SOHC.co.uk Forums > CB350/400
Should this shaft have end movement if I pull it by hand?
Nurse Julie:
That bearing is fitting far too proud for some reason, it should be flush 🤔 well, more flush than it appears to be in the photo.
McCabe-Thiele (Ted):
--- Quote from: 400 Cafe Racer on July 20, 2021, 09:50:11 PM ---Hi Ted,
This is the overhang on my bearing FWIW. ;D
Dennis
--- End quote ---
Hi Dennis, My overhang is about the same or marginally more. Not sure if new half moon clips would change anything. My bearings were installed dry maybe a smear of Hondabond would help stop further lateral movement. I have a spare gear cluster set that came with a casing from a member. I'm planning to try them for comparison. If they're a tighter fit I will use them. There is no ovalation on the needle bearing locator hole.
K2-K6:
"It might be both bearings are not as planted as the design suggests. Perhaps constant gear changes on a revvy little 400 engineb takes its toll on the bearing fittings. Very useful info thanks. Ted"
Typically of bikes in general and certainly in these engines, there's essentially no real thrust load of any significance with all the gear teeth straight cut.
Clutch operation is the largest (which should be opposed by the clutch assembly clamping it's shaft on that principle bearing) but the rest of tolerancing is to facilitate accurate movement and controlling engagement of the dogs and their relationship to the shift drum along with it's forks. Insignificant load that would cause wear though in that direction.
Even the crankshaft has no effective thrust bearings as it's not subjected to that force.
In a car with helical cut gearbox and clutch pushing directly onto crankshaft end, then they need to be mitigated, but on these it's just positional accuracy without much force that could cause components to wear.
McCabe-Thiele (Ted):
--- Quote from: K2-K6 on July 21, 2021, 10:07:40 AM ---"It might be both bearings are not as planted as the design suggests. Perhaps constant gear changes on a revvy little 400 engineb takes its toll on the bearing fittings. Very useful info thanks. Ted"
Typically of bikes in general and certainly in these engines, there's essentially no real thrust load of any significance with all the gear teeth straight cut.
Clutch operation is the largest (which should be opposed by the clutch assembly clamping it's shaft on that principle bearing) but the rest of tolerancing is to facilitate accurate movement and controlling engagement of the dogs and their relationship to the shift drum along with it's forks. Insignificant load that would cause wear though in that direction.
Even the crankshaft has no effective thrust bearings as it's not subjected to that force.
In a car with helical cut gearbox and clutch pushing directly onto crankshaft end, then they need to be mitigated, but on these it's just positional accuracy without much force that could cause components to wear.
--- End quote ---
Well made point about the gears being straight cut not helical I hadn't given that factor any thought.
One of the reasons I love this site so much is the knowledge of its contibuters being greater than the sum of the whole - its not just "corroborative detail intended to give engineering verisimilitude to an otherwise basic & unconvincing narrative" to misquote Poo-Bah of G&S fame.
Nurse Julie:
Are the half rings proper half rings? We have had numerous engines through here where someone has been in them in the past and they have used half of a piston ring as a substitute.
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