MP4.2+6.0

Sometimes when I drive slowly I hear a minor clicking noise when the windows are down. Not very loud; a staccato click and periodic in nature, like during wheel rotation. From experience hearing (and sometimes feeling) CV joint issues on other Audis and usually with more miles and torn boots, it's not those. CV boots are in great shape and suspension is all tight and well maintained with replaced front upper arms, lower links and tie rods along the way. It has no effect on the driving dynamics, can't be heard at any decent speed or with windows up, and has remained pretty unchanged for 35K or 40K miles and several years now, as I think about it. One of those things you often say, that's just the way it is, or a fluke in the front diff (also in apparent good mechanical shape, gear oil fully just serviced, etc.). Also, not at all the gravelly internally failing bearing noises or any symptoms like that.

At one point I thought it was maybe some built up dust in the drilled brake rotors I ran, but switching back to OE plain for a while made no difference. No rocks or junk caught in the rotors or hub area either, and of course lug nuts tight, plus wheels removed and replaced (snows, etc.) periodically with no changes in the clicking.

The clicking is most obvious when parking in a concrete structure with lots of sound reflection and window down, or sometimes driving along a concrete wall to the side of the car with the windows down. Or if someone is parking the car in a pretty quiet setting, maybe you hear it if you are out of the car but pretty near it.

Here are the TSB's which I just found in excerpted form, one published or updated quite recently. Has anyone else had a similar experience hearing this or getting it diagnosed? It basically takes a removal of the hub assembly and some lubrication before putting it back--not an insignificant labor exercise. I may tackle it with an upcoming worn out front rotor related "heavy" front brake service. Now knowing about the TSBs, I will also try to load up one side or the other with slow turns to see if I can isolate the apparent noise to one side or the other as my first pass at it; I have a sense from my most recent sweeping to the right turn into a concrete garage space the other night that the driver's side is my more likely suspect.

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40 Clicking noise from wheel bearing
40 12 27
2024318/3
November 8, 2012.
Supersedes Technical Service Bulletin Group 40 number 12-26 dated September 26, 2012 for reasons listed below.


Affected Vehicles (list includes all D3 years)

Condition
Clicking or clacking noise when maneuvering or parking.

Technical Background
Normal driving dynamics may cause microscopic movements between the wheel bearing and wheel bearing housing.

Production Solution
Not applicable.

Service
(bad news--picture shows bearing shell obviously loose from the steering knuckle for this)

1. Remove any corrosion and dirt from the wheel bearing housing and the wheel bearing.

2. Using a brush, apply a thin coat of paste G 052109A2 on the wheel
bearing housing as shown in Figure 1.


Here is the older one like it:

Drivetrain - Front Wheel Bearing Click/Pop On Turns

40 08 06
2010331/4
October 28, 2008. Supersedes Technical Service Bulletin Group No. 40 number 08-04 dated September 11, 2008 for reasons listed below.

(List includes all D3's, and most all Audis from 2005 through about 2010).

Condition

Front wheel bearing makes clicking or popping noise when turning the steering wheel.

Technical Background
Surface corrosion can accumulate between the wheel bearing and bearing carrier.

Production Solution
--
Service
For vehicles produced prior to VIN 4E_4N 006891
1. Disassemble wheel-bearing unit (Figure 1, 6).
2. Acquire new front wheel bearings, part number 4E0 498 625 B (Figure 1, 3) centrifugal discs/dust seals, part number 4E0 407 623 (Figure 1, 4), one collar screw and four cap screws (Figure 1, 2).
2. Prior to assembling new parts, apply a layer of Optimol paste (part number G 052 109 A2) on periphery of mating surface of wheel-bearing unit as indicated by slash marks in Figure 2.
3. Apply paste on flange area of bearing unit (Figure 2, blacked out area).
NOTE: Do not apply Optimol paste to the threaded holes.
4. Reassemble the wheel-bearing unit. See Repair Manual >> Suspension >> Wheels and Steering Group 40 >> Wheel bearing, replacing.

For vehicles produced from VIN 4E_4N 006891 [seems like my 2006 is in this latter VIN range]

Tip:
Do not replace front wheel bearings.
1. Remove both front wheel-bearing units (Figure 1, 6) from wheel bearing housings (Figure 1, 1). Do not separate wheel hub (Figure 1, 5) from wheel bearing (Figure 1, 3).
WARNING : The collar screw and all 4 cap screws must be replaced when disassembling and reassembling the wheel-bearing unit.
2. Apply a layer of Optimol paste (part number G 052 109 A2) on periphery of mating surface of wheel-bearing unit as indicated by slash marks in Figure 2.
3. Apply paste on flange area of bearing unit (Figure 2, blacked out area).
NOTE: Do not apply Optimol paste to the threaded holes.

mannyo1221

Are you sure it's not something stuck in the tire, like a stone or nail wedged in the tread pattern.

JohnnyJ A6Q

"and has remained pretty unchanged for 35K or 40K miles and several years now, as I think about it"

That stone is holding on tight .....

Good thought though, MP are they the same tires for 30-40k miles ?

also it was either my son's A6 4.2 or 3.0 had that clicking, it was too light of a sound to be CV, it turned out to be brake pad fitment from previous owners brake job, when Vince replace all pads and rotors the noise was gone.

mishar

If it is bearing clicking inside the housing I would replace it. It should be a tight fit. Actually Audi should replace it.

Or just play some music while entering concrete structures.

tjf

If you apply the brakes lightly does the clicking stop? I had something very similar on my A4. Driving slowly in parking lots with the window down, I could hear clicking. When I started looking I noticed the TRE's needed replacing, so I did them, along with the suspension arms. Still had clicking. Then I rebuilt the calipers, seal, bushings, etc. Clicking went away for awhile. Finally the root cause of it was the pad retaining spring. It must have weakened over time allowing the pad to push it away from the carrier and then pop back in some way.

MP4.2+6.0

Treads are clean; new rubber and brake pads in last 5K miles and no change in clicking.

MP4.2+6.0

since I have multiple sets and the S8 style ones. But the S8 ones were on there with the drilled rotors that I dismounted for a while, and the sound continued. Clips got R&R'ed too for the recent pads only swap out when the wear light came on in mid winter. Clicking does occur either if driving slowly, or lowly braking to a stop, like parking maneuvers in a parking structure where you hear reflected sounds better. I will test both more systematically though.

Also dawns on me since I use spacers that--akin to Audi's TSB about some bearing shell mechanical chafing--I can pull those temporarily to see if any effect at all.

MP4.2+6.0

Having had these same style bearings out for replacement in both front and rear in the A6 4.2 w/ the similar aluminum suspension and same bolted in cartridge bearing set up, I can see the potential issue that the TSB is flagging. It is a precise fit, but it slides in by hand with no press at all, but also no real slop/looseness. Maybe you changed one or more out so far? Kind of a perfect set up for noise like this since the four bolts that hold the bearing cartridge to the hub assembly/knuckle can't probably fully control some stress related movement below the 1/1000 type stuff. More so if you throw a little surface corrosion in there that the TSB mentions cleaning up. I suspect the magic paste the TSB is talking about is some kind of grease like an axle sort, or anti seize stuff. Both would avoid the corrosion and let the parts slide instead of click in the tiny stress movement seemingly going on at the margin--per the implicit assumption I think underlies the TSB.

mishar

Four M12 (I believe) bolts are strong enough to prevent any movement between the knuckle and the cartridge. I thought they are talking about movement of the bearing inside the cartridge?

MP4.2+6.0

I think they are definitely referring to movement between the bearing cartridge assembly and the hub/steering knuckle casting into which it bolts. They published it across most of the whole model range, including ones a fair amount lighter than the A8. So I guess the issue has come up. Also why the bearing doesn't have to be replaced as long as it is still good, since you don't have to press out the hub along the way.