Have a problem with Vibration on the back of my car

[S4]

Yes am thinking Rear hubs or bearings...

I would not think that both sides would be gone... usally just 1 side will brake down before the other.

Darren

[buzzard]

hard launching can damage or even bend and twist half shaft/drive shafts
not so easy to diagnose but all that torque of a modded motor can put a serious strain on standard gear

[BRETTCOLLINS]

Swopped the wheels front to back and it has made no difference. the wheels do spin freely. At a loss now....

[boxerdogted]

Possible prop shaft. Center bearing worn or missaligned shaft.
Does it vibrate without braking ?.

[rolskii]

hows the condition of rear bushes(lower-outer + upper outer) ...? condition of rears shocks ...
could be a drive shaft worn in excess that its getting a bit gyroscopic effect and/or inner diff. bearings from stubs ..?
how are yr diff/subframe mounts ..? looking past the obvious now....

[quattronutter]

get the car up with all 4 wheels free to rotate,try driving/braking with someone observing to see if anything becomes obvious,had similar troubles in the past with different cars

[grizz]

Try a brake pipe clamp on one of the rear flexi pipes ,then on a quiet road at slow speed brake and see if you still have a judder ,then try it on the other one .

[BRETTCOLLINS]

Possible prop shaft. Center bearing worn or missaligned shaft.
Does it vibrate without braking ?.

Only vibrates when braking, there is no vibration under hard acceleration, cruising speed or turning.

[rolskii]

do the pads pass the inner edge of the disc ...?
do the pads overhang the centre of the floating disc ..? ..... enabling the pad to grab the underside edge of the disc ...?

do the pads sit in the carriers too deeply and extend pass the inner edge of the braking area ...?

[BRETTCOLLINS]

will check this today. but as i said. don't think that it has anything to do with the brakes. because after changing all rear calipers, pads, discs and hoses. the problem i still there.

going to try clamping each hose on the rear later, to see if i can work out which side is the problem.. (good idea grizz) thanks

[Blue_Thunder]

Did you get anywhere with this Brett?

[BRETTCOLLINS]

have all the bits to fit (very large box), just haven't had the time yet. set of rear hubs, new rear wheel bearing, All top and bottom rear arms, Full powerflex bush kit, 034 motorsport Engine, Gearbox and rear Diff mounts.

[Blue_Thunder]

Ah, so wasn't a quick fix then?

[BRETTCOLLINS]

Don't know what is the problem, Could me a couple of things. So just fitting everything at once and help it goes away.. LOL

[BRETTCOLLINS]

update on this problem. once we took the rear hubs and arms off the car, we saw that the lower bush that sits in the rear hubs were in very bad condition. Ps: theses bushes don't come in the poly bush kit. so off to audi to get a set....