Primary case leak cause?

[coater87]

 This is the first B.S.A. I have ever restored, and I noticed an odd ball thing with the inner primary case.

 My inner primary is N.O.S. and dead straight. I bought this because my original was warped out about 3/16 of an inch, and had maybe one cover hole with threads left in it.

 Anyway I am working on the primary today following Johns excellent write up for getting everything lined up.

 With all the motor and gearbox mounts torqued down tight, the two gaskets and circular plate behind the inner and five bolts holding the inner to the motor....i have a 3/16 gap between the inner and the frame lug just above the foot rest. Odd coincidence..

 What I am going to do is leave that bolt out, install the outer cover with all it's screws than measure that gap. That is the size spacer I will install there.

 I wonder if some people have not just torqued that bolt down, distorting the inner cover and causing leaks. Then end up pulling threads trying to get it to stop leaking. It looks like that's exactly what happen to my original one.

 Lee

[RichardL]

I believe there has been no shortage of owners who have ignored the gap and torqued the bolt to the point of distorting the cover. Some here make their own spacer and others use a stack of washers. I test the gap to find the right stack of washers, then, super-glue them together to make them easy to manage when running the bolt through.

Richard L.

[coater87]

 I think it's really important to tighten the outer onto the inner first Richard. They will pull / twist each other into the position they want to be in, then size your spacer.

 The inner seems really too long and thin for the one mounting bolt they used?

[JulianS]

That rear bolt is often left out . I have done so for 4 decades and it has not broken yet.

 It can be difficult to fit especially with a rear chaincase on the bike.

[bikerbob]

On my A7 I made up a distance piece to suit then found it decidedly difficult to fit the nut and bolt having a fully enclosed chaincase, so I drilled the rear case out and tapped it I think offhand it is 10mm which makes it much easier to fit a bolt instead of fiddling around trying to get the nut on I did have to enlarge the hole in the frame.

[duTch]

 I don't have this problem ( Plungie*smile*)...but would using a snug fitting rubber spacer work wonders ?