Hello All

Finally allowed back into the shed to start the spline lube and GPI replacement on the 86 K100

I have never done a spline lube on a k before and tried to educate myself as much as I could before starting

everything has gone really well until, checking the condition of the existing rear coupling spline  ( not sure what the actual correct term is )


To me the coupling spline looks like there is a major flat spot before or after the peak not sure what way the coupling splines spins  

The shaft is definitively gone.
Do a good cleanup of the splines on the final drive and take another picture. It maybe salvageable.
However, replacing both would be recommended but it's very expensive.

The shaft has had the fritz for sure and the splines on the drive aren't much better.
The shafts are easy to fix but expensive and new are eyewateringly so.
The only place I have heard of that fixes the drive is Bruno's in Canada but I am sure that there are many engineering places in Australia that would be able to fix it.
If the uni joint is OK then buy a replacement spline from Motobins and get it welded in to the shaft. If that is not possible Munich in Perth has new shafts.
https://www.motobins.co.uk/bmw-parts.php?model=K%20Series&bikeref=K100
I do have a Good shaft and drive and an almost new shaft plus a K100 that I got recently that has yet to be inspected.  PM for more details.

sad to see Mathew

I have a set here almost exactly the same

a second hand bevel box and drive shaft may be the simplest (and cost effective)  fix

and a good reminder to keep the maintenance up on "known to wear" parts

good luck mate

Well finally completed the spline lube and thanks to RickG for the spare final drive the K can now come down off the work bench 

Hello,

I was finally able to do my first spline lube job since I've got a lot more free time for home projects now. I want to confirm that my splines are in okay condition. To me, they looked good and were still a bit wet with lube, but I am well aware of my ignorance in this area. I have attached pictures of them below. I would definitely appreciate some opinions on their condition if anyone has the time. For reference, my odometer reads 81k (miles) and stopped a couple of thousand miles ago, probably something else I'll be able to fix now. 

Thank you,

Those are some of the best photos I've seen posted of splines.  The splines are clean and the light emphasizes the flat at the top of the spline and the ends as well.  Very nicely done.

As far as the condition, they look new to me.  I don't see any wear.

First post is Z20 splines. John A pic is Z16 splines from 85 and earlier that don't wear nearly as fast.

John A

 Contrast the crisp straight faces and the flat tops to those in the OP. Very nice.

Thank you for the feedback. Also, I had no idea that there were different splines after 85 and I got one that'll wear slower. I was worried a bit before because I'd had some false neutrals building and was hoping it wasn't the splines that caused it. Next up on my service side will be all the oil changes, and clutch line adjustment to hopefully cure that issue. I have been preloading the shift lever and that does make it shift better, but I think there might be a bit more going on. That or I'm just a worry-wort about my bike.

False neutrals on downshifts are a symptom of the transmission input splines (not drive shaft splines) being dry. It doesn't mean that the transmission splines are worn. (Yet. But they will wear quickly if you don't lube them.)

Add 20-25 grams of LiquiMoly gear oil additive to the transmission gear oil to improve shifting.

Is there play in the shift lever? grub screw?

Try pulling the clutch in just a little when shifting.  I have found on my bikes that pulling it all the way in actually makes it harder to shift.  It may be that the input shaft needs to be spinning a bit to facilitate the moving of the gears.