Quote Originally Posted by cowboywildbill View Post
I think the new torque convertor and the tighter trans with less % of slippage and the larger cooler and maybe better engine temp control play into the lower LML's trans temps. I think a lot of the higher temps on the LBZ were due to the engine temps fluctuating and the trans cooler lines picking up heat from the radiator rather than dumping it in there. As for the rear, it is the same internally from what I've read, But the axle tubes are now 4" in diameter and larger than before to increase the wieght rating. I don't know if the larger tubes help with cooling the rear diff fluid or not. I wouldn't think so but who knows? I changed our rear diff at 1,000 miles. It only had 2.5 quarts of fluid in it. I let it sit level for a 2 hours before I drained it on a very warm day. I put just a little under 4 quarts back in and stayed the recomended 1 and 1/2 inch below the fill hole. I think the rear is the most critical first early maintance for break in that should be done. And then engine oil.
I think the biggest drop in tranny temps with the new LML is the variable pressure control system that it now uses for line pressure. It is no longer on a fixed static control circuit that regualted it to roughly 250PSI and held it there. They can now vary from about 60 all the way up to 300 IIRC. I doubt it is any more efficient at holding engine power than a built trans, and a triple disc aftermarket converter will definately out couple anything GM puts in them. People who raise there line pressure on a built trans notice an immediate increase in trans temps. I didn't raise mine when I built my trans, and if I'm not in summertime stop and go driving it normally won't go over 130-150 even with the LB7's small cooler.