Author Topic: Oily drive shaft  (Read 3543 times)

Offline pdg

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Oily drive shaft
« on: January 21, 2014, 05:56:15 PM »
Not a problem, but a thought....

Seems to me that the rear splines are one of the biggest 'weak' points on a monolever K. Even keeping on top of moly pasting the splines doesn't eliminate the problem entirely. Earlier BMWs and a lot of jap shafties run wet shafts and never have any spline wear issue at all.

Has anyone 'converted' a monolever to run wet? Or heard of it?

I just bought a cheap swingarm to play with and see how feasible the idea is, but if anyone has any pointers it might save a bit of time.

I reckon it could be a winner :2thumbup:
1988 K75S

Offline Motorhobo

  • +25 years of K75
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Re: Oily drive shaft
« Reply #1 on: January 23, 2014, 11:10:21 AM »
Just curious -- aren't these shaft splines designed for specific lube viscosity? If you run them wet with a lower-viscosity lubricant won't they wear anyway because the lube is too thin?

I don't know...just asking.
1994/1995 K75 ABS Frankenbike: original engine 136k miles, frame from Gary Weaver (RIP), 173k miles -- Current Odometer: 198k miles
1994 K75 since 2013, 82,000 mi (19k mine) w/California Sidecar Friendship II Sidecar & Black Lab 'Miss B' - RIP

Past: 1974 Honda 550/4 (first bike), 1994 K75 (sold), 1995 K75 ABS (parts bike), Sidecar Dog & Best Bud 'Bo' - RIP

Offline pdg

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Re: Oily drive shaft
« Reply #2 on: January 23, 2014, 12:02:02 PM »
If you go too thin with the lube that might be the case, but using 90w should see it right. After all, the material is the same as used on most other shaft drives and they are oil lubed rather than moly'd.

Personally, I prefer the theory of a thinner lube being there all the time over a thick lube being applied once every few thousand miles.

My 'new' shaft housing has turned up, so experiment time is almost upon us.....
1988 K75S

Offline Inge K.

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Offline pdg

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Re: Oily drive shaft
« Reply #4 on: January 23, 2014, 01:08:53 PM »
Thanks for the link Inge, had a look.

My idea is a little different to that - something I didn't mention is that I've lifted the rear of the bike a bit..... This puts the UJ at more of an angle (so more movement on the UJ bearings) and introduces more 'slide' on the splines. All that means that I'd like the oil to splash lube the UJ as well.

Sure, I could add UJ lube to the service list, but an oil change is so much easier.

I don't see oil contamination (or even immersion) affecting the rubber cush. It's designed to be in an environment which is exposed to grease and also has a high chance of oil ingress.

Still, it's not exactly an expensive experiment for me to do and given the amount of rear splines I hear of failing even when serviced I think it's worthwhile for me.
1988 K75S

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