BMW K bikes (Bricks)


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

StefanMajonez

StefanMajonez
active member
active member
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!


__________________________________________________
1994 - BMW K1100LT
Dyno results 2017


Previous bike:
1989 Honda CB450S
    

2Back to top Go down   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Tue Oct 30, 2018 3:33 pm

Dai

Dai
Life time member
Life time member
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.


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

3Back to top Go down   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Tue Oct 30, 2018 4:01 pm

StefanMajonez

StefanMajonez
active member
active member
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.

Final drive crown gear bearing P_201811
Final drive crown gear bearing P_201810
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.

Final drive crown gear bearing P_201812
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   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Tue Oct 30, 2018 6:08 pm

92KK 84WW Olaf

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Life time member
Life time member
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 Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

5Back to top Go down   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Tue Oct 30, 2018 6:19 pm

StefanMajonez

StefanMajonez
active member
active member
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   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Wed Oct 31, 2018 7:26 pm

Snod Blatter

Snod Blatter
Life time member
Life time member
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?


__________________________________________________
1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL, '01 R1100GS
http://justbikethings.blogspot.co.uk/
    

7Back to top Go down   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Thu Nov 01, 2018 6:25 am

StefanMajonez

StefanMajonez
active member
active member
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   Final drive crown gear bearing Empty Re: Final drive crown gear bearing Thu Nov 01, 2018 9:12 am

Dai

Dai
Life time member
Life time member
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.


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

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