SCL

I'm not sure if this is a new problem, or if I am somehow just noticing it...or if I am imagining things.

If I have my foot on the brake, and shift from drive to reverse back and forth, the transmission or final drive seems to clunk a bit. It's not the axle shafts, CV's or center drive shaft. If I had to guess, I'd say there is slack in one of the three differentials -- or as I mentioned, maybe it's always been like that. I'm just not sure. I also feel a bit of a lag when on/off the gas at slow speeds, such as in stop and go traffic.

I'd love to hear back that this is completely normal and they all do that. :-|
It a 98, 4.2 A8 Quattro w/180K on it, and it runs excellent otherwise. But now I wonder if it's nearing the end. :-/

silverd2

Someone who really knows will probably chime in, but I think some rotational play is normal in the rear differential (I hope so). My car ('01 A8) has always had some...didn't notice it so much in driving as actually grabbing the drive shaft (when changing a leaking output flange seal) and rotating it several degrees back and forth with the parking brake locked...all the play was in the diff...any in the rear CV's would definitely be abnormal.
I can't find a spec (if there is one) anywhere in Bentley or elsewhere, stating how much (if any) rotational play is normal.
Maybe Gabor (TozoM8) knows...I'll be he does.

SCL

thanks for the reply -- If you get a chance, open the door and shift from drive to reverse and back again while stepping on the brake...and tell me if you notice that sound of the slack in the drive-train.

I recently started driving the car more often...and also driving in traffic more often...and so I am not sure if this slack was always there or if it's getting worse. I suppose I can just ignore it and see. :-/

ltooz_a6_a8_q7

I've not felt anything with mine 98 175k miles. If it drives smoothly why do you care about the clunking, the only clunk I would hear is parking on the drive way with the incline and move from park to reverse.

Cheers,

Louis

SCL

It's just something I noticed, and now it's been bugging me for a few weeks. I was starting to like it again after getting 4 new tires and some other things. I've fixed everything else, but it also needs a front bumper and a windshield...and so I wanted to at least inquire about this before I spend more money on it.

Thanks for the reply.

audinutt

I experienced the same exact symptoms... I went on a road trip and it got much WORSE. I drove 1000 miles and then it became very apparent I had an issue.
It ended up being the cv joint on my center driveshaft was dry.
I found a wrecker local (60 miles) and changed it at a relative's house.

I would recommend repacking the driveshaft cv's if the sound is coming from this area.

I believe I could have saved the joint if I would have addressed the issue earlier.

-Richard

silverd2

Sounds like more of a question of making a sound than the presence of rotational play. Mine does not make a really noise rocking from D-R-D...just the usual automatic "feel"...BUT, I would challenge (request) anyone to reach under there and grab the drive shaft while parking brake is set, shifter in park, twist the shaft and tell me you have NO rotational play. There can't be play (zero, by the nature of their construction) in a CV joint, so anything felt should be the rear diff...I've always thought this normal, esp if you don't have some sort of "rock crusher" competition diff.

I'm curious...check it out...unless you're allergic to getting dirty

P.S. More clunk could also be the result of a harder engagement in the transmission, making normal slack much more noticeable. In normal operation , the shift from D-R-D should be cushioned a bit.

ltooz_a6_a8_q7

Audinut,
Booking flights from Dallas to SFO or SJC 2 weeks in advance would be cheaper? Just let me know. I'll be picking up the car today.
Believe it or not, I sold my 91 Alfa Romeo on the forum to a member who flew from Washington State. I was nervous, but the guy got home safe and sound and loved the car.
Although it's great now, but it's 175k miles, anything can happen. I'll update the condition up until the day you plan to fly over. BTW, silverD2 mentioned about the headrest, I checked yesterday, the driver still works, but the passenger doesn't, I remembered I fixed both of them. You can fix it again when you get the car for your passenger.
Do you want to get the 4 17" wheels, very nice condition for extra $200?

Cheers,

Louis

SCL

Good point. I noticed this morning that it didn't make so much noise. maybe it's only noisy when it's hot? I'm sure there is play is in the diff.
thanks again for the feedback.

SCL

gee... I hope that doesn't happen to mine, :-| thanks for the warning though.