MTFCA Forum

Today I went to work on the 1923 touring that died from a shattered low drum. All I've done so far is take the magneto parts off the flywheel, clean up all the parts, and remove all the shredded band lining.

The flywheel is toast. That pin is out because it spun and wallowed out the hole, making for a a wobbly gear. The middle gear spun on the bushing, which is still stuck to its pin.

The bluish color tells me the gear got pretty hot. Is it still usable, or should I find another one?

Probably ok. Heat didnt get to the teeth. Those gears are surface hardened like glass.
For conformation, take a file to it. If the file cuts the teeth, its annealed soft. - replace. If the file slides off & gear looks good otherwise - use it.

I have never seen a pin waller out a flywheel.
Obviously, bushings were set too tight. I like a bored or honed .0035- .004" clearance minimum. Drums also.
Service manual says over .006" replace. Anything under is good. A little racing clearance never hurt a stock motor.

If you have another triple gear I would replace it. You probably have another good one or if you have another flywheel with good triple gears use that. You probably have a few good transmissions you can get a set up from.

Chances are the fixed bushing wore the bore of the triple gear. May be too oversize now to press in a bushing, you need that bushing firm in the gear.

Measure the i.d. of the bore on that blue triple gear, to be sure it's 1" dia.

I would replace all three with the earlier riveted three piece gears. Because the one piece gears have narrower teeth, they tend to wear far more. The only problem I have ever found with the riveted gears is the occasional one with loose rivets. The teeth are usually excellent. They are harder to balance though.

Allan from down under.

Its not the narrower teeth as much as the 3 piece gears are much harder than the 1 piece.

Another T transmission destroyed because it was built too tight thinking it would last longer when the opposite is the result. I have never seen one fail because of sloppy bushings, they just get noisy. I have had to salvage a bunch of them that seized bushings and welded thrust washers together and to the clutch drum.

If you replace one triple gear, be sure to use one the same weight as the other two. Not all gears weigh the same amount and if one is heaver or lighter than the others it will throw the entire transmission out of balance setting up harmonic vibrations as you drive the car.The pins are press fit into the flywheel, and if a new one will still press in, you can use the flywheel. If not, the flywheel should be replaced.
Norm

If you replace one triple gear, be sure to use one the same weight as the other two. Not all gears weigh the same amount and if one is heaver or lighter than the others it will throw the entire transmission out of balance setting up harmonic vibrations as you drive the car.The pins are press fit into the flywheel, and if a new one will still press in, you can use the flywheel. If not, the flywheel should be replaced.
Norm

That makes sense Dan. I rarely find a worn/through the hardening/pitted/ three piece gear. They are tough to machine when balancing them. I usually resort to match weighing them before installing new bushes so there is less machining to do.

Allan from down under.

Allan wrote: ↑

Thu Jul 01, 2021 12:43 am

That makes sense Dan. I rarely find a worn/through the hardening/pitted/ three piece gear. They are tough to machine when balancing them. I usually resort to match weighing them before installing new bushes so there is less machining to do.

Allan from down under.

Use a small solid carbide mill between the rivets. Once you plunge about .030” they cut like butter!