BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down    bearing rumble on Sun Jul 16, 2017 1:57 pm

Beamer

avatar
Silver member
Silver member
Hi, I'm in need of a bit of advice.

I use the K75 as everyday transport and recently I have been feeling a slight vibration in the right-hand foot-peg. It's light for the moment and intermittent but feels like a worn bearing.

I'm trying to pin it down a bit as to where the problem lies. I want to catch this before it becomes a bigger problem and keeps me off work waiting for parts or similar.

Now, I have a spare g/box and final drive which was donated to me by an acquaintance. He says he removed it from a working bike and it was in good working condition. I don't know his competence level and how to read that comment but it's a guide that it is not scrap.

I just pulled the final drive unit off the bike and there was nothing suspicious in the oil and and it feels smooth moving it by hand. There is very little backlash in the bevel gears. Turning the drive shaft by hand with the g/box in neutral also feels fine. However, I'm not sure whether  the problem will show up under no load, since it is only a light vibration on the road.

My guess is that it is a gearbox bearing, though swapping the box seems like quite a lot of work. I may recondition the spare box in advance so I have a known good replacement.

any suggestions?

Thanks.

    

2Back to top Go down    Re: bearing rumble on Sun Jul 16, 2017 2:33 pm

92KK 84WW Olaf

avatar
Life time member
Life time member
Well since you are in Cork.....

My final drive did that not so long ago and first off I had to deduce where the rumble was. As in was it at engine speed or wheel speed. Eventually sussed out it was wheel speed which means it can only be coming after the gear box and must be somewhere in gearbox output or the final drive. Some I did in neutral downhill to feel what was happening.

Mine was in the final drive and the failing bearing could not be felt.

Since you have a spare final drive I would swap it and see what happens. Only takes a few minutes. Odds are it's the big bearing in the final drive and if neglected will bugger it up as you rightly say. Unfortunately in early stages you won't feel any movement, leave it and its big trouble. New bearing and mine was sorted.

If you diy it that's ok, if not Jim Ellis will do it for you. If swapping the final drives sorts it then keep your € in your pocket
.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 74,700 miles
    

3Back to top Go down    Re: bearing rumble on Mon Jul 17, 2017 8:18 am

Dai

avatar
Life time member
Life time member
Go check the simple bit first - pull the alternator and check that the monkey nuts (rubber buffers) are still in good condition. It should take you about half-an-hour from start to finish.


__________________________________________________
'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)
    

4Back to top Go down    Re: bearing rumble on Mon Jul 17, 2017 9:05 am

AL-58

avatar
Life time member
Life time member
I had that happen years ago, just felt the rumble through my foot, mostly on the over-run decelerating off throttle.  In my case it was the gearbox output shaft bearing.  The easy way to check and be sure was to pull the rear end and swingarm to get to the output shaft, you could feel the roughness in the bearing when turning it by hand.

Al


__________________________________________________
'87 K100RS/HRD sidecar (1100 motor)  sc25 
'92 K100RS-16v (Paint it Black)

'87 K100RT with Paralever backend

"When I'm too old and too foolish to handle a sidecar I'll buy a Sportsbike"

    

5Back to top Go down    Re: bearing rumble on Mon Jul 17, 2017 10:23 am

92KK 84WW Olaf

avatar
Life time member
Life time member
If you have swapped the final drive and get no improvement that's the other place to look.

Not sure how easy or difficult that job is but expect it means opening the gearbox.


__________________________________________________
1992 K100LT 0193214 Alaska Blue 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Mystic Red 58,645 now 74,700 miles
    

6Back to top Go down    Re: bearing rumble on Mon Jul 17, 2017 11:13 am

Beamer

avatar
Silver member
Silver member
Thanks for the suggestions .

The spare FD turned out to have a lot of back lash and was ruff as nutts. Not worth putting on.

Had the alternator off a while back and all is OK.

My gut feeling is that it's a gearbox bearing. There was a small amount of metal filings on the drain plug when I did an oil change as well. I may recondition my spare g/box so that I have one good one ready to drop in.

    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum