Rattling Noise from back near left wheel. Shocks replaced but noise returned a few weeks later, any ideas?

Question

Had the left rear shock replaced 4 months ago as part of NCT test. After 3 months knocking noise came back. Had the shock replaced free under gaurantee. A few weeks later the knocking noise is back.

Tried to google, and got some info re shock mounts?

Might this be the problem ? anyone any ideas, is it likely to be something costly?

Answer 1

If the noise was temporarily cured by replacing the shock each time then it sounds like you have found the likely cause. Depending what vehicle you have (helps to say what the car is), what I would do when I worked as a wrench was have someone drive me over a bumpy road (or better still a bumpy parking lot) whilst I sat/lay in the rear seat/trunk/hatch area and listened and felt around to pinpoint the source of noise. Then look for any visual evidence - rub marks, chafing, shiny spot, and anything that feels loose when yanked hard. Suspect you may have a shock mounting bolt that is not tightening up sufficiently or is loosening over time. These are often supplied with self-locking nuts top and bottom...check/confirm that the nuts are as new as the shock that was fitted. When fitting shocks it is a good idea to use a bit of lubricant on the top and bottom bushes to help ensure they fully seat during installation - to avoid the bush seating under load in service and then the nut is no longer tight.

Good luck and happy motoring!

Answer 2

There are a number of rubber mounts on the rear suspension, depending on what type of vehicle you have. (It helps to tell what kind of car you have: they are NOT all the same!!~!!!)

It could also be exhaust mounts.

The trick is to get under it while someone bounces up and down on it and listen for the noise. A piece of hose (I have a mechanic's stethescope) can help isolate the noise.

Answer 3

ball joints? or shock mounts

Answer 4

possibly bearings.. also, this sounds daft but check all the wheel nuts are in place.