Hi,

A while ago I found an article describing how to fit a K100 rear wheel and drive onto a K75 but I can't find it now.

Anyone know anything about this. IIRC there were some differences and you need to change the drive shaft as well as the final drive pinions.

The K75 started making a nasty noise a last week and there is a un unsightly amount of metallic flakes on the magnetic drain plug. Does not look at all good.

I'm in the process of removing it but I'm already regarding it as probably dead.

Any tips on removing the speedo pick-up too. removing the allen screw and small cross head does not let it come out.

Any tips , thanks.

When I went to France in 2014 with 88 at the last minute he took the final drive off his K75 and put it on the K100.

Straight swap, no need to change the drive shaft or anything. That was bolt on and ride. It would be the same going the other way round too. Usually the drive shaft will be shot so may be changing it anyway.

Unless1:
You have a K75 drum brake model in which case you will need the disc brake set up as well as the final drive.

Be sure that the K100 drive you are using is for a 20 spline drive shaft. Early K100s are 16 spline and would mean a drive shaft change but I don't know if anything else will be needed. I don't know when the changeover occurred. As far as I recall all K75 are 20 spline. You have some small choice of final drive ratio as in K100RS is taller geared than the naked or LT. Difference is minimal.

Speedo you don't take out the small cross head, only the Allen bolt, its a squeeze in due to a seal and will just wriggle out.

Wait and see if anyone corrects me on the 20 spline comment.

Hi Beamer,

Olaf is right expect for one thing...it was 2015 ! The K75 rear drive and prop shaft was a straight swap as both k75 ands k100 were disc brake models. I had the same difficulty with removing the sensor in the K100 drive so I took the K75 one with the final drive and it was a straight plug in. 

The reason for swapping them was because the splines on the K100LT drive shaft were toast and I figured it was better to keep the drive shaft and FD as a matched pair. Shafts are interchangeable.  

They are long since returned to their respective original machines but it kept me rolling for that holiday.

Many thanks Olaf.

Yes, I sussed the speedo I was just being cautious not knowing how it came out.

I've stripped it and there is severe damage to several teeth on the crown gear and lots of loose iron the bottom. It's stuffed.

In fact the gear faces look OK where they're not smashed off, so it may turn once cleaned out.

To cause this kind of damage I'd expect to see loose roller missing from somewhere but have not seen anything yet. Sad mess.

Anyway the tips on drive swap seem to be in line with what I recall. Some incompatibility with spline numbers, so from what your mate did, it seems model dependent. That very useful into. Going to have to dig in and compare bits.

This is a drum-brake which was my initial interest in doing the swap but it sounded like a lot of messing. Now I have added motivation.


PS Thanks for the added info 88.

Yeah, this is a bitch because the gears did not really have any obvious wear, they looked pretty good.
But they seem to have eaten something and chewed it up.

All the bearings look good too except that there is a good mm of end float in the shaft with pinion. I don't know whether the nut clamping bearing has started to undo or what. Still doing the autopsy.


OK the coroner's report is just in : it's a kind auto-immune conditions where it starts eating its own bearings !

The needle roller bearing on the end of the shaft sounds prett aweful now it's been washed down, so my guess is that it has failed and allowed the excessive end float in the shaft and probably spat a broken roller into the main gear.

I'm pretty pissed off since this is a low mileage bike and the gears had very little wear before this incident. 

Don't have time to strip it further now, I'll have to stick the wheel back in to move the bike. I think I know all i need to for now. The exact reason  will be rather academic.

Beamer

We know you are hiding out somewhere in Cork, have to put a face to you some time.

The disc brake conversion does not seem to be a difficult one, disc, caliper, master cylinder, fluid reservoir, brake hose, probably brake pedal and brake switch too. Also possibly battery carrier tray support for the fluid reservoir. You may get a final drive with all the stuff on it. I am refurbing a K100RS final drive at the moment and plan to do a straight swap on the RT along with a drive shaft. Both are 16 spline and am looking at doing a rear engine seal job and of course it means do everything in there. The RS drive is taller gearing but it was what I had available.

Just a thought as to whether the footrest hanger differs between drum and disc brake models.

If you want to rebuild it Jimmy Ellis is your man. Take it anywhere else and ..... it ends up on his desk anyway.

Thanks for the tip Olaf, but if it needs rebuilding it's gonna be on my bench and no one else's/

There were some minor differences around the footpeg support but it looked like a case of drilling a hole or two.

I think the spline count is the key thing. I have it back on two wheels now. So i'll have a think about where I got with this later.

Thanks for your input. 

I sent you an email via the forum , did you see it ?

OK, I'm back to trying to swap the K100 and K75 final drives. Sadly they are not the same number of splines so I have to go right back to the gearbox output shaft.

I've the got the swinging arms off but can't seen how to remove the drive shaft itself. It has a couple of mil. of play but feels like there's a circlip or similar retaining it.

The hopeless french language workshop manual I have seems to refer you to a section they forgot to write. then says remounting is the reverse of taking it off. Fine.

I found this here:

Indy wrote:The paralever driveshaft is fixed to gearbox output by a circlip, same as the monolever.
Brute force isn`t what`s needed, but a sharp snatch backwards.

So I'm still confused. Where is the circlip and what is this about a sharp snatch if there is a ciirclip :?

Can someone who has done this indicate where the circlip is?  It's awful dark in there and I'm not sure where I'm supposed to be looking.

Thanks.

Beamer - once the swing arm is off, it is simple to get the drive shaft out. Use a crow bar (or similar lever) to gently lever against the front of the universal joint using the gearbox casing as the fulcrum (pivot point) - use a thin bit of plywood or thick cardboard to protect the gearbox case from being marked. With very little applied force, you will feel the drive shaft pop out as the spring clip that retains it at the front end is displaced from its slot. Others use a hammer to give the universal coupling a good clonk to achieve the same effect - I prefer the non percussive approach.

I call it a spring clip because the usual description of circlip is misleading - a circlip usually has drilled lugs (either internal or external depending on the application) that allow the insertion of the prongs of a pair of circlip pliers to either compress or expand the circlip to allow it to be removed from the groove that it is housed in.

At the front end of the drive shaft, you can't get to the spring clip and it just needs a little backward force to pop it out of its housing.

When you replace the drive shaft, a gentle whack on it's free end with a wooden mallet is sufficient to drive the shaft forward enough to allow the spring clip to pop back into its slot and thereby re-secure the drive shaft.

Thanks a lot BAE. I got it in the end, I found somewhere describing it as a "snap clip" and I got the idea. It was the description "circlip" that threw me since they usually go into a square sectioned slot and are designed NOT to come out under load. The last thing you want to do it give it a sharp shock.

Anyway I have the K75 with a disc rear-end now and just a few nuts and botls to tidy up to tomorrow.

Thanks for your reply.