You could change out the trans to one with more gears. You could also add more power to your engine to push the lower ratio, or update the engine via a swap?
I doubt the T1138 will take the power of a big cam with some umph thru the CAT without it going caput. No sense in breaking it when a heavier case like the HEMTT would benefit me. The T1138 front drive line angle is pretty difficult with the how the transmission sits. with a HEMTT case since they sit vertical. I could easy canter it to the drivers side to line up the front tandem axle plus the front driveline angle is more towards the drivers frame rail.
The PLS unit we believe has an overdrive unit built into it. Different transmission is out of the question. Too much work into this one to deal with all that over again. and a clutch is not gonna happen. You will see how old it gets in traffic or city driving. You may run into the same issue as the power going thru your transmission is going to be a lot more than before and something has to give. In your case your torque rods will be first. Ive blown T1138s in low range with a stock 250, G177s went a quarter turn, dug in and boom. nothing major. Seeing breaks as the T138 case doesn't have any case splits vs the T1138. its about internal pressure. You take yours to the offroad park and you pop that clutch trying to rock it out of a hole sometime and I bet something is going to give.
My plan is to go to a big cam so being that the T1138 was not put in the bigger 915 series trucks means it probably wont stand up to it. The 915 series truck transfer cases are massive. If not bigger than the HEMTT case. I know one guy here swapped the HEMTT case into a 916 since the supply of 916 cases is slim if not none. Plus it is only a single speed case.
Researching so far the PLS case is a lot different with its PTO unit, but the round drum on the rear of it has me confused. CSMDavis thinks its an overdrive unit. I found it in the TMs but it doesn't give me a NSN or description in figure 183. If its an OD unit for the 10x10 trucks I would be more than happy to go for it. The Axles are the least concern of anything as the 5 ton rockwells are well built.
The .98 in high range would allow me to run the 445/80/25s with the big cam and not loose any road speed hardly but still have strength.
As far as how I feel about my current setup. On the way to the rally 2 weeks ago I pulled up this 2lane mountain grade near signal mountain in Chattanooga. I was in 8th gear pulling up the hill at around 43,000lbs. it is an 8% grade for 5 miles from Dunlap thru to signal mountain. pulling not too bad actually. but you can feel the torque and jerk when shifting 8 to 9 or 7 to 8 while climbing a hill. its power to the ground. The 700 ft lbs of torque or maybe a little more from the little 250 is nothing compared to a big cam @ 1000 to 1250ft lbs. If you are going to up the power you gotta get everything in the class behind it. The HEMTT case stands up to the C15's 515hp and 1650ftlbs so it may be better game.
