More 240z Suspension Questions

[Tom Donnelly]

Ok, I've gone over the new car's suspension and I've found something I don't really understand. My old car had 8" hyperco hypercoil springs in the front and 8" carrera's in the rear. Why? I dunno. That's just how I bought it. 350lbs front, 325 rear.

New car, same manufacturer but different rates. Unknown front and 300 rear. And, the new car has 12" hyperco's in the front and 10" carrara's in the rear. I just ran it at driver's school and the last 2 events as it was, but now its time to get to a known baseline and start from there.

I'm going to purchase a few sets of springs to test with, starting with katman's series of springs and a couple of David Spillman's as well. Maybe 325/275, 350/275, 350/285, 400/300 and 400/350.

Here's the questions. Is there an advantage to longer coils? The fronts are almost out of room on the adjusters (but the car is low enough) and the rears are similar. Do longer coils have better progession? Or do they bind easier due to more coils? I have found that the 12" coils weight about 2 1/2 pounds more than the 8". So there is at least a weight savings on the smaller springs.

I was going to go with possibly a series of 10" or 8" with the front and rears being the same height. But I'd like to know the trade offs in each direction if anyone knows.

Another question is.. Hyperco or Eibach or Carrera or Landrum? Any feedback on manufacturer?

The last two sessions at Road Atlanta the car was real twitchy in the esses and even in turn six, where I spun. And I've never spun in six. The setup was an unknown spring rate in front and 300 lbs in the rear, with 8 year old tires. (which may have been the problem, besides rusty driving)

Thanks in advance,

Tom

Oh, and the car is a 1970 240z, Bilstien shocks, speedway front bar and no rear bar.

[pballance]

What matters Tom is you need to set the shock in the center of it's range of travel. You will need to find the specs on the shocks, then assemble everything w/o the shocks in place and make sure you have enough travel, both compression and rebound, with your car set at the correct ride height. You may find that changing length of the spring will allow you to center the shock while obtaining the correct ride height.

A lot of work, but worth it to get the suspension working right. Go read the "strut" thread at hybridz when you have time. Lot's of good info.

[Tom Donnelly]

Paul,

I didn't think about shock travel, that's a good point. Any feedback on manufacturer?

By the way, which strut thread? There are a bunch.

Tom

[pballance]

Try this one Tom,
http://forums.hybridz.org/showthread.php?t=138601

I am using Eibach but have used hypercoil and carerra. I would think that consistent rate would be more important than brand. Then it comes down to the weight of the spring.

Good luck!

[Tom Donnelly]

Paul,

Thanks.

Tom

[Tom Donnelly]

What about spring length? Does it make a difference? Say a 300lb 12" spring versus a 300lb 8" spring. One is lighter than the other. And longer. What about travel, binding etc. If it's just length, then why doesn't everybody run lighter 8" instead of 12". It seems like travel would be greater with the 12's but there are more coils than the 8's so is it different. And I was just wondering about personel experience with manufacturers. Landrum is right downtown here in Atlanta, (sort of, they're in Conley). They're all priced about the same. Just different colors as far as I can tell.

Tom