MaxPF
Expert (please obsess)
- Joined
- Mar 23, 2011
- Messages
- 61
i put 11,000 on the truck since i got it(86,000 on the ODO when i got it).. 95% loaded did all the basic upgrades except harmonic balancer repalcement.... upon removal i did find out the engine has been opened up before i got it and straight water came out for coolant...the history of it, i have no clue..
That sucks.
putting an allison in would increase cost some 2-3000 between buying tranny tcm drive shafts etc also the allison has close to 200lb on the 4l80 deeper 1st gear(3:1 vs 2.48) and taller overdrive (.70 vs .75)
The gearing is the biggest advantage with the Ally. The reverse gear is especially nice when backing a trailer. Weight difference is 170lbs, and there is a reason the Ally weighs that much more - the internals dwarf those of the 4L80.
honestly i can buils a 4l80e to handle 400hp cheaper then a allison and still be lighter... shift kits dont work on either long term.. 3k to put an allison in pluse another 1700 in parts for basic upgrade or 2500 in the 4l80 having someone do it with dyno test that i already have or toss in another 6-800 for a used 4l80 and have it built..... and save wieght.
It's false economy for what you are doing. All an otherwise healthy 6 speed Allison would need is a Transgo SK Jr. and a Transgo converter valve. A better converter wouldn't hurt, but you could get by without it. At the 400HP level that is a 200,000+ mile transmission. The 4L80E will not last nearly as long doing what you do. It simply doesn't have the clutch area, and you're likely to kill the OD sprag with the DMax's torque. There IS a very good reason GM derated the DMax when it was backed by the 4L80E. You can beef up some stuff in it, but the OD sprag is what it is, and unlike the Dodge 47/48's, nobody ever bothered making better upgrade parts for the 4L80E for DMax use because everyone used the Ally.
I'm just trying to keep you from doing stuff twice and spending more money in the long run. You're truck is a working truck, and there is no better transmission for that use than the Allison.