Spring rate Front & Back for Track Car??

[Sooley]

I have a 2000 GTS Production Racing Car. The series I run in allows minimal mods (PFC, Suspension, Strip interior and thats about it.)

I am having problems with corner exit understeer and am thinking it may be my spring rate. I have heavier spring rate in the front of the car, so should I be looking to have heavier spring rate in the rear instead?

Any help would be great.

P.S. here is some in car of my last round last weekend.

http://youtube.com/watch?v=6Em0rpYnJSk

[redbull]

You should look in the autocross/ road race section, tons of help there. You do want heavier springs in the rear, I think there was a guy running 400lb springs in the front with 1300lb springs in the rear and was doing very well in STS. I plan on going with a set up close to that but my car is still my daily driver so it won’t be that high.

[zuoom]

corner exit understeer.

hmm, maybe entry speed too fast?


dun know if this would help, try toe out for the front to get the "oversteer" you require. similarly, try some toe in at the rear to get it to rotate.

another aspect to note is the ride height. what's the height on the front n rear? if you are currently running a higher rear, you might wan to lower the rear just slightly, and up the front. that should aid in grip to the front.

basically, soften the front to have grip. harden the rear to break traction.

[autxr]

I would be looking at rear spring rates nearly double the front, give or take a few kg/mm.

[renfield90]

From another thread:

From an email they sent me: "John Hotchkis use 550#F and 1650#R on his race Celica."

Those are obviously in lbs./in. Sorry, I'm not metric enough to deal with kg/mm. :sadpace:

Here's another data point: http://newcelica.org/forums/showthread.php?t=256239
He's using 850f/1050r but with a monster rear sway bar.

At any rate, you definitely need to have stiffer springs in the rear compared to the front, and by quite a bit. The car even comes like this from the factory.

Interesting moment at 1:27 on your video! :eek:

[leppardized]

if your limited in what you can do I'd HIGHLY recommend the Hotchkis setup w/ Koni's(or KYB's will work) and get the Comp swaybars. I recently got this installed and its got near 0 understeer. This was the best 1000 bucks Ive ever spent. the ability of this suspension is just NUTZ.
good luck!

[renfield90]

if your limited in what you can do I'd HIGHLY recommend the Hotchkis setup w/ Koni's(or KYB's will work) and get the Comp swaybars. I recently got this installed and its got near 0 understeer. This was the best 1000 bucks Ive ever spent. the ability of this suspension is just NUTZ.
good luck!
The springs that Hotchkis sells for use in street cars are small beans compared to the spring rates you need on a real race car.

[euromotorsports]

The Hotchkis Race Celica uses F 550 and R 1650???

Is that a legit email? or any way for this to be confirmed? I always assumed they used the Hotchkis TVS coilover which were rated at F 300 R 450

[renfield90]

Is that a legit email? or any way for this to be confirmed? I always assumed they used the Hotchkis TVS coilover which were rated at F 300 R 450
I have no way of confirming that. I suppose you could email Hotchkis and ask yourself...

I don't know anyone who would use those rates (300f/450r) on a proper race car...unless you like getting passed by everyone. Way too soft. I still haven't gone yet and done all the math to find the natural frequency, wheel rate, etc. for any given spring rate, but those are going to be too soft. Pretty much any off the shelf spring kit or "lowering" kit is going to have spring rates way too soft for a race application.

[Sooley]

I spoke with Hotchkis and that is the spring rate they use. I still haven't got an answer as to WHY they use that setup, being so heavy at the rear. Does that help improve grip at the front, don't know???

[dannysgtcel]

^^ i have the tein ssp's with swift springs instead of the stock coils that come with the tein set,and it made my car handle alot better on the track,cant remember the exact spring rate but you can find out on there website.

[Soo__Fuego]

^^ i have the tein ssp's with swift springs instead of the stock coils that come with the tein set,and it made my car handle alot better on the track,cant remember the exact spring rate but you can find out on there website.

http://img168.imageshack.us/img168/7662/teinonswiftqc8.jpg

:eek::thumbup::bowdown: