This one had a early inertia ring gear and a Japanese starter and about half a dozen teeth 180 degrees apart were thin enough to shave with. I checked with the UK boys and they were concerned due to different tooth count and profile there would be a issue. I also have run a pre engaged Rover starter with an inertia ring without issue. 

This is another one of those he paid to much for the car, first shop charged $4000. for complete engine repair did not complete the 20 mile trip back home without major failure. Second shop went though it and never was able to get it to run long enough to get out of their shop. Second shop stripped and sent everything to machine shop. Cyl. head cracked, cyl. walls 73.5 with .007 wear, center main bearing spun. Crank already 20/20 with bad center. 

I took a look at tranny and none of the synchros are doing anything and shift forks very loose. The real kicker is one of the diff. ball bearings were installed backwards/ upside down. Being the late type this allowed the crown wheel bolt heads to eat away at the case. The fluff on drain plug magnet was as big around and little finger and half as long. 

While ring gear and starter were not issues yet, imagine if he got this back and within a month or so it would not start. Steve (CTR)

Early type Mini inertia type ring gear works fine with a pre-engaged starter without flipping it over. Here in Oz we do it all the time. Isuzu starters, modified Bosch starters, aftermarket Japanese starters, etc. No worries.

And if you'd like to know a correct pre-engaged rover starter is replacing the aftermarket converted hi torque one. I think I have a 5 gallon bucket of them. All quit at worst possible time. Steve (CTR)

Thanks for not keeping the rest of us in suspense!

Sorry figured no one wanted of needed to know. Turns out all pre-engaged starter ring gears are of the thin type. And no on flipping the pre-pre-engaged ring gear over. I had both ring gears in stock just had not looked them in a long time. Done deal now cut away the weld and gear leaving the flywheel untouched. Heated ring up dropped it on and for meanness tacked it in six places every 60 degrees. Steve (CTR)

..And the answer is?????

I have a similar issue..

Sorry, should have looked ... i found where you found the answer...

Cheers, Ian

Never mind I have found the info I needed on another board. Thanks for looking. Steve (CTR)

I'm working on a pre verto flywheels which has been run with a JAP starter which has chewed up the ring gear 180 degrees apart. The flywheel is a street light steel one with a thin gear welded in three places. It's clearly a inertia starter ring gear. I have been able to cut the weld and gear away without touching the fly wheel. It turns out I can find a new thin inertia gear but not a proper thin pre-engaged gear. I did read some place that the inertia gear can be flipped over and used with a pre-engaged starter. I realize the tooth count for the gears is different. I can buy a new flywheel with the correct gear and that may be the finial choice. Steve (CTR)