Trans Temps, What are people seeing? Options

[Matt Romanowski]

This weekend after a 40 minute stint on the track, we saw our transmission temps getting to 247F. That is on a day were it was about 45F ambient and we had the pump and cooler running.

Doing some research, the answers I've heard on safe temperatures are all over. The oil is good to 300F according to the manufacturer and some folks say they run there, but that seems really hot. Most folks say they like to be around 225F.

We just rebuilt the transmission and set the R+P to the factory backlash setting of .007", but we're going to open the transmission up and loosen things up a bit.

[john rogers]

Some questions and some observations. First off, where is your cooler and second what is the temp drop across it? The trans cooler needs cool and clean air, not hot and dirty air from under the engine which happens when folks put the cooler under the rear bumper. If you run the car on a dyno, you can shoot the oil line temps across the cooler since the fans dyno shops use will generally replicate the outside air flow. Does the shifting get harder as the race goes on, if so then the internals are expanding and they will fail possibly. Do you use the transmission to help brake the car, if so the change in load will cause accelerated wear and failure. Wayne Baker would always say "brake like hell and then down shift".

Observations from 10 years of vintage racing, I noted the 3L + sized cars used a 901 transmission a year if no cooler and every 2 years or so if a cooler was run. If the transmission was upgraded then there would usually be a year added but the extra expense would cause the whole thing to level out. I found shifting would get hard when temps went over 300 degrees which is why I went to a cooler. I also found that having the transmission inspected and any parts replaced yearly saved me from the failures which are always MORE expensive! Finally I found the JWest shifter reduced the wear and tear on the transmission significantly but they are no longer around. The best and also most $$$$$$$ is to install a Fortun 6 speed or similar and they last forever.