HELP - Knocking sound from the rear!

[Jsomerville]

My E85 has developed a knocking / clunking sound from the rear of the car. It's only noticeable when coasting at about 5mph but is fairly loud.

Checked springs and rear top mounts so thinking it could be diff related. Can anyone shed any light on this?

Thanks in advance!

 

[Jfgoldfish]

The first question has to be - have you removed everything from the boot? :wink:

Some people *ahem* chase suspension knocking noises when there is actually just junk flying around in the boot.

Ok fine... it was me I promise I only wasted a few hours on it!

 

[Tich]

Also check the front, wife said knocking in the boot, turned out to be a front drop link.

Phil :?

 

[Wookster78]

Could be the rear diff bush, they are subject to quite hard wear and need changing on higher mileage car, mine had a cluck/knock when going into the reverse and the rear bush was shot. Have a look at the top bush for signs of any cracking.

 

[Jsomerville]

Thanks for all the feedback guys! Tried the empty the boot trick and alas no luck!

Brand new front drop links so at least that is ticket off.

Will check the diff bushes, thanks for that Wookster

 

[Wookster78]

Also check the rear sway bar mounts and links and they can sometimes cause a knock

 

[mjennings23]

My experience of rear knocking is that it's often the rear control arm bushes or the suspension top mounts. The drop links on the rear are pretty hardy and the diff bushes can fail, but a bit less common

 

[Jsomerville]

My experience of rear knocking is that it's often the rear control arm bushes or the suspension top mounts. The drop links on the rear are pretty hardy and the diff bushes can fail, but a bit less common

Will check those as well thanks! Rear control arms are fine so could be the bushings. Would you recommend switching to powerflex?

 

[ph001]

Exhaust rubber mounts?

 

[Any1else]

Battery not secured properly?

Have you changed anything in the rear suspension?

 

[enuff_zed]

Is the knocking regular or random? Does it feel related to wheel rotation, or happen more over bumps, or when you brake/accelerate.

 

[Spriteracer]

Another candidate is rear subframe bushes. Mine is currently awaiting the fitting of a new set along with diff bushes as soon as I can get the car to my indy in London. It knocks from the rear over bumps etc. and on unmade roads at v. low speeds. Everything else has been checked or replaced over the last year or so. Indy found the bushes moving when "driving" the car with wheels off the ground on the ramp. Car passed MOT with no issues so not that obvious.

 

[Jsomerville]

Is the knocking regular or random? Does it feel related to wheel rotation, or happen more over bumps, or when you brake/accelerate.

It sounds like it is wheel rotation related as it doesn't happen over bumps. It's very audible at slow speeds whether using the accelerator or just coasting

 

[Jsomerville]

Battery not secured properly?

Have you changed anything in the rear suspension?

Battery is fine, changed rear shocks recently but the noise was there before. Thought it was the rear top mounts bit fitted new ones.

 

[Any1else]

Battery not secured properly?

Have you changed anything in the rear suspension?

Battery is fine, changed rear shocks recently but the noise was there before. Thought it was the rear top mounts bit fitted new ones.

I asked because I had a knocking when I changed the shocks and it turned out that I had put the bump stop washer on upside down under the rear mounts. My noise was going over bumps though and wasn’t linked to the wheel rotation. Good luck.