rear end knock on deacceleration

[bazpro88]

got a bit of a problem with my 3.0 z4.
changed the rear springs few days back for some eibach ones ( fronts still to do ) done about 50 mile and car has been fine.
got in it today and took it to the jetwash, cleaned it and now whenever am not on the accelerator theres a knocking noise coming from the rear that matchs the speed am going, gets less the slower I go.
if I depress the clutch and coast it does it all the time.
checked the drive shaft when I got home but don't really know what to look out for, the noise sounds like the shaft or something hitting off the car.
seems odd its come all of a sudden, hat no knocks previous to today.

 

[firebobby]

What happens when you brake, is it still there? If it's only happened since jet washing, sounds like you have dislodged something and it's either brake related or rubbing on the drive train.

 

[bazpro88]

i think the noise was still there when i broke but cant be 100 % sure.
went out for a short journey in it and the knock had pretty much gone.
going to get it on the ramps and looked at today.

 

[firebobby]

Pressure washers are good, but they can do damage too, I don't like them personally. My son has one and I have warned him not to get to close to brakes or seals with the jet.

 

[dhobbs]

Have you checked your wheel bolts?
I did this years ago where I hadn't done them up properly and gave a knocking on deceleration.
I learnt to check and double check.

 

[bazpro88]

i havent but will go check. it isn't making the noise all the time which is odd.

 

[bazpro88]

it was the driver side rear wheel like dhobbs suggested.
bolts weren't loose but by no means tight either, so torqued them up and checked the rest which where fine and problem has gone.
cheers mate.

 

[Scooba_Steve]

Easy win