Cook1e
Registered user
OK, belated update due to other things, delays getting sealant, yada yada...
Gearbox is now back together, seems happy and installed in the bike. I saw no point in pictures, detailed descriptions etc, as there are plenty already all over t'interweb, by folks smarter than me. However, I will post the information which I couldn't find...
I didn't bother changing the taper bearings for sealed balls, it's actually a bit of a kludge. There is a rumour that BMW did it to make their assembly process more tolerant of mistakes.
I first of all made the assumption that the box had been properly shimmed in the first place. Reasonable, as it had 60K on it with no significant wear or damage.
I then miked-up the width of the old plastic-cage ball bearings and the new sealed (BMW calls them "clean") bearings on the output shaft and layshaft, but I left the plain roller on the back of the layshaft as it was as new. Balls were replaced with SKF's Explorer range, C3 clearance. There was no more than 0.02mm difference, so I didn't change the shims.
I installed new taper-roller bearings on the new input shaft and assembled the gearbox with just this shaft and it's original shims. I twiddled it (technical term there - look it up) whilst torquing down the gearbox cover and established that all the play was taken up, plus a bit, without the twiddling getting at all tight. Those who have adjusted old-fashioned car taper wheel bearings will understand. This gave an approximation of the spec in the book of +0.2mm preload, and 0.5 - 1.0 Nm at 1 rpm with a BMW friction meter. This corresponds to "near enough for jazz" in old money.
I was very happy when the re-assembled box went through all the gears smoothly and seemed OK. For budgetary reasons, I used a second-hand complete clutch with 6mm on the friction plate (4.5mm wear limit) for the same price as a new friction plate: seems to be working fine in stationary mode. Thanks for the tip re eBay.de, but this came from Latvia, of all places!
I was less happy when I discovered that the inner race of one of the paralever bearings was missing and the pivot pin was chewed up
So, on to Motorworks for their alternative bush kit, £70 for both sides...
When the rear end is all back together, I'll hope it starts & runs OK and try to figure out why the front brake is completely fecked. I'll start a new thread as and when.
Gearbox is now back together, seems happy and installed in the bike. I saw no point in pictures, detailed descriptions etc, as there are plenty already all over t'interweb, by folks smarter than me. However, I will post the information which I couldn't find...
I didn't bother changing the taper bearings for sealed balls, it's actually a bit of a kludge. There is a rumour that BMW did it to make their assembly process more tolerant of mistakes.
I first of all made the assumption that the box had been properly shimmed in the first place. Reasonable, as it had 60K on it with no significant wear or damage.
I then miked-up the width of the old plastic-cage ball bearings and the new sealed (BMW calls them "clean") bearings on the output shaft and layshaft, but I left the plain roller on the back of the layshaft as it was as new. Balls were replaced with SKF's Explorer range, C3 clearance. There was no more than 0.02mm difference, so I didn't change the shims.
I installed new taper-roller bearings on the new input shaft and assembled the gearbox with just this shaft and it's original shims. I twiddled it (technical term there - look it up) whilst torquing down the gearbox cover and established that all the play was taken up, plus a bit, without the twiddling getting at all tight. Those who have adjusted old-fashioned car taper wheel bearings will understand. This gave an approximation of the spec in the book of +0.2mm preload, and 0.5 - 1.0 Nm at 1 rpm with a BMW friction meter. This corresponds to "near enough for jazz" in old money.
I was very happy when the re-assembled box went through all the gears smoothly and seemed OK. For budgetary reasons, I used a second-hand complete clutch with 6mm on the friction plate (4.5mm wear limit) for the same price as a new friction plate: seems to be working fine in stationary mode. Thanks for the tip re eBay.de, but this came from Latvia, of all places!
I was less happy when I discovered that the inner race of one of the paralever bearings was missing and the pivot pin was chewed up
So, on to Motorworks for their alternative bush kit, £70 for both sides...When the rear end is all back together, I'll hope it starts & runs OK and try to figure out why the front brake is completely fecked. I'll start a new thread as and when.
