Rear suspension bottoms out under hard acceleration.
01-12-2015, 01:48 PM
#1
Rear suspension bottoms out under hard acceleration. I'm having a problem and want to know what I can do to fix it. My Z28's rear suspension is bottoming out under hard acceleration. I'm running Nitto 555r's out back on stock suspension. The car's mods are listed below. Under hard acceleration in first gear, the car's front end lifts in the air a lot and I can feel the rear end hit what would be the bump stops. The bump stops have worn out and are no longer there. This happens again on the shift into 2nd gear. It is not the transmission mount/bushing, checked that and its intact. Once 2nd gear bottoms outs, I can feel the car lurch forward like its twisting or something. This is on the street mind you, I haven't taken it to the track yet.
The car has 77K miles and is in great shape. Will Strano lowering springs, Koni shocks, adjustable panhard rod, tubular rear lower control arms, lca relocation brackets, front/rear sway bars, 3 point subframe connectors, tubular torque arm, and a strut tower brace help my problem? The car is a weekend street car and not a track car.
The car has 77K miles and is in great shape. Will Strano lowering springs, Koni shocks, adjustable panhard rod, tubular rear lower control arms, lca relocation brackets, front/rear sway bars, 3 point subframe connectors, tubular torque arm, and a strut tower brace help my problem? The car is a weekend street car and not a track car.
01-12-2015, 02:11 PM
#2
I'd definitely look into your stock bushings on your PHB & LCA first, and if they are warn out I'd look into replacing them with what ever suits your needs.. This is also one of the reason when I upgrade personally I use heim Joints, a lot longer life over rubber and polyurethane.. As long as you use a quality heim joint that is..
01-12-2015, 02:31 PM
#3
Out of all the parts you listed, the ones that will fix your problem will be rear shocks, relocation brackets, tubular lower control arms, and the torque arm. It sounds like your rear shocks are worn and have lost some of their compression resistance, so a shock upgrade will help, as well as increasing control arm angle and inducing anti-squat will help keep the rear from dropping. The stamped steel lower control arms and torque arm can cause the "twisting" or "lurching" feel you get under hard acceleration. They tend to twist and deflect, then spring back to their rest position. This can cause some strange movements in the rear. If you are keeping it primarily a street car, poly bushings will be a great improvement over rubber while maintaining ride quality.
01-12-2015, 02:37 PM
#4
Out of all the parts you listed, the ones that will fix your problem will be rear shocks, relocation brackets, tubular lower control arms, and the torque arm. It sounds like your rear shocks are worn and have lost some of their compression resistance, so a shock upgrade will help, as well as increasing control arm angle and inducing anti-squat will help keep the rear from dropping. The stamped steel lower control arms and torque arm can cause the "twisting" or "lurching" feel you get under hard acceleration. They tend to twist and deflect, then spring back to their rest position. This can cause some strange movements in the rear. If you are keeping it primarily a street car, poly bushings will be a great improvement over rubber while maintaining ride quality.
01-12-2015, 03:47 PM
#5
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I would replace the front shocks also. If they are extending to fast the sudden weight transfer can overwhelm the rear shocks and springs. This is ok for a drag car but problematic for a street car. Also if you want to fix the bump stops just search on here. There are some universal ones that will fit with slight modification and are much less expensive than the OEM ones.
01-12-2015, 06:01 PM
#7
TECH Senior Member
The stock shocks makes these cars feel so loose, unplanted, and "flexy". Koni SAs will have the car feeling super solid and tight.
Im making the same power as you (+20 extra ft.lbs) and have no such issues on my Koni/strano setup. The car hardly has any weight transfer (which is SO nice). Just stick and go, no drama.