Now I know alot of this will depend on the quality of the shock, but what is the general maximum spring rate for a well rounded track car? In this I mean a car where the rates are not changed from track to track. I know too stiff of rates on a bumpy track can equal some not fun times and from your experience (whoever replies) on multiple tracks when did you draw the line or feel uncomfortable?

This is mainly in regards to my ITR which I someday hope to eventually turn into more of a weekend track car once I get a daily driver. When I do decided to upgrade the suspension I don't want to go easy on it being as it won't be daily driven much anymore at that point, but at the same time I don't want it to be too much of a hassle (a little hassle I can handle) on a bumpy track.

I know this might be a difficult question to answer, but I'm looking for personal preference and opinion. Thanks in advance.

 

whatever you do...If you start flirting with high spring rates... make sure your dampers can hold it. Underdampered or over sprung will transfer the braking hp of the car by causing a little more lock up in the rear.

 

1. The stock ITR suspension is one of the best I've ever driven. If you haven't messed with it yet, leave it be for a year and then decide if you need more. This is not to say it can't get faster, just that it's pretty damn fast stock.

2. A very simple rule for springs rates: you only need enough spring to keep you off the bump-stops. Any stiffer isn't needed. Of course, if you get into serious engineering/analysis you may/will end up with stiffer springs, but that takes time/effort/knowledge that most of us lack.

3. Is the car driven on the street? That will be your big limiting factor - a street car needs to be able to absorb potholes, which means you need to stay somewhat soft (stock works well).

 

I have went through a year of HPDE's and my comp school on a stock ITR suspension (stock springs, shocks, and rollbars). I only NOW feel the need to go to an aftermarket suspension since I will be racing next year.

If you do not plan on racing, there is absolutely no need to change a stock ITR suspension...just my opinion.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by davidnyc &raquo;</TD></TR><TR><TD CLASS="quote">I have went through a year of HPDE's and my comp school on a stock ITR suspension (stock springs, shocks, and rollbars). I only NOW feel the need to go to an aftermarket suspension since I will be racing next year.

If you do not plan on racing, there is absolutely no need to change a stock ITR suspension...just my opinion.</TD></TR></TABLE>

david is fast , REAL fast on stock suspension.

untill you know you are at the limits of the suspension , dont upgrade it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Crack Monkey &raquo;</TD></TR><TR><TD CLASS="quote">3. Is the car driven on the street? That will be your big limiting factor - a street car needs to be able to absorb potholes, which means you need to stay somewhat soft (stock works well).</TD></TR></TABLE>

Funny thing happened yesterday. (I have 'high spring rates in my WRX Wagon 8KFront/10K Rear) Anyways.... I did about 45 min of Karting in bridgewater MA at F1 Outdoors... 1:26 second 17 turn euro style kart track.

When I was leaving... it made my car feel SOFT.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Doctor CorteZ &raquo;</TD></TR><TR><TD CLASS="quote">

david is fast , REAL fast on stock suspension.

untill you know you are at the limits of the suspension , dont upgrade it.</TD></TR></TABLE>

Yes I know how awesome the stock suspension is. I compete in STX and haven't placed lower than 2nd out of the 4 Alabam region events I've done so I'm aware that it is plenty capable. I also plan on running it for a good bit longer. However I wasn't asking how good the stock suspension is.

I plan on having a beater car by the time I upgrade so streetability isn't a huge factor. I was just wanting input on the highest rates you guys have run comfortably and yes I will be running shocks that can take them (Zeal S6's, Buddy Club or something of that nature).

 

it has been proven that the stock itr setup is plenty capable.

should you decide to change it out, 500# +/- in the rear is probably the highest you would want to go on a daily driver. front shouldn't require much more than 400# +/-. and that's a moderatly rough ride on the street, and a good start on a track setup.

track-only see rear rates as high as 2000# i have read (realtime rsx).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ruthless013 &raquo;</TD></TR><TR><TD CLASS="quote">
it has been proven that the stock itr setup is plenty capable.

should you decide to change it out, 500# +/- in the rear is probably the highest you would want to go on a daily driver. front shouldn't require much more than 400# +/-. and that's a moderatly rough ride on the street, and a good start on a track setup.

track-only see rear rates as high as 2000# i have read (realtime rsx).
</TD></TR></TABLE>

Thanks for the input. I don't think Realtime runs 2000lb springs. I remember the old R's running around 1000lb in the rear. I guess I could be wrong, but thats a ton.

Again I say I know of good the stock suspension is, why does everyone keep telling me this . I compete with it and have won on it, but that isn't the point of this post.

I also said the car won't be a street car anymore. I'm asking for track use only on a wider variety of tracks what have you found to pretty much be the limit for a car that doesn't change rates for every track it visits.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ActiveAero &raquo;</TD></TR><TR><TD CLASS="quote">

TI remember the old R's running around 1000lb in the rear. I guess I could be wrong, but thats a ton.

</TD></TR></TABLE>

800F/1200R were the published rates for the realtime car.

but thats with a 1 3/4" rear bar

 

I think they're up to 900/1400 this year

Warren

 

a recent Sport Compact Car issue (september?) had an article on the realtime rsx and stated that they use a 2000# rear spring

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by camberangle &raquo;</TD></TR><TR><TD CLASS="quote">a recent Sport Compact Car issue (september?) had an article on the realtime rsx and stated that they use a 2000# rear spring</TD></TR></TABLE>



alex ratcliff (kingrat) is selling his its/hc gsr, dedicated racecar, and i think the rates on it are/were 600F/1000R. it's a similar chasis so use that as a reference point.

 

Any stiff setup that is stiff enough to start approaching "really fast" is not only going to damage your teeth driving the car on public roads, but I suspect would be hard on the tub of the car as well. I use 600F/1000R and I could not imagine driving that to work. It would be awful. Even for short trips and certainly for trips to the track.

FWIW, I know Catch 22 was running 800/1200 last year. At Summit Point this was too much spring. Summit's a bumpy track. So "ideal" isn't the same from weekend to weekend.

One last thing, don't skimp on the shocks. I didn't realize it but I was underdamped at 425/600 for a while. Only after I had CRX Lee revalve my Konis and going to 600/1000 did I realize that the underdamped rear shocks were part of the cause of some rather nasty handling demons the car had. It could get violently, abruptly loose in transitions. I was afraid 600/1000 would be far worse and I'd spend most of my weekends in the kitty litter, but not so. It's actually better.

 

The true high end of "what is too high?" is when the suspension spring rate gets up to or eclipses the spring rate that is inherent in the tire's sidewall. Since energy will find the easiest place of compliance to have it's motion, if flexing the tire sidewall is easier than moving the spring, the car will bounce on the tire. Problem is the spring has a damper (shock) to control it and the tire does not. I have heard a number of tire sidewall numbers and they are often in the 1300-1400+ rate number depending on the carcass. If you wantch a lot of the Speedvision cars, especially at bumpy tracks like Sebring, you can often see a regular hopping/bouncing motion and this is often the tire sidewall flaxing if the spring rate is really close.

An article that I read this summer mentioned that the Realtime RSXs run between 1200-2000 lbs rates on the rear depending on the track. Smoother tracks can take more rate, bumpier ones can't. Remember also that you can't just look at spring rate alone as the motion ratio and wheel rate are really the best measure across multiple cars as different cars have different ratios depending on how far inboard or out toward the wheel the spring is. I don't recall the motion ratio of an RSX but would guess the spring may be a bit farther away from the wheel and thedsefore allow a higher spring rate to get the same wheel rate.
Below the spring rate of the tire, then you just need to make sure that whatever spring rate you run that your damper has enough rebound damping to control it.

 

I seem to recall Realtime telling me that they ran 1600 pound springs in the rear at VIR in 2002.

I just purchased a Grand Am Cup Integra from Nonnemaker Racing and the current setup is 700/1300 (which was last used at Mont Tremblanc) though for Summit Point I may have to change to lower spring rates.

Much of it depends on the overall suspension design and other attributes of the car. It sounds as though my spring rate may be too high on my Integra which weighs a relatively light 2350 pounds and runs on lightweight Hoosiers.

My other car which is a Ferrari Challenge car weighs more (2950) and runs on Pirelli slicks. That car has 2000 pounds springs in it and it doesn't mind the bumpy Summit pavement at all. Also a huge difference running a a 18 inch race slick vs. a 15 inch Hoosier.

There is a lot more to it than just calculating spring rates between different cars.

Regards,

J.Kofod