Suspension: What's rattling?

[Moosejaw]

My 240 has a rattle from its rear end, more from the driver's side. To describe the noise I'd say it's it's a deep pitch clunking sound, audible almost constantly when the car's moving, but not a particularly loud or violent one.
My 'man who can' has had a quick look when the car was up on his ramp last week, and after yanking on all the suspension arms, bars and brackets, can't find anything obviously loose or badly worn.
Are there any known spots where these cars develop rattles that aren't immediately obvious when you're looking for them? There were three of them on the job, one bouncing up & down inside the car, another hauling on the suspension, and one listening carefully.
The car's booked in on Wednesday to get its leaky gearbox fixed, any guesses where the search might be concentrated?

[redboy]

just a guess- could it be exhaust rattling against the axle or undercarriage?? Its on the driver's side. These can resonate against the undercarriage and produce strange noises.

[Skunkola]

Could it be an item in the o/s storage compartment under the boot floor? Other than that if nothing's loose then the exhaust touching the bodywork as suggested earlier sounds about right. Mine did once and rattled my bones all over shop...

[Moosejaw]

I hadn't really thought of the exhaust, but I'm pretty sure the exhaust's on the nearside/passenger side on my car, and the noise seems to be coming from the o/s.
It does sound more like something that's not part of the car's sprung mass hitting anything, if you know what I mean.
I'm fairly certain it's not anything in the boot either, the noise seems to be coming from underneath the car rather than in it.

[wooble]

A common cause of clunking from rear suspension is worn out bushes on the upper control arms on the axle, I've seen it on my 240 and a customer's, it's not always evident when the car's on a ramp as the weight of the axle hanging on the arms restricts the movement and the bushes themselves are hard to inspect without removing the arms.

The customer who had this problem had bushes worn enough that when moving off, the axle was visibly moving about 1/2 inch forwards and backwards on the offside when moving off and stopping. It's not a particularly expensive repair, the bushes are about £8-10 each and they're fairly easy to fit.

Could well be an exhaust too, as others have said, it runs up the offside of the car then crosses over to the nearside right after the axle.

[honestjoe]

Hi moosejaw..do you hear a clunk when pulling away from stationary..There are quite a few bushings fitted in connection with the rear axle..as described above..axle bushings..panhard rod bushings and the reaction rod bushings..all can cause the clunk you are describing ..My axles bushes were completely trashed but still would have not seen the extent of the damage had i not had to remove trailing arms..(hard to see them)...hj.

[Clifford Pope]

Does it go away if you touch the brakes? I've always found them very prone to brake pads rattling on the pins, and the pins chattering in the caliper.

[Moosejaw]

No clunk when pulling away from rest, and it doesn't stop or get worse when I brake, accelerate or turn.
It's a much heavier noise than would be produced by brake pad pins too.
Like all noises it's hard to describe in words...
It's a deep, bassy clunk that happens all the time the car is moving, unless the road is billiard-table smooth, imagine a rat-a-tat-a-tat noise but deeper-sounding. Something fairly big is hitting something else fairly big, repeatedly, but without much force. May be the exhaust rattling against something, it's that sort of sound or some suspension part knocking on something else.
The suggestion of it being the upper control arma is something I'll pass on to the garage tomorrow when it's in, if these are hard to see from underneath it's possible they might have missed them.

[honestjoe]

also get them to check front wishbone bushes..these behave exactly like you described when worn out...cheers hj.

[PTJS]

I had and still have an interesting rattle which I eventually found the cause of. One of the retaining clips securing one side of the offside rear seat headrest had broken allowing the headrest to rattle when going over rough surfaces. This is one thats quite a way down the 'to do' list.

I get a clunk from the rear axle. Its not the hand brake shoes settling as I've adjusted these. So it looks like the anti roll bar bushes or more likely the reaction rod bushes as I have noticed there is quite a gap in the bush/its housing when I took the offside rear wheel off.

Cheers

Phil