Happy new year all

I am in process putting new bearing in secondhand K100 gearbox as my original has died. The condition is good but changing bearings and seals anyway.

Question: 1

In bmw manual it talks about the output shaft measuring 125.8mm - 0.1mm, the shaft i have measures 122.5 and the old shaft from dead gearbox 123.4mm?

Question 2

What is the correct procedure for shimming shafts and gears in case. I have read and understand from the manuals what to do but not sure what i measure is right or wrong?

Question 3

When put bearings on shaft e.g output shaft do they but up against shaft or do you only need to put them to a certain gap?

Main issue is unknown origin of new gearbox. Dont really want to do this again in future,

Hope someone can help me stretch my brain and get my head around this :D

Thanks

Smoll:D:face:

Have you got a copy of the Clymer manual to hand? If so it go's into great detail on how to shim it up correctly P202, 203 are where you want to be reading for the shims

P213 covers putting the shafts back together... A quick glance says the bearings bottom out but it's worth having a proper read though to confim of course.

Once your past that stage have a look here gearbox back together I did a write up on putting a gearbox back together with lots of pic's as a guide... Didnt cover re-shimming mind as it was aimed at anyone who found the grub screw had come out or had stripped the gearbox to check for any problems

Smoll1,

How have you got on with the gearbox rebuild did you have any luck?

Yes sorry work hectic as usual, I download manual from download section and printed gearbox section off and read it lots of times:D.

It quite clear once read all of text through. Measured the lay shaft and output shaft, and there was problem and found out the bearing was not seated all the way as it says in manual that bottoms out.

Put bearing on properly and checked clearances between gears now and they are fine. Have shimmed up these two shafts and just input shaft to go but seems to be a lot clearer.

I think it was confusing me because of the bearing being in wrong place and once read manual and said it bottomed out i was alot happier. The figures once I measured the clearance made sense as they did not before as there was no gap.:D

Just input shaft left but should be ok and then have to paint gearbox housing as mine is supposed to be black. So will let you know how it goes :D

That is good news then I find the Clymer manual provides the best level of detail, the BMW manual isn't the best out there but then it's designed for use in a BMW workshop where there is more than one pair of hands.

What paint are you going to use out of interest.... Halfords engine paint hasn't stood the test of time for me I have various bits that I need to redo

Hi twincarb,

I'm a fan of Plastkote paint. I used it on my Vincent engine about 13 years ago and it's still excellent. Also, the outfit crank cover was done in '07 and early last year I painted the swingarm and bevel box on the outfit, again with good results. But with all painting, prep and priming are more important than the top coats, with an etch primer being essential for painting aluminium parts.

Paul.

I have used halfords paint as well but might change this if problems have done cases already so might change if get something to look the same.

My prep was all good... the failing point and the only bit I wasn't sure about was primer... I used High Temp paint which shouldn't need a primer!

I will probably grab some can's of plasticote this time will use an etch primer.... I have a couple of can's in the garage at the moment lol!!!

sounds like good idea to me :D