Could this be the cause of my driveline vibration...?

[tHatOne guY]

Sup AZ, recently noticed some drive line vibes @ 40-60 mph around 2000 - 2500 rpm in 4th 5th and 6th gear. The vibes seem to be emanating from the bottom of the seat up to the steering wheel. It happens while accelerating and decelerating w/ and w/o brakes applied.

Recent work include all OE parts- clutch/DMF, front wheel bearings, all front control arms, trans mount, engine mounts. Before the work there was no drive line vibration. The engine mounts were leaking, the rest were ok.

In the pic it looks like the driveshaft is sagging or bowed in the middle. Everything else is tight like axles front/rear, steering rack bolts, all the mounts, sub frame bolts, tie rods, ball joints, snub mount are all new, OE and in good condition.

Have a look at this pic, let me know if you guys have experienced this before. And oh 2004 A4 1.8T AMB 6MT

Notice how the rubber is bulged at the bottom of the rubber mount, shouldn't it be uniform all the way around the drive shaft?

[coffeysm]

Try grabbing it and see how much play there is. I just replaced mine and I could bang it around in the housing. Everything looks relatively clean in your heat shield area, but what's that black blob in front of it?

[tHatOne guY]

Try grabbing it and see how much play there is. I just replaced mine and I could bang it around in the housing. Everything looks relatively clean in your heat shield area, but what's that black blob in front of it?

Good amount of play in there, when I grab the drive shaft just in front of the bearing I can move it radially a good amount. It moves so much so that I can get that bulge in the bottom of the mount to even out and look normal and not all squished like it does in the pic. I don't hear any bang noises though, not during driving or moving the shaft by hand.

That blob is a piece of road debri/asphalt that's baked onto the heat shield.

[tHatOne guY]

Look at this! found this video last night. I can move my driveshaft the same amount maybe a little more. Granted the video is of a B5 car but the principle should be the same for the most part.

https://www.youtube.com/watch?v=hSImsUmuxlk

[rollerton]

Honestly I think the center mount on the driveshaft is rarely the problem if you have vibrations. I've seen some that were literally wrecked and clunking around and they are just fine. Greater odds that it's one of the CV's at the end. Or a CV joint on the transmission, they see way more wear than the driveshaft that operates in a pretty narrow plane from horizontal, but always in a straight line.
It's always possible, but a total bitch to isolate driveshaft vibrations. You can always loosen the hanger there and shift it around a little bit, snug it back up and see if anything changes. There's an actual 'alignment' procedure for the driveshaft, but truth is the alignment is about as likely to fix a vibration there as just random chance.

[tHatOne guY]

All the CVs attached to the trans are tight, next to no radially movement and very little axial movement on the front half shafts. When the engine/trans were out I replaced the front drive shaft cv joint but not the drive shaft cv joint attached to the rear diff... If anything the rear half shafts have a little more radial play than the fronts. The right rear has the most of all.

There were a few posts of guys on here fabricating their own drive shaft alignment tool so, if need be that's an avenue I could take too. Pretty much will try anything before I spend money to buy a new drive shaft.

If I remove just the right rear half shaft and go drive the car that should indicate whether the problem was the half shaft or not right ?

[rollerton]

If I remove just the right rear half shaft and go drive the car that should indicate whether the problem was the half shaft or not right ?

Well. You could try that, and I bet there would be no vibration...becaaaauuuse....the car won't move if one of the axles is disconnected. You'd have to also lock the differential to the rear wheels to make FWD mode activate!

[tHatOne guY]

Ha! Was afraid of that. Guess I was thinking traditional transfer case, not Torsen diff.

[19jdog]

Sounds like center bearing issue to me.

[coffeysm]

I had tons of vibrations from the driveshaft and the rear tires would thump upon acceleration. I could also feel a nasty vibartion at idle like clock work, since I replaced the driveshaft all those issues have gone away. I need a CV axle in the front now, but that's not related to the other issues.

[tHatOne guY]

I had tons of vibrations from the driveshaft and the rear tires would thump upon acceleration. I could also feel a nasty vibartion at idle like clock work, since I replaced the driveshaft all those issues have gone away. I need a CV axle in the front now, but that's not related to the other issues.

Where did you end up getting your driveshaft from?

As I've been researching I have found a bunch of sources for a new driveshaft assy.

[coffeysm]

I found a used one on eBay for 100 bucks with about 40K miles on it - It was in perfect condition - ; I purchased the two gaskets and replacement bolts as well there.

I also replaced the output flange seal while I was down there, but it was a PITA taking it off. I had to take a MAPP blow torch to several of the bolts in order to loosen or even break them free, I also had to cut the head off one of the bolts. Then it was seized to the rear diff pretty good, so I had to pull the top half down, bang it with a BFH a little bit, and move it side to side to pop it off. Luckily, they're through bolts and you can do that, but I did have to heat up the shaft of the bolt and use some vice grips to unscrew it. They have some strong ass Loctite or something on them.

Make sure you have one or two extra allen head sockets if you do this and especially if you buy them from Harbor Freight, I broke one of them in half.

[tHatOne guY]

Yeah the factory stuff is patch lock and it is pretty strong esp after all the heat cycling over what 11- 12 years... hopefully propane will be hot enough if it comes to that. I really try not to heat anything on my cars but sometimes that's what it takes.

So I went ahead and ordered a new shaft assy from Amazon, it's a Dorman brand shaft. I couldn't get a new one from Audi like I wanted originally but there were some new Genuine Audi shafts on eBay a week or two ago going for 700ish shipped.

I chose the shaft assy route over replacing the ends and/or center bearing mostly due to the labor factor and by the time I pieced together a used shaft and all it's bits that could go wrong not including the unserviceable middle U-joint I'm already in the 400ish ballpark. To me a new shaft is the easy way out, now just hope that fixes my issue.

After I get it installed and aligned just right I'll be sure to report back what I find.

[claudiovagkraft]

I had the same symptoms as you and I totally thought it was the centre bearing but once we had it on the hoist and poked around it ended up being a torn front outer cv boot that had allowed the cv joint to go dry. Luckily I got away with the cost of new boot repair kit (new boot, clamp, grease, etc.) and labour and it was good again.

[tHatOne guY]

Well the entire front axle is re-booted completely. The rear seems ok but I haven't pulled them out to actually check for any excess play or binding/stiffness.

I feel confident it is prop shaft related whether it be the CV ends, the rubber mount deformation and allowing the prop shaft to bow, or the u-joint behind the center bearing gone south. The vibration just seems so fast paced and the fact it changes w/ and w/o load on accel and coasting not to mention the resonance it sends through the cab from the floor up.

If it is not the prop assy this will be one of my most expensive lessons learned yet.

[mkv]

Sorry to drag up an old thread, but did you ever solve this? Was it your driveshaft/propshaft after you fitted the new one?

Thanks

[2004a4b630QT]

Sorry to drag up an old thread, but did you ever solve this? Was it your driveshaft/propshaft after you fitted the new one?

Thanks

I just had mine out, and back in but it was for the center diff replacement and output shaft seal. Inspect your carrier bearing. When you grab the shaft and pull on in it to see if there's play. Mine still felt snug like the rubber bushing is still doing it's job but I can see it deteriorating. Usually if it moves too much and the rubber looks bad, it's the bearing.

Pay careful attention to @coffeysm post number 12, because everything he mentions that could go wrong did go wrong with me. The bolts have this bubblegum-like red loctite on them. I had to cut 2 off and destroyed my flange in the process (If you are TIP, read up on updated seal/flange). I also damaged my front boot and had to take the CV off and re-boot the front. If you reuse the bolts, you have to remove the old loctite and put new on or the accumulation of both will make sure they never come out again.

Getting the rear out of the diff was next to impossible. Also, secure the CV ends with a rag or something and then bag them after removal whether or not you plan to re-grease. If the joint rotates too much, the bearings fall out of the "puck", and you'll be repacking.