RichardH Posted August 27, 2018 Report Share Posted August 27, 2018 Does anyone know the thread types/sizes on the Cub engine? I'm particularly interested in the fasteners that attach the gearbox casing to the crankcase. On my engine I've dispensed with the outer cover, meaning I've got 10 2BA screws of various lengths, plus two larger diameter screws at either end of the casing. These are the two I need sizes for. Many thanks. Quote Link to comment Share on other sites More sharing options...
section swept Posted August 28, 2018 Report Share Posted August 28, 2018 Unfortunately the British Motorcycle Industry had access to many types of threads, BSW, BSF, BSC (cycle) and of course Unified. At some stage all of the aforementioned may have been used on one type of bike or engine or both and this makes selecting replacements difficult. Possibly a reason why no one has responded with an answer. A thread gauge will only be of use for bolts and some nuts. One solution might be to drill out the unknown gearbox to crank cases threaded holes and tap them to a known size, not a hard job to do if done with care and planning. At least you will be able to have a choice of fastener types and this wouldn’t detract from originality. Quote Link to comment Share on other sites More sharing options...
RichardH Posted August 28, 2018 Author Report Share Posted August 28, 2018 Thanks for your reply Section Swept. I've been told by a Cub expert that they are 1/4 BSF. I've ordered a tap so hopefully that will solve my problem! Quote Link to comment Share on other sites More sharing options...
section swept Posted August 28, 2018 Report Share Posted August 28, 2018 1 hour ago, RichardH said: Thanks for your reply Section Swept. I've been told by a Cub expert that they are 1/4 BSF. I've ordered a tap so hopefully that will solve my problem! If it all goes pear shaped there is always the option of thread inserts. Quote Link to comment Share on other sites More sharing options...
old bones Posted August 28, 2018 Report Share Posted August 28, 2018 RichardH, Your cub expert is right they are 1/4BSF (26TPI) Quote Link to comment Share on other sites More sharing options...
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