knocking from rear

[EThreezero]

alrighty all!!

ive developed a knock in the rear which only occurs when i pull away in first. it sounds like prop or diff area. im hoping someone else has had this problem and can direct me on what to do to save me having to explore. cheers geezers.

[astondg]

I think I have this too. I haven't narrowed it down to the any particular area but it is from the back somewhere. It is just as I get to the grab point of the clutch and start to move forward, something makes a knock sound. I thought maybe it was a little bit of play in the driveshafts from the diff or something, although my diff was rebuilt completely about 1 1/2 years ago so I'm not really expecting any problems from it and it still seems to grip just as well (LSD). I have been using it for a lot of racing though.

The other thing I thought after a couple of threads recently is that it might be the shock absorber mounts? I don't know when mine were last replaced and like I said I have been doing a lot of racing and on rougher dirt surfaces too. I think they would knock all the time though? Maybe they do, I'll listen more carefully next time I drive it.

Sorry I haven't helped but if anyone can help us both that would be great.

Thanks,

Aston

[jb81]

check your rear beam bushs, diff bush, and rear swing arm bushs, thay can all make knocking noises from the rear when seting off, swing arm, and diff bushs are ok to do but beam bush can be bad as the beam can be hard to remove from the car, hope this helps and good look sorting it out

[astondg]

Thanks!

I think my diff bushes were replaced with the diff about 1 1/2 years ago, but probably worth checking. Trailing arm bushes were replaced with polyurethane ones recently. Are beam bushes the same as sub frame bushes? I really have no idea. If not where are they?

What about your bushes toitliketoiger? Replaced recently?

Aston

[stuartgallafant]

ive got the exact same problem on my 318iS. ive had it for ages and its pissed me off so much, but ive just gotten used to it.

a while ago, i replaced my centre bearing and prop donut, as they were knackered. when i put the exhaust back on, i had rotated too far one way, and it was really close to the spare wheel well. when pulling away or turning hard left, it knocked on the wheel well. i took it down and put it back on again, and its been fine, although like i said, i do still have only slightly.

however, checking your top-mounts (at the top of the rear shocks), your rear axle mounting bushes and your traling arm bushes would also help you to determine the fault

let me know how you get on mate

[calder]

astondg - is your noise when you pick up drive when moving off and also when changing up a gear? Could be loose diff mounting bolts to the rear sub frame.

[jonbuoy]

The problem you are having is the UJ between prop and diff, they gradually wear out and this is caused by wheel spinning and is not a replacable seperate part. The prop must be changed but you can pick one up for about Ԛ£20

[astondg]

astondg - is your noise when you pick up drive when moving off and also when changing up a gear? Could be loose diff mounting bolts to the rear sub frame.

I don't get it when changing gear, only from a standing start. I'll check those parts, thanks.

The problem you are having is the UJ between prop and diff, they gradually wear out and this is caused by wheel spinning and is not a replacable seperate part. The prop must be changed but you can pick one up for about Ԛ£20

Ok I'll check that, thanks. I never get wheelspin during normal road driving or even on the bitumen race tracks when it is dry. I have on the road 3 or 4 times when it has been wet. BUT I go to autocross (dirt circuit) often where I get fair bit .

Aston