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1Back to top Go down    Final drive crown gear bearing on Tue Oct 30, 2018 7:02 pm

StefanMajonez

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Hi!

Recently my rear end started to feel abnormal, and since I've already done this I popped the rear open. After determining that my new-to-me shaft is, in fact, okay, I started to investigate further.



Not a professional bike mechanic, but my guess is that it shouldn't make that noise Laughing

So, my question is - what parts should I get to properly repair this?

I've found this topic and it says I need the bearing (obviously), a new o-ring and the main seal.

I'm planning on replacing the o-ring and the bearing. A new main seal costs an amount of money, and the current one looks okay-ish - should I leave it as-is or is it a very vital part to have brand new?

Thanks in advance for any answers or info!


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1994 - BMW K1100LT
Dyno results 2017


Previous bike:
1989 Honda CB450S
    

2Back to top Go down    Re: Final drive crown gear bearing on Tue Oct 30, 2018 9:33 pm

Dai

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That indeed sounds like it could be a dead main bearing. As for the seal; if you were very careful in disassembly and can be absolutely sure that you did not catch or tear the lip, then it should be safe for re-use.


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

3Back to top Go down    Re: Final drive crown gear bearing on Tue Oct 30, 2018 10:01 pm

StefanMajonez

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@Dai wrote:As for the seal; if you were very careful in disassembly and can be absolutely sure that you did not catch or tear the lip, then it should be safe for re-use.

I wasn't exactly careful with the disassembly, but I did disassemble it vertically so the wheel hub fell straight out.



The seal looks and feels smooth, with no notches, and the rubber isn't dry and doesn't feel old. And if it leaks I'll replace it, Winter is coming so no rush, and plenty of time to observe it Very Happy

@Dai wrote:That indeed sounds like it could be a dead main bearing.


Doesn't feel VERY worn, but it is rough.


__________________________________________________
1994 - BMW K1100LT
Dyno results 2017


Previous bike:
1989 Honda CB450S
    

4Back to top Go down    Re: Final drive crown gear bearing on Wed Oct 31, 2018 12:08 am

92KK 84WW Olaf

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Replace it, that saves you losing the rest of the final drive. Mine was like that wasn't really any discernible play but it FELT different and my expert friend confirmed it was gone. Bearing replaced without even removing the final drive. We had done a rear main seal and spline lubes etc a few months before and knew the rest was all good.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 83,050 miles
    

5Back to top Go down    Re: Final drive crown gear bearing on Wed Oct 31, 2018 12:19 am

StefanMajonez

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@92KK 84WW Olaf wrote:Replace it, that saves you losing the rest of the final drive. Mine was like that wasn't really any discernible play but it FELT different and my expert friend confirmed it was gone. Bearing replaced without even removing the final drive. We had done a rear main seal and spline lubes etc a few months before and knew the rest was all good.

Oh don't get me wrong, ANY roughness or play in a bearing means replacing it. Especially since it's a rather important bearing.


__________________________________________________
1994 - BMW K1100LT
Dyno results 2017


Previous bike:
1989 Honda CB450S
    

6Back to top Go down    Re: Final drive crown gear bearing on Thu Nov 01, 2018 1:26 am

Snod Blatter

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I did replace the main seal as it's not very expensive but the old one seemed absolutely fine.

Do you have a plan to get the old bearing off?


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1989 K100RS SE ABS 8v VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

7Back to top Go down    Re: Final drive crown gear bearing on Thu Nov 01, 2018 12:25 pm

StefanMajonez

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@Snod Blatter wrote:I did replace the main seal as it's not very expensive but the old one seemed absolutely fine.

Do you have a plan to get the old bearing off?

I carefully cut the old bearing (not even a scratch on the gear) and I plan to press the new bearing on - my friend has a press in his shop.

I found a local bearing store in which I ordered the brand new bearing that also has similar looking main seals, I'll bring the entire cover with the main seal to this store on Friday (when the bearing should arrive) to check if it fits.


__________________________________________________
1994 - BMW K1100LT
Dyno results 2017


Previous bike:
1989 Honda CB450S
    

8Back to top Go down    Re: Final drive crown gear bearing on Thu Nov 01, 2018 3:12 pm

Dai

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Put the drive box in the freezer for a couple of days (yes - it needs to cold soak). Put the bearing in the oven on the lowest heat possible for around fifteen minutes. You may find that the bearing is then a push fit rather than having to press it on using a tool. I'm old - I used to replace main bearings in two-strokes and big Japanese singles using this technique, except that it was the other way around - cold-soak the bearings and cook the crankcases.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

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