Hi guys ever since i had my little fight with the kerb and my drive shaft and lower arm replace something strange has been happening. wondered if you can shed some light on the subject...

whenever the engine is at 4k rpm and i mean only 4k rpm no higher no lower i get a slight vibration in the steering wheel and the engine note gets deeper and this is either under load or when i just rev it to 4k standing, i have no idea what it is as it only happens at 4k rpm and no where at any other revs

thanks guys its a weird one

Not that weird. It's resonance, is all. Could be caused by something loose (bolts,shields,panels,engine mounts,exhaust mounts etc. the list is endless), or a worn mount/bush. Or there could be nothing wrong whatsoever.

How bad/annoying is it?

+1 to something slightly loose. I bet it happens at 2k rpm as well, just so faint as to not be noticable.

Similar to how a wheel balance vibration at eg 25mph is also bad at 50.

Hope you find the source, id say just get underneath with some spanners and tighten everything a little.

+1 to something slightly loose. I bet it happens at 2k rpm as well, just so faint as to not be noticable.

Similar to how a wheel balance vibration at eg 25mph is also bad at 50.

It doesn't always work exactly like that, but it is to do with harmonic content. For instance, if the resonance occurs fundamentally at say for arguments sake, 1kHz, you will notice diminished vibrations at 2kHz and 4kHz, which are second and third order harmonic distortions of the original resonance.

i shall just tighten everything then just got concerned as it does it when in neutral aswell, most likely something loose and the driveshaft ect was just replaced

I shall get the wrench out when its sunny and tighten it all i just tested to see if it did it at 2k rmp and it does lightly

I had a feeling ;-)

in terms of annoyance its only a bit annoying ill just tighten it all up its very noticable at 4k but once your past it no probs so i dont get too bothered unless im in 5th gear and plant it

It'd be even worse at 8k RPM. Probably followed by a f'kin great big bang!

You might end up having to go through the car with a fine tooth comb. Even something like a loose panel/wing can easily cause such resonance. Tuning forks come in handy for when you are really struggling to find the culprit.

well that takes the mick i know it will be something envolving the driveshaft, lower arm and anything to do with the replacement of those items

Well start there for definite, but don't assume that's where the problem lies. It really could be anywhere.

If this was my own car, I would be inclined to check the engine mount on the kerbed side to make sure all is well there as the shock/force of the impact may have partially split the mount.

With you bashing car on one side with enough force to damage bottom arm then its prob shifted subfame slightly,

I would loosen subframe on its bolts and make sure none of the bolts are bent and resonating into car, subframes only made of pressed steel you may have damaged that slightly