Drivetrain vibration

[Bigglezworth]

Had been driving with an slight vibrations for the past few months due to a trio of things (tires that are wearing out, balancing weights that have come off, a slightly bent rim after plowing in to a pothole, and the occassional instance where the rims pile up with debris on the insides after driving through crappy weather and rocks/dirt. etc buildup). Yes, call me lazy I guess for not getting any one of the trio of things rectified to eliminate the slight vibrations, but knew that I was going to be swapping rides here at the end of April with winter finally releasing it's grip on this part of the world and spring finally coming.

Well, as luck would have it I couldn't wait that long to swap rides. I was driving up to one of my job sites on Tuesday when I noticed a more pronounced vibration than just those that were clearly wheel situated. I cannot however discern for certain what it is. The vibration is significant under load/acceleration. There is no vibration when simply cruising in neutral which leads me to believe it's bearing related. If it was drive shaft related it would do it irrespective of being in gear or not. I had just replaced the tranny in this particular car 4 months ago and it's been just fine. I just parked the car on Wed evening and am going to take a looky underneath it later in the weekend. Time will tell if it's something obvious or not.

With the crude description provided above, does anyone else have any insight on where to focus my looking at? If I was a betting man I would bank on it being a U-Joint, but we'll see I guess.... lol

[Beardown1]

Possibly front lower rear control arms? (The curved ones) Only reason I say that is because mine need replaced and a similar vibration issue is driving me crazy.

[hahnmgh63]

Rubber in center support bearing on the main driveshaft disintegrated?

[4.2Crew]

Rubber in center support bearing on the main driveshaft disintegrated?

My thoughts too... Had similar symptoms on a 2001 4.2L A6 with the culprit being the center support bearing.

[mik15]

^ what they said, i am pretty sure too it's prop-shaft related, however i heard different stories regarding the bearing, Audi says it can't be replaced separately as in a BMW for example, but you must get the whole prop-shaft which comes with the bearing and flex-joint, my buddy has the same issue and he narrowed it down to the prop-shaft and he is now about to pull the trigger to get a new one.

[ttboost]

Mine did that when I needed tires. Jack it up and check your wheels bearings.

[Brav]

center drive shaft (carrier bearing), or control arm bushings, as mentioned. I ended up replacing both.

[Bigglezworth]

So, there's good and bad with owning tooooo many rides..... Good that you are never without, but bad that you put off repairs until a later date. With winter approaching in the next 6-8 weeks in my part of the world I am looking to get the winter ride ready so that I can do a simple plate swap. I had a bad shimmey in the spring that was only under acceleration and felt worse when the vehicle was 'loaded' with people and luggage. I checked my center support bearing and while wasn't disintegrated, it 'felt' loose'ish to me. I elected to swap it out. As many an owner know, Audi doesn't sell the center support bearing by itself and instead only offer the entire driveshaft assembly for stupid $$$$. I decided to source the bearing through 034 Motorsports. Ended up having them confirm three times with measurements and descrptions on how the bracket needed to mount. They confirmed the one from the B5 S4 V8 would work. So I purchased it..... Got it a few days later in the mail and of course it wasn't a direct replacement.... Sigh. After various excuses from the seller I simply kept it and went ahead with a mod plan. I didn't want to piss more $$ down the drain with return and possibly the same result with another. Was optimistic I could simply use presses and vice to bend the bracket in to a new shape and make new holes as necessary. After a valiant attempt I got really close, but alas the pre existing holes on the one end of the bracket were off center and even with drilling a new location I wouldn't have sufficient metal left to ensure a solid fastening point. Accordingly I elected to do a hybrid by cutting the arms off the old bracket and mounting them on shortened arms on the new. In the end the size and bolt-up was bang on.

As for the bearing removal and retrofit, it was straight forward and without problem. I marked the two drive shafts clearly to ensure realignment was bang on (otherwise you would be out on your balance), and then modified an el-cheapo 17mm box/open end wrench by grinding things down so that the wrench was only and 1/8" thick. That facilitated loosening the 17mm bolt and once it was cracked, it simply backed out as you pulled the yoke further apart. Cut the bracket housing clear from the bearing and then used a tie-rod puller to pull the bearing off. All in all, it was a solid 3 hour effort including the grinding of the wrench.

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Oh, and BTW the vibration is still there - albeit less. Have replaced all upper control arms already, so on to lowers and then report back. lol

[mik15]

wouldn't this have been a good replacement? http://www.ebay.de/itm/Kardanwelle-Zentrum-Lagerabstutzung-Audi-RS6-Quattro-30x15mm-227MM-71MM-Neu-/131181344345?pt=DE_Autoteile&hash=item1e8b047659

i have also found this if need it: http://advancedautomotion.com/shop/product_info.php/cPath/65_70_77/products_id/126

[lswing]

I had a bad shimmey in the spring that was only under acceleration and felt worse when the vehicle was 'loaded' with people and luggage.

Bigglez, this would be some vibration felt in the car/steering wheel under heavy/WOT acceleration correct? I've always had some "shudder" under WOT, and it seems to increase with more weight in the car as you mention. Center support bearing is the main culprit to address sounds like. Any other spots to look for? Thanks!

[RSoverAll]

Inner CV joints worn maybe...? more specifically the fronts.

[pohsib]

Have you ever removed your subframe bolts? I had a bad shake at around 80-100kph and I replaced the 4 main subframe bolts. Almost all of the vibration went away. I will try the other 4 for the engine mount brackets and see if that takes care of the rest.

Other places I'm looking at are the hubcentric adapters for the Hartmann DTM-RS4's I have. They are plastic so I figure it may be damaged and causing a slight wobble if the subframe bolts don't fix the issue. I may opt to try the 3M window bond fix for my center bearing if all else fails.