So I finally cleaned up enough of our garage so I could strip the bike down to put in the new gear selector shaft I bought last month. Not bad, only a 2 1/2 hour job to get the gearbox out and pull the cover off.

Looking at the parts diagram (http://www.realoem.com/bmw/showparts.do?model=0504&mospid=51753&btnr=23_1158&hg=23&fg=31), I figured you remove circlip 24, and slide shaft 25 out of the box. But no, the breather hole is smaller than the diameter of the shaft. So now I'm sitting here wondering how the smeg I replace the shaft (6) ?? I have the grub screw ( out, but yanking on the selector shaft isn't doing anything, so I'm pretty sure I have to disassemble it all, the first step of which would be pulling out that shaft 25.. But that would mean drilling the case to open the breather hole up a little, and I'm not real keen on that idea!

While I'm here, that reminds me.. I have a whine between 3-4krpm, which gets louder under load (rolling on (OR) off the throttle).. Any idea which of the bearings that would be? I'm figuring input shaft bearing, but I wasn't sure if it would be the front or back bearing? Looking at those, it looks like it's going to be a case of heat the bearing, cool the shaft, to replace them?

Thanks,

Damien

To me it looks as if you have to pull the whole breather out not just the cap off.
As for the rummble probably is a bearing but from what you describe more a ball race than a roller. I always work on the assumption that if one is shagged then all are on the way, you should get all the bearings and seals except for the tiny seal in the main shaft at any bearing loint for about $75-$80. You need a knife edge puller to do the main shaft but all the rest come off easilly using levers. I use tyre levers and make sure not to mix up the shims.

Thanks rick,

I had another look at it, and I reckon someone shagged it in the original build - the inside lip of the breather is very thin, and had been squashed over in one place.. found a drift the right size, and carefully tapped it through from outside, and it's all good now! Seems my original thought was right, with the grub screw removed, the selector shaft should just pull straight out.. But because mine was SO shagged, it was binding up on the inside of the lever!

Pic of old vs new:

So it also turned out that the loctite on the grub screw had not made it way into the threads.. I guess the oil kept them out? Is the normal red loctite petroleum-safe? Or should I be looking for a different thread locker when I come to put it back together? I don't want to ever have the box open again!

Oh nice, they just lever off? that'd be handy. Looks like the input shaft shells are pressed into the housings though? Are they easy to get out?

yeah, I would have thought that whine would come from balls more than rollers.. but it's at a certain rev range in every gear, so has to be input shaft.. Well, either that or it's big an engine bearing, but that doesn't bear thinking about :-p Stupid question, how do I tell the bearing place, what bearings I want? (75-80 sounds way better than 190 from munich's!)

I am not sure of the sizes but take them in with you is best, they are very common sizes one of the roller races is actually the same as the early holden outer wheel bearing. You need a bearing puller and slide hammer to get the cup out of the main case.
BMW have a very special dept which studies how to make things hard to work on if you dont buy the special tools from them at inflated prices.

Putting the new bearings on.. Do I *have* to press them on, or can I just pop em in the oven and heat them up, (and gear shafts in the freezer) the way I did the headstem bearings?

Just press them on, make sure they enter square and no problems. With the roller bearing on the drive shaft make sure you pull it back against the circlip before checking shims.

Bugger, ok, will press em on

You can just gently knock them on they are just a snug fit just put the bearing in the sun if there is any and shaft in frige and all ok just that a press is the easy way for me.

Oh, ok cool - I thought you meant they'd need the strength of a press to get em in - a couple sure weren't easy to get off! that's about the one thing I don't have, is a press!

Actually my big problem right now is getting the @#$@#$@# bearing shells out from the two cases, for the input shaft. My usual trick is to hit em up with the little cutting wheel from the dremel, and cut a nice wide cut down to JUST before I hit the outside of the shell, then give em one hit with a chisel, and they crack.. But not these little bastards! Seriously considering pulling out the mig tomorrow night, and welding a bar across the shell, so I can get my bearing puller onto something! (the cap between shell and casing isn't big enough to get my L shaped puller heads into, and the shell itself is too big for my circular expanding puller heads.. GRRR!

Either that, or weld a blob onto the end of a screwdriver, then grind it down till the end of the screwdriver is an L shape so I can hook it into the little slot between the shell and the casing..

I made a special driver to get at them from a piece of stainless bar but running a bead of weld will shrink them and then they just fall out. BTW dont use a bronze or brass drift to put them back in as it flakes and then contaminates the bearing. Mild or stainless.

Rick G wrote:I made a special driver to get at them from a piece of stainless bar but running a bead of weld will shrink them and then they just fall out. BTW dont use a bronze or brass drift to put them back in as it flakes and then contaminates the bearing. Mild or stainless.

+1 on that Rick

Is it my pc or has the forum slowed up

oh, that's a darned awesome idea! Thankyou!

I usually use the old bearing shell to put the new ones in

The one in the lid off the gearbox, the weld bead worked great! in the main gearbox case, I just can't get behind it to tap it out, so I'm going to have to head to bursons or something tomorrow to find a head for my gear/dent puller that'll actually get behind it..

Rofl, so I ended up at bursons this morning, no go for a puller, though he could order me exactly what I needed.. For $156! He suggested I try the bike mechanic just down the road.. Popped in there, he took one look at it and went 'nah, you need the special BMW tool, or you'll be dicking around for hours.. OR.. Do you have a die grinder?' 'Umm, yeah?' 'Well just grind the fucker away till there's only a tiny bit of shell left, then hit it with a hammer, and it should crack right out!' 'Oh, I did that for the first one, but it looked kinda agricultural...' 'so? It'll work!'

So an hour and a half of careful grinding later (and a gearbox full of iron filings! argh!), and that damned shell is out!

About half a litre of petrol, and the gearbox looks great again. Shoved the bearing shells (and drive shafts) into the freezer, and heated the gearbox cases, and the shells dropped in nicely! Got the first of the bearings onto the input shaft (the tricky one - have to compress the spring..), and now waiting for the shaft to cool again before I do the next..

I'm not going to bother cleaning and painting the gearbox this time.. Given i've got it down to a 2 hour job to get the bike apart and gearbox out, I'll take a few weeks during winter when I *really* can't ride, and clean it up then.. I REALLY want to go on the black dog ride tomorrow! Fingers crossed!

!@#$(@#$&*($!@#(!@*(#&

Seems despite double-checking twice, I still managed to get the two bearing shells switched around (so the rear shell is in the front, and the front shell is in the rear) for the input shaft

DAMMIT, and the sucky thing is I've already replaced the oil seals, so I'm going to have to be insanely careful while cutting the shells out

Although it just occurred to me.. If I could source the actual proper bmw/kukko bearing race puller.. could I just pull the races out, and insert them in the correct spots? AKA does removing them with the puller damage them?

Wonder if it's worth phoning motohansa on monday?

I have got the KUKKO puller here it does make the job very quick and easy to do... But they do say the bearing shells are a one use job as removing them will distort them just a bit. Who knows if there is enough distortion in reality....

Oh, hrrm, I thought I'd be ok, so long as I hadn't actually had them 'in use' yet.. I assume the shells are matched to the bearings? AKA I couldn't just go and buy new bearings+shells, and only use the shells, and use my existing bearings?

Rendrag wrote:Oh, hrrm, I thought I'd be ok, so long as I hadn't actually had them 'in use' yet.. I assume the shells are matched to the bearings? AKA I couldn't just go and buy new bearings+shells, and only use the shells, and use my existing bearings?

You could use them again provided you don't damage them and to do that you need the correct puller, even then I would not be sure of it. Probably best to get 2 new bearings you wont need to change the races that are already on the shaft
The shells and race are not matched they can grind to close enough tolerances to not have to do anything like that.
When you are putting shell in or out you have to be careful not to bruise the face or they will start to delaminate (the hard facing will crack and pit where the bruise is and flakes come off then it fails in very short order. A lot of the time you wont even be able to see the bruise.
The two main reasons I see for bearing failure is contamination and bruising of the face.

Ok thanks rick, I'll see if I can get a hold of the correct puller, just so I keep my box clean - and then sort out two replacement bearings to use the races from..

If you go for the Kukko pullers they are not cheap but are available I just had a look and they are available in Aus.

Thanks twincarb, you inspired me to do a bit more googling, and got to see exactly what it is that the bmw manual reccommends (the 21-4). And what do you know, it's exactly what I already have, EXCEPT that the internal pullers I have aren't large enough.. So time to see if I can get a 20-30mm internal puller head for mine

I seem to recall that there are a couple of mistakes in the manual it says to use one size but it's the wrong one! I found that out by experience lol!

Sykes Pickavant also supply internal expanding cones. I use them all the time for blind holes and the likes of head bearings etc.

Mike