OK, had to dedicate a couple of days for getting back to the "never ending" problem with my Henderson gearbox. This seized last summer and I was very close from hitting the woods with a locked rearwheel. This is the second time there have been a problem with the gearbox output shaft seizing in the output shaft bushings.
When I built the engine I had the shaft ground and new bushings where made with 4 / 100 of a mm in clearance. First time the heat built up in the blind ended bushing and the clearance was increased to 6 / 100 of a mm to ensure more oil getting into the bushings.
Second time the output bushing got really stuck to the shaft causing the rear wheel to lock at cruising speed. OK, this time I new there was not a clearance problem and it had to be either the two threaded holes in the cases not being in line after machining or it was an issue with the shaft itself. When checking the shaft in my Myford I soon realised the shaft ends where not paralell, they where actually out with 4-5 / 100 of a mm. This have caused the shaft to stick to the bushings when heat have built up.
The learning will be, always check everything even if work is taken care of by others who are professionals in what they are doing.
And I have been so lucky that I didnt ruin my cases when the shaft seized in the bushing, god grief!
Lets just hope the shaft is hardened deep enough to take another grinding.
tirsdag 15. mars 2011
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