Originally Posted by jeepman3071
Originally Posted by borgward
I worked at a company that had a fleet of Chevy 1 ton's w/flatbed. Some had the Turbo 350 transmission. They lasted 3 to 6 months after repair. The others had Turbo 400 transmissions. They were rock solid. Outlasted the 350 engines. That was in the 90's into the early 2000's. Don't know if GM has improved their transmissions or let them go south. In general automatics usually don't last long after rebuild. Get the beefiest transmission for a GM truck.
A small under powered engine will wear out an automatic faster than a more powerful engine as the transmission has to work harder to make up for what the engine lacks. Especially true if you are doing any towing or carrying heavy loads.
That's not really how it works. The enemy of a transmission is heat. It will wear out from shifting constantly under heavy loads (over what it was designed for) or because it is not able to handle the power supplied by the engine. A smaller engine won't wear out a transmission faster.
That's my thinking too. A transmission actually doesn't "do" work, it just translates rpm and torque, but the same amount of power comes out, minus losses.
Now a poorly controlled setup could be very lossy and burn up, if held in a gear that results in engine rpm hanging out near stall speed and lockup convertor off with high output engine torque. And shifting under load is hard on the trans (although "modern" stuff has communication between trans and engine, and can back off engine power for smooth shifts).
Ok, maybe the OEM might use a lower rated trans behind a smaller engine, that does happen too, as does skimping on cooling on the "lesser" models.