Revisit an old issue....rear end chatter on hard acceloration.

[Aronis]

Hello all,

I asked this a few years ago but no one had any experience with a similar issue. I waited until more cars had lower suspensions and more miles on them.

About the time I lowered my car, I began to feel a chatter in the rear of the car on hard acceloration. At first more so when turning and accelerating. Now it's on straight runs and mainly on the passenger side as best I can judge. It's a chatter I can feel but cannot hear anything.

My mechanic thought it was the universal joints making the chatter due to the lowered suspension and a new contact point being established in a non-worn area of the joints.

Anyone have anything similar? I hate to have a catastrophic sudden failure.


The rear differential was serviced at that time, new lubrication, and the rear clutch packs were 'ok'

Thanks,

Mike

[Bigglezworth]

Check for rubbing from the bottom spring seat on the drive axle. Should be an obvious rub mark that has removed the paint on the steel shaft and possibly steel also...

[MaxRS6]

You might consider chasis ears to help specifically isolate the noise location..

http://www.denlorstools.com/home/dt1/page_10333/how_to_find_squeaks_and_rattles___chassis_ears.htm l

[DHall1]

Both cars lowered and never an issue.

If your running oe rear half shafts...consider a new set of raaxles. At your mileage...it wouldnt hurt.

Then i would inspect the coupler in the driveshaft if the above doesnt fix it

[ben916]

Stick a gopro on the right side to "listen" and record.
If you get one with the wifi battery pack, you can d/l the gopro app and connect to the camera via wifi and view things while driving.

[hahnmgh63]

Mike, I've been running my KWV3's at a lowered setting for at least 5yrs with no issues. I started out too low but ended up raising it a little. Might come up another 1/8"`1/4" before my next alignment.

[Aronis]

thank you for the feed back, I'll check for wear.

Mike

[hahnmgh63]

Have you ever changed your rear diff fluid?

[vas160s]

I am not sure if I am experiencing the same issue or not but I hear a noise coming from the back only in 1st when accelerating hard every 5 times or so. It's like a "TRRRRRR" for 2 seconds and goes away. Car not lowered and rear diff fluids have been changed.

[RSoverAll]

Have you ever changed your rear diff fluid?

Any recommendation on fluid ?

[hahnmgh63]

I use Redline 75w-90 in the front & rear Diffs and Redline 75w-90NS in the Center Diff. Although, Redline now recommends MT-90 for the diffs so I have an E-mail out to them to ask them why the change.

[hahnmgh63]

Just got this reply from Redline:
Mark,

Thank you for contacting Red Line Oil, in the past Audi has called for a GL-5 gear oil in their Quattro rear differentials, now most models specify a GL-4.

Regards, Dave
Red Line Oil

* I think I'll stick with the GL5 in the differentials.

[vas160s]

Bump. Did you ever figure the noise issue out? If so what fixed it?

[Falltboat]

vas160s I believe I have the same issue as you. Have not been able to figure out what it is. Mine started immediately after replacing the TQ converter. only happens when under more than about 50% throttle from stopped (or just about) around 3100-3150 rpm in 1st gear (auto, sport, and manual). Feels/sounds like its coming from the rear end. I did some "tests" on snow a few weeks ago and I did not hear any noise at all, when I returned to pavement it was the same. It used to be 4 distinct "chatters", I just did a 75k mile service ($$$$ Tbelt and associated toys) and it feels more like 5-6 chatters now, but much softer. Drive-train is stock, no tunes, lowering or anything.

[vas160s]

vas160s I believe I have the same issue as you. Have not been able to figure out what it is. Mine started immediately after replacing the TQ converter. only happens when under more than about 50% throttle from stopped (or just about) around 3100-3150 (tel:3100-3150) rpm in 1st gear (auto, sport, and manual). Feels/sounds like its coming from the rear end. I did some "tests" on snow a few weeks ago and I did not hear any noise at all, when I returned to pavement it was the same. It used to be 4 distinct "chatters", I just did a 75k mile service ($$$$ Tbelt and associated toys) and it feels more like 5-6 chatters now, but much softer. Drive-train is stock, no tunes, lowering or anything.

Yeah sounds like it. Wonder wtf it can be....I don't want to just start replacing parts that don't need to be replaced. I took it to my guy and he was not sure without having to tear into it. Only happens in 1st gear and only when pushed a little hard.

[Other_Erik]

Only happening in 1st gear on hard acceleration? Low revolutions / high torque... Thinking out loud, maybe your diff mounts aren't holding your driveline steady / allowing flex? I'm lowered on KWV3's and haven't heard any chatter, but then I'm not sprinting out in 1st, couldn't afford to grenade my trans.

Words of wisdom o' the day: "Everything on this car was engineered to fit together exactly one way, and they didn't leave enough room under the hood for a battery. Tight tolerances are tight for a reason. Tight is tight, too tight is broke, no threads is better than cross-threads. If it doesn't fit back together like it was made to occupy its current space, you've probably gone and bungled it. Have patience, take it apart again, and put it back together again, until it slips into place like it was meant to be there all along. If you have to force it, you're doing it wrong."

[vas160s]

Yeah the harder it's pushed the louder the noise in my case....and only in 1st. Does not seem to cause any other issues and the car runs like a champ otherwise.

[vas160s]

So my euro shop that has looked at this advised that it's most likely the drive shafts and since I have a warranty that covers transmission, we are going to drop it and do a complete rebuild. Beast has 133k on it and from what we can see never had any major tran work done. Any suggestions on what to avoid? The car runs strong now other then that noise in 1st gear that this post is originally about. I have 3k in warranty money to spend and figured this is what I should spend it on. I am nervous as hell and excited at the same time lol.

[Aronis]

Yes, i spoke with Raxles,,,,they actually have an FAQ which discusses the very same chatter issue, it's from worn CV joints. LOL....

Mike

[vas160s]

Yes, i spoke with Raxles,,,,they actually have an FAQ which discusses the very same chatter issue, it's from worn CV joints. LOL....

Mike

did this fix your issue? Not sure we are experiencing the same thing or not but interesting. Is this FAQ Available online to read?? Thanks man.

[Aronis]

I did not replace them yet......

This was the quote from Raxles.....


"The axles for your 2003 Audi RS6 are $249.95(fronts)and $299.95 (rears) per side. Please keep in mind when comparing prices that at Raxles™ we use NEW outer AND inner joints on all of our VW/Audi axles. (An industry exclusive) (See our website www.raxles.com/nogrind.htm .For further elaboration on this important fact)."

I am waiting for my car to be back on the road before I spend another dime on it.......

Mike

[Aronis]

http://www.raxles.com/troubleshooting.aspx

See the trouble shooting table.....

Shudder while acceleration or deceleration. Worn inner CV joint. Replace worn shaft assembly.

[Bigglezworth]

A misaligned center drive shaft will product similar vibration if the joints are out of phase.

[vas160s]

A misaligned center drive shaft will product similar vibration if the joints are out of phase.

Yeah my issue is the same one falltboat has but diff then Aronis. Only noise is coming from rear end in first only when pushed just a bit harder and only on acceleration. Eh...rebuilding the trans and replacing shafts, torque converter etc can only help at this point I guess. It's more annoying then anything else.

[P1054]

I'm with Bigglezworth on this one, do yourself a favor and at least check the center support bearing. Easy and free fix if it's just out of alignment.