but no loose problems either.[/QUOTE]By 'bottoming out' it seemed like the whole rear was extremly stiff, and whenever we went over a pot whole it made a big BAM! I don't know....
-Mark
[url="http://www.MAPmotors.com"]www.MAPmotors.com[/url]
-Mark
[url="http://www.MAPmotors.com"]www.MAPmotors.com[/url]
| travmn | 08-04-2004 07:18 PM |
A lot depends on the driver... I believe I've seen some drivers go stiffer, but usually I see people with removed swaybars, stock swaybars, or somewhere in between (e.g. stock front w/ no rear bar). Depends on driving style & what you're comfortable with. I'd personally go with no bars.
| DrBiggly | 08-04-2004 08:21 PM |
Anders I believe runs with no swaybars in his H6 impregnated Impreza L. I got a ride in it at a rallyx...wheeeee! :D
I think Subie Gal is more likely the exception in the swaybar department. :)
I think Subie Gal is more likely the exception in the swaybar department. :)
| Davenow | 08-04-2004 10:50 PM |
[QUOTE=Subie Gal]a lot of them remove their sway bars entirely
creates a completely independent set up
i have a 20front 20rear setup on my rally car
completely neutral setup, works well for my driving style.
[img]http://www.subiegal.com/images/rallies/treeline04/subie_gal_jamie_thomas5.jpg[/img]
Jamie
[url]www.subiegal.com[/url][/QUOTE]
I see understeer in that pic :lol: :p
creates a completely independent set up
i have a 20front 20rear setup on my rally car
completely neutral setup, works well for my driving style.
[img]http://www.subiegal.com/images/rallies/treeline04/subie_gal_jamie_thomas5.jpg[/img]
Jamie
[url]www.subiegal.com[/url][/QUOTE]
I see understeer in that pic :lol: :p
| dch | 08-05-2004 12:37 AM |
I run front and rear sways. I don't know the size up front, but I believe I have a 20 in the rear. I like them because they make the car more stable in high speed corners. The trick is getting enough weight transfer to do what you need, without having the car wallow around dramatically from side to side. The need for and/or size of the bars depends on the car (power, suspension setup) and the driver (aggressive, smooth) and the course (Rim, STPR). Your best bet is to set up a test day and make small changes one at a time and see what works for you.
I personally don't see much advantage in a barless "totally independant" setup. It's not like off-road racing or the Safari rally where you're hauling over huge bumps, most stage roads are reasonably smooth as far as that goes. Plus the faster you go, the smoother things get and the more you need the stability. Somewhere I have a photo of Steve Gingras perpetrating some mad phat tripod action under braking around a corner at Ojibwe. That could just mean his suspension setup needs some work, but I asked him about it and he doesn't run sway bars.
Cheers,
-Doug
I personally don't see much advantage in a barless "totally independant" setup. It's not like off-road racing or the Safari rally where you're hauling over huge bumps, most stage roads are reasonably smooth as far as that goes. Plus the faster you go, the smoother things get and the more you need the stability. Somewhere I have a photo of Steve Gingras perpetrating some mad phat tripod action under braking around a corner at Ojibwe. That could just mean his suspension setup needs some work, but I asked him about it and he doesn't run sway bars.
Cheers,
-Doug
| Subie Gal | 08-05-2004 10:53 AM |
[QUOTE=Davenow]I see understeer in that pic :lol: :p[/QUOTE]
okay well that photo above is a really bad example :D
that was a rally where I NEVER got the WRX out of 2nd gear
corner... into corner.. into.... - no time to set the car up properly ;)
some oversteerage for ya :D
[img]http://www.subiegal.com/images/rallies/oregonrally2004/subaru_rally_wagon.jpg[/img]
[img]http://www.subiegal.com/images/rallies/rimrally04/fromglenn6.jpg[/img]
[img]http://www.subiegal.com/images/rallies/doowop2004/wrx_wagon99.jpg[/img]
okay well that photo above is a really bad example :D
that was a rally where I NEVER got the WRX out of 2nd gear
corner... into corner.. into.... - no time to set the car up properly ;)
some oversteerage for ya :D
[img]http://www.subiegal.com/images/rallies/oregonrally2004/subaru_rally_wagon.jpg[/img]
[img]http://www.subiegal.com/images/rallies/rimrally04/fromglenn6.jpg[/img]
[img]http://www.subiegal.com/images/rallies/doowop2004/wrx_wagon99.jpg[/img]
| cowapult | 08-05-2004 01:30 PM |
Before some noob takes all this advice and pulls the swaybars off his stock daily driver.... Removing sway bars probably only makes sense in few, specific situations. Generally I think this would hurt performance in a big way. For example, with stock springs and struts, removing sway bars would probably create a mess because you are just adding MORE body roll. But, if you've got a prepped rally car with stiffened springs and struts, maybe you can get away with removing the roll bars because the springs are stiff enough to prevent body roll.
Also, maybe this only makes sense on extremely rough surfaces. On the contrary, I've heard conventional wisdom say that for smooth surfaces you should do the opposite of removing the sway bars. Instead, I thought you were supposed to augment the roll bars as much as possible to specifically address stiffness in the roll direction - allowing (relatively!) softer springs and struts to absorb the bumps and irregularities.
So don't take the sway bars off your daily drivers people!
Did I get any of that right?
PS - I can't see how stiffer suspension would ever make you bottom out. The opposite is true - whether we're talking about springs, dampers, or roll bars.
Also, maybe this only makes sense on extremely rough surfaces. On the contrary, I've heard conventional wisdom say that for smooth surfaces you should do the opposite of removing the sway bars. Instead, I thought you were supposed to augment the roll bars as much as possible to specifically address stiffness in the roll direction - allowing (relatively!) softer springs and struts to absorb the bumps and irregularities.
So don't take the sway bars off your daily drivers people!
Did I get any of that right?
PS - I can't see how stiffer suspension would ever make you bottom out. The opposite is true - whether we're talking about springs, dampers, or roll bars.
| jmott | 08-05-2004 01:47 PM |
[QUOTE=rallynutdon]Don't understand your bottoming out. Bottoming out as I know it would have nothing to do with sway bars but would be struts/springs. My 96 Impreza with WRX drive train I've been stage rallying stock 96 sway bars for 4 years. Don't really see a need to change them. It handles well, not too stiff, but no loose problems either.[/QUOTE]
It affects bottoming out mid turn.
if the car sways a lot, the outside suspension travel is taken up more.
It affects bottoming out mid turn.
if the car sways a lot, the outside suspension travel is taken up more.
| GravelRash | 08-05-2004 09:13 PM |
A stiff bar can effect ground clearance in some cases, e.g.:[list][*]going straight down the road...left front hits a rock/bump[*]left strut compresses to take the impact...[*]...and the stiff bar transfers some of the load to the right side, which [I]may[/I] tend to compress the right strut also, or it may inhibit the left front from compressing as much as it otherwise would (because the right strut is sharing the load via the bar)...
The actual reaction will depend on multiple factors, including how compressed or not the suspension already is at the point of impact, the relative stiffness of the bar vs. the strut springs, unsprung weight of the front suspension vs. sprung weight of the front of the car, friction in the system that inhibits transfer of the load, and probably more that I'm not thinking of.[*]...at which point the car hits the next bump, and the whole front may be a bit higher [I]or[/I] lower than it would have been w/o that transfer, in which case...[*]if it's lower, then of course it may bottom on that next bump; if it's higher then it may get pushed higher still, which means it will come down harder after that second bump.[/list]This is why suspension engineers usually look like :(
:lol:
And, of course, if this all happens when the car is loaded into a corner, and/or the car is sideways enough that the rear hits a bump the front didn't, or vice versa, it just gets that much more complex.
The actual reaction will depend on multiple factors, including how compressed or not the suspension already is at the point of impact, the relative stiffness of the bar vs. the strut springs, unsprung weight of the front suspension vs. sprung weight of the front of the car, friction in the system that inhibits transfer of the load, and probably more that I'm not thinking of.[*]...at which point the car hits the next bump, and the whole front may be a bit higher [I]or[/I] lower than it would have been w/o that transfer, in which case...[*]if it's lower, then of course it may bottom on that next bump; if it's higher then it may get pushed higher still, which means it will come down harder after that second bump.[/list]This is why suspension engineers usually look like :(
:lol:
And, of course, if this all happens when the car is loaded into a corner, and/or the car is sideways enough that the rear hits a bump the front didn't, or vice versa, it just gets that much more complex.
| dch | 08-05-2004 11:49 PM |
Yeah, what he said. It all depends. Yanking the bars or adding stiffer bars isn't a miracle cure for anything. It's a pretty painstaking process to get everything set up just right for a specific driver/vehicle/course. If you're good at it, I mean really good at it, it's a huge advantage over the rest of us who just sort of flounder around with what we've got and live with it.
By the way Jamie, aren't you supposed to be driving on the gravel part of the course instead of mowing the lawn? :D
Cheers,
-Doug
By the way Jamie, aren't you supposed to be driving on the gravel part of the course instead of mowing the lawn? :D
Cheers,
-Doug
| Chaste Automotive | 08-06-2004 12:34 AM |
Cowapult you are not right, not even close. Body Roll is nothing to be afraid of it is more drivers that are uncomfortable with it. Frankly most people run their car too stiff which is understeer inducing in itself. As a very wise old fin the master of Left Foot Braking himself Pentti Airikala told me you do not need a rear sway bar and in some situations they slow you down. Now that being said everyone will go and buy stiffer swaybars and poltec crappy endlinks.
| Mark V | 08-06-2004 03:46 PM |
OK - I have to ask, why do you consider the Poltec endlinks "crappy".
I'll admit I've never seen them in person, but surely it's a good idea to have adjustable endlinks, so as to be able to eliminate any swaybar preload?.
Or is it just the build quality you consider "crappy".
Thanks - Mark
I'll admit I've never seen them in person, but surely it's a good idea to have adjustable endlinks, so as to be able to eliminate any swaybar preload?.
Or is it just the build quality you consider "crappy".
Thanks - Mark
| quikSTi | 08-06-2004 04:42 PM |
Keep in mind that the purpose of sway bars is a band-aid to compensate for soft springs, because most people would never tolerate a daily driver with springs that are stiff enough to prevent excessive body roll while cornering. The price we pay by using sway bars is our suspension loses independence, more so as you go to stiffer sway bars, and less independence is a bad thing for traction, more so when bumps are random.
| travmn | 08-06-2004 05:15 PM |
[QUOTE=quikSTi]Keep in mind that the purpose of sway bars is a band-aid to compensate for soft springs.[/QUOTE]
Yes, and given some people's input in this thread, I don't think they actually have ever been in a car with a real rally suspension. That and they don't understand that big honkin' swaybars aren't better and usually will hinder performance to a degree on a road car.
Let's just say this... roll isn't a bad thing and most rally suspension's are WAY stiffer and don't exhibit the traits one may be more familiar with given a garden variety stock wrx suspension.
In the end, it really all comes to a balance that depends on the rest of the suspension setup, the terrain experienced, and most importantly, the driver. And even the driver can be mistaken. I used to have a wagon I would rally-x and took to an auto-x or two and the most foolish thing I ever did was stick a thicker swaybar on because I didn't like the roll... car handled WAY better on the stock swaybars.
Yes, and given some people's input in this thread, I don't think they actually have ever been in a car with a real rally suspension. That and they don't understand that big honkin' swaybars aren't better and usually will hinder performance to a degree on a road car.
Let's just say this... roll isn't a bad thing and most rally suspension's are WAY stiffer and don't exhibit the traits one may be more familiar with given a garden variety stock wrx suspension.
In the end, it really all comes to a balance that depends on the rest of the suspension setup, the terrain experienced, and most importantly, the driver. And even the driver can be mistaken. I used to have a wagon I would rally-x and took to an auto-x or two and the most foolish thing I ever did was stick a thicker swaybar on because I didn't like the roll... car handled WAY better on the stock swaybars.
| zzyzx | 08-07-2004 03:17 AM |
Man, this has become the misinformation thread.
You guys theorizing about swaybars need to go out to the track and get some first hand experience. This isn't a mental exercise. This is about doing your homework - on the track.
I autox and road race and I don't use swaybars. Period. They are nothing more than a cheap tuning device with the downside of connecting what happens on one side of the car to the other. Swaybars provide no advantage over springs/shocks other than being cheap and easy to swap.
Think live axle if this helps understand the problem. Trust me, when I'm behind an A-Sedan car on the road course and their rear end is skipping around each bump, I'm all to happy to leave them behind me. Makes me nervous.
It's true that this is a driver "comfort" issue as well. I know a few people who just plain aren't used to that much grip at the front end of their cars. ;)
If you know what I run, you may conclude that I don't need swaybars because I run insane spring rates. Well, not true. I haven't run swaybars since Solo II Nationals in 2002 where I took 5th (out of 50) in STS. My spring rates at that point were a pitiful 225/180.
I had swaybars on the car at Nats that year until I heard the speach from Carroll Smith. His words: "Swaybars reduce grip where you need it most..." That was the end of swaybars for me and I've never had or wanted to look back. That, and there's one other suggestion I'll provide: balance your car by increasing grip at the end that needs it. For understeer, don't put a "big bar" out back, get a smaller one for the front, or change to softer springs in the front. So many people go about this backwards and never focus on the ultimate goal: maximizing grip.
As to rally, running w/o bars is more advantageous due to the fact that the conditions are rough. The rougher, the more benefit you'll see in not using bars.
As to running no bars on a stock car, that's something to think hard about. There is a point at which body roll and camber loss will overcome the benefit of removing the bar for more grip. Witness the STi which benefits from a larger front bar in autox events. This is only on camber-challenged setups, however and not necessarily related to the absolute spring rates involved. If you took that same car on stock struts and put camber plates in the front, it'd work just fine.
Oh, and while I'm at it - one other myth. People always argue - in theory - that removing bars would necessarily mean you'd have to run stiffer springs and hence the overall ride would be more "harsh". Absolute hogwash. Do it and see for yourself.
Phew, I need to get up in 3 hours and go run out on Forbes Field concrete - must sleep. :)
- Steve Sulatycki
[URL="zzyzxmotorsports.com"]Zzyzx Motorsports[/URL]
You guys theorizing about swaybars need to go out to the track and get some first hand experience. This isn't a mental exercise. This is about doing your homework - on the track.
I autox and road race and I don't use swaybars. Period. They are nothing more than a cheap tuning device with the downside of connecting what happens on one side of the car to the other. Swaybars provide no advantage over springs/shocks other than being cheap and easy to swap.
Think live axle if this helps understand the problem. Trust me, when I'm behind an A-Sedan car on the road course and their rear end is skipping around each bump, I'm all to happy to leave them behind me. Makes me nervous.
It's true that this is a driver "comfort" issue as well. I know a few people who just plain aren't used to that much grip at the front end of their cars. ;)
If you know what I run, you may conclude that I don't need swaybars because I run insane spring rates. Well, not true. I haven't run swaybars since Solo II Nationals in 2002 where I took 5th (out of 50) in STS. My spring rates at that point were a pitiful 225/180.
I had swaybars on the car at Nats that year until I heard the speach from Carroll Smith. His words: "Swaybars reduce grip where you need it most..." That was the end of swaybars for me and I've never had or wanted to look back. That, and there's one other suggestion I'll provide: balance your car by increasing grip at the end that needs it. For understeer, don't put a "big bar" out back, get a smaller one for the front, or change to softer springs in the front. So many people go about this backwards and never focus on the ultimate goal: maximizing grip.
As to rally, running w/o bars is more advantageous due to the fact that the conditions are rough. The rougher, the more benefit you'll see in not using bars.
As to running no bars on a stock car, that's something to think hard about. There is a point at which body roll and camber loss will overcome the benefit of removing the bar for more grip. Witness the STi which benefits from a larger front bar in autox events. This is only on camber-challenged setups, however and not necessarily related to the absolute spring rates involved. If you took that same car on stock struts and put camber plates in the front, it'd work just fine.
Oh, and while I'm at it - one other myth. People always argue - in theory - that removing bars would necessarily mean you'd have to run stiffer springs and hence the overall ride would be more "harsh". Absolute hogwash. Do it and see for yourself.
Phew, I need to get up in 3 hours and go run out on Forbes Field concrete - must sleep. :)
- Steve Sulatycki
[URL="zzyzxmotorsports.com"]Zzyzx Motorsports[/URL]
| Chaste Automotive | 08-07-2004 04:03 AM |
Steve you are correct, sway bars are a typical band aid handling trick that everyone runs out and gets because they are cheap and easy to install. That being said I would venture to say that almost everyone in this thread couldn't tell me how to properly set up a car to save their life. Even at the professional level drivers have difficulty finding good set ups, and last I checked nobody on NASIOC was driving in F1, WRC, NASCAR, etc. Now I know there are few of you out there that will swear that you can set up a car but if a real professional came in and set up your car you would notice a tremendous difference.
Poltec endlinks are of poor design, shoddy construction, and generally a total waste of money. THe bushings fail, the overall design I understand but they should have chosen to go with a complete spherical bearing. Next problem is that for most of you cannot feel the difference. On the 2004 STis (this is most of the ones I see) you could fix the end links being bent for free and save yourself the 100 dollars. Now they are almost as much of a waste as most aftermarket sway bars I see but hey nobody listens to me so I could care less.
Poltec endlinks are of poor design, shoddy construction, and generally a total waste of money. THe bushings fail, the overall design I understand but they should have chosen to go with a complete spherical bearing. Next problem is that for most of you cannot feel the difference. On the 2004 STis (this is most of the ones I see) you could fix the end links being bent for free and save yourself the 100 dollars. Now they are almost as much of a waste as most aftermarket sway bars I see but hey nobody listens to me so I could care less.
| dch | 08-07-2004 11:49 AM |
I couldn't set up my rally car to save my life. It came with those bars from Prodrive, that's what SOA was running at least on their pre-WRC cars in 2002, and I set up according to their spec sheets for various events. Lovell ran a 22mm rear bar. I just assume the Prodrive engineers knew what they were doing when they set up these cars. Maybe some day I'll yank both bars and see what happens, but my car handles phenomenally well as it is and is capable of going much faster than I am.
The one thing I'm pretty sure of, is that if your car was designed with sway bars and you take them off without changing anything else at all, the odds of you improving anything are pretty slim. Likewise if your car was designed without them and you just slap some big ol' bars on. Suspension tuning is a very complicated process and "bars" or "no bars" is just one of the many variables to be considered.
-Doug "yes, that was my ass talking" Havir
:D
The one thing I'm pretty sure of, is that if your car was designed with sway bars and you take them off without changing anything else at all, the odds of you improving anything are pretty slim. Likewise if your car was designed without them and you just slap some big ol' bars on. Suspension tuning is a very complicated process and "bars" or "no bars" is just one of the many variables to be considered.
-Doug "yes, that was my ass talking" Havir
:D
| Chaste Automotive | 08-07-2004 03:21 PM |
Doug I thought you might be in So Cal this weekend, heading to the UK as I write this I will call you when I get back!
| GravelRash | 08-07-2004 06:53 PM |
A few more observations about bars...(and related effects)
Re body roll: true, body roll - by itself - isn't necessarily detrimental to handling. But consider...
First off, suspension movement - and geometry - is inextricably tied to the attitude of the body of the car. So body roll is never a "by itself" phenomena. And on a strut suspended car, where the hub is rigidly fixed to the strut - which effectively takes the place of an upper control arm - there are far fewer articulation possibilities than with a double contol arm, or multi-link, suspension.
Ideally the suspension would:[list][*]keep the wheels perfectly vertical - no camber change - as the car rides straight over bumps of any size, i.e. fully extending and compressing the suspension; significant camber changes can make the steering very squirrely over bumps[*]in a turn set the outside wheel at an appropriate negative camber angle so that the tire contact patch is maximized - no matter what the body roll angle is[*]...and maintain the inside wheel attitude to again maximize contact patch, which in this case will be either neutral, or slight positive camber (the inside tire is more lightly loaded so the contact area of the tire isn't distorted as much as the outside tire's)[/list]All of this would minimize contact patch disturbance, and maximize traction no matter what the attitude or direction of the car.
Well, so far no one's quite pulled all that off ;) First to go is the inside wheel geometry in a turn, since it's contributing the least traction and cornering force. This can easily be seen on virtually any production based race car in a corner, where the inside tire is often contacting on just the inside edge of the tread.
There are many discussions of ideal camber set up, for various purposes, on this board. And lots of camber plates/bolts for sale :) And that's largely due to the limited articulation available with our strut suspensions - and the effects of body roll on wheel/tire attitude.
(And while we're at it, an aside on camber plates vs. camber bolts: while either can be used (within their mechanical limits) to set the same static camber, their effects through full suspension travel will [I]not[/I] be quite the same; the difference will probably be subtle, but could potentially be used for fine tuning on a race car.)
Another effect of body roll is the momentum effect of moving all the sprung weight of the car through the roll angles, especially in tight transitions, e.g. esses or slaloms. As the car rolls from one extreme to the other a) the side getting unloaded adds to the roll rate as the springs unload and push that side up, and b) the angular momentum of 3000lbs of mass has to be absorbed and stopped by the suspension getting loaded - on top of it's "normal" job of resisting the roll from a static attitude, i.e. just rolling into a corner from a straight. And that angular momentum is at maximum as the car transitions through straight ahead - at the point where it's at minimum if you're just starting a turn from straight ahead.
Minimize body roll in this context, and you minimize the difference between straight > turn and turn > turn scenarios.
So, can you get the same effect on roll from springs vs. anti-roll bars (hereinafter referred to as "bars" :p )? Well, not quite. Suppose you stiffen the springs (with appropriate front/rear balance of course) to limit body roll to 5deg. Ok, so that's a bunch stiffer - on both sides of the car. So, you've not only had to stiffen the outside springs to counteract pure weight transfer, you've had to add more spring rate to the outside to counteract the stiffer springs' effect on the other side of the car, where they want to lift that side more as it gets unloaded by the turn - effectively [I]increasing[/I] body roll. Oh, oops, now we've got to add the same amount to the other side to balance the car...and we're chasing our tail (This is one place where active, or semi-active suspensions come in...) So to win this game you've had to stiffen the springs more than just weight transfer would necessitate.
So now we've got much stiffer springs on both sides, and we're rolling into a max G turn. The outside spring compresses, but not much, and the inside spring extends...and the net effect may be that the c/g of the car actually rises (lots of complexities come into play here, e.g. roll centers, etc.). What it almost certainly doesn't do is lower the c/g.
Ok, so instead of stiffening the springs we add bars of sufficient stiffness to provide the same 5deg roll limit. So now we go into the corner, weight transfers to the outside, compressing the suspension... Only this time it's the bar resisting the roll: as the outside suspension compresses - lowering that side of the car - the bar twists, against the spring tension on the inside suspension, which tends to resist extension of the spring on that side. Net effect: the c/g stays lower than than it did in the stiff spring scenario, and the lower the c/g the less weight transfer takes place (all other things being equal)...which is a good thing.
At this point I should say far be it from me to contradict Carroll Smith :) I'd love to hear him do a full discussion of all these issues! So far I've just been addressing pure body roll issues and effects, not overall car balance and practical results. There are some other bar discussions in these forums that do note one [B]very[/B] pertinent effect of the usual quick-fix bar solution: [I]adding a stiffer bar to the rear actually decreases total traction[/I]. The effect is to lessen rear traction, allowing the existing front traction to have a higher proportion of the total and giving it more authority to change the direction of the car.
So we can get the car turned in faster and more smoothly, and with less tire scrub at the front (smaller slip angle), and if we haven't overdone it on the rear bar :lol: more easily modulate the total traction through the corner. But we've actually [I]potentially [/I] reduced the total traction available in steady state cornering; "potentially" because if it was tuned for terminal understeer to begin with the fronts were probably being way overloaded and limiting total traction anyway.
Lastly, for this post anyway :cool: , is the practical consideration of tuning via springs vs. bars:[list][*]to tune with springs you need...lots o' springs! And springs ain't cheap... We're talking actually tuning the car here, not just adding any vendor's package that is their and/or your best guess of appropriate spring rates and lengths for your specific application, including all your other mods (struts, weight, wheels/tires, alignment, etc.).[*]changing springs isn't trivial, and neither is getting the alignment set up properly again after each change.[*]changing bars, at least in the rear of our cars, is trivial, and a single bar usually significantly cheaper than springs. Changing front bars, while not at trivial, is still much easier than springs - and doesn't effect the alignment.[*]changing the setting of adjustable bars, for fine tuning, is even more trivial, and can be done almost anywhere, between test runs.[/list]So it's no wonder that more people tune with bars than springs in the real world...and also no wonder that real race teams do a [I]lot[/I] of spring tuning.
Re body roll: true, body roll - by itself - isn't necessarily detrimental to handling. But consider...
First off, suspension movement - and geometry - is inextricably tied to the attitude of the body of the car. So body roll is never a "by itself" phenomena. And on a strut suspended car, where the hub is rigidly fixed to the strut - which effectively takes the place of an upper control arm - there are far fewer articulation possibilities than with a double contol arm, or multi-link, suspension.
Ideally the suspension would:[list][*]keep the wheels perfectly vertical - no camber change - as the car rides straight over bumps of any size, i.e. fully extending and compressing the suspension; significant camber changes can make the steering very squirrely over bumps[*]in a turn set the outside wheel at an appropriate negative camber angle so that the tire contact patch is maximized - no matter what the body roll angle is[*]...and maintain the inside wheel attitude to again maximize contact patch, which in this case will be either neutral, or slight positive camber (the inside tire is more lightly loaded so the contact area of the tire isn't distorted as much as the outside tire's)[/list]All of this would minimize contact patch disturbance, and maximize traction no matter what the attitude or direction of the car.
Well, so far no one's quite pulled all that off ;) First to go is the inside wheel geometry in a turn, since it's contributing the least traction and cornering force. This can easily be seen on virtually any production based race car in a corner, where the inside tire is often contacting on just the inside edge of the tread.
There are many discussions of ideal camber set up, for various purposes, on this board. And lots of camber plates/bolts for sale :) And that's largely due to the limited articulation available with our strut suspensions - and the effects of body roll on wheel/tire attitude.
(And while we're at it, an aside on camber plates vs. camber bolts: while either can be used (within their mechanical limits) to set the same static camber, their effects through full suspension travel will [I]not[/I] be quite the same; the difference will probably be subtle, but could potentially be used for fine tuning on a race car.)
Another effect of body roll is the momentum effect of moving all the sprung weight of the car through the roll angles, especially in tight transitions, e.g. esses or slaloms. As the car rolls from one extreme to the other a) the side getting unloaded adds to the roll rate as the springs unload and push that side up, and b) the angular momentum of 3000lbs of mass has to be absorbed and stopped by the suspension getting loaded - on top of it's "normal" job of resisting the roll from a static attitude, i.e. just rolling into a corner from a straight. And that angular momentum is at maximum as the car transitions through straight ahead - at the point where it's at minimum if you're just starting a turn from straight ahead.
Minimize body roll in this context, and you minimize the difference between straight > turn and turn > turn scenarios.
So, can you get the same effect on roll from springs vs. anti-roll bars (hereinafter referred to as "bars" :p )? Well, not quite. Suppose you stiffen the springs (with appropriate front/rear balance of course) to limit body roll to 5deg. Ok, so that's a bunch stiffer - on both sides of the car. So, you've not only had to stiffen the outside springs to counteract pure weight transfer, you've had to add more spring rate to the outside to counteract the stiffer springs' effect on the other side of the car, where they want to lift that side more as it gets unloaded by the turn - effectively [I]increasing[/I] body roll. Oh, oops, now we've got to add the same amount to the other side to balance the car...and we're chasing our tail (This is one place where active, or semi-active suspensions come in...) So to win this game you've had to stiffen the springs more than just weight transfer would necessitate.
So now we've got much stiffer springs on both sides, and we're rolling into a max G turn. The outside spring compresses, but not much, and the inside spring extends...and the net effect may be that the c/g of the car actually rises (lots of complexities come into play here, e.g. roll centers, etc.). What it almost certainly doesn't do is lower the c/g.
Ok, so instead of stiffening the springs we add bars of sufficient stiffness to provide the same 5deg roll limit. So now we go into the corner, weight transfers to the outside, compressing the suspension... Only this time it's the bar resisting the roll: as the outside suspension compresses - lowering that side of the car - the bar twists, against the spring tension on the inside suspension, which tends to resist extension of the spring on that side. Net effect: the c/g stays lower than than it did in the stiff spring scenario, and the lower the c/g the less weight transfer takes place (all other things being equal)...which is a good thing.
At this point I should say far be it from me to contradict Carroll Smith :) I'd love to hear him do a full discussion of all these issues! So far I've just been addressing pure body roll issues and effects, not overall car balance and practical results. There are some other bar discussions in these forums that do note one [B]very[/B] pertinent effect of the usual quick-fix bar solution: [I]adding a stiffer bar to the rear actually decreases total traction[/I]. The effect is to lessen rear traction, allowing the existing front traction to have a higher proportion of the total and giving it more authority to change the direction of the car.
So we can get the car turned in faster and more smoothly, and with less tire scrub at the front (smaller slip angle), and if we haven't overdone it on the rear bar :lol: more easily modulate the total traction through the corner. But we've actually [I]potentially [/I] reduced the total traction available in steady state cornering; "potentially" because if it was tuned for terminal understeer to begin with the fronts were probably being way overloaded and limiting total traction anyway.
Lastly, for this post anyway :cool: , is the practical consideration of tuning via springs vs. bars:[list][*]to tune with springs you need...lots o' springs! And springs ain't cheap... We're talking actually tuning the car here, not just adding any vendor's package that is their and/or your best guess of appropriate spring rates and lengths for your specific application, including all your other mods (struts, weight, wheels/tires, alignment, etc.).[*]changing springs isn't trivial, and neither is getting the alignment set up properly again after each change.[*]changing bars, at least in the rear of our cars, is trivial, and a single bar usually significantly cheaper than springs. Changing front bars, while not at trivial, is still much easier than springs - and doesn't effect the alignment.[*]changing the setting of adjustable bars, for fine tuning, is even more trivial, and can be done almost anywhere, between test runs.[/list]So it's no wonder that more people tune with bars than springs in the real world...and also no wonder that real race teams do a [I]lot[/I] of spring tuning.
| PolTec Inc | 08-09-2004 11:13 AM |
[QUOTE=Chaste Automotive]Poltec endlinks are of poor design, shoddy construction, and generally a total waste of money. THe bushings fail, the overall design I understand but they should have chosen to go with a complete spherical bearing. Next problem is that for most of you cannot feel the difference. On the 2004 STis (this is most of the ones I see) you could fix the end links being bent for free and save yourself the 100 dollars. Now they are almost as much of a waste as most aftermarket sway bars I see but hey nobody listens to me so I could care less.[/QUOTE]
I have to admit that I am a little disturbed by the comments above and I would like to address them one by one.
1. You are certainly entitled to your opinion about our rear end link for the STi (since I have not received your response to the email that I sent to you I am assuming that you are referring to only those end links and not the others). Our design is a best compromise between the cost and benefits and if we were to go the rout that you suggested we would end up with end links that cost 50% more. I can only imagine your comments about wasting $150 for the end links.
2. Regarding the failed bushings, we did have some customers with STi end links that experienced those problems and we resolved the situation to the satisfaction of both sides.
3. We never claimed that our STi end links give you a better response/performance (unlike the WRX/RS end links for example). They do, however, resist bending much better that the stock end links.
4. You can certainly straighten the STi end links for free, but will this address that cause of the failure or will the person have to stop at your shop again to fix the symptoms without addressing the cause. Our STi end links are longer to prevent the flipping of the sway bar and thus they address the source of the failure. And our sway bar collars address the issue of moving sway bar that is another cause of the failures of the end links, both stock and others.
5. Finally, they give you option to eliminate preload of the sway bar (yea, I know what you are going to say abut that) or add preload if needed. All this for the price that is still much lower than competitors' offering.
Regards
Dariusz
PolTec Inc
708/308-0947
I have to admit that I am a little disturbed by the comments above and I would like to address them one by one.
1. You are certainly entitled to your opinion about our rear end link for the STi (since I have not received your response to the email that I sent to you I am assuming that you are referring to only those end links and not the others). Our design is a best compromise between the cost and benefits and if we were to go the rout that you suggested we would end up with end links that cost 50% more. I can only imagine your comments about wasting $150 for the end links.
2. Regarding the failed bushings, we did have some customers with STi end links that experienced those problems and we resolved the situation to the satisfaction of both sides.
3. We never claimed that our STi end links give you a better response/performance (unlike the WRX/RS end links for example). They do, however, resist bending much better that the stock end links.
4. You can certainly straighten the STi end links for free, but will this address that cause of the failure or will the person have to stop at your shop again to fix the symptoms without addressing the cause. Our STi end links are longer to prevent the flipping of the sway bar and thus they address the source of the failure. And our sway bar collars address the issue of moving sway bar that is another cause of the failures of the end links, both stock and others.
5. Finally, they give you option to eliminate preload of the sway bar (yea, I know what you are going to say abut that) or add preload if needed. All this for the price that is still much lower than competitors' offering.
Regards
Dariusz
PolTec Inc
708/308-0947
| BHawk | 08-11-2004 10:01 PM |
The Noble M12 from England uses NO sway bars. possbily the most competent out of the box track day car. It's handling is considered by the automotive press to be the best out there. What's more it's easy to drive and doesn't have the fancy computer nannies like most sports cars nowadays. The major sport car manufacturers all have bought Nobles to test with. I don't fully understand it, but I do know with the right suspension setup and tuning a track going / road going car can be a monster even without sway bars.
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