Primary shaft assembly

[John10b]

Hi All am a bit of a newby, I am rebuilding a cb750F 1980 which I bought in bits, although most of the gearbox shafts have already been assembled-just about ready to mate the two crankcase halves together and noticed a plastic spacer which is in two halves on the primary shaft, this is between the shock absorber and the bearing next to the oil pump drive pinion-just doesn’t look right and could float about after assembly—anyone got any ideas
Thanks John

 

[Flash]

Hi All am a bit of a newby, I am rebuilding a cb750F 1980 which I bought in bits, although most of the gearbox shafts have already been assembled-just about ready to mate the two crankcase halves together and noticed a plastic spacer which is in two halves on the primary shaft, this is between the shock absorber and the bearing next to the oil pump drive pinion-just doesn’t look right and could float about after assembly—anyone got any ideas
Thanks John

Hello John...did you get this sorted.
I am working on the same model and not sure how to disassemble the primary shaft to fit the new seal.
cheers Des

 

[ScottishBadger]

It's a seal, and really ought to be replaced if the cases have been parted, same as the output shaft seal (essential!). Primary shaft comes apart easily, circlips on bearings then drift shaft out of bearings with a plastic mallet. Separate the two halfs of the drive coupling and replace the 8 rubbers (use assembly lube to push back in or you'll tear the new ones!). Personally, I'd be replace primary chain and "A" camchain whilst in there.

 

[Flash]

Thanks Mr Badger
I took the outrr circlip off thinking this would release the sprocket…the other inner circlip must need to come off as well?
Did not want to use too much force
cheers

 

[ScottishBadger]

Thanks Mr Badger
I took the outrr circlip off thinking this would release the sprocket…the other inner circlip must need to come off as well?
Did not want to use too much force
cheers

If you haven't got the workshop manual, I strongly urge you to get one. Also, the exploded parts diagrams on the CMSNL website can be handy....

 

[Flash]

Thanks....I was tricked when the manual said to remove the circlip and the sprocket will slide off....it didn,t and took a bit of heat and a puller with moderate force in the end but all good now.

 

[Flash]

Just a small follow up on this if anyone is interested....on close inspection I found a crack radiating from one of the drive sprocket retainer pin holes.
This caused the shaft to spread which in turn held the oil pump sprocket firmly in place. Once the sprocket was removed , the crack was clearly visible.
I have obtained a good second hand shaft to finish this part of the rebuild.