primary case a10 1958 swing arm model

[rockthedog]

hi any one know the thread size for the outer primary case bolts that go through the larger dowel holes at the front of primary case ,looks like i need to helicoil and looks like they go through to the crank case ,cheers mal.

[bikerbob]

Hi there
I believe they are 5/16 BSW and yes they go through into the crankcase so make sure that your bolts are not too long or they will come up against the flywheel.

[rockthedog]

Hi there
I believe they are 5/16 BSW and yes they go through into the crankcase so make sure that your bolts are not too long or they will come up against the flywheel.

thanks for that, screw bolt is ok just threads in case that seam poor,dont know how someone can over tighten a screw .must of been very heavy handed cheers mal.

[chaterlea25]

Hi Mal and Bob
Yes 5/16 whitworth for the front 3 screws
A problem can occur if helecoils are used !!
Sometimes they can wind inwards with the screws and foul the crank as will too long screws
"Timesert" thread inserts have a shoulder on the outside to prevent this happening, and are a better solution in my opinion.
HTH
John O R

[BSA_54A10]

As a general rule I use solid inserts ( timecerts etc ) for any place that has to be oil / gas tight and wound inserts ( helicoils ) for blind holes as wire inserts can leak quite badly.

[rockthedog]

Hi Mal and Bob
Yes 5/16 whitworth for the front 3 screws
A problem can occur if helecoils are used !!
Sometimes they can wind inwards with the screws and foul the crank as will too long screws
"Timesert" thread inserts have a shoulder on the outside to prevent this happening, and are a better solution in my opinion.
HTH
John O R

thanks on that john kind regards mal.