BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: DEDGE on 10 Apr, 2018, 18:44

Title: Engine shock absorber
Post by: DEDGE on 10 Apr, 2018, 18:44
Hi All
1950 B31 Engine shock absorber, How do you compress the spring to get the fixing nut on and when you have it done up how do you bend the lock washer which is inside the spring.
All The Best
Dedge
Title: Re: Engine shock absorber
Post by: ANDY HIGHAM on 10 Apr, 2018, 19:51
The thread should be long enough to start the nut without it contacting the spring. Forget the tab washer and use loctite
Title: Re: Engine shock absorber
Post by: BeenyBoy on 11 Apr, 2018, 10:15
Its a **** sight easier to put on than get off !!!
Title: Re: Engine shock absorber
Post by: brian thombs on 13 Jul, 2021, 10:28
Hi. guys I am having the same problem as Dedge  had.
I am building a 1946 B31 from a complete stripped bike.
to fit the spring to the engine shock absorber I have to compress the spring in my vice and keep it clamped to allow the nut to start on the crank shaft, other videos I have watched the nut appears to start with the spring in its free state, what am I doing wrong ?
Title: Re: Engine shock absorber
Post by: idie on 13 Jul, 2021, 11:25
The components that make up the cush drive do vary in their dimensions. The nut should fit without having to compress the spring. Is yours the 4 lobbed sprocket with the square wound spring. The problem may occur if you are using a round  wound spring.
Title: Re: Engine shock absorber
Post by: Pete Gill on 13 Jul, 2021, 12:10
I had the same question when i rebuilt my B31. 4 lobe cam.
In fact i found that by holding the nut in the 'heel' of my right hand to collapse the spring as I rotated my wrist clockwise was enough to get the nut going on the thread. used the same technique for the first 2 or 3 turns to keep the pressure off the threads as I was screwing it on. I was surprised it worked as I expected it to be one of those things you struggle with for hours.
Then used an adjustable C spanner to tighten up.
I agree I have no idea how the lock washer could really be effective.
Title: Re: Engine shock absorber
Post by: brian thombs on 13 Jul, 2021, 14:22
guys , the spring is definitely square sectioned, and I am having to compress it by nearly 10mm to get the nut started. I made some little steel u section brackets to hold the spring compressed until it had the nut well on the shaft then as the spring compressed more the keeper plates were released. it is now assembled, but my other question is will the spring be under too much tension and prevent the shocker from working correctly.