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Last weekend replaced my rear driver's side wheel bearing. YMMV.
About a year and 8000 miles ago, my 2006 A6 started to make a howling noise, which was initially hard to pin down. However, over time it continued to get louder, to where it was approaching a near-growling noise.
I surmised that it was a wheel bearing since: It's a not-uncommon problem with C6s, it was proportional to speed and did not change when accelerating, coasting, braking, or shifting in/out of gear. Unlike some have said, it did not change noise when loaded in curves; perhaps it has to get worse to do so. You could not tell by agitating the wheels while parked.
In my case, it was sufficiently annoying and worrying that I chose to not put it off any longer, as it greatly diminished the fun of driving the car, and I Take longer trips from time to time.
Over time it got louder to where it was apparent it was from the rear (I was hoping it was the front so I would not have to fool with axles), but I could not positively determine which side it was. I am now at 80,000 miles.
I ordered a replacement and confirmed it was a fit for either side, so if I guessed it wrong, I could use it for either. Since I have a spare car, I could also order a second bearing if both were determined to be bad.
I guessed the driver's side rear. No static test or rolling test would confirm it however.
My only major difference was that my ball joint studs were hard frozen to the knuckle (I did use PB Blaster penetrant, but did not have a 24 hour soaking which would have been good). It took a ton of heat (be careful here) to torch the knuckle to the point where it would release the ball joint stud. You cannot get a pickle fork under these ball joints without damaging the boots.
Breaking the axle nut was easy with the 34mm socket in a 1/2" breaker bar with a floor jack handle used as a cheater bar. I also knocked the axle loose with a BFH (protecting the axle of course) from the hub while the car was still on its tires.
All in all, about a two hour job if I need to do it again. Not too hard.
The old bearing was oddly enough not that rough seeming once removed. I had done this same job on a '02 Explorer a few years ago, and the old bearing, once removed, clearly felt like crap. For the C6, it was only slightly 'sticky' unsmooth if that makes sense. It probably could have gone many more miles prior to failure, inconsistent with the loud growling noises it was making.
After bolting the left side back together, I elected to do a test drive to see if that fixed it, which it did. So I luckily guessed right. Now the car drives as good as new.
Anyway, that's my story for posterity for anyone that is considering tackling this job. Bottom line - it's not that bad, just have the right tools, and be safe.
Back at Pearl, beside of lacking finesse, one of the major difference between a Inside(X31) and Outside(X38) Machinist is the 5 lbs sledge hammer. Guess who is the "Hammer" Mechanic.
Hammering the aluminum ball joint housing with a BFH is never a good method - there is such a tool as ball joint separator - using it will not damage rubber boot nor distorting the "soft" aluminum.
Wheel bearing noise is easily to determine if a person knows the proper, yet simple procedure and all without suffering for a year before finding out.
For anyone don't know but want to learn how to determine wheel bearing noise and alternate method of wheel bearing replacement, go to Ytube and search videos by Froggy47 - he is a CF member but only post in Autocrossing/Roadracing Section. Although he claims not to be a mechanic but he has excellent Shop practices and he has excellent explanations on why not to use "Pickle Fork", "Hammering" and use of proper "Ball Joint Separator".
Get the proper tools as the above member suggests, used with the solid experience you earned it'll be even easier. Nice job. An inspiration to all mechanically challenged souls, like me.
First off: Thanks for promoting my video... Every little bit helps. $$$
I used Moog Bearings. There is a Moog plant here and I try to support US companies.
However, you have to be careful when buying Moog and ask where they are made.
The ones with a three year warranty are US, the ones with one year are made everywhere else. Does that tell you anything?
Keep an eye on the axle shaft. A few weeks After my first bearing replacement the axle shaft went bad and dumped all its grease under the car.
This video was made when my left axle shaft died.
I replaced the bearing mainly because I had the car a part and what is a couple hundred dollars extra to not have to pull all of this apart again?
First off: Thanks for promoting my video... Every little bit helps. $$$
I used Moog Bearings. There is a Moog plant here and I try to support US companies.
However, you have to be careful when buying Moog and ask where they are made.
The ones with a three year warranty are US, the ones with one year are made everywhere else. Does that tell you anything?
Keep an eye on the axle shaft. A few weeks After my first bearing replacement the axle shaft went bad and dumped all its grease under the car.
This video was made when my left axle shaft died.
I replaced the bearing mainly because I had the car a part and what is a couple hundred dollars extra to not have to pull all of this apart again?
No, thank you for making the video. It gave me the confidence to tackle this job which, as it turns out is not hard at all.
Back at Pearl, beside of lacking finesse, one of the major difference between a Inside(X31) and Outside(X38) Machinist is the 5 lbs sledge hammer. Guess who is the "Hammer" Mechanic.
Hammering the aluminum ball joint housing with a BFH is never a good method - there is such a tool as ball joint separator - using it will not damage rubber boot nor distorting the "soft" aluminum.
Wheel bearing noise is easily to determine if a person knows the proper, yet simple procedure and all without suffering for a year before finding out.
For anyone don't know but want to learn how to determine wheel bearing noise and alternate method of wheel bearing replacement, go to Ytube and search videos by Froggy47 - he is a CF member but only post in Autocrossing/Roadracing Section. Although he claims not to be a mechanic but he has excellent Shop practices and he has excellent explanations on why not to use "Pickle Fork", "Hammering" and use of proper "Ball Joint Separator".
I prefer using heat to hammers.
The use of heat to unstick fasteners is an underutilized skill, and does not stress components.
The use of heat to unstick fasteners is an underutilized skill, and does not stress components.
As I recalled, you were not a turn wrench type when you were with us back in PHNSY (Pearl Harbor Naval Shipyard)days.
We only use heat in extreme situations such as dealing with class 5 interference fit, fasteners had cured red loctite or fasteners had galled. Even in those situations, you might recall - shops will seek help from "Special Tooling Branch" and Toolmakers and Design Engineers will come up with an solution all without damaging the components.
Professional garages use heat and pickle fork on cars because its not their cars! Looks easy and certainly fast, but aluminum is a low temperature alloy. Heat will have an direct effect on it. Aluminum can easily be annealed with low heat - if you know the technique!
Suggest for those doing this job use the correct tool with the proper designed and built in mechanical advantage - it will cleanly separate the taper fit and without damaging the rubber grease boot.
As I recalled, you were not a turn wrench type when you were with us back in PHNSY (Pearl Harbor Naval Shipyard)days.
We only use heat in extreme situations such as dealing with class 5 interference fit, fasteners had cured red loctite or fasteners had galled. Even in those situations, you might recall - shops will seek help from "Special Tooling Branch" and Toolmakers and Design Engineers will come up with an solution all without damaging the components.
Professional garages use heat and pickle fork on cars because its not their cars! Looks easy and certainly fast, but aluminum is a low temperature alloy. Heat will have an direct effect on it. Aluminum can easily be annealed with low heat - if you know the technique!
Suggest for those doing this job use the correct tool with the proper designed and built in mechanical advantage - it will cleanly separate the taper fit and without damaging the rubber grease boot.
I found this old thread while searching some other topic, and thought - for those wondering about to heat or not to heat: the poster quoted (hi there), makes a good point about the use of heat. In short, be careful.
I use heat for things like stuck fasteners, if penetrant does not do the job. However, you must be careful - first with flammables (keep a fire extinquisher close by, and possibly even a dedicated fire watch stationed), and for low temperature materials I recommend use of a IR heat sensing gun to track maximum temperature.
For non-metallics use a hair dryer, or for heavier items use a heat gun as is used for paint removal.
For metals, keep an eye on not exceeding the phase transformation temperature of the metal can google this, but get the right alloy), to avoid annealing or tempering the metal.
I changed all 4 wheel bearings and both drive axels. Took about 6 hrs total and did not need any heat. Even with 164,000 miles on my 07 the ball joints came off easily with a light blow from a rubber mallet.
Took longer to do the first one as I was learning what needed to be done. This applied to both front and back as they are slightly different.
I'm having trouble getting a bearing hub out of the knuckle. I see the parking brake assembly around the hub. Does that need to come off first? I don't think it does. But, it doesn't want to come out.
I've also got an axle stub that doesn't want to come out of the bearing. I'm bringing them to a shop with a press bigger than mine.
Last edited by Jack Boelte; 08-14-2023 at 09:04 PM.
Been there, done that. In my case, I was replacing everything (arms, knuckles, bearings, etc.) so it didn't matter if I mangled up the boots or beat on things with a BFH.
The other really annoying issue is that none, and I mean absolutely none of my local parts houses had a separator tool that worked for our knuckle/joint area. I tried 3 or 4 different tools any couldn't get any of them to reach properly.
This is one area where I would absolutely recommend spending the money for the exact tool recommended by GM.
I use a two leg wheel puller to crack the lower ball joints from the control arm. The picture is simulated. I do this on the car. Notice the nut between the wheel puller and the ball joint stud. It prevents damage to the ball joint hex socket.
Instead of using a BFH to separate a stuck drive axle from the bearing hub, I use a 6" 3 leg wheel puller. However you have to partially disassemble the parking brake to allow the the 3 jaws to grab wheel bearing stud plate. The parking brake pads will rotate out of the way after you remove the spring keepers and loosen the 2 bolts.
Once the axle is out I use the wheel puller to separate the lower ball joint.
10-19-2013, 09:05 AM
Rear Wheel Bearing Replacement - Observations
