'Thunk' heard when turning or going over bumps

S

superiormirage

Member
As the title says: when I turn the car at speed, I hear a loud 'thunk' coming from the front. Same when I go over rough roads or bumps.

It doesn't happen at low (parking lot) speeds, nor does it happen when the car is stopped and you turn the wheel.

I suspect a front suspension component. Any suggestions on where to start?
 
Failing front shock top mounts can commonly cause this. I advise going only for OEM or other top make if this is the case. When carrying out a full front suspension refit as precautionary maintenance, I fitted brand new cheaper top mounts from Germany and the continual 'thunk' drove me mad until I took the shocks off again to check the new top mounts and found that the metal housing around the bearing and rubber was slightly smaller diameter than the OEM mounts I removed, which was causing metal to metal fouling as the shocks compressed when going over rough roads or small corrugations in the road. New BMW top mounts cured the problem. I should have known better and bought these in the first place.
 
Is it possible to diagnose a worn shock top mount without removing the strut?
 
Not sure it is as mine has been in the garage for a similar thunk recently. Everything they could check without disassembling the front end had been checked and they can't find the problem - though they can hear it. Next step is apparently to take it all apart :(
 
Midhurstman said:
Failing front shock top mounts can commonly cause this. I advise going only for OEM or other top make if this is the case. When carrying out a full front suspension refit as precautionary maintenance, I fitted brand new cheaper top mounts from Germany and the continual 'thunk' drove me mad until I took the shocks off again to check the new top mounts and found that the metal housing around the bearing and rubber was slightly smaller diameter than the OEM mounts I removed, which was causing metal to metal fouling as the shocks compressed when going over rough roads or small corrugations in the road. New BMW top mounts cured the problem. I should have known better and bought these in the first place.
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Would this cause the noise when turning?

Thanks for the idea.
 
I would say the most common cause is drop links, check they are tight and see if they have play along with arb bushing condition. Could be top mount but that should be obvious to see. Could also be any of the wishbone bushings.
 
Bing said:
Not sure it is as mine has been in the garage for a similar thunk recently. Everything they could check without disassembling the front end had been checked and they can't find the problem - though they can hear it. Next step is apparently to take it all apart :(
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Are you sure there isn't a clog in there somewhere rolling around :lol:
 
It didn't specifically cause the noise when turning but it was a bit worse when turning and going over a bump than driving straight over the same bump. If the top mount rubber around the bearing is splitting then it can sometimes be seen without a complete dismantle. From memory, this problem was featured on an old wheeler dealers episode when Mike bought a BMW (M5, I believe). On the test drive he described such a thunk and mentioned it to the seller who said it had been diagnosed as front top mounts and that he had a new pair in the boot. When fitted later by Ed, the problem was solved. A noise of this type could of course be other faults such as drop links as has been suggested, possibly worn front ARB bushes or several other possibilities.
 
I would say rear wishbone bushes cold cause this too, my car made a similar noise when mine went.
 
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