Need help!! I bought a 4BT Cummins and a 4L80E...

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LandBruiser69

LandBruiser69

It feels good to be lost in the right direction.
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Hey guys, I bought a Cummins 4BT and a GM 4L80E Tranny to go with it. I have the adapter plate to go from the cummins to the 4L80 but I need to know if anyone here has experience with this tranny and what I will need to make it work with the 4BT as far as the electronics go. Please let me know ASAP. Thanks guys!!
 
(i'm no expert).... you'll need a controller for the transmission. Did the 4bt ever come mated to a GM 4L80E Trans?

By the way who makes an adapter? Yes from what I've read you need plenty of depth under the hood to clear the oil pan.

Seems like most of the guys run a NV4500 manual trans? Autos are cool but I would bet it might get pretty expensive to mate a "hybrid pair"...
 
I dont know of the two mating before. The adapter is the same adapter for the turbo400 etc that usually comes on the 4bt. I know I will need a controller of some sort. I just don't know which. I am doing a SOA conversion at the same time I am putting the motor in. So no, clearance isn't an issue. Just need to know where I can get the computer controller for the tranny. The 4L80E has been used in tons of race cars and adapted to every motor imaginable. I just need to find the best controller setup for the CTD.
 
I have a 4bt mated to a 4L80E. They never came mounted together but the GM adapter has the bolt pattern for it to bolt right up. There are a couple of ways you can run it. I've chosen the manual route and converted the 4L80 to full manual control. Transgo makes the full manual kit but they don't take care of the line pressure part so you can use the vacuum modulator in the kit and come up with a way to get it vacuum. I had a little vacuum pump and a vacuum regulator to modulate the signal to the tranny. You can probably figure out a way get a signal to the force motor and use it to control line pressure. It would be rudimentary, but it would work.

Currently I'm playing with a control box that basically allows me to send signals to the shift solenoids and that allows me to shift the tranny so that it's still manual control. I'm working with a friend from work to set up a better control box to get the functionality I want since this one came with one of the 4L80's I bought and I didn't design it. Anyways it's still in testing. I'm running a circuit to turn the force motor on and off to modulate the line pressure. With both of these manual control methods you'll have to wire up the t.converter lock up separately so it works.

Then there is talk of using a TCU from a 4L80 that was hooked behind a GM diesel. I haven't done research on that but I'm sure there is something out on the net.

If you choose any of the above methods then you will want to buy a tech manual to get the wiring harness diagrams and learn about how it works.

Then there are different aftermarket TCUs that are available to control the tranny electronically. That ranges from ~$500 to $1200 depending on what system and what kind of adjustability you want.

For the t.converter the stock "low stall" for the diesel application is not low enough and you are better off looking into getting someone that can set one up for a 1100-1200 rpm stall.
 
A friend has a 6.5td backed by an auto trans. I'm guessing that it would be a 4L80E since it is a 3/4t truck. The 6.5td's in the civilian trucks use a throttle by wire system, so there may be some integration that would need to happen to send the TCU the right throttle signal. The military's HMMV's used an auto trans (presumably a 4L80E) and a cable throttle with their 6.5td's and possibly with their 6.5 NA's. I think I'd start looking for those parts. Perhaps on Steel Soldiers?
 
Did the military trucks use a 3 speed (400) or the OD 4L80E? I was thinking they used the 3 speed auto trans?
 
The early, 6.2 stuff I know used the TH400, but I am under the impression that the later stuff with the 6.5's in them got an OD auto and the 4L80 makes the most sense.
 
Boots4 did you use the yota transfer case? Do you have any good pics of the underneath of you truck you could post up for me? Tranny mount, motor mounts etc etc... any Ideas would really be helpful!! It would be much appreciated!!! Also, Would you recommend me sticking with the 4L80E??? or should I go another route? I am paying 400 for the tranny with the converter... anyone else have any comments??

Also Boots what is your setup??? Post some pics up of your rig!!! I would love to see it!! How do you like the 4BT?? What gears you running, tire size, and what is your MPG?
 
Please visit my build thread in my sig to get details, way too many to list here. Might be worth a read. Lots of pics.
 
OMG Boots, What a BAD A$$ Build up!!!!! Can I ask you how much not including time... But just money Parts Alone You have into this build??? You can PM me the response if you want... or if you dont want to share thats ok too. Im just curious...What an amazing build-up though!! I spent like three hours looking at it last night !!! I'm still cleaning up drule off my chin!!! Just amaizing detail!!! I only wish I had that kind of time to put into mine, Let alone the finances!!!
 
Honestly for a 4bt you would probably be better running a built 700r4. Thats just my opinion but it would eliminate some headache and save money. It will easily handle all that the 4bt is going to put out even tricked out. The way boots did it is really one of the only ways to make the 4l80e work without spending 800+ on controllers. My neighbor is a transmission builder and he told me a good controller is really about 1100+. The controllers are by far the safest method though as its pretty easy to burn one of these transmissions up if something isn't quite right. A moderately built 700r4 is going to be less than the used 4l80e + controller and its going to be rebuilt with a warranty. 4l80e s are not cheap to have rebuilt either if you don't do the work yourself. If I was going to use the 4l80e I would just throw down for the controller and make the process a little easier and safer. One screw up and it will totally negate the savings of not using the controller.

If money was no Issue-4l80e with aftermarket controller.
If money is kind of an issue rebuilt 700r4 with corvette servo and upgraded hardparts- defiantly the easiests and still plenty strong for gobs of power.
If money is really an issue 700r4 out of a vette -plenty strong for a 4bt and dirtcheap. Very little additional modifications needed.
If you have more time than money and are set on the 4l80e- I would do something like boots did and get a stronger transmission for a cheap price.
 
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ntsqd said:
The early, 6.2 stuff I know used the TH400, but I am under the impression that the later stuff with the 6.5's in them got an OD auto and the 4L80 makes the most sense.
Click to expand...

This is correct. The HMMWV's did come with a TH400 years ago, but any truck that has a "OD" position on the shifter is a 4l80e. They do have a stand alone computer mounted behind the pass front seat that controls the shift points/limp mode etc.
 
Since those are stand-alone TCU's and I was told by a GM Proving Grounds Engineer that the Military 6.5's have a real throttle cable and are not TBW, then it seems to me that this would be the perfect choice for using the 4L80E behind something that is mechanically injected.
 
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