MTFCA Forum

Hey all,

On 09/10/2025 I post a new post about a knock during start up.
This afternoon I started to install the new ring gear with new right bolts.
Here is what happened.
During the tied up of the bolts two teeth of the brand new ring gear just gest loss.
I looked to the brake surface. Here is what I found.

A new ring gear is ordered. Hope this will be the right one.

Andre
Belgium

I suspect that that ring gear has been incorrectly hardened. ring gear teeth will usually wear right down rather than break off.

Allan from down under.

That would be a real nightmare here. Let alone in Belgium.

I'd rather have a used Ford unit. They really don't wear out.

Too hard, I'd think. I had a riding mower with electric start, and the ring gear broke during the winter. I guess it was too hard or too tight. The puny little starter and plastic pinion sure as heck didn't break it.

Your original issue involved a similarly fractured gear tooth. This is most likely due to these ring gears being improperly heat treated and/or being made of the wrong material. I would very much expect that any replacement from the same source would yield the same result.

This one failed near a mounting bolt, similar to the first. Is this the same bolt location on the flywheel for both failures? Not suggesting mounting bolt stress could cause this, but both failures seem to be similar location relative to mounting bolts. I agree with others that something is faulty with metallurgy and/or heat treatment. Sorry for your loss, jb

If you have some good used original ring gears maybe use one of those. A ring gear doesn’t have to be perfect to last many years of normal use.

Hi Andre,
Do I understand correctly that the teeth broke when you tightened up the bolts not when the starter drive contacted them????
Craig.

Craig,

The first gear ring broke during a start up of the engine.
This gear ring was mounthed on the flywheel the day before and broke while I was mounthing the oil carter and touched the gear with my wrench, one tooth dropped off. The second came off as I set a screwdriver in a small crack under the next tooth.
As there is rust in the breake zone, I think the teeth were broken before. Why... I don't know. The other tooth on de gear ring look to be solid.

All new parts arrived Yesterday, I will mounth it all this afternoon.

Andre
Belgium

Check the hardness of the ring gear with a file. A ring gear should not be so hard that you cannot file the edge of a tooth. Those look like brittle failures, which a hard gear might cause. Just something to easily check.

Check the hardness of the ring gear with a file. A ring gear should not be so hard that you cannot file the edge of a tooth. Those look like brittle failures, which a hard gear might cause. Just something to easily check.