Shims

[Barnsey]

Hi Folks, 

   I have no shims between the crankshaft bearing, on my C15, and the primary sprocket, which might explain why it was out of line with the secondary sprocket. 

  I ordered the shims shown in the photo, but they are a very loose fit.  They are 1" internal dia and the shaft is more like 0.9"  Externally a bit small too.  So I suspect that I ordered the wrong thing.  Could someone please point me in the right direction? 

   BR,   Ian

[DAVE BRADY]

Hi,

Although that does not look like a C15 part number they could be what is available.
As they are in between the crank spacer that goes in the oil seal and the sprocket they are not taking any load as such. The torque used on the nut will keep everything in place.

Dave.

[Barnsey]

Okay, thanks!   I'll give them a go.  I'm trusting that the tiny amount of weight is not enough to throw the engine out of balance and damage the bearing? 

  BR,  Ian

[DAVE BRADY]

Hi,

They had not really heard of 'balance' much in those days and as the shims are on the crank and weigh very little they can be discounted in that regard.

Dave.

[MadPete]

Excuse me interrupting.I thought the crank shims went on the timing side of the crankshaft rather than between the sprocket spacer and the drive bearing. It is so for a B25.
I have no idea if a C15 is different without investigation. Of course if one didn't want to split the crankcase then that might be a convenient option.
I agree with all other comments the shims are light and off centre mounting is not of great consequence.

[DAVE BRADY]

Hi,

These shims are to get the primary chain alignment correct. There, I think 3, different engine sprocket spacers listed but I do not know if they are available so shims between the spacer and sprocket so the shims same job.

Dave.

[Barnsey]

Thanks all!  I'll give the shims a go next weekend.  I got distracted by another job today.  Such is life!

   Ian 

[Mark Cook]

You just have to look in the right places.

https://pesltd.uk/?product=71-1629

Mark

[Barnsey]

Thanks Mark!

   I ordered them, but now I have to wait for them to arrive by snail mail!  It's a pity Amazon doesn't stock BSA spares....    However, on the plus side they were only £3

  BR,  Ian

[Barnsey]

The shims arrived.   There are nowhere near enough to fill the space though!  It needs maybe 5mm of shims to fill the space between the bearing and sprocket.  Should there be a spacer to fill the space with shims for fine adjustment? 

  I am digging through Hugh F's videos to see what he does.   

[Barnsey]

Sadly Hugh missed the important bit out of his video,  but I am wondering if this might be what I need:
https://www.ebay.co.uk/itm/226794333750?_ul=GB&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338365712&toolid=20006&customid=EAIaIQobChMIiJL08cfkjwMVTKNQBh1u5AESEAYYASABEgIqafD_BwE%7C0AAAAADANKJkazPz5BeXdqBWleJJtvj8bU%7Cnull&gclid=EAIaIQobChMIiJL08cfkjwMVTKNQBh1u5AESEAYYASABEgIqafD_BwE&gbraid=0AAAAADANKJkazPz5BeXdqBWleJJtvj8bU&loc_physical_ms=9222320&adtype=pla

[DAVE BRADY]

Hi,

In the attached image you can see the oil seal, a thick spacer with 3 numbers for the different thicknesses, the sprocket, a thin spacer/washer and then the alternator.
The shims go between the spacer and the sprocket.

Dave.

[Barnsey]

That is very helpful thanks Dave! 

That is a rare part, but I managed to find the middle one (11740-0526)  at Kidderminster motorcycles. 

So I might have to pack it out with shims or file it down. 

I can't believe that the previous owner left it out, but he did a few things like that.  I can't help but wonder what else there is that I have missed.   

[Barnsey]

The spacer arrived today and is spot on. Just one question, does the chamfer end go inwards or outwards?
Not clear in the diagram.

  Even one 0.4mm shim is too much, so I might try a 0.1mm shim from the 'wrong' set which I bought previously, or just not bother with shims at all. 

[DAVE BRADY]

Hi,

Chamfer goes towards the bearing so inwards.

Dave.