Ground Control spring spec choices

[Ludachris]

So I'm going to be swapping in new springs with stiffer spring rates before long. I have a Ground Control kit with the default spring rates, which are way too soft for road racing. So I've been doing some research on my options. Looks like I can either go with stiffer Eibach springs, as that's what GC comes with. Or I can go with Hypercoil springs. I know there are arguments for both springs.

My main question is this: What length should I go with? Should I stick with the default lengths that GC started with or go longer? Why or why not?

 

[jtmcinder]

Longer springs are heavier, but are less likely to run out of travel and bind. You want the smallest, shortest spring that leaves a little spare travel. Then match the bumpstops.

The only other issue is availability of rates. There are more rates available for 8" Hypercoils than 7".

The only differences between ERS and Hypercoils are the color (red vs blue) and quality (OK vs excellent). That part is a no-brainer.

If you are starting over, then consider running 2.25" ID springs, instead of 2.5"s. They are lighter and still fit around Koni Sports with room to spare.

- Jtoby

 

[Ludachris]

Longer springs are heavier, but are less likely to run out of travel and bind. You want the smallest, shortest spring that leaves a little spare travel. Then match the bumpstops.

The only other issue is availability of rates. There are more rates available for 8" Hypercoils than 7".

The only differences between ERS and Hypercoils are the color (red vs blue) and quality (OK vs excellent). That part is a no-brainer.

If you are starting over, then consider running 2.25" ID springs, instead of 2.5"s. They are lighter and still fit around Koni Sports with room to spare.

- Jtoby

Good info - the 2.25" diameter Hypercoils will be okay with the Ground Control sleeves? (edit)oh yeah, I guess they would since the Eibachs are that diameter...(/edit) When you say "match the bumpstops" what is meant by that exactly? Use taller bumpstops with longer springs?

 

[Elvenhome21]

what is your current spring rate in lbs, for road racing between 400 and 550 work good, but are kind of to hard for street driving (softer rate if you bigger sway bar). 300-350 work good in the rear with stock sway bar.

Diameter and weight aren't a big issue/difference. Length does not matter at all if the springs have the same rate as long as it fits on your adjuster. .

 

[Ludachris]

what is your current spring rate in lbs, for road racing between 400 and 550 work good, but are kind of to hard for street driving (softer rate if you bigger sway bar). 300-350 work good in the rear with stock sway bar.

Diameter and weight aren't a big issue/difference. Length does not matter at all if the springs have the same rate as long as it fits on your adjuster. .

I have the default rates that GC sends out with their kits, 375 front, 250 rear. I'll probably go somewhere around 500 in front. I'm not sure about the rear yet. I have a RMDSM swaybar and still have AGX's in the rear, as where the front is Koni. I was actually thinking about using the 375's I have in the front for the rear for now to see how it feels. Then once I get Konis for the rear I'd go a little stiffer if needed.

 

[Elvenhome21]

I have a several crates full of coilover springs, If you want to try playing with different rates I can ship a set of 4 springs if you want to find a spring rate that works.

 

[Ludachris]

I have a several crates full of coilover springs, If you want to try playing with different rates I can ship a set of 4 springs if you want to find a spring rate that works.

Really? Wow man, that would be really nice. I'll send you a PM.

 

[Elvenhome21]

I used 450 at road america in the front, thats with fwd swaybar and touring tires. They work pretty good considering the tires were bricks. As far as the rear springs/sway bar I can't help very much as far as what works and what doesn't. But as a rule of thumb, the bigger the swaybar the softer the spring. I really want to start playing with 1 3/8-1 1/2 front swaybar and run 250-300 front springs. That way at tracks like road america the faster the speeds are the more the car squats down from the downforce.

 

[jtmcinder]

GC sleeves are for 2.5" ID, which is what the ERS springs that come with the kit are. You would need new sleeves for 2.25" ID springs, which you can get from Koni, for example.

- Jtoby

 

[Ludachris]

GC sleeves are for 2.5" ID, which is what the ERS springs that come with the kit are. You would need new sleeves for 2.25" ID springs, which you can get from Koni, for example.

- Jtoby

Gotcha, thanks.

 

[Eagle 5]

I have GC's and Konis with 500 lb front/ 400 lb rear with the RMDSM rear sway bar and poly suspensions bushings, minus the lower control arm one in the rear (havent put it on yet)

Litt rough for the road sure but I drove on them for months. Just get used to it. Never got to take it to a track to test them out yet due to other reasons but as far as handling, I love them. Fairly easy to get the tail to come aorund if needed, and even with the spool, I don't really notice any understeer or pushing. Though, maybe I have not gone fast enough into a turn to know or not.

Those rates are what DSS suggested if I did not mind a stiff ride on the road. If the stiff ride would bother, I believe they said 450/300, can't remember that part though.

 

[Elvenhome21]

400 in the rear is quite stiff, When I raced my fiero I only used 250s and thats with 60% rear weight on a 2500lb car and a 1in rear sway bar.

But then again having stiff rear springs will make the car looser which is what you want. But that would be better achieved with a bigger rear sway bar. so with a stock rear SB I guess 400 would work.

 

[jtmcinder]

Fieros have the same rear motion ratio as a 1G DSM?

- Jtoby

 

[Elvenhome21]

Well it is pretty close for rear weight comparison I think a dsm tail weighs 1400 lbs and my fiero weighed 1500 lbs its a pretty close comparision. As far as motion ratios I have never bothered with calculating them out. Granted I am sure it works to get you in the ball park but I am a Saturday night racer where we take the same corners 100 laps a night all summer long so we can go by the week before on what we should change. I go more by feel and what I am comfortable with the car doing. Personally I prefer a looser car so typically I would have softer springs in the front than I would normally run and more rear sway bar.

 

[jtmcinder]

As far as motion ratios I have never bothered with calculating them out.

Please forgive my bluntness, but if you don't know the motion ratios then your comparison across the cars is completely meaningless at best and possibly very misleading. For all we know, the rear motion ratio on the Fiero is .95, making the rear wheel-rate for a 1G on 400s exactly the same as that for a Fiero on 250s.

- Jtoby

 

[Elvenhome21]

When I said I never bothered is because there is no real point in circle track racing. And up until the last couple months I never heard of it before. The big thing right now in circle track racing is roll center and moment center.

WHere Im coming from is a spring rate is a spring rate, and actual weight on a given corner/ wheel is a constant, and the component weights are pretty equal so that is why I said it that way. It has been proven for many years in racing that a softer spring will grip the road more but the swaybar has to increase also. That is why stock springs don't work good until you get a monster swaybar.

 

[jtmcinder]

It has been proven for many years in racing that a softer spring will grip the road more but the swaybar has to increase also. That is why stock springs don't work good until you get a monster swaybar.

I do not know of this proof. Please provide examples and/or links. Thanks.

- Jtoby

ps. the only ways for the weight on a given wheel to remain constant are (1) you never accelerate in any direction or (2) your CG is at ground level

 

[Elvenhome21]

Right now NASCAR is the perfect example of Big sway bar (2"-2.5") Soft Springs. A 3400lb car and they run I believe 400lb springs in the front. THe softer springs is only an american thing because our tracks are so rough comparative to Europe tracks, but in Euro racing they run unbelieveably stiff springs or no springs. A guy I was talking to that races a morgan said that when he bought the car (He bought it from Europe) it had 1400lb springs in the front. At Road America and North American Tracks he only runs 400lb springs.

Back to nascar chassis stuff, at Watkins Glen they do switch to a smaller bar but it is still huge, 1.5-1.75". and springs are 50-100lbs heavier.

 

[WatchItExplode]

GC sleeves are for 2.5" ID, which is what the ERS springs that come with the kit are. You would need new sleeves for 2.25" ID springs, which you can get from Koni, for example.

- Jtoby

I don't suppose you know a part number for those Koni sleeves? Thought I'd ask before wasting my time calling around

 

[Elvenhome21]

here are some coil over kits for a 2 1/2" spring
http://www.stockcarproducts.com/coilovr2.htm
http://www.speedwaymotors.com/p/218...iPro-Carrera-Monroe-QA1-and-Bilsteinandi.html

 

[jtmcinder]

Truechoice are the best people to get Koni stuff from. At least, I like them better than Koni, oddly enough. They carry the sleeves for 2.25" ID sprngs, which I assume was the (real) question.

http://www.truechoicekoniracingservices.com/

- Jtoby

 

[steel_3d]

Looking at their catalog... What do you guys think of their Phase III setup for 2g's? Phase II looks like an expensive yellows + gc setup.

 

[WatchItExplode]

Truechoice are the best people to get Koni stuff from. At least, I like them better than Koni, oddly enough. They carry the sleeves for 2.25" ID sprngs, which I assume was the (real) question.

http://www.truechoicekoniracingservices.com/

- Jtoby

Many thanks.

 

[mavisky]

I'm thinking the 500/400 setup may be ideal for me. Collier is running around 100lb's heavier on both the front and rear, but since my car still sees some street duty, I think the 500/400 will be about the maximum you'd want to go to, especially for a light in the ass fwd like mine.

 

[AndrewD5418]

here are some coil over kits for a 2 1/2" spring
Carrera Shocks and Pro Shocks - Coil Over Kits
COIL OVER KIT, 5" SLEEVE, 2" BODY

Old thread yes; but what would I need for Koni's?

Pro, Carrera, Monroe, QA1 or Bilstein? I'm guessing 7"? And where are you people finding the springs?