Fitting New Ring Gear

[John P]

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.

[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.

[Stuart Giles]

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.

Where the redrilled flywheel bolt holes appear in the ring gear does look a bit scary at first sight admittedly; but the effort of splitting an old ring gear off a flywheel with a cold chisel where the flywheel flange prevents you cutting all the way through the ring gear with a disc cutter certainly shows how tough they are . 



Incidently, I have heard that an induction heater or similar is essential for shrinking on a ringear. here's a picture taken outside my workshop of heating a ring gear  that I fitted onto a flywheel last week.



When that soot starts to burn off the ring gear in the fire it will just drop on. This low tech method just uses a  good splash of old sump oil in a metal tray.

[Chris KC]

Did mine in the oven

[John P]

Stuart,

You mention a ring gear you couldn't cut off with a disk grinder because of the flange.

Does this mean that you actually machine just the gear teeth away leaving a shoulder against which the new ring gear rests?

Do you have any photos of the clutch plate machined but before fitting the ring gear.

I'm hoping a local small machine shop may be able to do the work but obviously I will need to provide them with a drawing showing what's required.

John.

[Terrytuned]

The damaged teeth on the cover plate are machined off to a diameter of 9.010" and to the thickness of the new ring gear leaving a flange to locate the new gear.
When the gear has been fitted the half holes that are left must be redrilled using a milling cutter as you are only drilling half a hole in the new ring gear and drilling it with a drill it will not cut true and wander off enlarging the holes.
Terry.

[John P]

Terry,

Thanks for the info.   That's what I had anticipated but I just wanted someone who had actually done the job to confirm it before I prepared a drawing.

John.

[John P]

Hi,

I've now got the clutch plate machined and am ready to fit the new ring gear.

However, when I offered the new ring gear up to the newly machined plate it became very obvious that the ring gear is out of round.   I don't have the means to measure it accurately but the difference between the maximum and minimum internal diameters is probably close to 1 mm.   The ring came from Tony Leslie and he said this is normal and once fitted the gear will shrink down and become round.

I'm sure this is true but I'm just a little concerned the ring will get stuck half on and be difficult to either get fully into position or remove again.   Has anyone that has done this noticed this and if so how hard is it to get the ring gear on?   Should it just tap into place or do I need to be prepared to apply considerable force.

Any advice would be appreciated.

John.

[Ruairidh Dunford]

Tony is correct, it will pull true once installed.

If you have temperature and machining correct it should just drop on.

[GK5268]

I replaced the starter ring gear on my 1965 Rover P6 recently, never having done this before, followed the workshop instructions for removal and watched numerous videos on Youtube for the fitting, it is actually very simple to do, the important point is to make sure that the new ring gear is well heated, I popped mine in the oven for about 20 minutes on its highest setting, have the flywheel close to hand, some heat resisting gloves (the ring will be very hot), a drift and a mallet/hammer. Check carefully the orientation of the teeth and put this in the oven so that when it comes out it can simply be dropped onto the flywheel without having to flip it over.

Once dropped on, it will not need any force, a gentle tap all round to ensure it is fully seated, allow to cool and job done.

If the ring gear is not hot enough it will not expand fully and you might end-up getting this part-on only and you will need to then re-heat this carefully with blow lamp or hot air gun to expand the metal, either to remove and start again or to continue fitting, it needs care as the flywheel will also start to expand and you are working against yourself.

It is an easy job so long as the ring gear has expanded! Definitely look at Youtube videos!