debo

I have a C6 Z51 lowered on stock bolts and I've been having problems with my car being unstable when driving over bumps or hitting a dip. The rear-end will sway from side to side as if something is not right. I've done a few searches but couldn't find any info. I'm wondering if someone can tell me what is causing this problem whether it's shocks or rear-end bushings? Any help is appreciated.

RicK T

Is this a brand new problem?

First thing I'd look into is the alignment. While they're working on that they can check the rear cradle and suspension mounts. Then I'd suggest new, and better shocks, if you don't already have good shocks.

AORoads

They can also check to see if you have a broken rear spring, worn sway bar end links/bushings, or leaking shocks.

debo

This problem is not new, it's been going on for over a year and I'm finally able to diagnose. I will get my alignment checked with a visual inspection underneath to see if the problem can be identified. Thanks for your help.

Dano523

Nature of the z51 shocks to a degree (but have the alignment checked, and maybe even 4 corner balance done to make sure that you have the corners weighted correctly when you blindly lowered the car).

Also to point out, with the car lowered, you now have less upward suspension travel, so don't confuse a minor dip that still have the suspension still with stroke, and a bad dip that is putting the suspension against the stop buffers to cause problems with not enough suspension stoke instead.

Back to the shocks, and the z51 shocks have a lot of charge to them, so the back end tends to loose grip more than normal on hard dips and bumps than other shocks (will hold the car stable in the corners, but have that nasty habit of unsettle when one of the tire does dip down rapidly via bumps and dips).

The Koni's are really good to settle the car back in during such, and as for the DRM Bilstein, have not had a chance to buy a set and check them out.

And back to the less stroke you now have from lowering the car, depending on how far down you lowered the car, and if you are bottoming out the suspension now, may need to go to stronger cross springs so you are not bottoming out ever hard dip/bump instead.

debo

My car was lowered 1" on each corner, thank you for the feedback.

cclive

If the car was lowered without being re-aligned, then that would contribute to the problem. Also all the oem shocks exhibit this to some extent. I found a big improvement when I went to Bilsteins.

debo

cclive, what's a good location to purchase Bilsteins?

cclive

I found mine on Ebay...$300 for the set, shipped. But there are lots of places online. I have had mine on since 2008, so they have gone up a little. eshocks.com is a thought also.

debo

Thanks for the feedback.....

hrt vlv

Installed Koni sport shocks on my c4. the dampening was adjustable. They are a bigger piston/ bore. Had 3 setpoints, first time I used the 2nd setting, way to hard for pa. roads. second time was the first setpoint that was just right. rear shocks had to be removed to change setpoints. front shocks the adjustment could be accessed from under the hood. I believe it was Duhamel,said "there is only one correct setpoint"

61X

My money is on a bottoming out suspension as Dano commented .

Dano523

If you are going to go with Bilsteins, get the DRM Bilsteins that have been valved better for the vet than the standard Bilsteins.

With poly bushings, they are only $475 for a set.
http://dougrippie.com/products/c6-co...hocks-for-c6z/