SOHC.co.uk Forums > CB350/400
Gearbox Stuck - The last straw?
SeanFD:
I had forgotten about this series of videos:
400 Four Engine Rebuild:
https://www.youtube.com/watch?v=vR-MiqdHi1w&t=62s
I think the retaining pins Ted mentioned are the two he shows right at the beginning.
K2-K6:
As a general guide to fault finding, there's as many sliding gear items as selector forks, obviously ;D
Each of these should move freely with the forks removed. The important bit in contrast though, is that ALL of tbe remaining gears should be fully located on their shaft such that they absolutely cannot move along the shaft. Anything substantial (probably more than 0.5 mm ) for these "fixed" gear items, and you'll likely have thrust washer, circlip etc that's compromised, missing, misplaced etc as a fault.
With the gear set in neutral, there's very little clearance between moving items and stationary gears (for movement along each shaft) that stops the whole thing getting into a mess with potentially two gear ratios part engaged simultaneously.
Of course, the selector forks must have positive and functioning engagement, usually via spigot pin to the selector drum. Also the selector to be not obviously bent such that it can cause out of tolerance position in moving gear item.
K2-K6:
Additionally, the end float of both gear shaft and the selector drum will cause variance of control between the two as gear selection is then a moving target, which it shouldn't be.
McCabe-Thiele (Ted):
Just realised the clip I was refering to earlier was not on my 400 gearbox.
Its the end clip that holds the pin on a 500 K1 selector fork, its my age I guess.
Dolomite_:
I spent a few hours investigating the issue today. Drained the oil, took the clutch casing and clutch drum off and also the sump.
I noticed that the bolt circled in red had become loose enough to allow the disc to have some play. I think this then meant that the shift arm in blue wasn't snug up to the pins. It was catching them and then slipping off. Because the bolt was loose I think it also meant that the part behind the disc wasn't straight like it should have been.
I took the disc off and put the bolt back so I could see what was happening and when I held the arm in place it shifted fine. I added the disc back and tested it again and it felt like it was slipping off the pins again. The arm had some stiffness against the disc when it tried to return flush against the pins. This turned out to be because the gear shift shaft had moved out slightly and was putting some pressure on the arm, I pushed the shaft back and it seems to be fine.
What actually holds the gear shift shaft in place? Is it just the gear shifter? Does anything hold it in place on the clutch side?
One other thing to double check. Does the arm held in place by the yellow bolt help shift it that last little bit? When I removed the arm when testing and I would shift I would need to manually rotate the part behind the disc slightly to get it to engage the gears. This gave me a little panic because I was hearing sounds from the gear box I thought that something had become loose inside.
Lastly does anyone know the toque settings for the red and yellow bolts and also the bolts that hold the clutch springs in place? I will also be putting a bit off loctite on them.
Im not sure why the image isnt showing Ive done [img ]http://[\img ] (without the spaces)
https://imgbox.com/ZkK3587b
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