Fitting New Ring Gear

[Zetomagneto]

I now have a new ring gear to suit my early style clutch where the starter motor faces the rear of the car.

I understand the old ring gear needs machining off leaving a 9.010" diameter onto which the new gear is shrunk.

The pressure plate is 1/2" thick and the ring gear 5/16" so it looks as though you could either simply machine right across the plate leaving the correct diameter or only machine away the part where the teeth are actually cut which would leave approximately a 3/16" thick flange and this would still have the fixing holes in it.

Machining right across would be simpler but creating a step would presumably give you something to locate the heated ring gear against and because there would still be full diameter fixing holes in the flange part these could be used to guide the drill when transferring the holes through the new ring gear.

Not sure if this makes sense but I just wondered what people normally do.   Also can anyone can recommend a place to get the machining done, ideally in South Devon?

John.

Hamlins at Bridgwater have just done one, no idea of cost.
I would suggest redrilling the flywheel cover bolt holes on a smaller PCD as the bolt holes are very close to the bottom of the teeth when redrilled.