Hi,
I wonder if anyone could confirm the correct length of the two spacer pieces for the central mounting bolt for a 1967 B44R Victor Roaster GRP petrol tank please? Rupert Ratio says the smaller one that sits inside the expanding rubber bung should be at least 1/4" shorter than the bung itself to allow the bung to compress. I've tried Burton and they didn't have in stock any ready cut pieces so they've sent me a small length of spacer pipe to cut myself but I can't find correct lengths given in any of the manuals or bulletin sheets. There's also uncertainty as to the correct length of the central bolt itself for my model. I've tried one or two different ways but they vibrated loose so I'd like to go back to the original BSA method, if I can find out the correct sizes of the various pieces.
I'm stuck at the moment so would really appreciate some help.
It's easy enough to measure what is needed after putting the tank on the bike. Use a suitable rod or pipe poked down through the hole in the tank to rest on the top of the frame bolt mounting bracket and then mark on it where the top of the central tunnel comes. By separately measuring the depth of the tunnel you can then add a lower mark on the rod or pipe. All you then have to do is decide where you want the bung to go between those two marks from which you can then work out the length of the lower spacer (taking into account the thickness of the frame bracket) and how long the bolt needs to be. The exact position of the bung is not critical but, the higher it is, the easier it can make screwing the nut on the end of the bolt.
Thanks Spaceman. I'll try that.
As said, the tank is held in position on the bolt by squashing the rubber bung so that it expands sideways and grips the tank. Obviously you need to use large washers either side of the bung that are at least the diameter of the flat ends of the bung.
I made the bottom spacer 1 1/8" and the top spacer 1". All fitted now and seems to be good. There must have been a standard length for these and they would have been mass-produced for the Factory. I would be interested to know what the standard length of these was? Also, there would have been a standard bolt size and length which seems to have been lost in the archives.
Probably a bit academic now but the parts book shows a 5/16 BSC x 2.5" bolt and a 1" lower spacer. Interestingly, it doesn't show
an upper spacer and I therefore assume the a locking top nut was used which was tightened until the tank was firmly held.