I am changing some of the gears in my gearbox because I need higher ratios for my Mercedes Smart Diesel engined K 100. I’m also changing the final drive ratios and one of the guys in Germany as had a whole gear set cut. It basically doubles the overall ratio.
 
The gearbox is done. Removing the large gear of the intermediate shaft (the centre top one in the gears shown on the photograph below) needs a lot of pressure. 10 tonnes wouldn’t. 20 tonnes wouldn’t touch it. It needs 40 tonnes. The centre shaft is non-serviceable-allegedly
 
Here is the cluster before changing the gears. You can see the new shiny years adjacent to what they are going to replace.
 
DSC04621
 
Taking the final drive apart is not for the fainthearted. I’m sure that shimming it up, on rebuild, is going to be “interesting”. Mine is now in a zillion pieces and ready for reassembly.
 
Don’t even attempt to strip the K 100 final drive unless you have a 36 mm impact socket, a long bar, and a tool to remove the 4 slotted ring nut which holds in the final drive pinion. I made the tool by welding 4 wings onto an old socket. They are both v tight. The manual says use heat.
 
DSC04816
 
DSC04819
 
Because I’m replacing both the crown wheel and the pinion, all the parts which fit on the crown wheel and pinion have to be removed. The one job that took longer than anything else was removing the inner race of the nose of the pinion which fits into the needle roller bearing in the aluminium housing. There is nothing to get the bearing puller on.
 
The large bearing came off with the help of a 10 ton press and the centre part of the crown wheel (the aluminium bit) succumbed to a few tonnes less.
 
I’ve now got to think about putting it back together and doing all the correct shimming. Deep joy.
 
I do have one problem and that is that the input splines on the pinion of the final drive has 20 splines and my shaft is 16 splines. I may need to find another shaft. I’m assuming that all the front of the driveshafts are 16 otherwise I might have to change gearboxes or make hybrid shaft.
 

I just thought I’d share this little gem with you.

Well, if shimming it up is as 'interesting' as shimming Guzzi drives, then put aside at least a half-day. Or a full one, if it decides to fight back.

What ratio are you using in the final drive?

I have the Clymer manual so I can see the process. I guess it’s a case of just doing it carefully and not rushing.
 
RE: Ratios,  I haven’t counted teeth but here they are.
 
DSC04609 
 
DSC04608
 
DSC04607
 
 
DSC04605
 

DSC04604

Assembled cluster with new gears  in situ. Pretty isn’t it? Background is the back of a roll of wallpaper.
 

DSC04809

That Crown and pinion is 13/31 (2.38) did you get them made and if not where the heck did you get them. I've never heard of a BMW ratio that high. 2.52 was the best I could come up with when I went looking.

Interesting thread - thank you 'touchwood'

Keep us posted please.

rawdonball wrote:Interesting thread - thank you 'touchwood'

Keep us posted please.

 Indeed I will. The story so far is here:
http://www.suckindiesel.com/thingy/viewtopic.php?f=31&t=3216

I should have kept my gob firmly shut. I just spent six-and-a-half hours shimming a Guzzi bevel drive. I really hope you have better luck than I did.

Don’t even attempt to strip the K 100 final drive unless you have a 36 mm impact socket, a long bar, and a tool to remove the 4 slotted ring nut which holds in the final drive pinion. I made the tool by welding 4 wings onto an old socket. They are both v tight. The manual says use heat.

Thanks for the warning.   I'm having a hard time getting it moving so I came to look for tips.

I made a flat tool with two lugs and it's not going well . Just heating up the oven while I look for ideas.

Damned thing probably has not moved since it left the factory in 1984 !!


I don't have a suitable diam steel tube so I may have to make something like your tool.

Can that nut be taken off once the shaft is out?  I could not see how to lock the gears in place.

[EDIT]  OK I got bitch moving.  Now I just have to clean oven !!

My IR thermometer reported about 150 deg C and it got it moving with minimal effort using my two pronged bit of 1/4" steel plate. Phew.

Now I just need to wait a couple of hours for it to cool down again. 

from memory the cylindrical nut is locktited in 

blow torch - map gas to heat it up and break the bond ?

You missed my edit, I already removed it by heating.

Steel in ali locktites itself after a while.

I've wonder how people get around the 1st gear issue after changing the final drive for lower rpm, there must come a time when these changes deliver 1st gear with a feeling it's in 3rd. The close ratio K box would have to be close to similar centres of the R series and a gear swap maybe possible that way. The R100 or R1200c gears 3rd 4th & 5th would have to advantage a diesel. Have to advantage a K as it would give a wide ratio road box too. So many people these days not actually riding them in the upper ranges of rpm. High compression High rpm High deceleration if the throttle slips from your grasp all tend to cause people to gravitate away form high rpm riding.

I agree. The clientel who rides K-bikes these days are not about speed.

If second gear on my K75 RT was just a tad lower, it would be perfect to start in.

If 5th was a real overdrive, I could use 4th for longer periods on curvier roads, and 3rd for the really small roads.

I miss the advantage of the electronically controlled CVT of my Burgman 650. If only it could be transformed to the K75