I have the oportunity to buy a composite spring locally (Australia) for about half the price of shipping one out from the States. I am concerned, however that it may be too stiff.

The car is a small block 73 convertible. The spring rate is 420lb. It is only a Sunday car and I am comfortable with a reasonably stiff ride. I have had no experience with these springs so would really like to hear some opinions.

Cheers
Mark

 

That's more than twice the stock spring.

 

I'm betting you will not like a 420lb spring.

 

I have a 420# spring in my car, stock-rate springs in the front (albeit, 1 1/2" lower via cut coils). I like it.... but I also have a lifted, 83 Chev 4x4 pickup so I have an affinity for rough-riding skateboards. But still, the Corvette rides a lot better than the truck so it's not as rough riding as it would appear at first glance.

 

Stock spring was 170 lbs, so the one your considering is way stifer.
http://gmheritagecenter.com/docs/gm-...t-Corvette.pdf

 

Use a good shock with it like the Bilstein Sports.

 

I have the 330 lb composite spring in my '73 coupe. Big improvement over the steel spring it replaced and I wouldn't want or need a stiffer spring.

DC

 

The 360#/in fiberglass spring in my '78 works fine with no issues. IMO, a 420 would be acceptable too.

 

E=Easy Mike;1584153839]I'm betting you will not like a 420lb spring.[/QUOTE]

 

420# is nice. It really keeps body roll down

 

I started with a 330# spring - it's on Denpo's car now. My issue with it was kind of self-inflicted. I lowered my car a lot, with the 330# spring, I was constantly on the bump stop. I reduced the bump stop height and put the 420# spring on - it solved the bottoming out problem and it does handle better. I still want my rear sway bar back on, but it does make a huge, positive difference even without the rear bar.

 

Thanks for the feedback guys. As expected, a wide range of opinions.....My car has also been lowered considerably and as I am not adverse to a fairly hard ride I am going to give it a shot. I'll let you know what I think when I get it back in.

 

What sort of tires in the back? I find that tire selection plays a pretty big role in ride quality, too.

 

I do not think that you will be unhappy with the 420 lb spring rate but, I would encourage you to also change the front springs to match the rear. If you do not upgrade the front springs when you do the rear, you may find yourself in an evil handling car. I put on a 360 lb spring in a Corvette some years back without upgrading the front springs. The car was scary to drive because of a sever over steer condition generated by the mismatch. Check with a suspension expert like Dick Goldstrand to achieve an acceptable combination.

 

The tyres are 255/60/15 so there should be some give there.

The oversteer issue is a very valid one. The reason this spring is available is that it was purchased for a circuit racing 69 model and he could not get rid of the oversteer. Any idea how I can contact Dick to discuss front spring options ?

 

To compensate for the oversteer tendency of a stiffer rear spring, don't use a rear sway bar; further, increase the size of the front sway bar to about 1 1/8". Adjust from these values as you push the handling on an autocross course or the track.

 

I just did google search for Dick Goldstand and was unable to find anything recent. I can tell you that the F-41 Suspension option was 550 in/lbs front spring rate with 360 lb rear spring. The gymkhana spring rate was 550 front with 330 lb rear spring rate. It would be much more cost effective to set up your suspension using information from others experiences. Trial and error can be very costly when you are buying suspension components. If you can get access to some early GM publications regarding race set up, it would be of great value.

 

My 78 L-82 4 speed originally had the gymkhana suspension from the factory. I have changed the OEM front springs, the OEM steel spring, the shocks (multiple times over the last 25 years), the rear OEM sway bar using the front 1 1/8 inch front bar with poly endlink and mounting bushings, poly control arm bushings, 255/45/17 ZR ultra high performance tires and my car has never driven better. Every single change was done separately from the others so that I could gauge what effect the change had on the ride, steering, and handling. The front springs are 550's 1 inch shorter than stock, the rear spring is a 360 composite, the rear bar is an OEM type 3/4 inch sway bar (NOT an aftermarket one with end links like the front bar), Bilstein HD shocks in front with Bilstein Sports in the rear, and a custom rebuilt/blue printed OEM steering box. My neighbor with a Lexus LS430 recently was in my car and commented that my car rode great, not harsh at all. The handling and steering is beyond any C3 i have ever driven or rode in. I am thinking of replacing the rear spring at some point with a 420 since I prefer a solid riding car and the 360 spring is very comfortable ride now-I have a 2010 Z06 as well. Most C3's are either very harsh with a steel spring or have too much rear movement in my opinion with lower rated rear composite springs. A 330 composite spring will ride 10 times better than a 330 steel spring-the spring rates are not equivalent. Hope that helps!

 

Thanks for all the replies guys. As I expected a wide range of opinions as we all have different expectations of what we want from our rides.

Today I finally got around to installing the 420lb spring. I love it. I went for a drive on some fairly ordinary roads and in no way is the ride to harsh. The spring responds much quicker and the car feels allot more settled on the road.

 

So what's different with a OEM rear sway bar ? Have any pictures. I have a VBandP street / Slalom kit in my 1978. My car did not have a rear sway bar before so all I know about is what the VBandP kit came with. Also what wheels are you using. I am having a hard time finding a good looking 17 or 18 inch wheel for my 1978. I don't like the standard 5 spoke design. I like most of the C6 GS wheels. Of course because I also drive as 2010 GS.