The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Topdad on 17.05. 2017 10:29

Title: size of large journal crank thread on drive side
Post by: Topdad on 17.05. 2017 10:29

Could one of our esteemed boffins tell me the thread size required for the drive side of my LJ crank , I've managed to damage mine and intend to try sort the problem prior to a complete stripdown and repair , Please help a devastated twit in the (nearly ) frozen north!!

Title: Re: size of large journal crank thread on drive side
Post by: JulianS on 17.05. 2017 11:15

3/4 inch x 20 tpi cycle thread.

Title: Re: size of large journal crank thread on drive side
Post by: muskrat on 17.05. 2017 12:06

G'day Bob.
You'd like one of those nice SRM hex nuts wouldn't you? Then you could cut the old one in half, then put the halves on the crank behind the damage and hold together with a hose clamp clamp. Then unscew it over the damaged bit.
Cheers

Title: Re: size of large journal crank thread on drive side
Post by: Topdad on 17.05. 2017 13:09

Thanks Julian and Musky.