Bouncy rear
Thread Starter
Racer
Joined: Jul 2017
Posts: 399
Likes: 115
From: chico ca
Bouncy rear
I have a 68 that I have gone through. Replaced all bushings with stock rubber parts, but in Bilstein shocks and replace spring with 315 lb composite spring. Was told that would give best ride. Problem is the car seems to bounce all over in the rear. Never felt that before with stock spring. Do I have a defective spring or is the bouncing part of the good ride the salesman was talking about. Anybody have any suggestions, or have this happen to them? Any help greatly appreciated
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,212
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
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when you say bouncy, what do you mean?. If you hit a bump does the rear end just go up and down a few times then eventually stop or does it jump to one side. The shocks control the up and down and the rear alignment controls the jump to one side. I would think your shocks are bad. The fiberglaass springs do make the ride less harsh.Maybe your just used to the hard spring ride. IF you go to your car and push up and down on the rear bumper area and get the car going up and down pretty good, when you let go it should go down then stop on the way up. if it goes more than 2 time the shocks are bad, or not connected
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
There is this beltway bridge near me, 3.5 miles long across the river, and I noted that at speed in certain lanes, the undulations of the bridge, between cross supports, would make the car bounce a bit at speed, talking they typical 80 mph most folks are doing.....do like 50 mph and there is no bounce, except the last one when you get slammed by a TRUCK ....... on typical suburban roads there is no issue....
The spring is a VBP 360 glass spring, with Billy Stein sports shocks.....I don't think they are adjustable....I found the ride improvement was SO great over the steel springs from the factory, that it's no comparison....
BUT in typical wisdumb the locals here run a major access road to this burb right by a screwal, and of course put in rumble strips 4 of them per patch......drive ANY car over it and it hurts my spine/neck/sac-tailbone.....so I find the only way to drive it is ~40+ mph faster to go, less bouncing/pain.....funny, back 60 years ago, my screwal had much more traffic around it, and no speed bumps/rumble strips....
The spring is a VBP 360 glass spring, with Billy Stein sports shocks.....I don't think they are adjustable....I found the ride improvement was SO great over the steel springs from the factory, that it's no comparison....
BUT in typical wisdumb the locals here run a major access road to this burb right by a screwal, and of course put in rumble strips 4 of them per patch......drive ANY car over it and it hurts my spine/neck/sac-tailbone.....so I find the only way to drive it is ~40+ mph faster to go, less bouncing/pain.....funny, back 60 years ago, my screwal had much more traffic around it, and no speed bumps/rumble strips....
Thread Starter
Racer
Joined: Jul 2017
Posts: 399
Likes: 115
From: chico ca
I went out to push on the back and I have never seen anything like it. I will try and upload video later. I have replaced all shocks and spring. Before doing this the car seemed to drive fine. I can literally bounce the rear by pushing on it. It is strange though. It won’t keep going with out my help just when I am pushing it. Whatever is wrong, it is a serious problem. The front end with all new stuff is perfect. Some have suggested with composite springs you need adjustable shocks... if that is the case why would you by a composite spring. I guess I should have got a reg spring??
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,212
Likes: 9,350
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
My composite spring and holsteins didn't bounce like that. Maybe the shocks are valved wrong or have just failed
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Melting Slicks
Joined: Feb 2017
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From: PHX AZ
Fiberglas springs have no 'stiction' (inter-leaf drag,) because there are no 'leaves'.
It would be super-unusual to have a 'defective' fiberglas spring....1-1,000,000 it's just really hard to make a defective part with this process.
Pull one Bilsteinand do a jounce and rebound test in your hands....if the valves were 'defective' you'd feel it.
Corvettes usually have (original Delcos) more rebound than jounce dialed in...for ride reasons....this is kinda why C-3 squats on take-off...also geometry.
Are the Bilsteins Yellow?
Tires are a spring....try firming up your tire pressures (rear)
I have a 360 lbs fiberglass in the 69 Convt....Bilsteins.....pretty firm. So you're like 12% softer.
Unkahal
It would be super-unusual to have a 'defective' fiberglas spring....1-1,000,000 it's just really hard to make a defective part with this process.
Pull one Bilsteinand do a jounce and rebound test in your hands....if the valves were 'defective' you'd feel it.
Corvettes usually have (original Delcos) more rebound than jounce dialed in...for ride reasons....this is kinda why C-3 squats on take-off...also geometry.
Are the Bilsteins Yellow?
Tires are a spring....try firming up your tire pressures (rear)
I have a 360 lbs fiberglass in the 69 Convt....Bilsteins.....pretty firm. So you're like 12% softer.
Unkahal
Thread Starter
Racer
Joined: Jul 2017
Posts: 399
Likes: 115
From: chico ca
Yea it bounces. Shocks have less than 50 miles on them. If they were bad I would think I could have noticed before putting them on. I tried to load short video but can't quite figure out how. I am hoping it is just shocks? Do theses composite springs need time to wear in? Again there is about 50 miles on the whole suspension.
Pro
Joined: Jun 2014
Posts: 706
Likes: 294
From: New Jersey
Yea it bounces. Shocks have less than 50 miles on them. If they were bad I would think I could have noticed before putting them on. I tried to load short video but can't quite figure out how. I am hoping it is just shocks? Do theses composite springs need time to wear in? Again there is about 50 miles on the whole suspension.
As the leaves slide next to each other, they resist movement.
Look at your old leaf spring and you will see the wear points.
That wear is essentially a "friction damper"
The composite spring does not do that, so it is "bouncier"
Burning Brakes
Joined: Feb 2014
Posts: 1,045
Likes: 226
From: Cape Neddick Maine
2020 C3 of the Year Finalist - Modified
they do have different shock choices other than Bilstein's. Talk to some one that has something different with a composite spring. I have QA1 and they work good. They come non adjustable, single adjustable and dual adjustable. You could probably use the non adjustable super stocker style shock and be pretty happy if you decide to change shocks.
Burning Brakes
Joined: Feb 2014
Posts: 1,045
Likes: 226
From: Cape Neddick Maine
2020 C3 of the Year Finalist - Modified
both ***** are located at the bottom of the shock easy to get to you adjust both rebound and compression and tune to your driving style. Plus side is they are rebuildable and they are polished aluminum which adds to the cool factor. LOL
I use a VBP dual mount front and rear spring and have them both adjusted for the stiffest spring rate setting so I need to be able to adjust my shocks when I change spring rates....which isn't very often
I use a VBP dual mount front and rear spring and have them both adjusted for the stiffest spring rate setting so I need to be able to adjust my shocks when I change spring rates....which isn't very often
