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Just having a bit of a panic attack. I can't remember taking a seal out of the back of the flywheel but I am now not sure if it should have one.
The car is an 850 built about Nov 63 coil spring clutch. Can anyone tell from the attached pics. It doesn't have the very early crank bolt as can be seen.
Thanks Macker

that looks like the later primary gear (full length splines) and should not have a flywheel oil seal. If you put in an oil seal, the splines will stick into the seal and the clutch will not release.

Is there an oil hole in the crank, or has it been plugged with a brass pin.

Can you see what the internal bearings surfaces are in the primary gear - does it look like babbit (white) metal. Is there a part no on the PG.

Anyway - the oil seal is a std drum brake front wheel bearing seal.

woodypup59 wrote:
Anyway - the oil seal is a std drum brake front wheel bearing seal.

to be a massive pedant, its not actually a front hub oil seal, its a specific seal, which is difficult to find

you CAN use a front hub outer seal, which has the same I/D / O/D, but there is something different about it (cant remember what though)

people have been using the hub one for years though!

Thanks for your replies.
Woodypup 59 I checked the crank for a plugged hole but couldn't see anything. So I measured the size of it expecting it to be a thin tailed crank because of the coil spring clutch. Turns out it is 1.5".
That means the primary gear is the later type as spotted by Ivor Badger 2.
There is still something strange about it though as it doesn't have the spacer /washer down by the oil holes that the ones for sale these days have.

Macker

spacer washer by oil holes? Do you mean the light metal ring on the seal side of the primary gear teeth to idler gear?

Yes, as can be seen on this pic.
I don't understand how the holes work as it seems the oil will go through these holes and travel along the inside of the bearing surface with nothing to completely seal the clutch end ?

Macker

the ring just works as an oil thrower, a lot of primary gears don't actually have it fitted. its job is to try and help with excess oil passing through the main clutch housing oil seal - the thin plastic ring on the other side of the housing is then designed to fling any oil up around the case and keep it away from the friction disc

the idea of the holes is to allow a certain amount of oil to get into the void between the two bushes in the primary gear - without the bushes the rear bush (i.e the outer one) would run hot and nip onto the crank (unless the front bush (i.e the inner one) had a larger clearance, in which case it wouldn't be working very well.

with no oil, the primary gear can grab hold of the crank so hard that it wont let go, which makes the clutch drag, at worse they spin and either chew the bushes out the gear, or get so hot they will swell the crank, ive seen cranks get so bad (and blue) that number four big end has run.

any excess oil which can get past the rear bush can then just creep around the saddle and the 'c' ring and fling its self harmlessly out the way - such a tiny amount of oil will get out this way that 'in normal service' it wouldn't damage the friction disc if it did get onto it

Cheers Rich, that puts my mind at rest that it is going together properly.