Safe Spec Boxster Tranny Temp

[truegearhead]

Originally Posted by Black Sweeper

Searched around without much luck. Lots of talk about SBR tranny coolers but what is the proper temp range for the tranny oil. Looked at Redline specs they just tell you how the viscosity changes not where the oil starts to fail. Changed the tranny oil for the first time in a used SBR I bought and found that the tranny cooling pump doesn't work, so I am looking specing a proper cooling system. I have seen some general statements that manual tranny oil should be between 175 + 200, and anything over 240 breaks down the oil. 175 seems low.

Thanks for your help

Is this really a problem? Do people blow transmissions?

[thstone]

Originally Posted by truegearhead

Is this really a problem? Do people blow transmissions?

While not a maintenance item like tires and brakes, it is fairly common to have to replace a transmission. I know several racers who are on their 3rd or 4th transmission.

I will say that its hard to know if the failures are caused by high temps, too many miles, driver misuse, or something else. Personally, I am on transmission #2 and I blame the problems with trans #1 on myself (and some sloppy shifting).

Also, I see a few Spec Boxster's with external transmission coolers so there are some racers concerned enough about temps to try and do something about it. I do not run a trans oil cooler on my car but I do change the trans oil twice per year in the hopes that fresh fluid will provide some protection against heat. Still, I think that I (the driver) am my transmission's worst enemy.

In terms of trans oil performance, my limited understanding is that the trans oil is manufactured to a specification (like API GL-4 or GL-5) and then that spec has a defined test procedure (like ASTM D7450 or similar). I haven't done the research but you're likely to find the upper temp limit in those types of documents since all of the manufacturers just quote compliance with the spec's and rarely actually publish the numbers. With Porsche, it might even be more complicated since they might have their own spec which goes above the standard industry spec's (again, I don't know this for sure but its not unheard for Porsche to do something like that).

[itsnotanova]

Maybe it's a Texas thing but lots of guys run with transmission coolers down here and some even bring spare transmissions with them to the race. I agree with Tom and that most of the damage is caused by the driver.

Sorry Black Sweeper but I can't give you an answer but those temps sound about right to me and 175 doesn't sound too low to me.