pcates
Registered user
Hi All,
This is my first posting here, though I've been reading this site somewhat religiously since I purchased my 1987 R80. I thought I would ask the resident gearbox experts for their advice and opinions on what’s happened with mine. A little backstory first:
The previous owner was selling the bike because the gearbox had (in his words) ‘locked up’. I don’t remember the full story (I was far too busy admiring it) but it involved his friend taking it on the highway, something happening and the friend then having to get the bike towed home where it sat unused for a few months before being sold to me. The bike wouldn’t roll unless you pulled in the clutch (this is why he described it as being locked up), and when the bike was on the centre stand, in neutral, the rear wheel would spin.
From everything I read I knew this bike fell into the circlip-less category so when I pulled the gearbox I was expecting a mess of gears & bearings, except there wasn’t. In fact nearly everything looked to be in excellent condition, except a couple items, the output shaft bearing on the drive side, a gouge on the side of the case where it had been struck by the 1st gear, and some eccentric wear in the cover where the bearing seats. One other thing; the gear selector cams were misaligned, so the neutral position wasn’t actually neutral, it was in gear, which explains why it wouldn't roll without pulling the clutch.
Photos here!
The inner race on output shaft bearing, had been ground down substantially, allowing a significant amount of play. Now to my untrained eye, it would seem to me that something moved enough that it caused the balls of the bearing to grind down the inner race, allowing enough play that the shaft could rotate eccentrically, causing the wear in the cover bearing seat and first gear to strike the gearbox case.
The mystery (for me at least) is what would cause this to happen and how the misaligned gear selector comes into all this. Is it something as simple as the bearing just failing on its own? I’d considered the idea that perhaps someone had just installed the gear selector incorrectly, but I would have thought that would have been noticeable straight away and the previous owner hadn’t mentioned work having been done recently on the gearbox. My assumption is that whatever happened inside the gearbox, also caused the selector forks to slip out of the cams & and their misalignment.
The bike itself only has 50k kilometre’s on it, and all the gears & forks showed no signs of damage, or wear for that matter. Same goes for the rest of the bearings, everything spun freely with no play. The bike itself was leaking oil somewhere, but I couldn’t tell where since it was everywhere. After pulling the gearbox I decided to just pull everything and give it new gaskets and seals.
I know I could just replace the bearing, and close it all back up but it’s driving me nuts as to what may have caused this. The other concern I have is the eccentric wear at the gearbox cover bearing seat (and to a lesser extent the bearing seat in the case). Is there enough surface area for the new bearing to remain seated? Or am I going to have to replace the cover?
I apologise for the long rant, especially for my first post, but your advice, opinions, suggestions and theories are greatly appreciated.
Cheers!
Phil
This is my first posting here, though I've been reading this site somewhat religiously since I purchased my 1987 R80. I thought I would ask the resident gearbox experts for their advice and opinions on what’s happened with mine. A little backstory first:
The previous owner was selling the bike because the gearbox had (in his words) ‘locked up’. I don’t remember the full story (I was far too busy admiring it) but it involved his friend taking it on the highway, something happening and the friend then having to get the bike towed home where it sat unused for a few months before being sold to me. The bike wouldn’t roll unless you pulled in the clutch (this is why he described it as being locked up), and when the bike was on the centre stand, in neutral, the rear wheel would spin.
From everything I read I knew this bike fell into the circlip-less category so when I pulled the gearbox I was expecting a mess of gears & bearings, except there wasn’t. In fact nearly everything looked to be in excellent condition, except a couple items, the output shaft bearing on the drive side, a gouge on the side of the case where it had been struck by the 1st gear, and some eccentric wear in the cover where the bearing seats. One other thing; the gear selector cams were misaligned, so the neutral position wasn’t actually neutral, it was in gear, which explains why it wouldn't roll without pulling the clutch.
Photos here!
The inner race on output shaft bearing, had been ground down substantially, allowing a significant amount of play. Now to my untrained eye, it would seem to me that something moved enough that it caused the balls of the bearing to grind down the inner race, allowing enough play that the shaft could rotate eccentrically, causing the wear in the cover bearing seat and first gear to strike the gearbox case.
The mystery (for me at least) is what would cause this to happen and how the misaligned gear selector comes into all this. Is it something as simple as the bearing just failing on its own? I’d considered the idea that perhaps someone had just installed the gear selector incorrectly, but I would have thought that would have been noticeable straight away and the previous owner hadn’t mentioned work having been done recently on the gearbox. My assumption is that whatever happened inside the gearbox, also caused the selector forks to slip out of the cams & and their misalignment.
The bike itself only has 50k kilometre’s on it, and all the gears & forks showed no signs of damage, or wear for that matter. Same goes for the rest of the bearings, everything spun freely with no play. The bike itself was leaking oil somewhere, but I couldn’t tell where since it was everywhere. After pulling the gearbox I decided to just pull everything and give it new gaskets and seals.
I know I could just replace the bearing, and close it all back up but it’s driving me nuts as to what may have caused this. The other concern I have is the eccentric wear at the gearbox cover bearing seat (and to a lesser extent the bearing seat in the case). Is there enough surface area for the new bearing to remain seated? Or am I going to have to replace the cover?
I apologise for the long rant, especially for my first post, but your advice, opinions, suggestions and theories are greatly appreciated.
Cheers!
Phil
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