2nd gear should I file it? Do gears have a hard coating?

[AUSMHLY]

Just received a 2nd gear, one tooth is chipped. I showed this to the mechanic and he said you might want to file the cut out edge of the chip smooth. Your thoughts?

When looking at one of my other gears he said it looks like the hard coating is coming off, and that it will wear quicker because of that. I'll assume he has trained eyes, for I could not see any coating. Is what he says true? (I'm attaching photos of my newly acquired 2nd gear. It looks original. I don't see any "hard coating").

The welded rebuilt laygears seem to have a dark coating. (photo attached) What is that coating?

Next to that laygear, you'll see the 2nd gear I bought and showing close up photos. Your thoughts about the chip in the tooth? File the edge of that chip or not?

Thanks guys

 

[red57]

Gears are heat treated and very hard, I doubt if a file will touch it. You might try a small whetstone or Arkansas stone and see if you can smooth the edges a bit and make sure there aren't any burrs. BTW, this gear sure looks to be a lot better shape than the other one you showed.

The dark coating on the repaired laygear may be from nitriding or tuftriding which is are heat treating processes that add a high carbon content to the surface of the part - may be that is what he was referring to? I'd suggest asking him to explain what he meant.

 

[vette]

I’m not an expert on gears or metallurgy but I definitely would file that gear if it were mine. Just from what I read about sharp edges and stress risers I would do it. Look at it this way, when another gear comes into mesh with this gear it’s going to have a rough merger with it. That edge is going to get worn down in the least or possibly chip some more in the process possibly or causing a crack. Maybe damaging the other gears. The chipped metal is already gone. Smoothing that edge to make the mesh easier isn’t going to take that much off. Just enough to smooth the mesh.

 

[pkmh]

I can't say enough one way or the other if smoothing out chipped gears helps as in this case, but assuming so, then try "Dremel" it. Having the right grinding wheel at high velocity never stopped me from cutting or smoothing out virtual anything.

 

[Madflyer]

As gears go they are very hard and heat treated, not the body of the whole shaft. The point being gear surface does the work and the body is at the casting strength. As with your gears chip that what hardening does this can happen by just dropping a gear. If you use a grinder to dress the chip DO NOT LET IT GET HOT. It is only one tooth so loading is little in the life of the gear. When the face of a gear is gone it eats up quickly, the hardening is not very deep.

 

[Madflyer]

What is with the welding on your gear? This photo shows a gear made into an award. I have never seen gears welded. The temper is gone and unless reheat treated it would be junk. Anybody have any ideas?

 

[AUSMHLY]

I did not buy the welded laygear in that photo, only the 2nd gear.
It's my understanding that once the factory laygears weren't available, vendors began selling reconditioned laygears where the 1st gear section was cut off and a replacement was welded. Vendors sell these, wanting yours in return. It seems that new reproduction one piece laygears are being made and sold by some vendors now. Is your award a 22B141 laygear, NOS? I need it

 

[John Turney]

The "Big Teeth" on that gear are in constant mesh with the matching lay gear, so as long as there is nothing sticking up, there is no reason to file that tooth. When shifting, the "little teeth" come into play.

The sliding hub, with the help of the syncro/balk rings, engage those little teeth. The little teeth need to have sharp ends on them. A couple show wear, but as long as almost all are sharp, it should work fine.

It looks like the friction surface on the cone-shaped area looks to be in good shape to make the balk ring work properly. When you put the balk ring on the cone area and push it toward the teeth, the gap between the balk ring teeth and 2nd gear little teeth should be about 0.025".

The dark coating is the result of heat treating.

Is your award a 22B141 laygear, NOS? I need it

All you have to do is win the award.