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I am about to embark on rebuilding the whole rear suspension. Does anyone have experience with the new composite mono-leaf that is available? Does it ride nicer? Does it maintain grip better over bumpy road surfaces and potholes? The rear suspension is admittedly worn out but……this car rides like an old land cruiser we once had. I definitely do not want it stiffer, it rides like a hay wagon. Andy
2025 C3 ('68-'73) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
I put a fiberglass spring years ago in one of my previous vettes & wished I didn't. Much stiffer, hated the drive & eventually removed it. I installed a factory oem leaf spring & was satisfied, with the stance & handling.
And I put a composite spring in mine many years ago. With my Bilstien shocks it rides and handles great. A huge improvement over my original sagging gymkhana spring.
Honestly, over the nearly 20 years I've been on this forum, I have seen opinions both ways. But I believe far more like the mono spring. If they choose a quality spring of the correct spring rate and run shocks designed for the mono spring.
And they last. My original spring was sagged out when only about a dozen years old. My mono spring is now over 30.
The low arch composite spring from Van Steel is the only one to consider. Get it in a 330 spring rate if you want a nice ride and aren't tracking the car. Also consider the Bilstein shocks from Rock Auto for the best price.
My ‘78 has the Vansteel 330 spring. The ride is very similar to the OEM steel spring. Can’t say it improves ‘grip’ over potholes. I try to avoid those or slow down if unavoidable. The main advantages of the composite spring are weight reduction of 33lbs and much longer lifespan. Steel spring was replaced because it was sagging. Tried re-arching it at a spring shop, but it was too near the tire after lowering 1”. Ridetech dual-rate(480/700) lowering springs were used up front, but cutting a coil would get almost the same result. The Ridetech single adjustable shocks were easy to dial in to exactly what I wanted. If they had not been on a tremendous sale I would have settled for Bilstiens. Most amazing to me was the improvement in cornering and high-speed lane changes was the swap to 18” wheels and Continental Extreme Contact tires.
Charlie
My composite rear spring was probably the best upgrade I have done to my '79. And I have a full Grand Touring suspension kit, 550 hp, and a Tremec 5 speed. Mine came from Vette Brakes & Products years ago when they were still in business. For a long time the only springs available were the ones from TRW and they truly sucked. I understand the ones available now from Van Steel are similar to the ones from VBP. Assuming that's the case, just do it. You won't regret it.
As best I recall from McClellan's book, GM switched to the composite spring for weight savings and longevity without fatigue. It may very well have been more expensive for GM at the time and if so consider how compelling the argument must have been since automakers pretty much only want to cut costs. My '96 had one I believe - no problem but to be fair - I don't have a strong desire to replace the OE spring on my '71 w/ one of these - just doesn't fit my particular use case.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
We put a 315 lbs TRW spring on our '78 about 25 years ago and it is a huge success. I fitted Koni adjustable shocks all round, set to a fairly low setting. The car rides really nicely, much better than it did on the original spring, and is comfortable for long runs. I'm not into throwing it around corners etc, so I don't really know if handling was improved as such, but I'd never go back.
One upside is that a composite spring is a lot easier to deal with when doing any work on the rear end - much easier to unbolt from the T/A etc.
But of course, if you are going for originality you'll have to stick with the old metal unit...
I would bet most of your hay wagon ride is wore out bushings and shocks, etc.
for a while the plastic spring was not available and results varied. Not sure where market is now or more recent manufacturing quality. Someone or a vendor may chime in on today’s supply.
i went steel gymkhana option oem spring (6 leaf originally) from original 9 leaf. It is also much lighter than the original 9 leaf spring. At the time steel was significantly cheaper and available.
here is where i got mine a few years ago if you go that route.
79’ rear leaf spring
