Front Spring Rates

[Silk]

I'm currently running 450 lb front springs, but for autocross the nose is still diving too much for my liking. I was thinking of going up to 550 lbs, but before I did, I was wondering if any other Unique owners have had any experience with higher front spring rates? I know some autocrossers go much higher than this (700-800 lbs), but while I don't mind a harsh ride, I still want reasonable drivability. Any advice would be welcome. Thanks.

[Brent]

Unfortunately you can not have a racing spring rate and a reasonable ride at the same time. Variable rate springs will not give the performance you are looking for. You might consider having two sets and change when you are ready to thrash. Only takes a few minutes.

[gasman]

Hey Brent, when do we get to see what you are working on?

[Brent]

Motor is finished and I am just waiting for the jig at the race shop to become avail. so I can start on the frame work. May be a while. No hurry this time.

[Silk]

Anyone running 550 lb springs in the front?

[gasman]

Gary, Try it and let us know how it works out. I started at 375 and worked my way up to 450. Wish I had tried a little heavier just to see.

[Silk]

Steve,

That's probably what I'll do. The ride with 450s is fine, but the rear tires are just making contact under full braking (see below). Hopefully 550s will be a good compromise.

http://www.clubcobra.com/photopost/data/500/12500Cumberland_Turn2.jpg

[eliminator]

I am not so sure that your spring rate is the only problem, if I were you I would be looking at the shocks too. If your running Carerra's I would say it's time to change.

[Silk]

Rick,

I pulled the Carreras and put in new Pro Shocks all around.

[gasman]

Gary, Rick and I would agree on this, Bilstein shocks are the way to go. Looking at the picture you posted, you are definately carrying way too much weight into the corner. It almost looks like you are about to wheel hop the RR. Just thinking out loud, I've often wondered if a different spring rate from front to rear on the rear axle would help. It seems logical that heavy breaking would compress the front springs on the rear axle and carry that weight into the turns. I just have to think a heavier front spring on the rear axle would help. I'd love to have track time and a box of springs to play with.

[eliminator]

One other thing, get rid of the chromed springs, the spring rates are not consistent. If you read up on all the good springs they are all apinted or powder coated, not chromed. The chromeing process has an adverse effect on the metal and spring rate. A good spring is Hypercoil made in Indiana, these are used in ARCA, NASCAR, Sprint Cars, and others.

[Justin Upchurch]

Gary,
It is normal to pick up the rear tire enough to see daylight in some corners. I drove a stock C5 Z06 around a road course a couple of weeks ago and through the bus stop some daylight was showing under the inside rear. However from looking at the picture I would first start with a stiffer front sway bar, and if you don't have the rear bar I would get it. Next, do as Brent said and get a second set of springs, and go ahead and try 700 in the front and 450 - 500 in the rear. Once you go much past 450 with a small block the car will be very stiff for road use, so just have two sets. I know this sounds stiff, but turn in shoud be much quicker. Finally see if one of the guys will let you scale your car. Adjust the corner weight by adjusting the shock ride height until you get the car where it needs to be.

Justin

[DavidNJ]

Steve,

That's probably what I'll do. The ride with 450s is fine, but the rear tires are just making contact under full braking (see below). Hopefully 550s will be a good compromise.

http://www.clubcobra.com/photopost/data/500/12500Cumberland_Turn2.jpg

Hi! I'm new here. Not yet a Cobra owner. But with a little suspension experience.

First, is this problem the same in left and right turns? Has this car been scaled? Are the wheel weights symmetric? If the car wedge in it, the problem can be exaggerated in one direction. In addition to lifting the inside rear, it seems to be slightly oversteering underbraking.

The car pictured above seems to have to little front roll resistance and too little rear rebound on the shock. This problem also affected first generation Honda S2000s. The solution was a stiff front bar, fortunately allowed by stock autocross classes. Springs can also do this.

On an oval track race car, the problem might also be addressed with a higher front roll center, more anti-dive on the outside front, and maybe more front bump stiffness.

I'm not an expert autocrosser, but you also may want to make your entry a little less hot, a little more balanced.