Gsrob

2002 A6 2.7T Sedan 6MT

Over the last few weeks I have noticed what started as a clicking in the front end, definitely coming from the front passenger side of the engine compartment. I know it's hard as heck to pinpoint noises from inside the car but if I stick my head out of the window while driving it is not coming from the driver side. The sound has increasingly amplified and has become more of a repeated clunk - over and over. Bumps do not matter. It is happening on smooth road. Some of you will remember that I thought one of my wheels was bent, but now I'm wondering if it's an axle gone bad. I can definitely feel it in the steering wheel at all speeds. The only time the clunking sound goes away is under heavy load (ie throttle or downshifting) or when making moderate right turns. Has anyone experienced similar symptoms and replaced the axle? I've done a lot of research and found that raxle is probably the only place to deal with. I'll get back under the car to see whether or not the axle was OEM or not. Also is there anyway I can tell if it's bad? All boots were intact yesterday upon inspection.

Quick list of things I have already replaced/checked in correlation with the problem:

1. Checked the powersteering rack bolt under the battery tray. It's tight already.

2. Yesterday replaced all control arms upper/lower with a kit from FCP and tightened at static ride height. (Hey, at least it handles like a new car.) - Not one control arm was ever replaced on this car in 145k miles. Everything was still stamped with Audi logos and Lemforder.

3. Replaced and torqued sway bar brackets at static ride height.

4. Tightened all upper strut mount assemblies and torqued.

All of these things lead me to believe it may be an inner cv joint gone bad...

SloopJohnB@mac.com

Does the noise get louder on LEFT hand turns? That's when the right suspension is more loaded….
Inner triple spider joint generally makes noise/vibration under acceleration or deceleration when it's worn….outer rzeppa joint will click when wheels are turned either way…have someone listen outside the car as you bring the car around a corner slowly….

In general, unless the boots have been open for awhile and lost lubricant and the joint contaminated, there's nothing wrong with the joint. Even after 150K+ miles on my 2K4.2A6 when I replaced the inner boot on a front axle (leaking at clamp and boot was schpeckled with cracks) the lubricant was brown/mousse but the ***** and outer housing were still fine…all I did was clean and relube and reboot.

Gsrob

I'm not sure that the noise get's louder... However, as soon as the load is off of the suspension after a right turn, the vibration, clicking/clunking is back when the wheel is straight or when making a left turn. The only way I can describe it is if you had a bent wheel and a significant amount of rapid clunking until load is put on the drive train or a right turn is initiated.

I'll try to have my wife hear it from outside of the car, but I'm not sure what good that will do. I have yet to do tie-rods/ends, could those make such a racket? I have some solid metal tie-rods to install but may just use the ends...

On a side note, raxle already contacted me (on a Sunday morning) and it's 219.00 for either side with 39.00 shipping. On my previous car, I had a worn inner axle joint and similar symptoms except that the noise and clicking was worst under torque. It eventually broke and made it feel like I was running over a brick over and over.

Gsrob

Another thing to note: I got under the car for further inspection today. While I was there I snugged up every bolt I could get my hands on... Subframe bolts, the brace, engine mount brackets (or at least that's what they look like to me), etc hoping that it would alleviate some rattling/clunking. The problem is still there, duh. Anyway, I checked out all of the boots and spun both axles. They have part numbers stamped into the inner cv joint so I'm assuming they are OEM originals. Have you guys ever seen an inner joint go bad with a good boot? They both spin freely with very little noise.

Edit: I banged on everything I could get my flashlight on as well to see if something happened to be loose, both in the top of the engine bay and below the car. I also pulled back the firewall cover above the brake booster and battery and attempted to torque the driver side power steering bolt but it was already incredibly tight, just like the other one.

SloopJohnB@mac.com

Before I went to new axles I would remove the right hand one and feel it for play….you should even be able to feel play by rotating the axle with the wheel back and forth…there is some slop but there should be essentially zero in the spider joint and rzeppa joint. You can remove the entire axle assembly and feel it for play as well.
And no…I've not seen an axle go bad if it is lubricated and boot is good.
If you bought the car used it's possible the PO may have rebooted an axle that was contaminated with grit or whatever and it has finally let go.

4Driver4

Have you checked the lug bolts? Loose wheel? Hard to imagine that you haven't had the wheel off at least once during your diagnosis, but I thought I'd ask just to be thorough.

Gsrob

I've checked and double checked lug bolts... I'm very meticulous when it comes to putting them back in. Too many careless experiences of cross threading on other vehicles in the past. Every time I zip the lug bolts up lightly with my impact wrench with some anti-sieze before dropping the car to the ground and torquing to 90 ft. lbs. Usually I come home and verify torque once again after driving it into town if I worked on the car previously.

Speaking of work, I attempted to drive the car in this morning to see if the popping sound is louder on left turns but decided to turn around after there was lots of noise just leaving the driveway. I'll try to pull the axle today or tomorrow to see how much play there is in each joint. The last thing I want is to get stranded or damage another part of the drive train (if the axle is indeed the issue).

CRuby

Jack up car & place pry bar under front passenger tire & pry up. If in the suspension, you may be able to isolate the noise.

SloopJohnB@mac.com

You can determine the play in the rzeppa joint easily…just hold the axle and turn the wheel…if that's ok (should be essentially zero) hold the transmission output flange and turn the wheel…play should be essentially zero. If it's not, replace as necessary…the rzeppa joint is easy to replace, the triple spider and housing is expensive, at least on the 4.2. YMMV.

Gsrob

So after finally retrieving all of the tools to pull the axle, I will be getting it out today or tomorrow after work to check the joints. Most people said the only speciality tool was the triple square 10mm bit for the spider joint but what a pain to find the damn 17mm hex socket ... I should have just gone to harbor freight to get everything for a quarter of the price but it's over an hour away. I'll post as soon as I see how much play I've got in each joint.