BSA Owners' Club Workshop Discussions

 :) :) :)

Hi help please

We have reached the stage of offering up crank to casings etc. We appear to have two types of main bearing. The pic posted is the outer of the bearing and as seen it is a parallel bearing, allowing the roller race to enter from both sides and slide straight through.

However there also appears to be another version of the bearing that is "lipped", by which I mean that the roller race can only enter from one side.

So gents enlighten me please. Do I expect to have a lipped bearing in the engine and if so where is it placed in the casing.

Your help and advice really appreciated.

Mike 8) 8) 8)

 :) :) :)

Hi
On follow up to previous I think someone at some stage put in a wrong bearing ???????????. So that has probably sorted that.

The only drawings that I can find show three crankshaft bearings: - one ball and two rollers. Was that standard throughout the life cycle of the marque? Was there any shimming or was it straight fit pulled up tight to the drive side.? Was a taper roller ever used?

A couple of years ago someone kindly Emailed to me a manual. If have lost it(age) and apologetically can't remember from whom. May I ask that the kind gentleman re-send it. Email phahmah@outlook.com  and this time I'll print it straightaway.

Thank you for your patience.

Mike 8) 8) 8)

Not relating to beezas at all but a very similar bearing sits on the rear of the layshaft in Series Land Rover gearboxes. The bearing is a cylindrical roller with a 'lipped' outer race. When I last bought a new SKF bearing from my local suppliers using the same bearing code (original was an RHP LRJ7/8 from memory - how sad is that!) I got plain outer race with no lips, they were old stock boxes too (I ordered two). I thought that surely there would be a different bearing code or suffix but perhaps not?

 :) :) :)

Thanks for that. Its very interesting and now maybe we are closing in on the problem.

Mike 8) 8) 8)

Hi Mike,

I came across something maybe similar when restoring my SQ4.
Here's a link to a Drags page that might be of interest - search for 'lipped'

https://www.draganfly.co.uk/ariel/4-stroke/category/705-ohv-sq-bottom-end-1937-58

Cheers,
Bernie

 :) :) :) :)

Hi Bernie.

Just looked at that---very interesting, another clue to possible direction.

Thanks a zillion

Mike 8) 8) 8)

 :) :) :) :)

Hi All.

I think that I have now solved???the bearing problem. However the next apparent problem is the spacer that goes between the two bearings on the drive side. I sincerely doubt that anyone has one :) :) :)But I should be eternally grateful for any info that will enable me to produce same.

I shall also require the "cush" drive spring that goes on the engine drive sprocket.. Any chance that the M20 or similar will fit????

You advice and assistance really appreciated

Mike 8) 8) 8)

Hi Mike,

Looking at my parts catalogue and other data you should have:
-   2 ball bearings part Nr. M533 that go on the timing side
-   1 roller baring part Nr. 24-720 that goes on the drive side
-   1 engine shaft spacing collar part Nr. 24-725 on the drive side under the bearing.
-   1 collar part Nr. 24-730 on the timing side between the 2 bearings.

There are no dimensions given, but on the pic "useful data" there is some information on the bearings. All 3 bearings are open and have no lip. I would consider using a modern sealed bearing on the drive side, because there is only a felt washer on the outside of the case which does very little to seal anything and it will leak into your primary.

As for the collars, they are just that – spacers.  The OD & ID should be about the size of the bearing's outer race.  The thickness should be enough to keep the outer races flush with the inside lip of the bore for the bearings on the cases.  You could let them stand proud a bit to reduce the main shaft's float if needed, but not so tight that the crankshaft is pinched and rubbing.  I would just keep them flush with the cases.

Don't make it more complicated than it is.  These are simple 90 year old slugger engines and not modern 10 000 rpm precision racers.  Tolerances were large and she is perfectly happy like that.

Cheers
Gui

and another picture

 :) :) :) :)

Hi Guys.

Thanks a lot for all your help and advice. I fully understand the points about it being old tech etc, and the only point that I would make is that whilst that is true it is very expensive stuff to get wrong to say nothing of the time involved.

So we shall see.

Any idea if the cush spring is the same or almost as the M20 and others.

Take care

Mike 8) 8) 8)