BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Greenfield on 21 May, 2023, 15:47

Title: B40 crankcase tie bolts
Post by: Greenfield on 21 May, 2023, 15:47
Does anyone know the part number or length and thread of the top crankcase tie bolt (which clamps the bottom of the barrel) on a '63 B40? It's much longer than the ones beneath. Red arrow in attached photo.
Cheers
Title: Re: B40 crankcase tie bolts
Post by: Spaceman on 21 May, 2023, 16:33
There are 2 x studs shown in the parts diagram and it is not entirely clear to me which one is which. I think it is 40-0019 which is BSF/BSC 5/16 x 3". The other one is 40-0020 which is BSF/BSC 5/16 x 2.75" and I believe these are the 2 x studs that emerge to the left of the clutch.
Title: Re: B40 crankcase tie bolts
Post by: Greenfield on 21 May, 2023, 19:40
Thanks Spaceman
The parts diagram is very unclear. The bolt bottom left in the photo is 5/16" Cycle with a reduced head to allow a box spanner to fit. The one below and out of the photo is the same. The top one arrowed needs to be longer, probably around 2 1/4" long, possibly BSW. There was a non standard bolt fitted and hence the question. Or should there be studs with nuts rather than bolts? A 2 3/4" stud with BSW at one end to screw into the alloy and 5/16 Cycle at the other to take the nut would do the trick. I could ring Drags tomorrow to see if the can clarify things.
Cheers
Title: Re: B40 crankcase tie bolts
Post by: Spaceman on 21 May, 2023, 20:01
Looking at my B40, 40-0019 with 3" long studs look to be about right. The BSF ends screws into the crankcase with BSC for the thin nuts. Only studs are used to hold the crankcases together - no bolts.
Title: Re: B40 crankcase tie bolts
Post by: Greenfield on 22 May, 2023, 09:29
Just checked with Draganfly and they should all be studs with nuts and plain washers, not bolts.
Thanks Spaceman