Primary sprocket / clutch alignment/ modification guide

[Swarfcut]

Col. B and M crank splines are a different size from the A series, as I found when a bargain sleeve didn't fit. Turned out it was from a B31, but the sprocket is the same.

 As an aside, the A series  layshaft splines are the same as the crankshaft splines..   So take a spare layshaft when you're out and about looking for a drive sleeve.

 Swarfy.

[berger]

over the years I have come across many different cush parts and I have sleeves with different thickness shoulders. I was at gaggs motorcycle shop years ago and he invited me to look through his boxes of many different springs and the rest of the parts, I came away with an assortment to do my build years ago, he only pointed out to me the plunger ones being a lot different . it's a pity the part numbers for these things don't give measurements for each one

[RDfella]

Looking back at the earlier pics, I note the scroll on the Pearson adaptor is the opposite hand to the others.

[chaterlea25]

Hi RD,
Please re read the post again,
There is no pic of the Pearson adaptor, Those have the scroll cut off and a lip seal is used on an alloy sliding plate

Yes the pattern adaptor shown is one of the wrongly made ones that were floating about some years ago

John

[RDfella]

Hi John,
looking at the Pearson adaptor pic again, I see it's a 'gold star' adaptor. Surely A series and singles rotate the same way?

[chaterlea25]

Hi RD

Please re read the post again,
There is no pic of the Pearson adaptor

The headings are above the photos

John

[RichardL]

Trying to figure out how to pose my question here without appearing to have ignored what's been said, mostly by John.

Anyway, I bought what was the last in-stock 4-spring clutch from SRM and, as you may have guessed, the center adaptor does not seat far enough in to allow alignment with the engine sprocket or felt gasket against the sliding plate. I wonder if the production-run ran out because they are making a new center adaptor that fits. If I space the inner cover far enough out to make the felt washer useful, it will probably take two steel spacers and a spacer behind the engine sprocket. Does that sound about right? I will be asking SRM if they have a new center forthcoming.

Thanks for your ideas.

Richard L.

[chaterlea25]

Hi Richard
Can you post a photo of the adaptor fitted to the gearbox mainshaft, and of the rear face of the engine sprocket? ( the new Wassel sprocket I fitted back then had a pronounced shoulder at the back that gave good alignment
Does the new adaptor have a thrust washer?
When you fit the inner primary case to the engine with spacer and gaskets plus some dummy screws at the front to make sure it is clamped solidly to the engine,
Now how much space is there between the rear case mounting and the frame lug 
This needs to be packed with spacer washers (later on )

At the weekend I stripped the primary side on my SR to prep for fitting the electric starter....
Reading through the comprehensive instructions again (and again)
One of the first instructions from Steve is  to check if the engine is "square" to the gearbox plates
To do this place a straight edge along the crankcase face where the spacer plate sits and measure from the straight edge at the front and rear of the gearbox plate and see if the measurements are equal
If not loosen the engine and gearbox bolts a little , place a strong metal tube over the end of the crank
and persuade the engine in the required direction until the measurements are equal

I had not thought about this until now but can see how a small error could cause quite a difference of alignment  between engine and clutch sprockets

John

[RichardL]

John,

Thanks, so much, for your comments. There is good stuff there and I do have new findings, just not time to reply this moment but, probably. tomorrow afternoon. Just didn't want you to think I was ignoring it.

Richard L.

[berger]

i like that information john, i will use that to test the burger build plates because to the eye it looks odd.  the last time i put mine together i was scratching my head as to why the clutch centre was fouling the sliding plate.  when  i loosened the two 5/16th bolts it dropped into place

[RichardL]

I'm sorry about this image you will never be able to erase, but I was just out in the garage before breakfast in my bathrobe because of how this is gnawing at me.

I haven't yet confirmed this, but it is possible that, while the 6-spring center cleared the sliding plate, maybe the new center does not. More to come later (after work and when I'm dressed). Sorry if I've wasted your time (if this turns out to be the problem).

I did call SRM and they were very helpful by advising me to offer-up the center to the other bike, where it went right on.

Richard L.