New Drive shaft is bigger.

[41077]

Finally got around to installing a new shaft in my 86 K75T much to my surprise the universal end of the shaft will NOT fit through the opening of the swing arm. Did BMW beef-up the part, it is visibly wider than the old shaft. Now it appears my only option is to remove the swing arm an install the shaft then put the swing arm on. Any thoughts on this.
I did consider the Bruno option but a new shaft seemed to be a cheaper way to go at the time.
Photo isn't perfect but trust me the new shaft is wider. New one is on the right.

[jdiaz]

Yep. Gotta put the driveshaft on first, then the swingarm.

Its no big deal the second time. Actually, it wasn't that bad the first time, but be careful guiding the rubber boot and circlip around the u-joint.

[41077]

Shucks it was so easy the other way.
Thanks for confirming my conclusion.

[GregFeeler]

Yep. Gotta put the driveshaft on first, then the swingarm.

Its no big deal the second time. Actually, it wasn't that bad the first time, but be careful guiding the rubber boot and circlip around the u-joint.


I've changed two K75 drive shafts to the bigger units (thanks to previous owner's lack of spline lubing) and found I could get them to go in with some careful alignment and a deadblow hammer.

First, make sure you properly lube the front splines on the new drive shaft.

If you look inside the casting of the swing arm where the rear drive bolts up, you'll see there are several places where reinforcing ribs inside are machined to the same diameter as the opening in the drive shaft. Avoid these. Rotate the universal joint so the widest parts are trying to go into the swing arm between those ribs, then get it "just so" and tap with moderate force on the rear drive end of the drive shaft with a rubber dead blow hammer. A couple of good taps and it should pop right in. Yes, there will be a couple of slight marks on the inner surface of the machined opening of the swing arm, but they won't hurt anything.

Given that you keep the rear splines lubed properly, it could be a long time before you have to remove the swing arm and you've saved yourself a lot of work right now.

[BradfordBenn]

Fine engineering, installed with a hammer :rofl

[GregFeeler]

Fine engineering, installed with a hammer :rofl


Ok - just for you it's not a hammer, it's a "Tap 'O Meter". As fine a precision instrument as you've ever seen. :bolt

[41077]

I took the long route this time rather than the force it if it don't fit method.
My inlaws are visiting and I thought I might get a little alone time in the garage but nooooo, my father in law wanted to be helpfull and actualy it went better than I expected. Aside from being right where I needed to be a couple of times he was a handy extra pair of hands steadying the bike and tightening nuts and bolts.
One comment he made reminded me of why I like the older K-bikes.
"There is so much plastic and decoration on my Gold Wing it would take forever if I had to do something like this on my bike.
If it doesn't make it go faster or handle better what good is it? Exceptions made for radar detectors and gps units.

[PHMarvin]

Ok - just for you it's not a hammer, it's a "Tap 'O Meter". As fine a precision instrument as you've ever seen. :bolt

And if it doesn't work........., use a bigger hammer! I don't know when BMW changed the driveshafts, but I couldn't remove the driveshaft from Harriet's '95 K75. The universal wouldn't fit through the opening, and I didn't want to remove the swing arm.

[Bobmws]

A very small amount of work with a file or Dremel will give you eniough clearance to install the shaft with out resorting to a hammer.
What a concept.......... :stick