SOHC.co.uk Forums > CB750

Layshaft bearing holder removal.

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SumpMagnet:
How???

The manual says 'undo the 4 countersunk screws. The bearing journal will come away with the housing'

Simple.....no

How in the name of sanity do you get thoise screws out. They appear to have been put in by Hercules himself, and glued downwith the strongest threadlock known to man. Is there a knack to this? Should I use heat ( I only have a small blowtorch and a hot air gun... ) and is there anything I could damage doing that?  So far I have managed to shift none of them...not even a fraction. Screwdriver was not going to budge them, and hte impact driver won't shift them a mm either. Made me think they were left handed threads ...but the manual would have mentioned that....

It's the last barrier to splitting the cases for me and the only real issue getting it all apart ( well...that and the final drive sprocket being rust-welded on the splines...but once I get the thing out, I should be able to soak it some more and get a puller on it )

hairygit:
Drill the heads off with a sharp 6mm drill, start very slowly, and when all 4 heads have popped off (it's the countersink that is holding them so tight) pull the bearing holder off, and the remaining thread will probably unscrew with your fingers, but there will be plenty left to grip with pliers or mole grips if you prefer.

K2-K6:
They do hold tight on that countersink don't they  ;D

I use on countersink machine screws like this a multi stage routine.  Use a drift or ball peen hammer to gently tap the cross grooves into shape if they've been chewed at all.  Then get a really tight fit impact screwdriver bit that you can tap into the cross,  and either using a power drill with screw torque to rattle them until they come out. Or impact driver on same bit with one sharp hit with a club hammer to release them.

MrDavo:

--- Quote ---impact driver on same bit with one sharp hit with a club hammer to release them
--- End quote ---

Worked for me....

K2-K6:
Yes, you've got to hit it with a bit of commitment the first time,  a club hammer properly activates the camming arrangement inside the impact driver to give a good drive while the screw head is intact.

The most important bit though is getting that piece of skin between your thumb and index finger properly out of the way before you swing the hammer  ;)

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