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MG MGB Technical - Which way does the flywheel ring gear go?

I am putting a ring gear onto a 1970 MGB flywheel. It is to be used with a pre-engaged starter. Which way does the gear go onto the flywheel: with the beveled edges of the gear teeth pointing toward the engine or toward the clutch?

Thanks for your help!

Mike
M.E. Whalen

I think the bevelled edges go towards the starter pinion, which also has bevelled edges. I think the pinion overhangs the flywheel and is pulled in from the rear of the car.
Art Pearse

Mike. The bevel is towards the front of the engine on the vehicles having a pre-engaged starter.

Les
Les Bengtson

Doesn't really follow. Pre-engaged geared starters can be used to replace inertia starters that pull it into engagement, and as far as I know all pre-engaged starters push the pinion into engagement. The Workshop Manual doesn't say, Haynes says "fit the ring with the front of the teeth facing the flywheel register" but doesn't say how to identify the front!
PaulH Solihull

Paul. The factory workshop manual was designed for use by factory trained mechanics, not hobbyists. Thus, knowing which way to face the ring gear was part of the general knowledge that mechanics were supposed to know--or could ask a more experienced mechanic about.

As to the bevel facing forwards, my examination of three flywheels from 18V engines and one from an 18GF all show the bevel being towards the front of the engine. I consider that definitive when discussing engines with the pre-engaged starters.

I had a new ring gear installed on the last engine I rebuilt. I took it to some friends who have done this before in MG engines. Heating the ring gear in the oven and freezing the flywheel, then trying to assemble them is very interesting. We, then, took the ring gear and flywheel to a professional shop specializing is such work. It took them 15 minutes and cost $20 to have the work done. I will, in the future, use the professional shop for this job.

Les
Les Bengtson

Guys

The old inertia type starters have the side of the ringgear with the tapered end of the teeth facing the gearbox
The later(or pre-engaged)starter equipped cars have the tapered leading edge of the ringgear teeth facing the engine

Never heard of freezing a flywheel before, I doubt it would shrink much

I use an old foolproof method shown to me hundreds of years ago by a Martian - it never fails

Lay the flywheel down on it's flat
Set a couple of house bricks (clay not cement)up on their ends far enough apart to allow the ringgear to sit securely on them
Now the secret - wipe some oil onto the surface of the ringgear and sit it on the bricks correct side up ready for fitting to the flywheel
Then have a couple of pairs of pliers ready and a hammer and blunt ended punch
Now warm the ringgear up with the gas (natural gas is better than oxy.but whatever you have) by running the torch round and round the ringgear until it's hot enough to have made the oil go runny, keep going round and round till the oil has smoked off and leaving the ringgear looking dry and oilfree and hot
At this stage quickly pass the torch off to your loyal helper and grab hold of the ringgear with the pliers and drop it on the waiting flywheel,then as it is cooling/shrinking give it a few LIGHT taps with the hammer and punch to make sure it is seated against the step on the flywheel all the way round - finished
Cheers Willy
WilliamRevit

How Willy said, you do not need to cool the flywheel if the ring gear is the right heat. The secret to judge the temp is to rub a bit of resin core solder on it, as soon as it melts, which is still a black heat, its right.
The gear will fall on. You will even have enough time to give it a spin on the flywheel.
Denis
Denis4

Thanks for all of your comments! It is clear that my new ring gear was put on backwards!! Since I'm using a pre-engaged starter now, I understand that the bevelled edges should face the engine.

The question now is what to do about the wrong-way-around ring gear. Is it useable as it is, or should I cut it off and correctly put on a new one?

Your advice appreciated. Mike
M.E. Whalen

It all depends on what condition it's in. If the teeth and their leading edges are in good shape, you can re-use it. If their's any doubt about the condition of the ring gear replace it. RAY
rjm RAY

This thread was discussed between 17/12/2010 and 20/12/2010

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