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Author Topic: Final Drive Bearing replacement  (Read 3814 times)

Offline CTDOM!

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Final Drive Bearing replacement
« on: May 04, 2021, 09:43:03 AM »
Hi all,
I have play in my final drive (grab wheeling it rocks back and forth) and noticed my rear disc is very worn so I figure it is time to change the bearing.  From what I have read the large bearing is the one to change and the one I have procured.

In the process of disassembly the tapered bearing just slipped off.  I mean I turned the crown wheel over and the bearing slipped off, I hadn't even tried to pry the old bearing off.  Is it supposed to be so loose?  Or is that part of the looseness problem?  Bike has ~85K and I am at least the third owner.

Thanks!
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Offline johnny

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Re: Final Drive Bearing replacement
« Reply #1 on: May 04, 2021, 12:56:49 PM »
back n forthe = ok
side 2 side = poo
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Offline Laitch

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Re: Final Drive Bearing replacement
« Reply #2 on: May 04, 2021, 05:12:00 PM »
Quote from: CTDOM! on May 04, 2021, 09:43:03 AM
In the process of disassembly the tapered bearing just slipped off.  I mean I turned the crown wheel over and the bearing slipped off, I hadn't even tried to pry the old bearing off.  Is it supposed to be so loose? 
The bearing should be tight on its shaft; a loose bearing in this assembly is not typical. A loose bearing will damage the assembly.. Inspect the shaft and bore for damage and take dimensions of the bearing. Clear photos will help explain the situation here.
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Offline CTDOM!

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Re: Final Drive Bearing replacement
« Reply #3 on: May 04, 2021, 10:05:06 PM »
Ok I did some more investigating this evening.  The shaft looks smooth and OD measures just a needle worth under of 0.983" while the bearing looks not quite as nice but the ID also measures 0.983".  The bearing slides on and off like butter.  A press fit it is not.

I am going to go pull out the manual out to check to see if it has any tolerances listed.

I don't have the tool to pull the race out of the final drive housing so not sure what's next..

Thanks!
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Offline Laitch

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Re: Final Drive Bearing replacement
« Reply #4 on: May 05, 2021, 07:33:37 AM »
Quote from: CTDOM! on May 04, 2021, 10:05:06 PM
The shaft looks smooth and OD measures just a needle worth under of 0.983" while the bearing looks not quite as nice but the ID also measures 0.983". I don't have the tool to pull the race out of the final drive housing so not sure what's next.
What's next is getting a tool to remove the outer race from its seat. Many types of pullers are sometimes loaned without fee by NAPA, Pep Boys, AutoZone or other major auto parts dealers for a refundable deposit made with a credit card.

The marks on the inner perimeter of the inner race seem to indicate that it has been spinning. It shouldn't be doing that. If this were my project, I'd also remove the outer race then I'd get an OEM bearing assembly to determine if its fit on the shaft differs from the current one.

The ID of the inner race is 0.983" or a "needle under"? MaxBMW lists 25mm as the inner dimension of the tapered bearing race; yours is 24.96mm so it seems to meet that spec. I'd also be measuring in millimeters because that's the unit of measure BMW tends to use and it also usually beats "needles" or "hairs" for accuracy.  :laughing4-giggles:

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Offline CTDOM!

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Re: Final Drive Bearing replacement
« Reply #5 on: May 05, 2021, 08:15:17 AM »
I couldn't find my digital calipers last night so dial calipers it was..  Besides 3 decimal places is pretty good,  :laughing4-giggles:
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Offline Laitch

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Re: Final Drive Bearing replacement
« Reply #6 on: May 05, 2021, 09:21:16 AM »
Quote from: CTDOM! on May 05, 2021, 08:15:17 AM
Besides 3 decimal places is pretty good
Actually, it's four places—tenths, hundredths, thousandths, and needleths. That's even better than 3- decimal places.  icon_cheers
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Offline CTDOM!

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Re: Final Drive Bearing replacement
« Reply #7 on: May 05, 2021, 09:40:00 AM »
"Needleth"
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Offline CTDOM!

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Re: Final Drive Bearing replacement
« Reply #8 on: May 06, 2021, 01:08:05 PM »
Waiting for bearing to come in.  Will update when I have more info.

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Offline CTDOM!

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Re: Final Drive Bearing replacement
« Reply #9 on: May 10, 2021, 10:33:03 PM »
OK, got everything back together.  The new tapered bearing from the dealer did not require any real pressure to put on the shaft. I used some Loctite 638 on the shaft to get a good fit. The ID of the bearing isn't going to spin.  Tomorrow I go for a test ride. 

On a strange note, not sure why there would have been two shims on the rear wheel??  Seems if I remember correctly one was stuck to the disc and the other was free on the wheel. Only thing I can think of is that the one stuck to the disc went unnoticed so they put on another shim thinking it wasn't there.  I don't seem any reference to having two shims and it can't so someplace else.  Thoughts?

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Offline Laitch

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Re: Final Drive Bearing replacement
« Reply #10 on: May 10, 2021, 11:59:53 PM »
Quote from: CTDOM! on May 10, 2021, 10:33:03 PM
Only thing I can think of is that the one stuck to the disc went unnoticed so they put on another shim thinking it wasn't there.  Thoughts?
That's likely, or maybe it had a fat tire on the rear once upon a time and a second shim was needed to clear the swingarm. Instead, think about maple creemees licked beneath slow-moving clouds with ravens croaking in the distance.
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  • Along the Ridley in Vermont.
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Offline CTDOM!

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Re: Final Drive Bearing replacement
« Reply #11 on: May 17, 2021, 09:18:06 AM »
I want to close this out.  So I took her out for a nice long ride. What a difference! Since having the bike (4 years now), every time I had to snap the throttle shut the bike did this weird back end twitch, almost like a weird gyroscopic effect combined with a driveline lash.

Well it is all gone, I assume what I was feeling was the slop in the rear wheel.  It is like a new bike and it is sooo smooth. 

I had a wonderful ride, this bike becomes a joy to ride more and more.  Thanks to all of you!
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Offline Laitch

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Re: Final Drive Bearing replacement
« Reply #12 on: May 17, 2021, 11:51:10 AM »
 icon_cheers
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  • Along the Ridley in Vermont.
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