The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: BSA500 on 30.05. 2018 09:05

Title: Journal width
Post by: BSA500 on 30.05. 2018 09:05

Quick question what is the big end journal width on a a7 crank.
Thanks Andy

Title: Re: Journal width
Post by: Peter in Aus on 30.05. 2018 09:25

Just measured my A7 crank on the bench 0.977in

Title: Re: Journal width
Post by: muskrat on 30.05. 2018 09:58

G'day Andy.
I haven't got a crank handy so I measured a few rods.
Max side play of the rod on the journal is 0.024". All my rods (both A7 and A10) are 0.955" so that would make the journal width 0.979" MAX. I'd be comfortable with 0.020" side play making the journal width of 0.975".
Cheers
Peter got in 1st so we're pretty close.

Title: Re: Journal width
Post by: BSA500 on 30.05. 2018 10:02

Thank you both. The guy who might be grindi g the crank needed the width

Title: Re: Journal width
Post by: muskrat on 30.05. 2018 10:07

And the radius should be no less than 0.090" and no more than 0.110". A lot of grinders mostly do cars/trucks and are reluctant to re-grind their wheels.
Cheers

Title: Re: Journal width
Post by: BSA500 on 30.05. 2018 12:58

This guy does vintage up to modernish engines. He is also restoring one of two Amilcar racers  *smile*

Title: Re: Journal width
Post by: Greybeard on 30.05. 2018 13:55

Quote from: BSA500 on 30.05. 2018 12:58

This guy does vintage up to modernish engines. He is also restoring one of two Amilcar racers  *smile*

Even so, make sure he understands about leaving the radii. Removing them will weaken your crankshaft.

Title: Re: Journal width
Post by: BSA500 on 30.05. 2018 16:22

Yes I have a copy of the grinding service sheet