Now I'm an Allison guy to the core. BUT... Since the 4L80/85E is a fairly strong trans, and there is quite a bit of aftermarket out for it, do you think it's possible that we could could build a 4L8xE tranny to handle 500/1000 rwhp/tq numbers?

This would help to "dumb it down" a little, for those that are tired of the Allison SEM, and limp home problems. Not to mention the vendor wars.

The 4L80 has been around, and it's a product of the TH400, and there's all kinds of aftermarket for that trans. Hot rodders have built them up for years.

I would say that the TH400/4L80/4L85E trans is as strong or stronger than the 47re or possibly the 48re, with a little help it could be in the running, right?

Just a little food for thought. Lemme know what you think.

We are using a 4l80e behind our 12v Cummins and Love the way it works. We us a TCI trannie Controller, that you can Program Via Laptop. And we also installed a bigger Lock-up Siliniode. We have towed very heavy with the Trannie and have had Little problems(27,500LBS).

Have you done anything to your 4L80? besides the solenoid?

Is your 12v turned up much?

No we haven't done any other mods to the trans. The 12v is just a 91. so it has the small pump on it.The 12v does have artermarket injectors, HX-35, and The Timing and Pump have been played with a little, so on the power side it does pretty good for what it is. Right now we are doing another Conversion, and we are using a 94 cummins 12v with the Big Pump on it, and its going to be over 400HP, and we are going to Put the 4L80e behind it. One nice thing is that if you do start breaking hard parts in the Trannie, you can always go with the straight gut gears that they use in RV's that have the 4L80e, and wow that would be strong.IMOP the 4L80e is a great trannie, and is a lot stronger than what people think!!!

What adapter are you using to use the 4L80E with the Cummins?

Cummins Sells the Adapter, ITs the same they used for the 4Bt Frito Trucks with the TH400 behind them.
There is a Guy in Georgia that sell them Used.

I figured that. Do all of those adapters tilt the engine a little? I imagine that looks a little odd, but should help with hood and oil pan clearance.

Our Tuck is a 4x4 that we straight axled, so clearance isn't a issue for us. But yes it does put the motor at a angle, but its ok per cummins.

I also wonder how a built 4l80 would fair when mated to a modded duramax. I will proboably get a duramax van, but it sucks having a lesser tranny and a derated engine. Going to have to do it though because I am disabled in a power chair and the state will not approve funding for modifications on my truck.

I really think it would hold up fine. I think the Cummins makes a lot more torqe on the low end than a Duramax. I think the Duramax has to rev a little to make power, where a Cummins is making power at very low RPM. (I AM NOT SAYING ANYTHING BAD ABOUT THE DURAMAX!!! I THINK ITS A GREAT MOTOR)

Over 800FT LBS you will be gauranteed to twist the input shaft and strip the sprag assy.....
You can add a hardened input shaft, but never heard of any aftermarket performance sprag assy.... (will be the weak link).....:eek:

Not sure about what they use, but you see quite a few built 4L80E's in high horsepower drag cars. Granted these vehicles are alot lighter than our trucks but when you are putting down 1200-1800hp through them regularly and they hold up.......I'd be willing to bet that it will work very well in our apps as long as you have a large cooler on it and a big finned pan for more capacity. Of course, there is a limit to any part...:rolleyes:

These boys seem to build em strong:

http://www.redrider.us/4l80e_performance_transmissions.htm

These boys seem to build em strong:

http://www.redrider.us/4l80e_performance_transmissions.htm


I don't know about their 4l80, but there have been a large number of complaints over on www.ck5.com (http://www.ck5.com) about their "performance 700r4's". Most seem like a 1st grader rebuilt it.......FWIW.

I have been talking with ATS and they are building heavy duty 4l80's (actually 4l85e's) with triple disc converters.

http://www.atsdiesel.com/ATSWebsite/Home.asp

They don't list it on their website, but if you email them, they will discuss them with you