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MG MGB Technical - Ring Gear Replacement

Does anyone have experience in replacing the flywheel ring gear? I have the engine/gearbox out of the car in order to replace the broken pressure plate - going to replace all 3 clutch items. My ring gear teeth are pretty worn from the starter and the noise on engaging the flywheel can be pretty loud. I figured this would be a good time to replace the ring gear, and my local parts source/british auto repair shop told me it was a pretty simple process. Anything special I need to know other than getting the flywheel cold and heating up the new ring gear? What about getting the existing ring gear off?

Don Scott
don scott

Don. I watched two experienced mechanics, who had installed a ring gear before, struggle for an hour to install one on my MGB flywheel. I suggested that I simply take the flywheel and ring gear down to the local clutch specialist rather than spend any more time on trying to install it. Took about 15 minutes for the specialist to install it and cost $15 for the job. In the future, the specialist shop will be doing all of my ring gear replacements.

Les
Les Bengtson

Don,

Just noticed this thread. Totally agree with Les but if you want the 'fun' you can chisel or cut the old one off taking care with the flywheel. Flywheel in the fridge, ring in the oven and/or blow torch.

Older cars had no step on the ring gear but believe new replacements do. Step faces the rear for inertia motors but if you plan on a high torque replacement then maybe reverse this.

Must confess my last one was changed by the Owners Club.

John
John U

Don You cut the ring gear almost through with a hacksaw or carefully with an angle grinder then crack the last 30thou or so with a chisel. That way you wont nick the flywheel. Dont worry about cooling the flywheel just dont have it in the hot sun. Sit the ring gear on clay bricks or something that wont explode with heat and heat with a good blow lamp or such until you can melt solder no it (not red hot)Pick it up with multigrips (there the best shape for the job). The ring gear will drop on very easily. The main things to remember are - Dont hammer or press the old gear off (if you do the new one may fall off)You need a good heat source, and as other threads have said make sure you put the gear on the correct way round to suit the model and starter used.
DENIS4

Don,
If you do it yourself,a good suggestion to heat the ring gear is to use your Weber charcoal barbecue. Gives uniform heating with plenty of heat input.
David
David Overington

Remove the old one as described above. Wait until your wife / girlfriend goes out then heat the ring gear in a 350* F oven. Use heavy oven mitts, welding gloves or pliers to carry the hot ring gear to the flywheel. Drop in place, wait to cool (not long). Your done!

Tom
Tom Sotomayor

If you freeze the wheel you will get them on but the gear may crack after fitting.

The gear should not be heated above 250 degrees centigrade or the temper will be affected.

The heated ring gear should drop freely onto the wheel and should be spun immediately to make sure it seats on the flange.

Some replacement ring gears are a touch too small and won't expand enough to fit the wheel.

The solution is to take a thou or two off the wheel in a lathe before fitting the gear.
Chris at Octarine Services

This thread was discussed between 05/09/2007 and 15/09/2007

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