KorbenDallas

I'm getting a new transmission soon. I need to know what the torque rating for transmissions mean? If a tranny is rated to 400 ft/lbs, does that mean that its max handling is 400 ft/lbs and nothing more? Or does it mean that it can handle a minimum of 400 ft/lbs with no problem, but it is accepted that it can handle more?

Thanks! :seeya

jerryp58

I don't know for sure, but most ratings for anything are for MAX load. There is almost always a safety factor included (e.g., your 400 lb-ft trans might be able to take 440 lb-ft for brief periods), but I would think the 400 lb-ft is the maxiimum engine rating you'd want to bolt that trans to.

SharkAttack

Assuming the guys at the shop know the subject matter, it should mean the max torque output at the flywheel of your engine that the transmission will reliably support.

flynhi

The guys at TexRacing who build NASCAR transmissions told me that the rating for their transmissions is for instant load as is a drag race launch when the engine is revved to max torque and the clutch is popped. He said that if the torque is applied slowly, the trans will handle more than the rated torque. How much more depends on the trans and how quickly the torque is applied.

Allan71

The deal is, is that there is no standardized rating system, so you can only use the figures as a guide. Most trannys I believe are rated at a continuous torque being applied over a period of time, usually hours, and is not a shock load rating. Muncie never did publish any ratings as far as I know. Dumping the clutch with slicks of course is very hard on the tranny, and powershifting is hard on the synchros. Here the driver can go along way to helping make the tranny last. A higher rear axle ratio like a 3.08 also puts more load on the tranny. Just looking at the Richmond ratings, no way are their ratings to be taken that your engine's torque output cannot exceed the tranny's rating. Lots of drag racers use the 2.88 low gear T-10, and that tranny is only rated at 300 lb-ft torque.