s4cp

Hi guys,

I'm getting a soft whine in the rear right wheel arch area which only comes on under acceleration above 60mph (100kmph) i.e. it is not engine rev related.

Its tempting to think that it is a wheel bearing or diff bearing but in a straight line those suckers should be sounding off under acceleration AND deceleration shouldn't they?

Any ideas what it could be without dismantling the whole rear end first? I'm guessing it may be CV or diff related but would be very happy to hear otherwise

Thanks

Rod

2000 S4 B5

Chris's S4

Have you done any serious hard turns or donuts recently? About a month ago, it was raining here for awhile and I found a parking lot that was turned into a pool. Fairly deep water, easily 6 to 7 inches deep. It was all good fun and all. Did some high speed runs through it, hard turns into it, and donuts as well. I later, few weeks that is, picked up a noise in the rear also. Mine is a grown while driving period. Doesn't get louder as I go faster, nor when I turn. So that would tell me it's not the diff area. I'm guessing the wheel bearing took a beating, and since it was already on it's way out (I'm guessing), this night in the puddle of fun... finally did it. I could be wrong, but who knows.. hopefully someone here knows better.

As for yours, under acceleration would say that it may be one of the cv joints. Kinda like when you make a turn with a front wheel drive car and all that load is there on that outside tire with a bad u-joint... it clicks like crazy. Well kinda the same thing here, but under acceleration load is when it does it for you. I haven't noticed mine doing that, but I'm on my way to my po box. So I'll report back in a little while.

Chris

jordonb

if at highway speed, you turn to the left, this will put stress on the right bearings... if the sound is louder, that is an indicator, then if you turn right, it takes stress off the right side... if the sound disappears, the bearing is the culprit.
i would also be wary of the fuel pump and fuel filter, as they are in that neighorhood as well.
when is the last time you changed the fluid in your rear diff?

Chris's S4

just went out the S4, to listen to the fuel pump. It's got a different higher pitch whine to it, than the one I'm hearing. Plus you definitely can't hear it up at the drivers seat. Unless the pump changes speed as your drive, which I doubt. It sounds like to that of a trucks big tire. But no oscillation, just smooth quick grown. It could be the bearing, or just the tire. I've have a noisy tire on another car before. Pops would always point it out.... I'll try the left turn again when I drive it some time. I'm riding the bike this whole week.

Gas is gouging me.

ECS Tuning-Audi

I'm going to have to say its a wheel bearing.

You can also tell its a bearing if you jack that wheel up and the wheel has any sort of side to side play the bearing is shot.

Jason

Chris's S4

well I guess that means I gotta change out thefront too. Side to side steering has a clunk under heavy oad. Nomal doesn't do it.

EuroXS4

Im my personal experience I've done both rear wheel bearings and replaced the rear diff.I had a issue where the pinion bearing was no good under light load from about 60mph to 80mph it whined anything below or above it was dead quiet.I ended up swapping another diff in because it was cheaper for me to replaced the diff rather than to tear the whole diff apart to replace the bearing and then have to set up backlash on the bearing and yada yada yada.

Try putting the seats down see if its louder.As far as wheel bearings go I would think that It would be a constant noise you would hear it all the time say highway speed 60mph till you stopped and the faster you went the pitch would change.Thats just my experience.

I know that s4 rear diffs do get the the rear humm from that pinion bearing especially if they have been driven hard for some time and have a significant amount of miles.

Chris's S4

Thanks EuroXS4, sounds plausible, and true on the repair. Definitely cheaper for another diff than rebuilding... but then again, how long would another hold up. mmm... maybe a diff swap, then rebuild original to put back in as new, that way less problems later down the road (again).

Thanks for the idea, with mine, it's just a constant grown. Doesn't get louder on the frwy, just stays the same. funny how that is. Could be just me and my hearing too... who know's, I blow **** up every year for the 4th. (I do professional pyrotechnics firework shows) hahahah

jordonb

that clunk is probably your sway bar bushings or sway bar linkages.
maybe time to get a complete control arm kit

Chris's S4

it's what I've been planning for awhile. Start fresh with all new rubbers down there. As for the sway bars or links... well I suppose I could jack it up and give them a wiggle. Thought about going with much larger sway bars before suspension. But read somewhere maybe here, about the rear actually breaking the rear subframe. makes me think twice now... sigh. Fronts were going to be 32mm and the rear something like 22m... it's a kit that ecs tuning has I believe. Hotchkis sway bar kit... Is that too thick?