knocking noise under the back of the car when cold??

Post by **booski** » Thu Sep 17, 2009 8:57 am

Has anyone had this experience, as in the title i get a knocking noise going over any slight undulation or bump in the road from the driverside back of the car. I have had several shocks replaced but when they failed i had a permanent knocking noise.
This knocking noise goes away after the 1st 5 mins of driving i.e once the car has warmed up???

any help/advice appreciated

Post by **pippyrips** » Thu Sep 17, 2009 9:28 am

Bit of a long shot but are all the exhaust mounts ok? It could be hitting something until it warms up and moves or.... DRC!

Post by **booski** » Thu Sep 17, 2009 10:15 am

i thought it might be the exhaust aswell....
I've recently had a new clutch fitted and the stealer charged me for some new bolts for the exhaust - when i asked why - they said that the exhaust had to come off to complete the clutch replace?? anyway as it was only 65p i decided not to argue.

BUT i have a milltek so it's possible they haven't re-attached it correctly?

Post by **pippyrips** » Thu Sep 17, 2009 12:57 pm

Check the rubber bungs..

Post by **P_G** » Thu Sep 17, 2009 1:00 pm

And tighten the retaining bolts that secure the back box to the bulk head. Mine did this when one of the back boxes only had one of the two retaining bolts and it was gradually unscrewing itself and boucing up and down becaus of the slack. 20 seconds with a socket set tightened it up and took it back to Audi to have a second bolt put in again.

Post by **booski** » Thu Sep 17, 2009 5:12 pm

Turns out it's the dreaded shocking/knocking DRC..... One of the rear ones have exploded!

Post by **CHRISKL** » Thu Sep 17, 2009 5:28 pm

If not exhaust - DRC?
I had something very similar quite recently - intermittent knocking (metallic sounding) from underneath the rear end. Drove me crazy for a day or two as it would happen on small bumps and ruts - it was more noticeable (sound wise, but not handling wise) especially at slower speeds in side roads etc and especially after the car had stood for a while. At faster speeds, on motorways and when warmed up it more or less disappeared only to return later. Took an Audi Mastertech out in it for 45 mins and the car refused to replicate the problem when the guy was with me. Next morning it was back again. Audi took it in anyway and the Mastertech found that whilst the DRC was generally OK one of the rear shocks was not holding full pressure (it would only hold partial pressure), changed the seal part and re-pressurised - and I've not had any probs since.
Good luck.

Post by **booski** » Thu Sep 17, 2009 6:20 pm

booski wrote:Turns out it's the dreaded shocking/knocking DRC..... One of the rear ones have exploded!

Thanks for prompt advice guys

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knocking noise under the back of the car when cold??

knocking noise under the back of the car when cold??

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RE: knocking noise under the back of the car when cold??

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