Chủ Nhật, 22 tháng 1, 2017

help me pick a spring rate part 1

AlpineFD 07-14-2004 01:28 PM

help me pick a spring rate
Hi guys,

Time for me to get a coilover, I've decided to get a set from ground control, they offer shortend koni yellows with supposely custom valvings. I need to decide on a spring rate. My car is primarily used as a street car, 12 autox events and 4 HPDE events per year. The guy at GC recommneded 300lb front/rear, 6" length spring front, 7" rear.

What spring rate would you guys recommend? and spring length. and has anyone tried this setup before?

Thanks,

Randy
trhoppe 07-14-2004 02:10 PM

[quote]300lb front/rear, 6" length spring front, 7" rear.[/quote]

Good call for a daily driven car. I'd go with 300F/350R though to get a little more rotation. Go with a softer spring and a slightly bigger bar. A 24mm front, 26mm rear combo with 300/350lb springs should be nice.

If the car becomes more autox, less daily driven, a 450/550 combo is hard to beat. Most people run 22mm front, 24mm rear bars with that. Although I've been thinking about a smaller front bar and more front spring. 550 and go down 2mm on the bar.

-Tom
Midnight_Gold 07-14-2004 02:31 PM

[QUOTE][i]Originally posted by trhoppe[/i]
[B]
Although I've been thinking about a smaller front bar and more front spring. 550 and go down 2mm on the bar.

-Tom [/B][/QUOTE]

Uhh... the answer's no. That car is barely comfortable to drive around in as it is..

:lol:

- Miranda (teh boss of you:devil: )
Storm 07-14-2004 02:46 PM

[QUOTE][i]Originally posted by Midnight_Gold [/i]
[B]Uhh... the answer's no. That car is barely comfortable to drive around in as it is..

:lol:

- Miranda (teh boss of you:devil: ) [/B][/QUOTE] ...OWNED....:lol:

Jay Storm
KC 07-14-2004 02:51 PM

Alpine: [url]http://forums.nasioc.com/forums/showthread.php?s=&threadid=595614[/url]

Awesome on the street and autox/track.
Fred 07-14-2004 03:09 PM

I just installed the ground controls on my car with 8" 350 lb springs front & rear. 19mm front, 20mm rear bars. Rotates rather nicely, and feels really well-controlled. And with "normal" all-season tires on the car it's really not uncomfortable! First autox on this setup this weekend on concrete (running in STS) - I'll let you know how it goes if you're interested.
AlpineFD 07-14-2004 04:10 PM

I'm very curious about the rear bias spring setup. A fast local GC chassis driver uses 500lb front/600lb rear, although his power is stock, he is consistently faster than the local STi and SM WRX drivers :eek:

How does a rear biased setup handle on a road racing track? I'm worried about too much oversteer at high speed corners.
trhoppe 07-14-2004 04:28 PM

Shocks are what help the car be loose in entry and transitions while the springs handle steady state. We run the rear biased spring so the car is loose in steady state cornering, so the the car with a rear biased spring setup would be loose on track.

Of course, the faster you go the more the cars oversteer/understeer tendencies show. My car is loose at 50mph, it would be SCARY loose at 80 doing the same manuever.

If it was me and my daily driver/autox/track car, I would set it up with rear biased with a stiff bar for autox and turn the bar full soft when you go to the track. The full soft rear bar should make the car push a tad on track while having it stiff should make the car great for autox. You don't need every extra 0.1 on track, so go for safety.

-Tom
AlpineFD 07-14-2004 04:29 PM

[QUOTE][i]Originally posted by Fred [/i]
[B]I just installed the ground controls on my car with 8" 350 lb springs front & rear. 19mm front, 20mm rear bars. Rotates rather nicely, and feels really well-controlled. And with "normal" all-season tires on the car it's really not uncomfortable! First autox on this setup this weekend on concrete (running in STS) - I'll let you know how it goes if you're interested. [/B][/QUOTE]

Hi Fred,

Did you get a shortened koni yellow? or standard koni yellow. Is the 8" spring a good choice?

Randy
Fred 07-14-2004 05:00 PM

Off-the-shelf yellow inserts. Getting them rebuilt at some point (since they're just about maxed out with these spring rates), may have the rear shortened an inch if that's an option. The 8" springs only allow lowering a couple of inches or so, which is WAY more than I wanted. I have the front lowered about 3/8 inch & the rear lowered about an inch. Not sure this is optimal, but I was going for having the control arms & lateral links barely above level.
zzyzx 07-14-2004 05:15 PM

I've road raced on both 400/500 and 500/600 and oversteer is not an issue. You can really dial the balance in with the shocks, also.

The GC setup is similar to what I run now, but I've completely redesigned the strut bodies, spring perches, etc., to optimize things. The Konis have been revalved to handle some rather stiff springs, also. The stiff springs were necessary to avoid clearance issues with the 275 width Hoosiers:

[IMG]http://www.peatpics.com/web_gallery/sub_chlng/heat_two/images/DSC_3225.jpg[/IMG]

I'm not a vendor here on NASIOC, so I'd better not comment on where you can buy a custom Subaru specific setup. ;)

- Steve
[URL=http://zzyzxmotorsports.com]Zzyzx Motorsports[/URL]
DrBiggly 07-15-2004 01:22 AM

Do the shortened Konis come with a more lengthy pricetag?
AlpineFD 07-15-2004 02:06 AM

I was quoted $1499 for a set of 4 koni shortened revavled, with coilover kit, with adjustable upper mount. He also said they come ready to be bolted in. The person I spoke to is Josh.
AlpineFD 07-15-2004 03:13 AM

thanks to all for the great advice, I will soon be joining the no body roll club :lol:
SpeedAbsolute 07-15-2004 07:16 PM

Just wanted to add a bit here - 350# all the way around is a good everyday and autocross setup in my opinion...probably not the most ideal for rotation at an autocross, but as Tom mentioned, big bars help.

I am using 7" springs all the way around and my driver isn't as lowered as many others...about 14.5" in the front to the center of the wheel and 14.25" in the back. My struts aren't shortened so I really wanted the extra bump travel.

Matt
lukerussell 07-16-2004 10:48 AM

i use 500/500 on my sti for track days. JIC's w/ custom race damping.

i don't suggest them for everyday use, unless you don't mind jolts to the spinal cord.

on the track it still pushes w/ r compounds (245 victoracers), but is fixed w/ a big bar in the back. it's well balanced w/ the stock bridgestones. when i say balanced i mean it pushes under acceleration and oversteers when you lift in a corner, which is how i like it.

zzyzx - i didn't know you were getting into the coilover game. i was looking for something like what you're offering but wasn't smart enough to make it work. so i went the easy route. maybe next time.

luke
AustinTX 07-16-2004 11:21 PM

I just got a set of RA's, and I put the 6K on the front and the 8K on the rear. Is there any cause for concern here? It seems to be rather willing to lift the inside rear wheel now :)
trojan9x 11-15-2004 01:32 PM

What would you recommend for spring lengths? I've noticed most coilovers come with 8" springs. Since i sold my JIC's I might get GC's to put on my KYB's and would wonder which length springs I should go after. 8" seems to be the norm, but what would a 7" or 9" spring have to benefit?
MNbiker 11-15-2004 03:15 PM

[QUOTE=trojan9x]What would you recommend for spring lengths? I've noticed most coilovers come with 8" springs. Since i sold my JIC's I might get GC's to put on my KYB's and would wonder which length springs I should go after. 8" seems to be the norm, but what would a 7" or 9" spring have to benefit?[/QUOTE]

With a 9" spring, you won't be able to go much below stock ride height with most setups.

With a 7" spring, you may not be able to get quite up to the stock ride height, but you will be able to lower 2"+ with most setups. FWIW I wouldn't recommend lowering an Impreza with stock control arms more than 1.5" - 2".

-Steve
trojan9x 11-16-2004 01:24 PM

I'm not looking for a slammed look (too low is no good anyway). so 8" should get it pretty close to where I was with the JIC's then I would assume. I don't want to go any lower than that.
Corey 11-16-2004 02:11 PM

Tom,

FWIW, I used 8" springs when I had my GC/KYB setup.

Corey #89 STS
thrdeye 11-22-2004 02:26 PM

How stiff can you go with springs on normal Konis w/o problems?
trhoppe 11-22-2004 02:28 PM

[QUOTE=thrdeye]How stiff can you go with springs on normal Konis w/o problems?[/QUOTE]
~350lb would be as high as I would go, even though I've been told that 400lb is what they can handle.

-Tom
thrdeye 11-22-2004 02:35 PM

Thanks Tom.

[QUOTE=SpeedAbsolute]Just wanted to add a bit here - 350# all the way around is a good everyday and autocross setup in my opinion...probably not the most ideal for rotation at an autocross, but as Tom mentioned, big bars help.

I am using 7" springs all the way around and my driver isn't as lowered as many others...about 14.5" in the front to the center of the wheel and 14.25" in the back. My struts aren't shortened so I really wanted the extra bump travel.

Matt[/QUOTE]

Matt, can you post a pic of your car? I want to see how low that is. I am just on prodrive springs now, but I wouldn't want to go much lower.
SpeedAbsolute 11-22-2004 05:30 PM

[QUOTE=thrdeye]Matt, can you post a pic of your car? I want to see how low that is. I am just on prodrive springs now, but I wouldn't want to go much lower.[/QUOTE]I can't find one on my computer so I will try to take one tonight. I personally think it is a good ride height for daily driving because I don't scrape the front bumper anymore like I used to. I believe it is about 1.25" lower than stock but don't quote me on this...probably really similar to your prodrive springs.

Matt
thrdeye 11-22-2004 06:21 PM

[QUOTE=SpeedAbsolute]I can't find one on my computer so I will try to take one tonight. I personally think it is a good ride height for daily driving because I don't scrape the front bumper anymore like I used to. I believe it is about 1.25" lower than stock but don't quote me on this...probably really similar to your prodrive springs.

Matt[/QUOTE]

Great, I'd really appreicate it I'm trying to get all my ducks in a row to get a better suspension w/o selling my kidneys.

Right now, I'm pretty set on some koni inserts, and I'm trying to go as stiff as I can w/o revalving. I figured i'd just get some eibachs from ground control, Then maybe add some camber plates, and be done with it.
SpeedAbsolute 11-22-2004 11:44 PM

Sorry for the crummy pictures but I hope you get the idea. I will try to snap some pictures during the day when I have a chance.

[IMG]http://www.speedabsolute.com/images/NASIOC/sideview.jpg[/IMG] [IMG]http://www.speedabsolute.com/images/NASIOC/frontview.jpg[/IMG] [IMG]http://www.speedabsolute.com/images/NASIOC/backview.jpg[/IMG]

In regards to the revalving issue, I would call Koni and see what they say about what their inserts can reliably handle. As a motorsports company, I'm sure they could give you that info.

Matt
thrdeye 11-23-2004 12:37 AM

[QUOTE=SpeedAbsolute]Sorry for the crummy pictures but I hope you get the idea. I will try to snap some pictures during the day when I have a chance.

[IMG]http://www.speedabsolute.com/images/NASIOC/sideview.jpg[/IMG] [IMG]http://www.speedabsolute.com/images/NASIOC/frontview.jpg[/IMG] [IMG]http://www.speedabsolute.com/images/NASIOC/backview.jpg[/IMG]

In regards to the revalving issue, I would call Koni and see what they say about what their inserts can reliably handle. As a motorsports company, I'm sure they could give you that info.

Matt[/QUOTE]

Thanks for the pics. Looks a lot like my prodrives. That's about as low as I'd like to go.

After doing some internet searching, it seems like the max rate is gonna be about 500 lb./in springs. Some say they can hanlde 600, some say 400. I guess that this is based on how the car feels to each person, not hardcore data. I figure that I could play middle of the road and revalve later on if need be, when the funds go back up.

With the ground control setup.....

You get all 4 springs and perches for the $399, right? i couldn't tell from their site...it gave you the option to buy like 27 of the damn things. If so, I might as well do it that way.
srf 11-23-2004 12:45 AM

Yeah they come with 4 sets of perches, springs, sleeves, etc.
SpeedAbsolute 11-23-2004 12:48 AM

yes you get all 4 springs and upper/lower perches. You probably want to do more research on spring length as well as decide on which camber plates you want to go with. It would suck to have to buy things twice if you don't need to.

Matt
srf 11-23-2004 01:31 AM

I haven't done it, but I hear GC is quite liberal with spring swaps (one can search, it's been discussed here a few times).
thrdeye 11-23-2004 07:09 AM

Thanks for the help guys. I'll probably talk to some locals and see what they recommend for spring length and to figure out how low to go. Like I said, I don't want to go much lower at all.

I figure with the 500 lb rate, 7 in would be about right, eh? I have always had my eye on the cusco plates.
D_REX 11-23-2004 09:02 AM

As Per Koni NA

These calculations are based on an assumed car weight of 3200 lb and front to rear bias of 60/40.

The front 8610-1351 Sport should be able to handle a spring rate of 700-800 lb/in on the max rebound setting.



The rear 8610-1408 Sport should be able to handle a spring rate of 500-600 lb/in on the max rebound setting.

This insert can be revalved to increase bump and rebound forces to handle a spring rate up to 900-1000 lb/in.
thrdeye 11-23-2004 09:29 AM

Wow, thanks for the help. That's good info.
SpeedAbsolute 11-23-2004 11:48 AM

[QUOTE=srf]I haven't done it, but I hear GC is quite liberal with spring swaps (one can search, it's been discussed here a few times).[/QUOTE]
I ordered my GC's straight from the manufacturer and asked them about the spring trade thing as I had heard the same thing - they said it was a rumor. The only way they would swap springs is if the ones you returned were unused.

Matt
WillysPU 11-24-2004 02:32 AM

FWIW, I am running noltec rear plates and GC front top mounts. Originally they GC sent 7" springs and I felt they lowered the car too much. Both the gc top mounts and the noltecs replace your oem top hats so you loose about 1 1/2" of height at each corner, I felt I needed the longer springs to allow enough travel and retain enough threads on the gc threaded collar. GC told me as long as the springs look new they will swap them for the price of shipping, so I swapped out the 7" and went with 8" springs, front 340#/rear 300#. My fsb is 22mm and my rear is 24mm. NVH is a bit loud but rides around town ok. Great on the track.

Gc top mount vs oem tophat:

[IMG]http://img.photobucket.com/albums/v132/WillysPu/KYB%20AGX%20-%20GC/DSC00456.jpg[/IMG]
Here is a pic of my sedan:

[IMG]http://img.photobucket.com/albums/v132/WillysPu/Thunderhill%20Apri%201%202004/DSC00485.jpg[/IMG]
thrdeye 11-24-2004 08:57 AM

That pic above is with 8 in or 7 in?

Since I am running stiffer springs, I would think that I could go a little shorter (7in)
WillysPU 11-24-2004 09:54 AM

The pic is with 8" springs sitting on oem shocks with koni inserts. They leave plenty of room to lower or raise the car. My ride hieght is 14.5" measured from the hub to the bottom of the fender lip or 25 3/4" measured from the ground to the bottom of the fender lip. imho. If you go much lower without much harder springs you will loose too much suspension travel and bottom out on the streets. As it is I have about 2" of travel before I hit my 1/2" thick (cut up oem) bump stop.
lo-buck 11-24-2004 11:21 AM

10kf 10-12kr
worked good on the sm wrx i drove on 245 kumho victoracers
UkNuck 11-24-2004 12:05 PM

Been lurking with interest...

I have a wagon w/ SPT wagon kit (= JDM v7 STi struts w/ approx 215/195 springs - no lowering). I find that quite comfortable for a daily driver, but got into autox and looking to stiffen/lower a bit for next year. I'm thinking:

o Next year: GC's on the v7 struts; 22mm (F) and 20-22-24mm (R) antiroll bars

o Later year(s): move GC's to Koni inserts in the old WRX struts (keeping the whole SPT kit including strut tops as a 'hot swap' setup for winter). My Q's at the moment:

(a) Is it actually feasible to use the same GC spring / perch for the stock WRX struts and the STi struts (with the strut bodies having different diameters?

(b) What would be a good rate - not too stiff for the v7 - not too soft for the 'standard valved' Koni's? Could I get away with 300/300 on the v7 (the current setup does feel a little overdamped - or maybe I am just experiencing the 'inverted monotube stiction' that Whiteline talk about).

BTW I will NEVER be competitive in ANY class - the autox is just for fun.

thrdeye - like you, trying to do this w/o loss of kidneys - through cost OR daily ride quality ;)

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