gearbox question

mik667

mik667

Senior member
Location
San Francisco, Ca
Hey gang
getting ready to put my SF motor back together  - and wanted to get some opinions if i have my gearbox done right (it looks like the green book photos and pics i took - but still) and find out if anyone knows if there is a way to shift through the gears to make sure i have them correct before i put the cases back together
thanks as always
m
selectorforks_zpsb301fdd8.jpg

firstrack_zps044d3455.jpg

secondrack_zps9da220ef.jpg

anotherview_zpsca2575c0.jpg

 
Forks look good... can't fit them any other way without having something locking up.

You can change through the gears by turning the gear of the selector drum in the selector housing.  There's a special tool for this, very handy...

Just as important as checking if all the gears change properly, is to check axial clearance/spacing of the layshaft and possible side loading of the selector forks when a gear is engaged.  There is also a chance of 3rd and 4th gears meshing slightly (3rd mainshaft, 4th layshaft) with each other when 4th is engaged, with a bit of fiddling with the spacing this can be easily eliminated.

Assume you have rollers at both ends of the layshaft.  Axial movement should not exceed 0.3-0.4mm, must have 0.2mm minimum.  With the layshaft in the case, give it a little knock from both ends, this will seat the bearings at the maximum width, axial play can then be measured/felt.

With any gear engaged, the appropriate fork must still be free to move, best to have a little sideways play.  Push the engaging gear hard to its neighbour and feel the if the fork is still loose.  Fork clearance can be altered by swapping the 2 identical forks' positions, they are rarely exactly the same.

Have you renewed the output shaft oil seal?  You'll soon be kicking yourself if you haven't!  :D  Easier to check if the seal is seated correctly if the sprocket is removed from the shaft.  Yes, I know they can be a bugger to fit, easier than re-stripping to rectify a faulty seal though.

piet

 
Hi,
be sure that the collar that houses the 5th gear fork (left in the pic) is installed
the right way round. The flat side goes to the fifth gear.
My buddy phoned me yesterday after his first test ride after he had reassembled
the engine. He has "lost" his 5th gear..... :( Not the first time I heard of that.
Before closing the cases I test the gears by turning the main shaft by hand at the
clutch side and "shifting" the gear Piet mentioned with pliers, easy job.

hth, Ernesto
 
OK thx guys - was able to get it to shift through gears with a little motivations- yes all seals are new etc etc - getting the little metal spacer bar thats between the cylinder holes in the top half of the case that hold the inner bearing shells in place in the correct position was a bit of a cluster fck but looks good
m
 
You must log in or register to reply here.
Back
Top