putting power down on rough surface

[lennon]

My car has a hard time putting down power on any bumpy/rough patch. Mostly noticeable in corners, but happens in straight lines too. The bushings are fairly new OEM rubber. H&R race/Bil Sports, stock sway bars. The car has an LSD in seemingly good shape.

I'm not sure how to best describe the problem, but it feels like things get shaky back there over rough patches. It feels like it's wheel hopping under even moderate acceleration. Only a problem with rough pavement.

What's causing this and what do I need to do to fix it?

[Jean]

Disconnect rear sway and see how it goes....quick/easy/cheap.

[lennon]

Yeah i'm about to, but I don't think that's it. I'll report back with an answer. In the mean time... any more ideas or at least a probable cause or what direction I should be looking? Stiffer bushings?

[L8 apexr]

Usually that describes a bad shock(s),if the shock is weak or the spring rate too stiff for the valving the wheel isn't controlled over the bumps.

[lennon]

well the shocks are pretty new (purchased new by me within the last couple years), but i've never really been happy with them. if it is indeed a shock problem, what is my solution? have bilstien re-valve them? what is the process for re-valving? i tell them the car info/weight, spring rate, and they fix em up?

edit to add: the car also feels rougher/stiffer in the rear over bumps than the other e30s i drive. it feels almost solid back there over some rough bumps. running 205/60/14 tires, and Ireland Engineering rear shock mounts. the more i type the more i think i need better shocks/these need re-valving...

[Jean]

Yes, you ship them and they get re-valved, turn-around time is about 2 weeks usually.

What tires are you running?

[lennon]

A few different sets with no change. On street, falken ziex 912. Auto-x, falken azenis, yoko es100, dz101 on 15" wheels, various crap tires. I really only mentioned tire size to say that I use 14" wheels so I have a lot of tire cushion.

[Emre]

I'm not sure how to best describe the problem, but it feels like things get shaky back there over rough patches. It feels like it's wheel hopping under even moderate acceleration. Only a problem with rough pavement.

Could be a worn diff bushing. Or even a driveshaft issue, like a bad guibo or bent/unbalanced driveshaft.

[lennon]

almost everything is brand new in this car, pretty much redone down to the body. so all bushings/guibo/csb/etc are new. i guess i will focus on the shocks.

[JRKOUPE]

ruff rider

anything loose back there?...


how bout condition of subframe bushes?...


rear shock mounts?...

[joshh]

Usually that is a shock problem. The rear tires might also be losing some grip with the surface. In which case you would normally adjust the shocks softer.

[shiboujin]

Usually traction troubles in rough surfaces means you're setup is too stiff <_<. I'd go with disconnecting the rear sway bar.