I run the Bmax uppers and articfriends cryo'd lower gears...800+hp
After 1.5 seasons I broke a vertical shaft and upon inspecting the lower gears they were as new. I now swear by the cryo treatment.

Alco Marine in Lake Havasu City has done the rebuilds.
MD

Believe it or not....the pinion depth has been on the money on the last 4 new ones I have been in. The rolling torque has been in the 18 to 24 in/lb range. Enough to make the pinion bearing fail prematurely.....which would then change the depth...chew the teeth up and or spit the pinion assy out of the front of the case breaking it in the process. If you let the race spin.....it is within spec. So, whoever is setting them up at merc has it in a fixture and is overtightning it. They are looking at the needle and not realizing that the race is spinning. If you put you hand on the race....rolling torque goes up by 12 to 15 inch pounds putting it way over spec on the ones I have had apart lately. They have also been full of metal from a piss poor cleaning prior and during assembly.

Smitty, do you sell XR lower gears? I need a set of 1:50

BigMd..
The last few years the teeth on the upper gears have been failing. They snap off at the root. Merc's quality of process has gone down hill. I used to be able to run 1000hp thru an XR and make it live. It had a shorter life span but the gears didnt snap off teeth. Now it is very common. I really dont think Merc is going to fix it either. They offer the NXT behind the 525hp motor now.. so why would they. At $1500 a pop, they are making money selling them. Setup can affect life of the gear, but I dont believe it is the cause of teeth breaking off.
One solution is to go with the SCX. Friend of mine has 150hrs on his with no problems. 36' boat with 825hp motors. Used to break XR's all the time. I am an Imco dealer also.. I can get you prices for the SCX if you like..

Speed,
I have a set of 1.5, Cryo'd XR lower gears on the shelf.. pm me.

Dick

PM sent, thanks.