====>>>> Axel bearing removal from Final Drive

[RandyRandy]

Hello Ya'all.

Is there a trick to removal of the axel bearing from the Final Drive? (2002 oilhead) I tried pushing it in with a 23mm socket (1mm smaller than outer diameter of the bearing) after heating around the bearing with an hot air gun. Should I be pulling instead of pushing? I tried placing the 23mm socket on the bearing and tap-tap-taping with a rubber mallet. Is there a special tool? How's it done?

 

Should I use a hammer and a chisel?

 

Thanks,

RR

[Stan Walker]

axel bearing

 

I suspect the reason you are not getting an answer is that most of us aren't sure just which bearing you are having problems with.

 

We don't have a part inside the final drive that we call an axel, although the crown wheel could be considered as such. It does run in two bearings but I don't think that is what you are speaking of based on your confusion about which way to remove the bearing. They both press up against solid metal.

 

There are bearings that support the final drive and allow it to pivot up and down. Usually these are called the final drive pivot bearings. There are two more bearing at the other end of the swingarm and these are usually called the swingarm pivot bearings. All 4 of these bearings are removed by pulling from the outside or tapping from the inside. So if these are the bearings you speak of then you seem to be going the wrong way.

 

I hope this helps. Let us know if we (or you) are still confused.

 

Stan

[bmwmick]

Randy,

Can you reference the item in the ETK? Enter your VIN here: http://www.realoem.com/bmw/select.do?vin=&kind=M&arch=0

 

I'm sure you will get some help then.

 

Mick

[RandyRandy]

Mick and Stan - Thanks for the replies.

 

What I called an "axel bearing" is actually the needle bearing in the Final Drive. In the following diagram it is item Number 2 with BMW OEM part number 33172311091.

 

http://www.realoem.com/bmw/showparts.do?...hg=33&fg=05

 

These are what Stan termed the "final drive pivot bearings".

 

Stan wrote:

"...are removed by pulling from the outside or tapping from the inside."

 

That is what I thought. I didn't put much pressure from the outside of the bearing inward, so I'm sure I didn't mess up anything more. So to pull the "final drive pivot bearing" (needle bearing), is there a special tool? Is tapping outward from the inside of the final drive better than pulling out from the outside of the final drive with some type of a puller? Should the bearing slide out pretty easily after heating the final drive around the bearing? What is holding it in? Is it easy to get a new one in after successfully removing the old one? Are there any tricks involved?

 

Thanks in advance for the guidance!

RR

[smiller]

The bearing is just a press fit and can be tapped out with a screwdriver or punch from the inside, easier if you remove in the inner race first (if it doesn't fall out by itself!)

 

It's pretty easy to damage the bearing during removal since the inner race is just held in place with a plastic retainer, but usually this doesn't matter as you wouldn't be pulling the bearing in the first place unless you were planning on replacing it.

[Joe Frickin' Friday]

So to pull the "final drive pivot bearing" (needle bearing), is there a special tool?

 

Access to an arbor press would make life easy, but isn't required. You can get by with a socket, extension, and hammer. Find a socket big enough to contact the outer bearing race from the inside of the final drive (but small enough to not bind on the FD), then find a driver extension long enough to fit in that socket and extend through the opposite bearing, allowing you to pound the bearing out from the inside. Repeat on remaining bearing.

 

Is tapping outward from the inside of the final drive better than pulling out from the outside of the final drive with some type of a puller?

 

If you don't have a puller...yeah...sure...it's better. (either way works fine.)

 

Should the bearing slide out pretty easily after heating the final drive around the bearing?

 

Won't exactly fall out on its own, but it should be pretty easy to tap out if you heat it enough. I would not suggest a torch, as you don't want to mess up the aluminum or the paint (powdercoat?).

 

What is holding it in?

 

Friction. It's a plain ol' press fit. The pivot pins which screw into the swingarm push the inner races toward the driveshaft, which in turn make sure the outer races don't back out of the FD during operation.

 

Is it easy to get a new one in after successfully removing the old one? Are there any tricks involved?

 

Pretty easy. Put new bearing in freezer for a while, and heat the FD with a heat gun. Should be a pretty easy tap-in job with a socket/extension (or a very light press-in with an arbor press). Make sure your effort (whether hammering or pressing) is against the outer race and not the inner race; you don't want the needle bearings themselves to transmit that kind of load.

 

And don't beat the crap out of it. Drive it in far enough to positively seat against the shoulder in the hole (you'll see the shoulder when you get the old bearings out), and you're done.

[bmwmick]

RR,

You can also replace those needle pivot bearings with brass bushings that Tom Cutter sells. tpcutter@aol.com or http://www.rubberchickenracinggarage.com/

 

Mick

[RandyRandy]

Success!

 

and thank you for the kind advice. I found that my 21mm socket had the best outer diameter for removing the pivot bearings. I heated the FD around the bearings pretty good using a hot air gun and then drove them out with a hammer (actually driving the pivot bearings outward from the FD).

 

Then I put the new pivot bearings in the freezer and heated the FD once again around the pivot bearing holes. I placed the new bearing at the top of the hole and placed a 23mm socket on top of the bearing because my 23mm socket has an outer diameter that covers the outer race of the bearing and is about 1mm smaller in diameter than the outer diameter of the outer race.

 

Then I tapped (kind of hard, but not full force) with a hammer on the 23mm socket and it gradually went down into the FD pivot bearing hole. As it approached fully flush, I switched to a rubber hammer and finished with light tapping.

 

Sweet!

 

I cleaned the both pivot bearing bolts and the threads on the drive shaft housing with acetone (actually soaked the bolts over night in acetone). Then I took a small brass wire brush and cleaned all the softened Loctite. Then I checked that the bolts for both sides go smoothly all the way into the holes in the drive shaft housing. The outer ring on the left hand pivot bolt moves smoothly up and down the pivot pin.

 

I'm ready to install the FD per the Wisdom Page.

 

Hopefully, I'll ride today or tomorrow.

 

P.S. Before this job (which started as replacing the Clutch slave cylinder replacement) the onlyest wrenching I had done was oil change. Sure, I'm still a novice wrench, but I'm learning!

 

Thanks!