BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: davben23 on 26 Nov, 2020, 00:14

Title: A65 crankshaft bearing
Post by: davben23 on 26 Nov, 2020, 00:14
Hi guys
Bit of a newbie question im afraid I've stripped the engine down on my 67 A65 and was wondering what would be the best method removing the bearing from the crankshaft ? I have bearing pullers but would this also require heat ? Bearing looks in mint condition so don't want to ruin it etc
Thanks in advance Dave
Title: Re: A65 crankshaft bearing
Post by: DAVE BRADY on 26 Nov, 2020, 08:59
Hi,

No heat should be needed.  The bearing puller should be enough but make sure it pulls on the inner race so that no force is applied to the rollers/roller cage.  You say the bearing looks in mint condition but unless you know how much use it has had then is it worth taking a chance.  If you are stripping the engine down then there must be wear on other parts so this bearing may have done a bit of work.  A good quality main bearing is not cheap but compared to the total cost of a rebuild it is not.  Better to fit a good quality one now rather than have to strip the engine again to replace it.

Dave.
Title: Re: A65 crankshaft bearing
Post by: wardy on 26 Nov, 2020, 09:46
Also bear in mind that the crank shims and retaining cup are inboard of the DS main bearing. Imperative that the puller abuts the inner bearing race as the bearing cage can be fragile and easily damaged
Title: Re: A65 crankshaft bearing
Post by: davben23 on 26 Nov, 2020, 15:57
Thanks for the replies guys and point taken about the bearing it was stripped due to excess end float so guess its a no brainer and should be replaced 👍🏻
Cheers Dave
Title: Re: A65 crankshaft bearing
Post by: wardy on 27 Nov, 2020, 08:04
If you're going to replace the bearing anyway there's no harm in damaging it getting it off. In theory your crankcases and crank will have marks denoting the theoretical endfloat - i.e. 998 on the cases and 982 on the crank gives 16 thou endfloat which you can shim down to 3 thou or less. This is, however, a theory. Worth measuring the shims that come out and clarifying why you have too much endfloat now
Title: Re: A65 crankshaft bearing
Post by: davben23 on 27 Nov, 2020, 21:34
Thanks for the info Wardy I'm slowly learning 👍🏻
Title: Re: A65 crankshaft bearing
Post by: davben23 on 02 Dec, 2020, 19:47
After looking at the drawings today my motor didn't have a thrust washer fitted next to the main bush (non drive side)  ? Are these fitted just on the shaft ?
Thanks dave
Title: Re: A65 crankshaft bearing
Post by: Nanonevol on 03 Dec, 2020, 01:40
They fit into the timing side case against the plain bearing.
First image is with just the bush/bearing, second is with the thrust.
(https://i.imgur.com/tW6luy1l.jpg)(https://i.imgur.com/FZevA1el.jpg)
Title: Re: A65 crankshaft bearing
Post by: davben23 on 03 Dec, 2020, 07:56
Many thanks for the pics and mine was definitely missing. This would probably explain my excessive end float 👍🏻