I'm considering getting cryo treatment done on my 901 guts before I put it together. Jake said he pays $10 a pound. I'd do both shafts, 2nd through 5th gears, and the ring gear. Just wondering if anyone happens to know roughly how much that weighs.

would the cryo treatment affect the measurements of the parts significantly?

As far as I know, no. It just ups the hardness and decreases wear. My knife is cryo treated, and I've done things with it that would break the tip off of any other knife I've ever used. Jake sold me on it after describing a bug trans that would repeatedly break until he cryo treated the gears.

I dunno, but the gearbox weighs around 75lbs. You are stating that you want everything but the case (basically), I would wager a good 40lbs?

does the treatment make the gears more brittle or anything like that. why no do the case too, as long as you're at it?

Not quite as simple as everything but the case. I won't do the inner diff, syncros, dog teeth, sliders, shift forks, reverse or output flanges.

I doubt doing the case would help in any way. The cryo process helps carbon steel change into a harder form. I don't think it will help al or magnesium, and I'm pretty sure even low carbon steel doesn't see a benefit. Its greatest benefit is for heat treated high carbon steel.

I'm not sure of the effect of brittleness, but I don't think that's the cause of failure in a 901.

Every 901 that I have had let go was bearings...then they gears got all masticated....

so what parts are you planning on getting treated? just the main gears? input shaft?
could you treat bearings? hmmmmmm.

Well I've heard several theories on how they fail. One is that the shafts are able to flex out in the middle allowing 3rd and 4th to mesh incorrectly. Cryo treatment *may* prevent as much flex in the shafts. Another is simply too much torque on the pinion, causing its teeth to shear off. Then of course there's the bearing issue but I would think you'd get some noise from that before total failure. I'm most worried about the 3rd/4th failure because it would happen at speed, and possibly without warning. The last thing I want is trans lockup at 50 mph on a freeway onramp.

I'm also toying with the idea of a fluid cooling system, but I want to keep things simple. It would be nice to find a way to use the ring gear to pump the fluid through a cooler instead of having to add an electric pump. I'm told that just pointing the vent the wrong way will cause the ring gear to pump the fluid out, so if I design something specifically to do it it might work. Cooling the fluid will probably help bearing life.

I REALLY believe in cryo!!! Every engine I build gets some degree of cryo work, and alot get every ferrous part treated.

I have personally seen parts only survive because of the cryo!

I even have all my tooling for the lathe and mill cryoed and have seen some end mills and turning tools last 4-5 times as long

I work really closely with www.percryo.com they are great guys that really have their profiles down to a science.

Cool I'll check them out. Doing the bearings is probably a good idea too. Renegade has some 901 "secrets" and I think cryo may be one of them.

`Here is a list of companies
http://www.raceseek.com/coatings.htm