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I’ve purchased a NOS primary gear that is identical to my original item except for the metal ring on the seal surface, as pictured. Can anyone confirm the purpose of the ring? I’m guessing it’s an oil deflector, and advise if it’s possible to retrofit a new one or swap the one from my original gear.

Thanks, Diz

Only looking on my phone, but they don't look identical to me - one seems to have an A+ tooth profile, the other an earlier A-series profile.
If the tooth profiles are different then they aren't interchangeable.

Assuming the tooth profiles are the same, something that needs checking CAREFULLY! You can swap that little thrower ring from 1 to another without too many issues. But if you fit one of these when you assemble, you don't really need to bother.

http://www.minispares.com/product/Class ... o%20search

Thank you both for your comments, and Graeme, I think you are correct. It was sold to me as pre A-Plus and I had not got as far as checking the mesh with the idler but I've just done so now and there is clearly a difference.

The flat topped tooth profile is A-series (left hand in the photo), the more pointed profile is A+

The early primary gears didn't have the Oil Slinger, it was added later (64 or 65-ish off hand). I would advocate fitting one.

As Mark suggested, it can be swapped over, they are pressed on, but just go easy and keep it dead square removing and refitting, they get out of shape easily and not put back in to shape so easily ! Maybe even a few dabs of a retaining compound would be wise.

Easiest way to check for A or A+ if you are unsure is to count the teeth - A has 24, A+ is 29.

Easiest way to check for A or A+ if you are unsure is to count the teeth - A has 24, A+ is 29.

Is this true of a 998/1098? Only both of mine are 24 teeth but, as Graeme has identified, the new gear has a more pointy profile.

Yeap 998, 1098 and 1275

There was economy gears available in A+ that had 30 and 31 teeth to but all A gears were 24 tooth

mk1 wrote: ↑Tue Jun 20, 2023 5:05 pm Assuming the tooth profiles are the same, something that needs checking CAREFULLY! You can swap that little thrower ring from 1 to another without too many issues. But if you fit one of these when you assemble, you don't really need to bother.

http://www.minispares.com/product/Class ... o%20search

Thats interesting, are they worth fitting then ?