Re: Spline Lube

["John Dancoe" <jdan@xxxxxxxx>]

>Clive Liddell wrote:
> 
> Not sure if I have raised this heresy(?) on this forum or another but: 
IMHO
> all that lubing of the input splines does is to delay or eliminate
> corrosion.  I cannot see how lubing can prevent damage to splines caused
by
> torque application and/or reversal since there is the very minimum of
> sliding of the clutch plate involved and, when it is "sliding" there is no
> torque being transmitted.
> 
>Question.  Was the wear on your input shaft localised to virtually the
width
> of the clutch plate internal splines?

I don't know what the actual root cause was, but the wear was very real and
significant. Essentially, the crest of the spline at the forward end of the
shaft was so badly worn that the flat was completely gone, indicating one
of the flanks of the spline had been eroded (or possibly, deformed). I'm
pretty sure I recall it was one flank and not both, presumably the flank
loaded by engine torque transmitted thru the clutch as it engages.

The amount of wear decreased at a fairly linear rate along the working
surface (i.e., the distance the clutch plate moves over) of the spline, so
I would say "yes" is the answer to your actual question if I understand
you. 

The splines were naturally in essentially virgin condition where the clutch
plate did not travel, except for a thin layer of rust, so corrosion may
indeed have been a factor. They salt the roads in Michigan USA and I often
will ride in midwinter on dry days. Anymore I avoid that unless there has
been also been some rain to wash the salt dust away, but the first few
years I owned the bike I rode it every chance I got. In fact I recall the
3rd day I owned the bike (Nov 22 1993) it snowed and they salted the hell
out of the roads; the next day it was clear and I rode it to work. I
attribute that ride as the reason my header pipes, instead of turning the
usual soothing purple, became forever snot green.

Back to subject: it is a plausible failure mode that corrosion developed on
the splines during the idle periods in the winter and the iron oxide 
particles of the rust layer, and/or the compromised metallurgical
properties of the spline's case hardening, accelerated wear when I started
riding again. 

If periodic lube prevents that failure mode, great, that's what I'm
counting on. But my original point is that I was specifically told by the
dealer not to worry about lubing the splines, even after I'd seen many
reports of worn splines on this very list. 

Perhaps spline lube is not necessary in climates without salted roads (or
sea air!?!), but is indicated here in the great white north. I'm definitely
not going to blithely assume lube is unnecessary; I managed to wrangle some
relief from BMWNA and my dealer when this happened the first time, even
though my warranty had expired, but I'll never get that grace again, nor do
I want to put up with the downtime of a repair which was considerable.

I have some images of the splines that I took with my son's Intel
microscope, I'll see if I can dig them up and I'll mail them to you.

John Dancoe
'93 R11RS

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