BSA B31 Part 16 Primary Drive & Clutch

Fitted the clutch to find that it was out of alignment so had to make a spacer.

[@webber977]

Nice job lining up those sprockets I'd of missed that one 👍

[@Cobra427Veight]

I just pulled my primary off my B33 , because of a weird vibration /surge / bind , i found the primary chain out of alignment by about .060" , previous owner never lined it up ! , found that the early triumph 4 spring clutch hub adapter 42-3170 or 42-3170A , the A has a slightly bigger diameter taper and goes on to the shaft a bit deeper mabe .080 as the feked advert suggests . Cheers .

[@InTheShedUK]

Good that you have the Triumph clutch, much better than the BSA one

[@Cobra427Veight]

Sorry to be a pain but the seal retainer behind the clutch basket that is fixed to the rear cover , and then you adjust the chain and it could be way off centre? Is it best to re-center it . Cheers

[@InTheShedUK]

I assume you are talking about the odd shaped steel plate with the two bolts which retains the felt washer? If so the bolts are (or should be) stepped so when the bolts are tight the steel plate is still be able to slide front to back when the chain is adjusted. The rear of the clutch hub adapter which has a scroll on it which fits through the hole in the plate so when the clutch moves the plate moves with it, renew the plate if the hole is worn.

[@Cobra427Veight]

I don't like the black silicon rtv , have you tried loctite grey max silicon , or JB grey , it is heaps tougher.

[@InTheShedUK]

Not tried that but then I only use silicon as a last resort.

[@colinsmale3740]

The primary chain looks very tight

[@InTheShedUK]

Looks tight but actually within spec, 1/2" max up/down movement.

[@Cobra427Veight]

I got mine back together, and found the left stepped bolt had worn into the alloy and that made the sliding plate too tight , i found an extremely thin shim washer and fitted that , my plate was already modified for a seal and the rear of my hub adapter has a speedy sleeve over the scroll , but something is still leaking oil somewhere, is the big felt disc actually capable of stopping oil seeping behind it ? Has anyone ever welded a small ledge over the top of the sliding plate ? Or found a solution , i may get some dye and see if i can clearly see the leak . Cheers .

[@InTheShedUK]

The felt disc probably gets to saturation point and becomes less effective. I guess there have been many attempts to stop a leaking primary but don't know if there has been any really successful solutions, partly why I ended up fitting a dry clutch and belt drive!

[@markmathews6876]

mate the washer is wrong way round

[@InTheShedUK]

can you explain why?

[@markmathews6876]

@@InTheShedUK yes the flat underside of the nut needs to sit on the flat side of the washer the excess bolt length/ thread hanging out is another pointer. 👍

[@InTheShedUK]

Problem is the underside (contact area) of the nut is bevelled not flat, the bevel matches the bevel in the washer. If it was on the flat side of the washer there would be very little contact nut to washer. Thread hanging out is not an issue as there is enough clearance nut to splines.@@markmathews6876

[@markmathews6876]

your right ,I couldn't get a good enough look at it @@InTheShedUK