C3 Rear Composite Spring

[Ed A.]

Hi, I'm working on my 68 roadster small block rear suspension and need some advice. Some time ago I installed a TRW 340# composite rear spring using a 7 1/4 inch long spring bolt, this worked however the rear end of the car sat about 2 1/2 inches higher than the front.
Recently I decided to lower the rear end and purchased a 10 inch bolt kit from Van Steel which I just installed and found that after levelling the car the ends of the spring are touching the tires. I'm running BF Goodrich TA Radials P235/60 SR15 tires mounted on aftermarket knockoffs. Short of buying a new shortened spring ($500.00) does anyone have any affordable solutions to this problem, I'd prefer not to reinstall the shorter bolts if possible.
Any suggestions would be greatly appreciated.

Thanks

[Mark E.]

Re: C3 Rear Composite Spring

If you search here and other Corvette forums, you'll discover higher than normal ride height is a common issue with aftermarket composite springs.
A choppy ride is another.

Using longer spring bolts as a remedy introduces other problems including less clearance with the tire and ground. On one of the forums, I saw a photo of a tire destroyed by a longer bolt when flexing inward during a turn.

I recommend reinstalling the original spring.

[Ed A.]

Re: C3 Rear Composite Spring

Mark, Thanks for your input I'm sure this is what I'll end up doing.

[Steven B.]

Re: C3 Rear Composite Spring

Ed, one of my cars is a track car. I have a Guldstrand comp spring and long bolts with 8.5 wheels and tires equivalent to about 255. I had a clearance issue also and used the thinnest spacers I could and longer wheel studs. We did the samd on our old A Prod car at the recommendation of Dick Guldstrand years ago. Never an issue with either car. A friend with an A/P car had same setup with no problem. Just dont overdo the spacer width.

[Mark E.]

Re: C3 Rear Composite Spring

Never an issue with longer, makeshift bolts? Check how much these bolts extend below the bottom of the wheel. What happens when there's a flat?

Is there a composite spring that isn't unnecessarily stiff and doesn't require makeshift spring bolts to maintain proper ride height? It can't be that hard to make one with proper specs.

[Steven B.]

Re: C3 Rear Composite Spring

No issue with the long spring bolts on either track, Mid Ohio, IRP, etc or street. Havent heard of problem with supplied long spring bolts.

[Mark E.]

Re: C3 Rear Composite Spring

No issue with the long spring bolts on either track, Mid Ohio, IRP, etc or street. Havent heard of problem with supplied long spring bolts.

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Well Steven, you're living a charmed life.

[Gary C.]

Re: C3 Rear Composite Spring

don't know about C3's, but I used a composite spring on my 1964 for 30 years with no problems

Gary
....

[Mark E.]

Re: C3 Rear Composite Spring

I hope you guys enjoy the photo of Yorktown CV-10. I accidentally posted it using my phone but it won't delete for me.

Gary- the extra length bolts are the safety issue, not the spring itself.

[Ed A.]

Re: C3 Rear Composite Spring

Steve, Thanks for the info I've been looking into the spacers as an option but have not been able to find any thinner ones so far most seem to be 1 inch thick. I don't need more than 1/2 inch.

[Ed A.]

Re: C3 Rear Composite Spring

Mark, Van Steel makes a shorter spring with less arch than the TRW spring and can also make a spring to your spec's. The spring has a 330# spring rate and costs $500.00 part # is VSC 63330 ( www.vansteel.com )

[Ed A.]

Re: C3 Rear Composite Spring

Gary, the composite spring has been on my 68 for 10 years with the shorter spring bolt with no problems. the interference only occurred when I installed the longer bolts and pulled the spring down. I also have composite springs on my 66 coupe and my 79 L82 that have not been a problem.

[Mark E.]

Re: C3 Rear Composite Spring

Mark, Van Steel makes a shorter spring with less arch than the TRW spring and can also make a spring to your spec's. The spring has a 330# spring rate and costs $500.00 part # is VSC 63330 ( www.vansteel.com )

Ed,

The base oem spring is 170-190#, so this will be much stiffer. See Duke's post in this thread:

https://www.forums.ncrs.org/showthread.php?33515-rear-suspension-bounce&highlight=spring+rate

[Ed A.]

Re: C3 Rear Composite Spring

Hi Mark, Thanks for the info.

Ed

[Patrick B.]