Reverse and thump

[Attero]

When reversing and fully turning, I often hear a thump. I'm not particuarly sure what it is. I'm always concerned I'm hitting something, but then I think I'm sliding... but none of that's true.

 

I'm wandering if it's anything to do with suspension or any bearings? I don't know.

 

I'm going to get it checked, but does anyone have ideas? It's always happened.

[Morpheus]

Lsd

[Attero]

Any more info on that. Am I suppose to expect this from the LSD or it unusual and needs to be checked?

[Nic]

Check the sub frame bolts and suspension arm bolts.

[Morpheus]

Any more info on that. Am I suppose to expect this from the LSD or it unusual and needs to be checked?

 

If the thump is a regular 'grabbing' feeling on one wheel, that feels and sounds like someone's lightly hitting the tyre on the 'outside' wheel with a hammer every couple of feet on full lock or tight slow corners, then it's your diff letting go to allow the outside wheel to turn faster. Perfectly normal, as it allows a different turning speed for each wheel but grips enough to prevent one wheel from losing grip altogether and spinning while the other one doesn't, hence, limited slip.

 

You'll notice the car jerks slightly too, as you turn, even forwards around tight bends but always at very low speed, otherwise it's unnoticeable.

Edited December 21, 2010 by Morpheus (see edit history)

[Chris Wilson]

If it's from a front tyre it's the castor giving extreme camber change and the tyre being scrubbed over the ground. It is apparent in reverse only due to outside front tyre having a huge amount of negative camber and being more heavily loaded than the inside front tyre. Mercedes were notorious for it as they ran a lot of castor angle. Low profile, square shouldered tyres make it worse. just one of those things.