Problems Removing A10 Primary Chaincase Inner

[Brian]

Thats the thing, the original design relies on the bush in the centre of the plate to slide the plate along when the gearbox is adjusted. I dont think a seal would tolerate that much pressure and would distort to the point of destruction. I think you would need a bush as well as the seal so the bush can take the pressure of moving the plate and leave the seal to do its job.

What I had in mind was to run the seal on the back of the clutch hub with a bush alongside running on the shaft, the bush being there purely to take the pressure and move the sliding plate during adjustment.

Richard, can you remember what the other side of the plate looked like, did the seal sit in a metal cup with a hole just large enough for the shaft to come through. If not then I am very surprised the seal will survive. If so then I dont like the idea of a steel carrier rubbing on the gearbox shaft.

[trevinoz]

Brian,
               I guess the proof is in the pudding.
Maybe Richard will let us know how many miles he has done on his modified set-up.
Personally, I don't have any problem with the original. I had better check to see if there is any oil in the chaincase.
  Trev.

[Brian]

I dont have a big concern with the original design either and thats why I have thought about this mod but never got round to doing anything about it.

The only thing I do is make my own bush for the plate so its a neat fit on the clutch hub. I bought a new one for my 61' and it had more clearance than the worn out one !

I'm one of the ones that runs engine oil in the primary and while it does seep a little it certainly doesnt get to the point of dripping or making a big mess.

I've only got one swingarm A, the rest are plungers and now a rigid so its not a big problem for me.

[1660bob]

Hi Adrian, just had a look at your dynamo drive pictures- Look Out!- that looks more like GORRILLASNOT!!!!!!
Regarding the spacer `twixt inner chaincase and frame (47-4792), I have only found one parts supplier who lists it  and that`s Draganfly- but they cross reference it as a 5/16 plain washer!!!!!- I suspect the "gap" twixt case/frame will vary bike to bike, hence it may be washers as required, or perhaps none at all-certainly the gap on my bike initially looks to be between nothing and one washer here. Perhps BSA were somewhat grandly describing it as a spacer, when all it ever was, was a washer or two!
My advice would be thus: assuming engine crankcase is correctly bolted in, all faces clean and undamaged and nothing distorted,the spacer plate 42-7518 should be sandwiched between two gaskets (42-7509), and the inner case placed over them onto the crankcase spigot and bolted up using the two bolts 42-7516, AND all three forward  screws 42-7517(?) using suitable spacers  to mimic the outer chaincase cover.This will prevent any tendency for the inner case to tilt, and should, when all nipped up, leave the inner ch/case in its natural position.You should now be able to see the true gap between bottom rear end of casing/frame plate for "shimming" with washers as req. Correctly done, you should be able to tighten the bolt 64-6054 without straining or distorting the case.Thats how I see it, but I`m new to this so if anybody knows better,shout up!! HTH, Bob.

[brackenfel]

Thanks Bob,
Sounds like excellent advice to me & once I've sourced the necessary gaskets etc (and it warms up more than a bit!!) I'll make a start.. Thanks for the tip about the spacer, I'm sure production tolerances for frames meant that there's a good variety out there!   I'll get some more suitable grease for the dynamo chain as well, not too many gorillas around here I'm afraid..!!

Cheers,
Adrian

[Hubie]

Hi all,

Finally got the primary apart last night and fashioned a seal out of rubber sheeting and fitted it up.  Not a drip of ATF from the primary now after a decent 60mph run.  All is good!

Cheers

Hubie