Cal Club Autocross Forums

Hi guys

At this point I really need as much help as I can get.
Here is the issue.
Audi 2002 A6 3.0 CVT (FWD)

Crazy vibration even at low speeds (30 mph and up to 80+mph) when throttle is applied.
It seems like coming from he right side of the front wheel.

Even though the cult-print of the phenomenon doesn't seem to suggest that the wheels have a balance issue, I had a shop lifting the car checking the wheels.

background information
1) The car just had alignment - I though that they forgot to tight the alignment bolts or something like that but when I took it back to the shop they said that aliment can't do that and that it's probably the transmission (?)

2) I have the CVT transmission - I tried switching from auto to manual and to different gears - the vibration intensity is the same regardless.

3) The car is FWD and I had a blown tire so I was using a different size tire in the front right wheel. One of these days it was raining and I experienced torque steer while accelerating in straight line. I kind of kept my foot in throttle instead of backing off so now I'm wondering if I damaged the engine mounts.

Just to clarify I now have the vibration with same size wheels at the front (I put the rear wheels at the front and the front to the rear until I get my new tire).

Is broken engine mounts something common in A6s? How can I test for that? I know in manual cars you put the car in first gear and you release the clutch while applying the brakes - I can do the same on my CVT but I just want to check the common knowledge here since I know that these transmissions are a bit sensitive.

What else do you think it can be?
Do you have to suggest anything else to test?
I love my car but a new CVT tranny is like $9K so I need to figure out whats going on and if I need to cut my losses get rid of my baby .

Thanks,
Chris

I had a similar experience before and it was due to improperly torqued wheels on the Prelude. I thought something was seriously wrong with my car until I checked the lug nuts

Chris, you didn't say whether the vibration was rhythmic or not. Broken motor mounts can definitely create some strange noises/vibtration.

Thanks, Lily, I'll check that. What I already have done is to check that all the wheels lugs are tight - but it might worth to remove them and torque them in right sequence. Still I'm not sure how this will explain why the vibration stops when I don't apply the throttle.

George, the vibration is like a badly balanced wheel but it happens at any speed from 25-80+mph.

I was wondering if the motor mounts can introduced this kind of vibration.
Here is a video I took with my left foot on the brake and the right foot applying the throttle. It seems that the engine moves but I'm not sure what is considered good or bad - this isn't a racecar but a smooth cruiser... maybe someone with more experience can advice....
here is the link (I hope it works):
http://www.facebook.com/video/video.php ... nts&ref=nf" onclick="window.open(this.href);return false;

By the way it all started after I gave the car for alignment and I kind of feel that maybe something happened there. There was a clanking noise coming from the steering while turning (after the alignment was done). That makes me think that I might also need to adjust the steering rack preload – moments like these I think that having the car serviced at the dealership is not a bad idea…

I also noticed that the vibration goes away if the wheels are slightly turned not sure from what direction – I need to confirm that.

We had a similar issue with the Protege recently. You may want to check to make sure the axle is seated in properly.

Thank you guys and gals.
it turns out two of my rims were bent ... let me know if you know of a good and cheap place to straighten the wheels.

Christos Adam wrote:Thank you guys and gals.
it turns out two of my rims were bent ... let me know if you know of a good and cheap place to straighten the wheels.

Are they OEM rims? It might be cheaper/safer to find a set of used or replica wheels. VW Vortex has a whole classifieds section dedicated to wheels. Or, alternatively, just run the bent wheels on the rear axle

Good idea, I checked but these wheels are still expensive - even used - definitely more than double the amount of money for straightening

So, what's with how much the engine moves when you get on the throttle? That normal?

I'm not sure if it's normal, I believe I need to change the engine mounts.
I don't aggressively looking for a solution to that right now because I changed the front wheel with a spare and the vibration stopped.
Therefore I figured out that the vibration of the engine was not related with the vibration of the car during acceleration.

Here is a video that I took:
Update:
I put new tires all around and the vibration is still there.

It starts when I'm applying the throttle starting even at 15 mph or so...
Yesterday I wanted to check the driveshafts so I lifted the wheel and tried to rotate it.

http://www.facebook.com/video/video.php ... nts&ref=nf

There is certainly a clanking noise and a lot of movement (rotating the wheel).
Other than that there isn't too much play from the suspension.

I also noticed that the boot was cut and all the grease had leaked out - but is this a reason for vibration?

Looks like you have an electrical problem....

But seriously, it appears the axle area is the root cause or just part of the problem.

The broken boot could just put the assembly out of balance, or the whole axle joint could also be broken. There is probably an Audi rotational play range that is acceptable. It would be best to check that before you disassemble the whole thing. If you have a manual, it would be better to diagnose that way if you don't a mechanic to do it yet.

Engine mount issues are more noticeable during throttle tip in/out situations. There would be some shock and accerleration hesitation. This is difficult to evaluate in a CVT.

I just read your post again and you mentioned the clanking while turning. This is a common sign of broken axle joints.

Thank you so much Tin, hopefully my new drive shaft will fix the problem!

Drive shaft or axle?

Mike Simanyi wrote:Drive shaft or axle?

... my understanding is that the word axle usually refers to the De Dion axle that now-days can only be seen in RWD cars. This is for my Audi (FWD) so it has to be a drive shaft...

When you rev the engine while the car is in neutral and the engine shifts, like in one of the first videos, that's an engine mount.

The noise when you turn the car is probably a CV joint.

Hi Cris,

Had the exact same problem with my '02 Jetta a few years ago. Vibrations at just about any speed, clank while turning, but only when turning right.... no issue when turning left

Also showed up after an alignment.

We checked the motor mounts, axles, and a mired of other things. Turned out to be the rear A-arm mounts (though the spare set I have here says C-arm mounts, I'm assuming it's one in the same). According to Mike Potter (of Parts4VW.com,and Parts4Audi.com in Temecula), and an old autocrossing buddy / road racer, these are apparently a weak point as they mount differently than just about any other rear mount I've ever seen, and take the impact of every pothole, sidewalk curb ramp etc for the front suspension.

These are rubber bushings. I replaced mine at his suggestion with poly ones.

Bob Beamesderfer wrote:When you rev the engine while the car is in neutral and the engine shifts, like in one of the first videos, that's an engine mount.

I revved the engine in gear with brakes applied so that the car won't move. }:)

Craig Naylor wrote:Hi Cris,

Had the exact same problem with my '02 Jetta a few years ago. Vibrations at just about any speed, clank while turning, but only when turning right.... no issue when turning left

Also showed up after an alignment.

We checked the motor mounts, axles, and a mired of other things. Turned out to be the rear A-arm mounts (though the spare set I have here says C-arm mounts, I'm assuming it's one in the same). According to Mike Potter (of Parts4VW.com,and Parts4Audi.com in Temecula), and an old autocrossing buddy / road racer, these are apparently a weak point as they mount differently than just about any other rear mount I've ever seen, and take the impact of every pothole, sidewalk curb ramp etc for the front suspension.

These are rubber bushings. I replaced mine at his suggestion with poly ones.

Wow it kind of seems identical to your problem...
I know that all the Audi's have an issue and need to replace the control arms (since you can't replace the bushings) after 100K miles but I didn't see too much movement when I was checking the tolerances by trying to move the wheel in every direction.
Let me check again!

Christos Adam wrote: Wow it kind of seems identical to your problem...
I know that all the Audi's have an issue and need to replace the control arms (since you can't replace the bushings) after 100K miles but I didn't see too much movement when I was checking the tolerances by trying to move the wheel in every direction.
Let me check again!

That's what the dealer told me too.... but when I called Potterman, he said that they could be replace, they just need pressed out / in, old / new respectfully, and sold me the bushings for ~$20 (not at home to look at the price tag) vs. several hundred the dealer wanted for each complete arm.

There was no movement one could tell by movement of the wheel, even in the air. The blown bushing was found after it was in the air, by visual inspection. There was just no rubber left in it. Oddly enough the other one looked fine, but after removal, it too was obviously shot.

Art did the work for me... well rather, Mike did (rest his sole).

Craig Naylor wrote:

Christos Adam wrote: Wow it kind of seems identical to your problem...
I know that all the Audi's have an issue and need to replace the control arms (since you can't replace the bushings) after 100K miles but I didn't see too much movement when I was checking the tolerances by trying to move the wheel in every direction.
Let me check again!

That's what the dealer told me too.... but when I called Potterman, he said that they could be replace, they just need pressed out / in, old / new respectfully, and sold me the bushings for ~$20 (not at home to look at the price tag) vs. several hundred the dealer wanted for each complete arm.

There was no movement one could tell by movement of the wheel, even in the air. The blown bushing was found after it was in the air, by visual inspection. There was just no rubber left in it. Oddly enough the other one looked fine, but after removal, it too was obviously shot.

Art did the work for me... well rather, Mike did (rest his sole).

Thanks Craig, is Potterman's website the one below?
http://www.parts4vws.com" onclick="window.open(this.href);return false;
I might give him a call even though I'm thinking that I should try the parts that I already bought first and then see if I need to change the bushings.
I guess on the negative side, if the driveshaft doesn't fix the problem I'll need to do the same labor twice...