K75 Driveshaft

[CNRED]

I've got two K75's and I've service the Driveshaft on both a couple of times.  We all know the  drill, not really complicated, takes a little time but, well worth the effort.
I recently bought a third K75, a 1994 "C" model. The bike has just over 100K miles but ran deciently, had a lot of the parts I was looking for to bring back one of my other bikes.
  I decided I would pull the final drive and take a look at the drive line.
   It diidn't look too bad, not perfect by any means but not horrible either,
 
IMG_3696.JPG (32.63 kB . 768x576 - viewed 609 times)
   

   Not bad for 100K.
   While cleaning the splines for this picture I noticed there was something inside the driveshaft that would not allow me to insert the brush I was using more then about 1 and a half inches into the spline area.
   Here is what I found.
   
IMG_3698.JPG (38.81 kB . 768x576 - viewed 574 times)

   It appears that some one plugged the end of this shaft with some type of silicone, or some such material.
I saw a Chris Harris video sometime back where he was talking about cutting a drive shaft to insert a silicone plug to keep spline lube in the splines rather then allowing it traveling up the shaf. then welding the shaft back together.
   I don't see any evidence the shaft had been cut and welded.  I'm trying to figure out how this was accomplished.  I stuck screw driver inside the shaft and the silicone feels solid. 
   So now I'm wondering if someone filled the entire shaft with silicone?
   I weighed this shaft with the u joint just the way it came out of the bike, it weighs about 3Lbs 2 Oz. Anyone out there have a spare shaft sitting on a shelf that they could weigh.
   I'm pretty sure the driveshafts on my other two K's were hollow.
 
 

[Laitch]

Max BMW's parts fiche lists the weight of a 20-tooth drive shaft at 3.18 lbs

[CNRED]

That's pretty close to what this one weighs.
Thanks.

[daveson]

its a petty safe bet that the silicone was placed there from the open end, so there no need to cut the shaft

[daveson]

Never thought of using it on splines, is there less wear that way

[CNRED]

its a petty safe bet that the silicone was placed there from the open end, so there no need to cut the shaft

I agree, it had to have been put in through the open end, but how did they form it to make such a solid plug without filling the entire shaft with silicone?

[daveson]

maybe push in a sponge or dowel then silicone over the top of it
i think ill do it to my bike next time its off
i spose you want it light and evenly spread so its not too unballanced
i think i saw on youtube that some weld a washer in or something like that

[daveson]

maybe a welch plug or soft drink bottle cap, ill be keeping an eye out now for something the right diameter
do you know what the diameter needs to be

[Laitch]

maybe push in a sponge or dowel then silicone over the top of it . . . some weld a washer in or something like that

maybe a welch plug or soft drink bottle cap . . .

The lubricating pastes recommended for use on K-bike drive train splines are thin-film lubricants. They are designed to bond with metal surfaces at a microscopic level for a period of time and should be applied thoroughly but sparingly. If migration of lubricant away from the shaft splines seems to be a problem, maybe too much was applied. Also, if the tendency is for the lube to be slung off the shaft, the addition of a washer or silicone plug would only serve to collect the lubricant as it was deposited on the plug or washer surfaces by centrifugal force. What would be the force that slings it back onto the shaft? Isn't the lubricant already bonded to the shaft surface regardless of where excess travels?  It's a faith-based issue really, because microscopes are involved.

The addition of washers or plugs might appear to reduce the need for inspection of the rear drive shaft splines for sufficient lubricant but the shaft should still be inspected a couple of times at 6k-mile to 10k-mile intervals to verify that the new arrangement works as intended. If shaft splines are lubricated at appropriate intervals with a thin film of high-quality paste then I think the life of them is governed by their design, by the metal composing them and to a great extent by the way a moto's rider places a load on them.

I won't be doing this modification because preoccupation concerning whether to add bottle caps, dowels, corks (an industrial neoprene stopper would be a fun choice), plugs, insulation foam, wads of exotic or ordinary origin, Stove Top Stuffing, silicone or etc. into my moto's driveshaft in a search for mechanical immortality would reduce the enjoyment of my ride. :giggles

[rbm]

+1 with what Laitch says. The active lubricating ingredient in the grease is molybdenum disulphide.  This chemical molecularly bonds with the metal, forming a robust low-friction coating.  For a product like Honda Moly60, 60% of the product is this active chemical, the remainder is a wax or oil based carrier.  The carrier tends to migrate away from the working surfaces due to centripetal forces from the rotating drive shaft and spline pressure.  It carries away some of the moly that has not yet bonded with the metal, reducing the effectiveness of the grease.

One method to help the carrier stay in place to prolong the time for the moly to bond is to cap off the areas where the carrier will tend to migrate.  Silicone plugs help in this respect.  Another way to slow migration is to increase the viscosity of the carrier.  The popular way to do this is to mix the moly grease with a sticky base like Wurth SIG-3000.  This Wurth product is like very thick honey.  It resists spline pressure and remains in place for a long time, allowing more of the moly to bond with the metal.

[riots100]

The popular way to do this is to mix the moly grease with a sticky base like Wurth SIG-3000.  This Wurth product is like very thick honey.  It resists spline pressure and remains in place for a long time, allowing more of the moly to bond with the metal.

Is this procedure documented anywhere?  What are mixing ratios of the Wurth SIG-3000 and the Honda Moly60?

[rbm]

Is this procedure documented anywhere?  What are mixing ratios of the Wurth SIG-3000 and the Honda Moly60?

It's mixed 50/50.  This tip came from Paul Glaves of BMWMOA fame many many years ago.  I use this mixture myself and have found it to work very well.