Extreme Vibration Issue under acceleration, please advise
Thread Starter
AudiWorld Member
Joined: Apr 2007
Posts: 143
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Extreme Vibration Issue under acceleration, please advise
Good evening fellow Allroad fanatics,
I'm having an extreme, whole-car vibration under acceleration and am baffled. Clues:
1. Vibration is more pronounced the lower the car is. For diagnosis purposes, I lowered it 30mm below stock lowest and the vibration is extreme. At higher suspension levels there is no vibration.
2. Ride is silky smooth while not accelerating.
3. No clicking when turning either direction, forward or backing.
4. With vehicle on the ground, rear axles both have play when I yank on them, front are tight.
5. My butt senses that the vibration may be coming from the front but I can't be sure.
6. I'm thinking front CV joints. But how can I be sure? And which side?
7. Wheels are recently Road Force balanced.
Get this, I've got access to a fully-equipped shop and an on-staff mechanic who can provide full support (so long as I do the actual work). So what do I need to diagnose the problem, what parts should I order, and where should I get em'?
Thanks a bunch, again!
I'm having an extreme, whole-car vibration under acceleration and am baffled. Clues:
1. Vibration is more pronounced the lower the car is. For diagnosis purposes, I lowered it 30mm below stock lowest and the vibration is extreme. At higher suspension levels there is no vibration.
2. Ride is silky smooth while not accelerating.
3. No clicking when turning either direction, forward or backing.
4. With vehicle on the ground, rear axles both have play when I yank on them, front are tight.
5. My butt senses that the vibration may be coming from the front but I can't be sure.
6. I'm thinking front CV joints. But how can I be sure? And which side?
7. Wheels are recently Road Force balanced.
Get this, I've got access to a fully-equipped shop and an on-staff mechanic who can provide full support (so long as I do the actual work). So what do I need to diagnose the problem, what parts should I order, and where should I get em'?
Thanks a bunch, again!
Senior Member
Joined: Aug 2001
Posts: 7,956
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Too much ! You said 30mm below factory specs? Ain't gonna fly, you are riding on the frame and it
will damage the car. If you have used the instruction from allroadfaq written by Neb, then you'll see that 20mm wasn't even tested. 30 is more then pushing it. Undo the 402 and then post again, otherwise I'd think an engine mount or similar would give you such vibs.
AudiWorld Super User
Joined: Oct 2003
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If you are 30MM below the specs. you are stressing the CV Joints...
along with many othe front end parts. The fact that its eliminated when you are a higher level backs this up.
Do Reverse 402 MOd ASAP and get all 4 corners back to spec. as in NEW...402MM from the fende lip to the center of the hub on level 2.
Then see how you ride is at all levels.
Do Reverse 402 MOd ASAP and get all 4 corners back to spec. as in NEW...402MM from the fende lip to the center of the hub on level 2.
Then see how you ride is at all levels.
Thread Starter
AudiWorld Member
Joined: Apr 2007
Posts: 143
Likes: 1
Re: Too much ! You said 30mm below factory specs? Ain't gonna fly...
OK, I'll put it back to factory spec height. I only lowered today and took a short test drive for diagnostic purposes. You see, I noticed that at the lowest factory spec height (my usual driving position) that the vibration was pretty faint but that when I would hit a dip in the road and the suspension would compress, I'd get a good feel for the vibration. But it was too fleeting to diagnose. So I figured if I lowered it, I'd be able to ride in the "shake zone" longer than if I was just hitting the end of a dip in the road.
In conclusion, I'll put the suspension height back at factory defaults where I've always had it. I only lowered it for a short test drive and got the data I needed. Nonetheless, the issue remains whether I'm at factory default heights or 30mm below that. It's just much more pronounced at the lower setting.
Engine mounts? Really? If I were holding the engine in my hand I can't imagine it would shake as much as my car is shaking...
Thanks again for your feedback. I am always impressed with the collective wisdom of the Allroad owners in this group.
Best wishes,
-Josh
In conclusion, I'll put the suspension height back at factory defaults where I've always had it. I only lowered it for a short test drive and got the data I needed. Nonetheless, the issue remains whether I'm at factory default heights or 30mm below that. It's just much more pronounced at the lower setting.
Engine mounts? Really? If I were holding the engine in my hand I can't imagine it would shake as much as my car is shaking...
Thanks again for your feedback. I am always impressed with the collective wisdom of the Allroad owners in this group.
Best wishes,
-Josh
Thread Starter
AudiWorld Member
Joined: Apr 2007
Posts: 143
Likes: 1
Re: If you are 30MM below the specs. you are stressing the CV Joints...
Once again, I promise to restore factory suspension heights tonight. I only lowered the car for a temporary diagnostic road test today. The vibration problem is there even at factory ride heights. It's just more pronounced the lower I set the ride height. It's also more pronounced if I'm towing and it seems more pronounced if cornering. In summary, the 30mm lowered ride height is not the problem. The problem was there even before I lowered the car at all.
Thread Starter
AudiWorld Member
Joined: Apr 2007
Posts: 143
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Re: Check the play on the inner CV joints - particularly on the front axles.
I've not been able to detect any play while yanking on the front CV joints. The rear axles, however, both have some play in them. Should there be any play?
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New Member
Joined: Jul 2005
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I have exact same issue-tech advised to replace both front axles....
as mine shakes like a **** from 30 mph+ only under acceleration, otherwise silky smooth. Motor mounts ok, alignment and balance ok, so need to replace front axles per my tech.I have 99,000 miles on my 2001. I myself have no clue, so I hope he's right. You might have a pro take a drive and inspect. Also see posts here regarding Raxles if that's your problem too, a much lower cost replacement option than OEM.
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Senior Member
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Trust me on this, BTDT, once the gel is out of the mounts, they are rock solid ;-)
But going down the road chasing this vibration, it could have a few causes. The main drive shaft has the bad habit of vibrating screws lose, specifically the center mount under the car, it's right there in between Tranny and rear diff.
It's common for the S4 and allroads, so worth to be checked out.
Furthermore, any signs of uneven tire wear? If you can get the wheel off the ground then move them in 2 directions and listen to any clicking noise or play: horizontal or l/r = possible tie rods or steering; vertical or top to bottom = possible wheel bearings.
It's common for the S4 and allroads, so worth to be checked out.
Furthermore, any signs of uneven tire wear? If you can get the wheel off the ground then move them in 2 directions and listen to any clicking noise or play: horizontal or l/r = possible tie rods or steering; vertical or top to bottom = possible wheel bearings.
Thread Starter
AudiWorld Member
Joined: Apr 2007
Posts: 143
Likes: 1
Re: Trust me on this, BTDT, once the gel is out of the mounts, they are rock solid ;-)
Good suggest about getting the wheels off the ground. I'll try that as soon as I can get the car on a lift (maybe Saturday). As for the motor mounts, wheel bearings, and main drive shaft - can I rule them out? If they were the cause of the vibration, for instance, would the vibration go away at higher suspension heights or would it remain the same. My vibration is very much increased the lower the ride height. I think this leans toward CV joints... But I've got a LOT to learn about these rowdy Audis.
Have a good evening and thanks again for all the ideas and suggestions.
-Josh
Have a good evening and thanks again for all the ideas and suggestions.
-Josh