I keep breaking front wheel bearing FL... why?

[FNK]

I am having an issue that get quite irritating concerning the FL wheel bearing,

History
At 170 000 km I had to replace my first wheel bearing with the car. I didn't knew the trick about pounding the bearing out using the back 4 bolts, so I mostly chiseled it out. In the process, I've damage the surrounding flange (red circles). However, the mating surface is fine, so is the housing surface. All that is damaged on the housing is the bolting flanges.
Since then, I've replaced that bearing 2 more times. They do not last long.


Now at 190 000 km
I've replaced the 4 wheels bearing, they are all fine except the FL again, that lasted ~800 km.

Procedure I used
Torqued to yield the 4 back bolts [80 Nm + 1/4 turn],
Then the axle bolt [190 Nm + 1/2 turn].

Question and possible solution
Since the bolting flanges are lacking material, is it possible that torquing the back tripple square bolts, it binds the bearing thus pincing the inner races? It would make sense, since the other 3 bearings did not require as much force to do the 1/2 turn.
So as a quick solution, I was thinking about using "blue thread locker" instead of fully torquing the 4 back bolts to limit the binding, but still fully torque the axle bolt.
Make sense?

[BumblebVR6]

What were your signs of a failing wheel bearing? I’m at 170k mikes and starting to hear a “rubbing” noise. At first I though it was a nail in the tire since it only happens only once a revolution. Took the wheel off and no signs of anything rubbing and the tire is fine. I did replace the axle on that corner a few weeks ago so wondering if the bearing may have been loosened up during the process. I torqued everything to spec in the proper sequence and replaced the main axle bolt.

Did you replace the hub and the bearing or just have the bearing pressed into the old hub? Maybe try a new hub as well or buy one of the pre assembled assemblies ECS sells?


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[FNK]

Rumbling in the wheel is pretty much it, eventually the ball bearing will snap in multiple parts and it will be like rolling on rocks. Scary!

[BumblebVR6]

Rumbling in the wheel is pretty much it, eventually the ball bearing will snap in multiple parts and it will be like rolling on rocks. Scary!

So pretty common signs from the sounds of it. Have gone thru a lot of wheel bearings in my MK3 GTI but yet to have one go bad on my A4. I’m sure it won’t be long, the car is 13 years old.



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[Turbo510]

I'm in the middle of my 3.0's front bearings- at 200,000 miles I had a drone noise, and sure enough, the passenger-side front was the one.

I bought the Optimal kits which include the bearing installed in the steel mount, four bearing housing bolts plus a new axle bolt. I couldn't get the triple-square bolts to loosen with my Harbor Freight electric inpact, so I had the local automotive machine shop do it, plus press off and on the existing hubs. The new bolts I torqued to 60 lb-ft, and used blue thread locker, but didn't do the extra twist due to not having a good way to hold the aluminum forging. I would have been done days ago, but simultaneously I've been changing my power steering rack, which I got installed last night. What a bear on the V6!

[seanf86]

Are you replacing the axle bolt as well? I didn't for one of them and the threads were so stretched I'd get it tight but it wasn't putting the force on the axle into the back of the bearing and I had a few premature bearing failures, my own fault for getting the bearings with no axle bolt. I replaced the bearing and the bolt and no more problems.

[Gosser]

How much material is missing on the aluminum knuckle? I doubt thats the issue. How are you pressing in the new hub into the bearing? Are you ensuring you are supporting the inner race while pressing it in? When are you applying the torque to the axle bolt; in the air or while on the ground? And what brand are you using for replacements?

[FNK]

I used 2 time GMB (recently found out it only has a 6000miles or 3 months warranty, so it's trash).
1 time a Chinese brand found on the spot and installed by a garage because the GMB balls broke.
1st time was a SKF or ***, lasted 6 months.

Bearing was pressed in and supported by the inner race.

The Axle bolt was torqued with the wheel on the ground.

[Gin+]

Junk bearings would be my guess. I'd give it another shot with a SKF bearing and a new axle bolt. Also, make sure your brake caliper isn't hanging up, excess heat will kill a bearing.

[thedanplasse]

F.A.G bearings from FCPeuro are my vote.

also

You shouldn't be pressing any bearing by the inner race...Always use the outer race to press them in. That may be why you're blowing bearings so quickly.

[Gosser]

The hub seats into the inner race, which is where all the force is being applied. I guess time will tell, but thats how mine have been pressed together, 35,000km so far so good.

OEM is my first option for bearings, F.A.G is second. When installing the axle bolt, I've read to torque to 90 in the air, then do the remainder on the ground. I dont know if that much of a variance would blow bearings, but something to consider.

Do you let anyone else drive your car, who happens to enjoy curbs?

[seanf86]

I used 2 time GMB (recently found out it only has a 6000miles or 3 months warranty, so it's trash).
1 time a Chinese brand found on the spot and installed by a garage because the GMB balls broke.
1st time was a SKF or ***, lasted 6 months.

Bearing was pressed in and supported by the inner race.

The Axle bolt was torqued with the wheel on the ground.

Was the axle bolt new or re used?

[EuroxS4]

I have 493k miles on my a4 and have yet do to a bearing.However 9 times out of 10 the quality doesnt really matter.I've installed oem bearings all the way to the cheapest shit you can find.The biggest difference I can see is in the quality of the bolts that hold the bearings thats about it.Are you sure everytime the hub is pressed it correctly???Also is the bearing installed correctly??I never had a problem even on my b5 s4 I put a $20 bearing in and the car was fine after 9years then i sold it.

[Kevin C]

If you need to press the bearing into the spindle you want to press on the housing or use the bolts to pull it in. If you need to press in a hub, support the inner races as you press the hub.

Press forces will brinell the races and cause a premature failure.

As far as the spindle goes, if enough is missing that it allows the bolt to place a torque on the flange as the bolt is tightened (lacks support under ears of the flange), then you will distort the housing and reduce bearing life.

[A4SoftWalker]

Do not torque the axle bolt with all the weight of your car on it. This can lead to an uneven lock-down of the bearings and premature failure.

There are 2 good ways to do it and 1 cheater way:
1) Have someone in the car step on the brakes.
2) Place 2 long bolts in between the bolt holes where you bolt your wheels to the hub and the flange to keep it from rotating (I use old front suspension bolts).
3) Cheater method - In the past I have lowered the car just enough to prevent the wheel from spinning and have had success with this method as well. (Not responsible if your car falls off jack. Know your wrenching limitations. Use ONLY a beefy floor jack for this method - NOT the factory widow-maker).

[customa4]

Do not torque the axle bolt with all the weight of your car on it. This can lead to an uneven lock-down of the bearings and premature failure.

There are 2 good ways to do it and 1 cheater way:
1) Have someone in the car step on the brakes.
2) Place 2 long bolts in between the bolt holes where you bolt your wheels to the hub and the flange to keep it from rotating (I use old front suspension bolts).
3) Cheater method - In the past I have lowered the car just enough to prevent the wheel from spinning and have had success with this method as well. (Not responsible if your car falls off jack. Know your wrenching limitations. Use ONLY a beefy floor jack for this method - NOT the factory widow-maker).

That jack is really only useful for changing out a spare. It's good at that if setup properly(good alignment of jack and e-brake engaged). Only put body parts under the car that you can afford to lose when using the factory jack. I had my car fall off the jack on the side of the highway because I forgot to engage the e-brake. That jack is extremely dangerous if it's not used properly. Sorry for derailing thread.

[B6Sticks]

I've always torqued half the axle bolt in the air, and then the remainder with the car on the ground, i believe that's the official/correct way to do it. I've never had a problem doing it this way and it's the way I've always read to do it

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[Kevin C]

I've always torqued half the axle bolt in the air, and then the remainder with the car on the ground, i believe that's the official/correct way to do it. I've never had a problem doing it this way and it's the way I've always read to do it

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That's all you need to do. Get enough force on the bearing to keep the races together before any weight is put on it, final torque with the cars weight on it.

[FNK]

Well it make a lot of sense to preload the axle bolt before lowering the car.

More on the subject, I've removed the bearing with a 1000 km on it. Outer race was completely shoot. There was not much flange left, I will have to find a new knuckle. Reinstalled the previous bearing that was still good, minimal torque on the back 4 bolts with threadlocker and full torque on the axle bolt. For now, the car is silent.

[Kevin C]

One thing I want to add to this is the reason that bolts get torqued down to a specific value. The goal is to have enough preload that the clamping force of the bolt is always higher than the loads placed on the bolt in operation. As long as the preload is higher, the bolt never sees a load cycle that flexes the bolt. Basically, as long as the force clamping the parts together is greater than the load applied the bolt never flexes. No flexing = no loosening and infinite fastener life. A lower torque value will reduce clamping forces and may allow the fastener preload to be overcome.

If that happens the bolt starts to flex. Flexing is considered bad since the fastener now has a finite service life (it only has so many flex cycles).

Good to use loctite to prevent loosening. That still leaves the possibility that the bolt may not have enough preload and will have a reduced service life (a nice way of saying that over time it could fail).

[Turbo510]

That jack is really only useful for changing out a spare. It's good at that if setup properly(good alignment of jack and e-brake engaged). Only put body parts under the car that you can afford to lose when using the factory jack. I had my car fall off the jack on the side of the highway because I forgot to engage the e-brake. That jack is extremely dangerous if it's not used properly. Sorry for derailing thread.

Actually, good that you derailed the thread in my opinion- that factory jack ended up as a trip to the ER for me.

I used it to raise the car in my garage, on a polished concrete floor. Evidently Aluminum and polished concrete don't have much friction between them, and as I cranked the car up, the foot of the jack began to slid underneath the car a little, so I lowered it down and re-positioned the foot. I had my jack-stand ready to push under as soon as there was enough room, but just about when I was ready to move the jack stand under, the base of the jack began to move again, this time outwards towards me. I started cranking it down, and instinctively put my left hand behind it, as if to stop the movement. Suddenly it shot out; the sharp edges of the jack hitting my palm. I took one look and knew a band-aid wasn't going to do. So my wife took me to the hospital, while I had a towel wrapped around my hand. At the ER, with my hand under a bright inspection light, the doctor said "hey guys, come here. You can see this guy's tendons".