Heat treat or Cryo on tranny gears ?

I was considering heat treating some gears that I currently do not know the metallurgy of.

If a gear is already "heat treated", is there a penalty or benefit from heat treating again, just to be sure ?
Is there a benefit to Cryo treatment for tranny gears ?
Can you do both, Cryo and heat treat, in that order ?

I had the gears in my Richmond cryo treated with the face-plate mods and they are still on one piece. Liberty's done the work It only took about 10 months

Gus

I'd look at cryo treating. There would be no benefit to heat treating the gears again. Plus you've no idea what the exact metal composition is, so the heat treatment company would not know the correct heat treatment procedure.

My suggestion is to do some research on both and see how they differ and what the effect is on the particular materials involved.

When I was looking into the effect of cryogenic-treating aluminum rocker arms, I found a couple of research papers on the subject to see how it changed the metallurgy, tensile strength, etc.

I think all the Pro Gear ring and pinions are softer than stock OEM gears are so they will flex a little instead of cracking.
I would do all the research I could before deciding either way
Good luck

Add me to the Cryo treatment , I just had to buy a new cluster gear for a hemi 4 speed I had because 3rd gear was showing cracks , now I have a few others to have magnafluxed because I do not know the history of these trans' I have bought over the years .

Other than Liberty anyone got a recommendation for a firm to do this to transmission gearing?

I cryoed a 727 output shaft before Rick Allison sold me an aftermarket one. My metallurgist said I wasted my money because of the material. I forget what the material is but once I told her she said cryo has no effect on that material type.

What material? I didn't think cryo did anything to aluminum, but turned out I was wrong.

Has to do with carbon content. For life of me I can’t remember if the output shaft is high or low carbon content steel. Cryo works on one of them but has almost or no effect on the other.

An aftermarket output shaft would most likely be 300M, 4340 or something similar

Transmission gears will be 8620, EN36A, 9310 or something in that range. Something that is case hardened I would imagine, where as a shaft would be through hardened. I'll have to ask one of the material scientists at work about why cryogenic treatment might not work on some materials.

Neither, get the parts WPC treated.

I looked on a few sites and WPC seems to be in the family of shot peening, a surface treatment. Heat treatment and cryogenic are internal treatments. I think they all have their place depending on what you are trying to achieve.

Most production parts are already heat treated so the only thing you can really do to them is external treatments. The WPC process is a lot finer than than standard shotpeening.
A lot of the import cars never had aftermarket support for transmission parts or ring and pinions so it WPC became the trick to making stock parts live in performance applications. I use it a lot on my rotary engine builds.

Where do you get that done ?

The output shaft in the 4WD OD unit of the 47RE behind my 500HP Cummins was cryo treated because at the time billet wasn't readily available AND about 800bucks. I twisted off a factory piece power braking it against the convertor but I was too gunshy to try it again after fixing, but I never broke another with all the racing I was doing at the time.

I've been looking at some Youtube videos about this WPC coating and it looks like it has many applications in our drivetrains. I think oil pump rotors could really be a good application for this treatment. Transmission gears and rear gears would be a no brainer for this type of surface prep. I'm going to look into local outfits that may provide this service.
Thanks for the information

Gus

if you go this rout Gus, please let us know how this works out.

Wpc is originally from Japan, but they have an office in California. I haven't used the California service, when I buy new Oem parts in Japan from a friend, he just gets the parts shipped directly to WPC from the OEM there and they process then ship to him.
I think if I change the flat tapped in my other 440 truck, I'm going to get the cam and lifters WPC'd along with the rest of the valvetrain. I've seen entire engines and transmissions that have been WPC'd.

how far would the WPC coating go in preventing a solid flat tappet cam from loosing a lobe during break in ?