"Bouncy" rear end...
Thread Starter
Intermediate
Joined: Jun 2006
Posts: 26
Likes: 0
From: Kennesaw Georgia
"Bouncy" rear end...
Greetings all! I've got an '81 that a previous owner had installed the "Grand Touring" suspension kit from VPB. than kit came with a new fiberglass spring and the Bilstien Sport shocks. The problem is that the rear end is bouncy or has a pogo effect when I go over bumps..almost like the shocks have no rebound. I'll hit a bump that the front has no problem with and then the rear end d*mn near flings me out of the seat! When I push on the back of the car it seems to rebound too freely...allmost like there are no shocks. Here is the list of what the kit came with from VPB site...
http://www.vbandp.com/detail.aspx?ID=481
What I'm finding on the forum suggests that the bilstein sports do the trick with the fiberglass springs so I'm at a loss. Any advice would be very appreciated.
Thanks
Jerry
Name: Grand Touring Plus System 1980-82
ID: 42001O
Category: C3 Corvettes 1968-82
Manufacturer: Vette Brakes & Products, Inc.
Desc: The kit features: 1.125" front and .750" rear Addco¨ anti-sway bars, 460 lb/in powder coated coils, 330 lb/in Composite Monospring, Bilstein¨ Sport gas shocks, Poly-adjustable Strut Rods, and Monospring hardware kit.
Here's a link also...ID: 42001O
Category: C3 Corvettes 1968-82
Manufacturer: Vette Brakes & Products, Inc.
Desc: The kit features: 1.125" front and .750" rear Addco¨ anti-sway bars, 460 lb/in powder coated coils, 330 lb/in Composite Monospring, Bilstein¨ Sport gas shocks, Poly-adjustable Strut Rods, and Monospring hardware kit.
http://www.vbandp.com/detail.aspx?ID=481
What I'm finding on the forum suggests that the bilstein sports do the trick with the fiberglass springs so I'm at a loss. Any advice would be very appreciated.
Thanks
Jerry
Safety Car
Joined: Apr 2007
Posts: 4,435
Likes: 9
From: Kalamazoo Mi
the bilsteins are the way to go, you could have have a dead one, or both. Sounds like bad shoks, but bilstiens usually last a very long time. Take them off, its realy easy to do, and compress them, if you can do it without much effort, they are bad.
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
I experienced the same problem with my TRW #330 composite on my 69 ...sort of a weird lope or bounce when hitting bumps at highway speed...(something I never experienced with my 78 SA FE7 steel spring)...so I purchased a Guldstrand 7 leaf for my 69 and the problem is gone...
New Guldstrand 7 leaf/Bilstein Sports..
TRW with KYB's
Rich
New Guldstrand 7 leaf/Bilstein Sports..
TRW with KYB's
Rich
Premium Supporting Vendor
Joined: May 2000
Posts: 4,312
Likes: 70
From: Clearwater FL
The problem is the shocks, not the spring. There is to much rebound in the Bilstein shocks for a 330# spring.
You have 2 options, upgrade the spring to a 360# spring or go with KYB GR-2 Shocks that are valved for the fiberglass spring.
If you want a little stiffer spring in the rear, I would call VBP and ask them if they will sway the spring out. Keep the better shocks.
You have 2 options, upgrade the spring to a 360# spring or go with KYB GR-2 Shocks that are valved for the fiberglass spring.
If you want a little stiffer spring in the rear, I would call VBP and ask them if they will sway the spring out. Keep the better shocks.
Thread Starter
Intermediate
Joined: Jun 2006
Posts: 26
Likes: 0
From: Kennesaw Georgia
I guess I don't understand (my ignorance on display). It seems to me that the shocks are not preventing/minimizing the rebound and that's what leads to the bounce I feel after a bump. The car does sit low...could it be that the shock is not within proper operating parameters?
jz
jz
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
It is true shocks dampen the oscillation of the springs after the wheel travels over bumps and dips.......
Call VPB and tell them you are experiencing this "oscillation",bounce following a bump...they supplied the entire kit to you......can't hurt...
Rich
Call VPB and tell them you are experiencing this "oscillation",bounce following a bump...they supplied the entire kit to you......can't hurt...
Rich
Last edited by rihwoods; Jan 2, 2008 at 05:35 PM.
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
The problem is the shocks, not the spring. There is to much rebound in the Bilstein shocks for a 330# spring.
You have 2 options, upgrade the spring to a 360# spring or go with KYB GR-2 Shocks that are valved for the fiberglass spring.
If you want a little stiffer spring in the rear, I would call VBP and ask them if they will sway the spring out. Keep the better shocks.
You have 2 options, upgrade the spring to a 360# spring or go with KYB GR-2 Shocks that are valved for the fiberglass spring.
If you want a little stiffer spring in the rear, I would call VBP and ask them if they will sway the spring out. Keep the better shocks.
My 71' did the same thing when I bought it (TRW plastic spring installed by PO). Went with the KYB GR-2 Shocks and it is much improved (but still not as stiff as a steel spring).
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