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Garna

"Donk" noise when I reverse

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Hi all, I have done some searching and I have come across a lot of people saying they get a clunk when they engage reverse gear or first.

My issue isnt when I engage but in reverse, about a second after the car has started to move I get a "donk" sound. I also get the donk very occasionally when changing down from third to second as I'm slowing down.

I have changed the guibo/donut and the rear diff mount and it is still the same. To me it does sound like a mount has failed somewhere but I can't tell which one or where, although I do think it's diff related.

I took it to an independent bmw garage and they told me it's "just what bmws do" but I'm not convinced.  It doesn't seem right. It's too loud and frequent.

If I'm honest it's just annoying, it doesn't sound right and I want it sorted.

Any help is appreciated,

Cheers.

 

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I had an ongoing issue like this, turned out to be the rear brake pads moving slightly in the carriers, have tried a few sets now inc genuine ones, still did it until a bit of manipulation with a large club hammer [emoji108]

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Garna - did you find the source of the noise?

I get the donk / clunk / tap sound when in reverse gear and the clutch bites. It only occurs when power is being transferred to the rear wheels. The car was MOT'd this week and I fully expected a failed bush or brake issue to be flagged, but it passed with no advisories!

To test this I did the following - at standstill with engine running engage reverse, keepi clutch depressed, open drivers door as wide, lean out of car to help listen out for clunks. Let the clutch out fairly quickly, until feeling it bite, then push the clutch pedal back in. At biting point I hear the clunk. Sounds like a claw hammer tapping a piece of scaffold tube. Slightly hollow metallic tap / donk. Sound seems to come from the rear.

So where is the first place for me to start investigating? Examine rear brake pad seating first? Then bushes in the rear axle area? ...then examine the propshaft guibo?

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Noise remains FB.

Since posting the above I've replaced the rear shocks and springs - initially the noise disappeared and I was pretty smug about having fixed it. A couple of weeks later I hooked up my small 3ftx4ft aluminium camping trailer in order to take a pile of garden waste to the local tip (I like to keep the boot clean), fully laden it must have weighed 100kg at most. Anyway, in the days after that tip run the noise reappeared! 

I strongly suspect the rear brake pads are moving slightly in their friction clipped seating, haven't had time to get the car up onto stands and investigate. Ashamed to admit last time I replaced the rear pads and discs it was with some cheap chinese components sourced from fleabay - I've since realised the benefit of paying a bit more for better quality parts.  

Bought a pair of febi RTAB's, as many owners report they typically last 60k and mine has covered 150k. Any play in those would surely cause a noise to emanate from the rear underside.  Need to buy a bushing puller before tackling that job.

Again from research on forums another possibility is a worn propshaft guibo/coupling, which when past it's best begins to flex/stretch slightly when power is transferred thru it, causing a clonk sound. 

  

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5 hours ago, B.Merr said:

Noise remains FB.

Since posting the above I've replaced the rear shocks and springs - initially the noise disappeared and I was pretty smug about having fixed it. A couple of weeks later I hooked up my small 3ftx4ft aluminium camping trailer in order to take a pile of garden waste to the local tip (I like to keep the boot clean), fully laden it must have weighed 100kg at most. Anyway, in the days after that tip run the noise reappeared! 

I strongly suspect the rear brake pads are moving slightly in their friction clipped seating, haven't had time to get the car up onto stands and investigate. Ashamed to admit last time I replaced the rear pads and discs it was with some cheap chinese components sourced from fleabay - I've since realised the benefit of paying a bit more for better quality parts.  

Bought a pair of febi RTAB's, as many owners report they typically last 60k and mine has covered 150k. Any play in those would surely cause a noise to emanate from the rear underside.  Need to buy a bushing puller before tackling that job.

Again from research on forums another possibility is a worn propshaft guibo/coupling, which when past it's best begins to flex/stretch slightly when power is transferred thru it, causing a clonk sound. 

  

i had the same clonk,then after quite a while it really went,shaking at 20 mph and above,as if gearstick was going to pop out,changed the centre prop beairng as that was the problem,then few weeks later im getting the same clonk,i never changed the propshaft guibo/doughnut as it was fine, said the lad who changed it,but im wondering if its on its way out and the new centre bearing was masking the doughnut clunk for a little while,but my bet is it is propshaft related.

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