Wheel Vibration/bump bump bump When Slamming the Gas pedal

[ThoreauHD]

OK, So I think I know what the cause is, but I just wanted to make sure I'm not out in left field. I have a 1994 530i with the originial OE springs and new OE sachs shocks. I think my springs may be causing this, bit I'm not completely sure.

When I slam the gas pedal on this V8 I hear the right rear tire sound like its grounding out on the fender- and bump,bump,bump,bump and then stops when it levels out. Is this a pretty clearcut case of crap springs? Anything wierd on the backend that I should poke at?.. that didn't come out right. Any other components that would cause a bottoming out at quick acceleration, or is replacing the springs gonna fill the bill. Thank you.

[Alexlind123]

Wheel hop?

[632 Regal]

maybe with NoS...lol
Wheel hop?

dude inspect it and see whats up, kinda sounds like a CV joint or guibo.

[Blitzkrieg Bob]

turned out to be the eight 1LB propane tanks I had in the trunk.

[ThoreauHD]

It sounds more like the wheel is hitting the top of the wheel well. But I can't see it because I'm driving. Is this what a bumpstop is for?

[BillionPa]

yes, but it shouldnt hit the bump stop if you are just accelerating, unless the shocks are dead.

it could be one of the moto.........

sorry, just read your post again, the rear end is dead!

[Ausmpower]

Subframe bushes?

CV?

Guibo?

Check those first!

[John 535is (Sydney)]

Check the subframe bushes. Put the rear on ramps, take the plate off that covers the subframe bush on the side that makes the noise, then jack the car (body) up at that point as high as you can.
Inspect the subframe bush, it should be still nice and round and fully intact. If it has twisted and looks to be coming apart -it is.
If not, while the car is kacked up, slip you fingures between the top of the subframe bush and the car body. If there is sticky rubber, thats becuase the thump is the subframe bush hitting the car body under the rear seat. Either way, time to replace. - Check the dogbones while your under there too.

If not (and with the car only 10+ years they should last longer), try checking the other items Ausmpower suggested, as well as the centre drive shaft bearing. If the rubber around the centre bearing housing has failed, the driveshaft will distort under acceleration and the shaft bangs on the support surround. This feels more like its hitting under the drivers deat than the rear seats though.

If not any of the above - back to the spings or the shock mounts.


John 535is (now with new dogbones, centre bearing and subframe mounts).

[ThoreauHD]

Thanks guys. I know what to look for now.