Rear "clunking" sound

[Draculaw]

Picked up my first MCS yesterday and realised there's a somewhat strange clunking sound over bumps coming from the back. I probably should've noticed on the test drive, but we are where we are; was more focused on how the car drove at the time.

There's no difference in feeling, and the MOT had no advisories last week, so I'm fairly confident it's not something structural or suspension/wheel related. However, I did notice when cleaning the car the aero kit at the back seems like it has a lot of flex. I'm assuming that's not intentional and there's a clip or similar which has come loose causing it to clunk.

Separately, I'd like to have parking sensors installed for peace of mind (although I've never had an easier to park vehicle). Can anyone recommend a good place? I'm in Surrey and know of Cartronics who seem to do OEM Mini, but seem very expensive (although if they could also look at the body kit if that's the issue I wouldn't mind).

[johnoz]

Rear roll bar bushes worn, common problem..

[E-bmw]

Or ARB drop-links.

Add on parking sensor kits are barely more than £10 on ebay & easy to fit.

[Draculaw]

OK, I'll run it round to the garage at the weekend. Wouldn't they have picked up roll bar bushes on an MOT, at least as an advisory? I know my partner had to get his sorted for it to pass.

I've 0 mechanical skills, so wouldn't feel comfortable fitting myself. Was looking at Dolphin sensors which are about £170 colour matched which seems OK.

[sad61t]

Just check it's not the two rear parcel shelf weights. They hang down and bump against the rear wheel arches when you drive enthusiastically.

Yes, I did feel stupid when I went to the dealer a week after picking up the car.

[E-bmw]

Draculaw said:

Wouldn't they have picked up roll bar bushes on an MOT, at least as an advisory? I know my partner had to get his sorted for it to pass.

Perhaps they should, if that is what it is, yes. However it isn't always easy to replicate the forces that a car will put on suspension parts when using a pry bar by hand.

[Draculaw]

sad61t said:

Just check it's not the two rear parcel shelf weights. They hang down and bump against the rear wheel arches when you drive enthusiastically.

Yes, I did feel stupid when I went to the dealer a week after picking up the car.

Unfortunately not did a quick test and the weights would contact the arches, but still clunked when I removed the shelf entirely. Called the garage earlier and as soon as I said Cooper S rear clunk he went to bushes, so I'll take it round tomorrow for a look.

[sad61t]

E-bmw said:

Perhaps they should, if that is what it is, yes. However it isn't always easy to replicate the forces that a car will put on suspension parts when using a pry bar by hand.

Hopefully you're using a test centre with a suspension test rig (about £10000) rather than some bloke taking a pry bar to your pride and joy.

[R53rider]

Probably one of the rear drop link ball joints has a tiny bit of play. No, extremely unlikely they would have picked it up at the MOT. I do know what I'm doing mechanics-wise and the noise was so loud, so deep, so consistent I was convinced it was the exhaust hitting the body - BIG, chunky noise. Massively irritating. Turned out it was a drop link ball joint. Taken off the car the play in it is infinitesimal, almost imperceptible, when you wiggle it by hand.

Second, rear parking sensors. I had them fitted to my MCS. I didn't want wires etc running to the front - trim never seems to go back properly. So the beeper is in the boot. And that is fine. Got the kit from the company in Woking who specialise in these. Names a give away - Parking Sensors!! I got the Dolphin DPS400 Kit. Great price, great quality. Works. Here is the link:
https://www.parkingsensors.co.uk/product/dolphin-a...

Hope that helps.

[Draculaw]

Took it round earlier. Bushes are done for but the drop links fine. Other downside, however, started blowing blue smoke after idling for a while. Google suggests that's bad.

Going to get the bushes sorted Friday and try to book it into BMS Surrey on Saturday for a once over. I got a decent price on it, and I feel like I'm finding out why...

[csd19]

R53rider said:

Probably one of the rear drop link ball joints has a tiny bit of play. No, extremely unlikely they would have picked it up at the MOT. I do know what I'm doing mechanics-wise and the noise was so loud, so deep, so consistent I was convinced it was the exhaust hitting the body - BIG, chunky noise. Massively irritating. Turned out it was a drop link ball joint. Taken off the car the play in it is infinitesimal, almost imperceptible, when you wiggle it by hand.

Hope that helps.

Ironically I had a similar knock from the rear and it turned out to be the exact opposite, only after replacing the rear ARB bushes and drop links did I clock the clonk was due to worn exhaust rubbers. Over a certain section of road it would knock on the bottom of the car but I'd read about the bushes and droplinks so had been convinced it was those.

Some new OEM exhaust rubbers and the car became silent again... well apart from the usual rattles etc!