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Hi all,
I have an '81 currently running a healthy LS and recently upgraded front and rear suspension components. Running 275/40R 18's in the rear. Bilstein B6/B8 combo, and moog 5758 front springs, stock rear mono leaf. Current rear ride height is 28 3/4" which I'd like to keep. I also swapped out the 2.87's for 3.73's recently.
I'm getting a lot of rear end squat and sharp bumps really upset the rear end. I've been reading through old posts but not certain where things sit with the current crop of mono leafs other than to avoid the TRW and Hyperco ones. Is Van Steel the current recommended go to mono leaf these days? Any others to consider? And what spring rate for a street driven car? I just want to firm things up a bit back there and eliminate the easy bottoming and squat under power without breaking the bank. Thanks!
With your 474lbs front springs, it looks like Vansteel suggests:
“330 lb. Composite Monospring: A Plus one to the 300 composite rear spring. Can be used on any 1963-1982 small block car. Rides and handles great. Ideal when combined with GT front coil springs and QA1 Non Adjustable shocks.”
Their GT spring from what I gather has a spring rate of 460lbs.
Yes, Vansteel. They have been Corvette specialists for decades. Give them a call and they’ll be able to tell you what spring will give you the change you want. They’re currently about 6 wks out on new mono-spring orders. I’m getting a new 330 for the rear to match Hyperco dual-rate lowering spring up front; delivery today.
Ok sounds like Van Steel it is. Pricey but if it works well then so be it. Anyone running the 330lb spring and noticed an improvement to bottoming and squat? Thanks!
I’m running a 360lb van steel spring. Its noticeably stiffer, but not back breaking stiff. I’m going to pair it with 550s up front eventually. 330 would match nicely with 475 i think
Make sure you have great adjustable shocks. My experience with a mono spring wasn't so great. Of course I was putting a lot of power through it on sticky tires but it "porpoised" and bounced a lot. They rebound just as much as they compress without the added friction of leaves. It was a stiffer custom made one from VB that was made for me.
Heck it was so bad they nicknamed my car "Flipper" at the dragstrip!
I'm not aware of anyone but VanSteel making composite monosprings worth buying. I'd call and ask for a weight recommendation, and then get the highest rate they make.
I'm at 385 lbs (equivalent, 1" total chop) with my NOS VB&P spring, and it's still a bit softer than the uncut 550 lb fronts. It might match well with 475 front springs, though.
Another way to go is to add a rear sway bar. I added a used 9/16" bar with stock hardware. @leigh1322 has a great spreadsheet that will help make the right choices at all corners. I might just need more sway bar.
Does the rear sway bar help with the rear squat? The LS and 3.73’s really exacerbate the rear squat when you punch it and then if you hit a bump the rear leaves the ground. Not fun and I don’t want to screw up Gary’s beautiful work on the diff
Does the rear sway bar help with the rear squat? The LS and 3.73’s really exacerbate the rear squat when you punch it and then if you hit a bump the rear leaves the ground. Not fun and I don’t want to screw up Gary’s beautiful work on the diff
By design, it does nothing for the squat. It will help with the body roll in corners, though. It depends on what you want to do with the car. Do you have an iron diff mated to the Batwing? I didn't think Gary worked on Dana diffs.
I'd look for some other examples on the Forum of folks with composite springs and your application. 9/16" may end up being just right for me. 5/8" might be better. Some folks run 3/4", which is a LOT of rear bar. Your car should have a 1 1/8" front bar already, which is a LOT of front bar.
Whatever you do, you don't want to make a car that suddenly, and surprisingly, leaves the track ***-end first.
Yes I did the iron swap over the winter. I don’t have any issue with body lean. She still turns like she’s on rails but the combination of lighter motor, more power, and lower gears is just too much for the stock mono leaf. I’ll try the Van Steel spring and hopefully that will firm it up enough that it doesn’t feel like it’s taking a dump when you get on it 😝
Yes I did the iron swap over the winter. I don’t have any issue with body lean. She still turns like she’s on rails but the combination of lighter motor, more power, and lower gears is just too much for the stock mono leaf. I’ll try the Van Steel spring and hopefully that will firm it up enough that it doesn’t feel like it’s taking a dump when you get on it 😝
Thanks!
Then by all means call VanSteel, and ask. For drag racing, you'll want the stiffest spring they have. Even that may not be enough. Someone on this Forum (perhaps @gkull ) got VB&P to make a custom spring. I don't know if VanSteel is willing to do that, yet. Others have gone back to steel springs, or coilovers.
But anything is better than the stock composite spring your 81 came with.
As my power went up and better tires my steel spring was too wimpy. I had a spring shop add a leaf. Which was perfect for many years up around 500#. In the 1980s
Later on I decided to try a 420 VB&P with qa1 dual adjustable. 420 wasn't making so like 427hotrod I had a custom mono spring fabricated and it came out as a 520# like my steel and it's perfect again
I had friends do high frame rate videos of my rear taking off and my car goes forward with very little squat.
You want to put power to the ground and not wasted causing rear squat
This helps guys. Many thanks. I’ll probably try the 360# VS. if that’s not enough, I’ll save up for some coil overs.
I have their 400lbs rear mono spring and honestly it’s not that bad. However, I have crap shocks, still on 15” wheels and don’t use a rear sway bar. Eventually I’ll get double adjustable shocks and move up to 18” wheels. So the ride quality will obviously change. But, all that factors into how you want it to feel. Oh, and don’t forget you’ve added weight with the iron diff. A ‘79 Corvette weights 3,500 lbs and an ‘80 weights 3,300lbs.
theres some great deals on ebay on the same viking dual adjustable shocks/coil overs that are sold as the sharkbite setup... I got my front "sharkbite" coilovers for literally less than half the cost for $450 shipped... in the last 3 weeks the price has already increased about $150 but still a great value vs other corvette specific resellers (corvette tax?) I bought the matching rear shocks for $400 I plan to use with the gymkania spring I bought.
You have to look at weight bias front to rear. Stockish SBC is about 50/50. Poster installed a lighter engine and more weight in the rear.
Weight xfer under braking is greater than xfer to the rear under WOT with most engines. So rear spring weight should only be slightly lower. 420 # is more in line with the posters setup
I have their 400lbs rear mono spring and honestly it’s not that bad. However, I have crap shocks, still on 15” wheels and don’t use a rear sway bar. Eventually I’ll get double adjustable shocks and move up to 18” wheels. So the ride quality will obviously change. But, all that factors into how you want it to feel. Oh, and don’t forget you’ve added weight with the iron diff. A ‘79 Corvette weights 3,500 lbs and an ‘80 weights 3,300lbs.
I will put a call into VS and see what they recommend. I'm not drag racing just trying to minimize the squat/bottoming. With all the changes done to date, the stock leaf is just overpowered (not that is was all that good to begin with lol).
I will put a call into VS and see what they recommend. I'm not drag racing just trying to minimize the squat/bottoming. With all the changes done to date, the stock leaf is just overpowered (not that is was all that good to begin with lol).
I will put a call into VS and see what they recommend. I'm not drag racing just trying to minimize the squat/bottoming. With all the changes done to date, the stock leaf is just overpowered (not that is was all that good to begin with lol).
I'd still get a GOOD set of double adjustable shocks first.....you're going to need them anyway. You can dial up the jounce and dial down the rebound as needed and see how it acts with the current spring. I'd want a stiffer spring too...but before I changed I'd find out how close shocks could get me to the behavior i wanted. I drive on the street and drag race...so different requirements. I'm using a custom 5 leaf thick Daytona spring with an added main leaf to control things on a launch. It does ride rough on a bad road for sure.....but it flat works at the track!
Mono leaf recommendations request
