The reason that the gear box broke was that the person who renovated it had put in the wrong input shaft. It only had 22 teeth and it should be 23. So it did not match the cluster gear. It has had a mysterious sound all the time on the first three gears. Now I know why. I prefer to do as much as I can by my self on my cars so I can not blame anyone else.
// Thomas
Wow that was a big mistake. It had a bunch of backlash for sure. Just hitting on the tip of the teeth.
I know you already have your gears there. One thing that pretty much every part of the NASCAR racing parts go through is Cryogenic Treatment. Gears, axles, brake rotors, crankshafts, rods, engine blocks pretty much anything that moves or under stress is sent for Cryogenic. It totally changes the grain structure of the materials. You can treat a copper spot weld tip and increase it's life many times what an untreated is.
It is not just a matter of dropping into liquid nitrogen and freezing it. It has to be done in steps and for specific times and temperatures. It works and makes the parts last much longer. Here is a link to one of the suppliers.
http://www.300below.com/motorsports/
I did some tests in our shop just before retirement it does work.
When I was in tool & die and when we made our own hand tools, grinding vises, squares, parallels, gauges, anything that required extreme tolerances sometimes +o.0000 - .0001" tolerances we would, after normal heat treatment and draw, boil the parts and put if freezer or nitrogen and do it repeatedly before we finish ground or lapped the parts. That removed all the internal stresses from the heat treatment process. They would stay accurate and not change with time. This was back in the 1960's
When we would build an engine back then you never wanted a brand new engine. You wanted one that had heat cycles on it so that it was stable and would not change dimension when you were racing it. New is not always a good thing especially anything made of iron like a cylinder block or heads.
There are probably shops that do this in your country also. It does do amazing things to metal no matter what kind of metal. The grain structure is much better after the treatment and parts just last longer and perform much better. I understand the brake rotors last much longer several 100% longer.
They also apply coatings that reduce the friction. When me and my son kart raced we sent all our engine parts and had coatings applied and never blew and engine in 7 or 8 years of racing. We used the coatings on our automotive tooling to reduce the amount of lube required and extend the life of the tooling.
With a mistake like they did in your transmission you did not stand a chance. Good that you found the error and have a good reason for the failure.
One other thing that this is great for is firearms. In the past when I bought a new rifle I would take apart and heat the barrel in oven to 200 deg. then put in freezer. I do this a dozen times. It removes the stress from the manufacturing process. Then I lap the rifle barrel before I ever shoot the gun. I am not a long range shooter but I do go to Africa a lot and take baboons at 500 meters with out any problem. There are companies the do just guns. You shoot a target before you send it in and then when it returns. They guarantee you a better group. I just wish someone would do a ceramic lined high powered rifle. That would be perfect. You could not burn it out and friction would be gone. They have been working on ceramic engine for years, no coolant, no lubrication. A local ceramics company here did a lot of development on it for Toyota but have never seen anything hit the market.
