1985 K100 Drive shaft splines

[hhshort]

Quick and dirty answer with a fuzzy picture. I am not a mechinist but I have extra nerve and spare FDs. The space you need to fill is at the mating joint of FD and DS. There is only 14 mm of distance in that cavity. So I have center punched 7 mm from the mating edge. I have not done this yet but I plan to make my own plug from a shortened bolt with a 8 mm by 1.25 thread and a 8 mm crush washer. The final drill will be a 17/64 bit. If there is interest I will photo the procedure. Harold in Kansas

[98lee]

If your going to put in a fill plug, a drain plug would be nice so you can keep the oil fresh.

[85K100LT]

I believe this FD problem is due to mismatched or improperly aligned parts from the factory.

Original poster quote:


"Bob; I am using good used FD/DS pairs from the same bikes. They are matched."


Are they matched or do they just fit together with some alignment issuses??


While some people claim over 100K miles with splines still looking perfect. I have to believe these are aligned correctly or came out of the factory built right.


When someone has multiple failures - I tend to believe it left the factory mis- aligned and with a short life expectancy.

Factory Quality control - some badly aligned units got through

Now in this case K100 has a sidecar attached which may cause pulling / misalignment.

my thoughts after seeing muliple posts on FD failure.


TO: Original Poster - I wish you the best on your modification. Also check to see how these parts align and think about shimming the fit.

[angysdad]

A quick comment from a mechanical know-nothing.
I too have an EML equiped 85 K100.
It was assembled at the EML factory in Holland.
The PO told me that EML installed a hardened drive shaft.
True or not, no idea, but the shaft has around 300k miles of pulling a sidecar and it works fine.
You might try contacting EML and find out if the hardened drive shafts are still available (probably not), or if they ever had them in the first place.
speed safely

[tjtraver]

Hi Harold ,

Just wondering if you've added the fill plug and how it worked out ? I will be doing mine to my 1995 K75 in the next few weeks . Weather here in NY has just been so nice , that I've been riding rather that pulling the final drive . I am waiting for rainy week to do it .

I was reading my R90's shop manual. My 1975 R90 has filled drive axle . The procedure is to use a dip stick to reach down and touch top of drive shaft . Then fill with 90w gear lube to 2mm above the drive shaft . On my R90 that's 100cc.

Send pics if you've made the mod . I will post my pics once done .

Todd

[hhshort]

Sorry Todd, I thought this thread had fallen into ablivian(sp). I am still experimenting and the real true will not be known till next winter when I do winter service again. I put 100ccs in the shaft compartment and ran it a while and drained 75cc out when I took it apart because the drive shaft boot leaked. I am assuming that 25cc went up to the boot. So I only put 75cc back in. I will check it again and your method be for the real ridding season begins.

I had a small drill press vice and a drill press. It took me about an hour to make sure I had parrallel and perpendicular. After that it was just drill and tap. I used a 8 by 1.25 bolt that I cut off to make a plug with a crush washer. I suspect a normal washer and teflon tape would be suficient.

I cant seem to get more then one picture per post so will make 2more posts

[hhshort]

I used plenty of cutting fluid for both the drill and the tap because of the alloy.

[hhshort]

If there is any thing that I didn't include--- Let me know Harold in Kansas

PS don't look at the quality of the splines. This was an experimental piece not the one that went on the rig.

[tjtraver]

Well, I finally got around to drilling and tapping final drive , so I could fill it with gear lube rather than having to disassemble and grease it every year ( and hoping the grease holds up between lubes ) .

I sealed the final drive to swingarm with Hylomar sealant , then filled it with 130cc ~ 4.5 oz of 90-140 gear lube and took a nice 50 mile ride up and down a bunch of steep hills . No leaks !

Looking into the fill hole the lube comes 75% up the sides of the drive shaft. When giving the wheel a spin and I can clearly see the lube circulating . It's certainly getting plenty of lubrication now in this constant gear lube bath.

Backstory : My K75 has 38,000 miles on it . I've always lubed the drive shaft spline with Honda Moly 60 whenever I replaced the rear tire , and usually found the grease almost non-existent when I did . Because of that the drive shaft picked up some wear / notching in the splines but not too bad yet . I believe with this gear lube mod the shaft should now last indefinitely ( and my hands will stay a lot cleaner ! ) .

To me this mod is clearly worth the time and effort ... in case anyone else is interested ...

Regards , Todd

[hhshort]

I haven't had a lot of time to test my modification. I put it on my solo K100RT to test it out before I put it on my side car. The first time I used it the oil came out of the swingarm boot. It had a little rip in it so I replaced the boot. I replaced the boot and put 100 cc in the swingarm and it leaked at the boot again. At this point the bike was put for the summer. This fall I have returned to the bike and at this point I have greased the splines and put in 50 cc to see if the oil will stay in the swingarm. It this doesn't work I will pull the swingarm glue and clamp the boot. For the summer and my sidecar rig I tried my first senerio. I filled the driveshaft with insulation foam, stuffed in some plastic on top of that and filled the rest with grease. I have about 4000 miles on that test. I will pull it some time this fall and I will report. Please report on how your mod is working for you Harold in Kansas

[cycleman2]

The mod you have done is the same set up as the airheads had prior to the single side swing arm monolever. The oil does migrate up the drive shaft and into the boot area and then goes back down the drive shaft tube and so on and so on.

There is no reason it shouldn't work and looks like a fairly simple mod.

[PGlaves]

The mod you have done is the same set up as the airheads had prior to the single side swing arm monolever. The oil does migrate up the drive shaft and into the boot area and then goes back down the drive shaft tube and so on and so on.

There is no reason it shouldn't work and looks like a fairly simple mod.

The boot at the front is remarkably different. On an Airhead it clamps in place. On a K bike it just slips over as a friction fit - dust seal. Given the shape of the front of the boot I'm not sure how to clamp it. I'd have to pull a swingarm to figure that out and I'm not going there right now.