View Full Version : Spring Rates

12-13-2001, 07:06 PM
Ron here from Texas....
I would like to seek your help about spring rates.
Currently I have a coil over kit on my 83 A1 VW GTI.
The car is used in SCCA ITB.
Front springs are 375lb/in and the rear are 325lb/in.
Car handles very well, fairly neutral, with a little oversteer if I lift or trail brake in a corner.
This was fine for the first 1 years in the car. But the car does have some roll. Now I feel like I would like to increase the spring rates.
Being the cheap guy I am, ....I was thinking of taking my front 375lb/in springs and moving them to the rear. Then purchase a new pair for the front. So, I need to figure what rate to try next in the front.
I did a little math....325/375=a ratio of 0.866666, so I assume I would need to keep the ratio number close to the ratio I have now, since I like the way the car handles.
Plug in a new front spring rate of say 450lb/in.....and I get 375/450= a ratio of 0.833333
or maybe a new front spring rate of 425lb/in.....375/425= a ratio of 0.88235
Both are close, What does the group think? 450lb/in or 425lb/in?
Am I even doing this right?

Ron Vaughn
#32, SWDIV

Bill Miller
12-13-2001, 07:36 PM

Part of it depends on what sway bars you're running. Also, your shock valving comes into play as well. I'd probably go w/ the 450# springs in your case, or maybe even higher. But, you need to make sure the valving in your front shocks is adequate to control a 450# or higher spring.

MARRS #25 ITB Rabbit GTI

12-13-2001, 09:22 PM

Guess my first question would be....what changed after that first year and a half? If you liked it before, shouldn't you like it now? Have you changed anything on the car? Checked your corner weights, alignment? If you haven't changed anything lately, I would guess that either something changed unbenounced to you, or you've become a much better driver and realized the old setup really did suck! http://Forums.ImprovedTouring.com/it/smile.gif


12-13-2001, 09:27 PM

I run higher spring rates than you are looking at and love it! Have a little push dr.front, sticks all day long pass side (think I need to add more camber on Dr side). My driving style is very neutral though, I like to early apex and float out, not the type to square off corners like I see some guys doin http://Forums.ImprovedTouring.com/it/smile.gif

ITb #54 '84 GTi

12-14-2001, 11:11 AM
Thanks Bill and Chris,

Nothing changed on the car, but being a newby 1.5 years ago, I kept the "soft" springs to start with (came on the car when I bought it).

So, now that my skill level has improved, I want to make small jumps in spring rates, and then again wait for the skill level to catch up.

Last night I went thru my car prep notes and discovered I made a mistake in my first post, oops, should have done my homework before I posted.

My front spring is 325lb/in and the rear is 275lb/in. (275/325=ratio of 0.846).
So, now I am wondering if I should just suck it up and get 4 new springs, and go with 450 in the front as per Bill, and 375 in the rear. Again, my intent is to slowly jump up the rates.

Another aurgument would be, make a big jump now, and just deal with the learning curve. I guess the truth is that I am afraid the big jump will tend to make the car oversteer prone, and I may not be handle the car at first, and may crash, and maybe hit somebody else, etc... I really don't want to hit somebody. (I have never bent my car or anybody else in my little 1.5 yrs of racing. I drive off track when I see others losing it and coming at me).

I do, however instruct for a driver school, so I do get free track time in a none race atmoshere, and this would be a great place to learn the big jump in spring rates. (Assuming I confirm the shocks can handle it.)

It's never easy, is it?

Thanks for listening to me, I tend to just lurk, I really enjoy reading all my email's from this group, especially you Bill and Chris, level heads and good responses.

Best of luck to all during the 2002 race season.

[This message has been edited by ITB#32VWGTi (edited December 14, 2001).]

Mark LaBarre
12-14-2001, 02:54 PM
A little advice (if you want it). Resist the urge to tweak. Leave the car alone. At 1.5 years of driving it, your probably not anywhere near the limits of the car. All to often we feel that tweaking will give us another couple hundreths instead of concentrating on driving ALL of the car. I think you'll find your times droping for several years as your driving skills continue to improve. Leaving the car alone allows you to verify that it is in fact your skill that is improving, not the latest go fast gadget.
Food for thought.

12-14-2001, 04:22 PM
I must say, though I can understand Mark's suggestion of leave it be if it is what has worked for you so far, I still say change is good. I ran spring rates similar to yours Ron and let me say, after I switched a few things (i too got a car with existing springs), my times greatly improved! You seem to end up in the rut of driving the car the way it has to be driven because it just won't handle any other way, and in my case I started getting into habbits that probably caused me to loose time because I was having to compensate for the under performance of the tires via crappy suspension. I went the extreme route. The car was high off the ground (compared to other GTi's) had soft springs and not enough camber. Now the car is much lower, much tighter and with a good bit more camber. I still may need more in the Dr. side as it is, but the handling has so dramatically changed it is joy to drive! Now if I only had a monster motor to propel me!! http://Forums.ImprovedTouring.com/it/smile.gif Seriously though, tighten it up (especially the rear end), get your corner weights right on and you will be pleased. Then you can concentrate on your true skills and not car coaxing!


12-14-2001, 04:23 PM
Good point, I find myself giving that same advise to others. And so far, I have done what you suggest. I have done no mods to "improve" the car, only maintance stuff, since I bought it.

But here is the deal, yes I have only been racing this car for 1.5 years. (with big head, I insert: I am currently the SWDIV ITB points leader with (2) 1st places). I have many more years, of high speed auto cross, on Black Hawk Farms in IL. Then there is the 10 years of ice racing in WI. Also, I currently instruct for a drivers school at the same track I race ITB at. I must have hundreds of laps on this track now (not counting the laps in student's cars). On certain corners I can "feel" where the "softer" spring rate is hurting my exit speed. It was only after I could "feel" the effect of the existing softer springs that got me debating on this idea of incresing the spring rate. So, that is why I am thinking of breaking my own rule (and Mark's) of not replacing anything.

So gee, Mark, what you said is so true, I am now back to square one.

What does the group think?(Bill?, Chris?), if a driver is in the car and can feel the short comings of the suspension, does the driver...
a)upgrade the componet?
b)leave the car alone, and continue to improve driver skill?

I am not set on having to upgrade the springs, I like Mark's idea alot, and it wont cost me anything to not upgrade. On the other hand, I don't want to waist my time doing laps in the car, if it is time (based on skill) for the upgrade.

Ron Vaughn
#32 ITB

12-14-2001, 04:28 PM
I second Mark's comments. Before you go fiddling with spring rates, if you can stomach it, find a local driver that's faster than you (and drives the same marque or similar car) and have him drive your car on a test day or lapping day. This will accomplish two things: one, it will probably show you how much potential is left in the car WITHOUT changing anything and two, he/she will probably offer some suggestions to improve the handling.

This can also be very humiliating and humbling! But it could also save you a lot of $$$ down the road.

Here's a little trick/method I devised that helped me decide when it was time to start fiddling with my car's suspension: I have a video camera in the car and I time lap "segments" of me driving the car off of the videotapes of race/qualifying/practice/test sessions. After collecting many segment times through the same segment of the track I'd find my "best time." I'd repeat the procedure with other lap segments and ulitmately come up with a "theoretical best" laptime if I did all segments perfectly. What you'll probably find (I sure did) is that your current "real" best laptime is still quite a bit slower than your "theoretical" best laptime. If this is so, leave the car alone and focus on driving until you can get down close to your theoretical best lap. THEN you are probably getting pretty close to the limits of the car and it's time to tweak the suspension. What you'll also find is the tweaking will save at most tenths of a second improvements, not great big gobs of time.

Of course, if you have on-board data acquisition software it can do this for you automatically at the end of every session! I've found that my "poor man's" data acquisition has improved the performance of my car drastically by forcing me to be objective about my driving. My wife no longer rolls her eyes when she sees me "practicing" on the video tapes before race weekends...

That's my nickel's worth,

#14 ITC VW Scirocco - 2001 SARRC Champ - for sale
#14 GP VW Scirocco

[This message has been edited by racer14itc (edited December 14, 2001).]

12-14-2001, 04:54 PM
What size coil-overs? If you use 2.25 ID and around 8 inch free-length, I've got a bunch a near brand new ones to choose from from my "tweeking" days.

I think I have some 375, 450, 500 and 550 Eibachs and Hypercoils (I think).

They would be fairly priced.


Mark LaBarre
12-14-2001, 06:10 PM
I didn't know you had some racing experience, but still think holding off would be a good idea. As a point of reference, My ITC Scirocco was purchased from a guy with approximatly 225# fronts and 180# rears, 1" front bar. Every year at Blackhawk, my times droped until I was running 1:29's ( 0.4 seconds off the track record) with out ever changing the set-up. Hell, the car was never even corner weighted. With your rates, the car should be able to keep up with any VW at the 'Farms. If not, spring rates are not going to make much difference. P.S. Welded diffs are good for at least 1 second at Blackhawk. If you see the green Mountain Dew logo'd Scirocco (04) next year, stop by and say howdy!

12-14-2001, 10:53 PM
I don't think that anyone has mentioned this but, if you aren't already using really good tires (low-mileage, the fast flavor-of-the-month), then you might be setting yourself up by spending more $$ on the suspension.

There are LOTS of ways to look at the question of how to go faster but on immutable reality is that you are still only connected to the track through four tiny patches "where the rubber meets the road". (Where did you think that saying came from, anyway?) Tires are probably the single biggest factor in the whole equation - don't skimp there. A LOT of people fall into this trap...


12-30-2001, 10:09 PM
I'm trying to figure out exactly why you want to change your springs. You stated that the car is very neutral with only weight transfer oversteer (which is typical on any FWD neutral car especially one with a vehicle polar moment as low as a Rabbit).

Spring rates should be the absolutly minimum that is needed to prevent the car from botteming out. The botteming out is either the shocks, the body, the wheel to the vehicle or whatnot. After that is reached then you just change rates to get the final proper setup for being neutral which typically means only changing either the front or rear springs, not both.

Trying to prevent body roll with springs is bad any way you look at it. It might feel faster but the loss in bump control and drivability is not worth the increased rate IMH&TO. Why would you want to make your car more prone to under/oversteer and being very skatish (4 wheel slides) when you already have a vehicle that is driveable?

This obviously assumes that you already have the proper setup of anti-roll bars, both front and rear (if you run a front at all). If you are planning on changing anti-roll bars do so before changing spring rates. Once you are happy with the anti-roll bar setup then you should begin to work the spring rates down to the absolutly softest possible.

One of the biggest misconceptions that I see people make regarding suspensions is in the choice of spring rates. Just like shocks (which IMHO is the biggest misconception), having too much is actually worse then not having enough.

12-31-2001, 11:00 AM
Thanks Guys,
After reading the posts, I am NOT going to change my springs. I will keep the existing springs and improve my driving skill.
Over the holidays I pulled the front shocks out (Koni Single adjustables), and one is pretty shot (drivers), and the other seemed ok, but slightly weak.

Today I will order new shocks (ok, dampers) and put it all back together.
I think I was getting caught up in the whole "I need higher spring rates because I want to go faster" without really thinking it thru.

Yes, the car handles fine, it just seemed to roll. I have no front bar, and a large (maybe 1-inch) rear from Neuspeed that came with the car and old shocks, maybe 5-6 years of road racing, and I think the car was auto-crossed prior to that possibly with the same shocks.

Anyhow, thanks guys, I am glad we have this IT site, you guys have a lot of knowledge, and I am glad I can tap into it every once in a while.

Happy New Year
Good Luck with your 2002 races.

Ron Vaughn
83 GTI
#32, SWDIV.

01-02-2002, 12:08 AM
If you are using the Koni Strut inserts why don't you just send them out and have them rebuilt/revalved. It will save you some cash just on a basic revalve and you could always use that towards adding the secondary compression damping which IMHO is the best way to go. There's a ton of companies that work on Konis and even Koni NA themselves can do it. I've been using Truechoice on my last several suspensions and I've always got what I wanted with great results. I just picked up my GTI's Phase 4s and they are incredible.