View Full Version : 4L80E force motor interchangability from '92 to '98

01-01-2008, 03:15 PM
I have a 1998 4L80E in my 1992 truck. It's been there for 25,000 miles or so.
Reading the ATSG manual it says there was a change in the force motor, seperator plate, torque signal compensator valve, and ecm.
Basically it gets rid of the cleaning cycle, which I've noticed when taking pressure readings on my truck the pressure does spike high every ten seconds.
It also says the 1991-1993 force motors operate at 292.5 hertz, and the 1994 and up operate at 614 hertz.
Is this going to cause problems running it like this?
Do I need to do a mechanical conversion to a 91-93 force motor, plate, and accumulator housing?
I can't change the ECM.

I'm still trying to figure out why this trans runs so hot anytime the converter is not locked up.
I posted about that and about finding clutch flakes in the filter, well it made the 1310 mile trip towing my camaro and 1000 pounds of cargo. During that trip the temps on the highway ranged from 165* most of the time to 220* tops.
The last 30 miles was low speed and hills, the temp got up to 245* because it doesn't lock up under 50 mph. I'm really anxious to get the filter out and see whats in it now, the fluid is not burned.

I may start collecting parts for a rebuild or at least a tear down and inspection. I'm really concerned about this force motor issue now. If anyone can offer what they know I would really appreciate it. :chug:

01-01-2008, 03:31 PM
All my catalogs show the same force motor from 1991 up I checked all three sources and all were they same . Now they did make a change in the plug type in late 2004 up but functionally and resistance wise it remained unchanged

01-01-2008, 05:10 PM
I was thinking about that also, if you read into the ATSG book it says the change was made to improve line pressure stability and standardization as the same part number will then fit 4L80E, 4L60E, 4T80E.

But then it makes no sense by saying none of the listed parts interchange, and lists two part numbers for 91 to 93 and 94 - up.
Going by what the book says makes no sense.

I guess I could make my question a lot shorter by asking if any trans shop/builder has run into any problems putting a 1994 and up 4L80E trans into a 1993 down vehicle with the stock ECM that pulses the line pressure for a cleaning cycle.

01-01-2008, 05:56 PM
That I can answer and the answer is no problem at all.

Gilbert@Ace Racing
01-01-2008, 06:25 PM
If you were to look at the solenoids they are different, they exhaust differently. As are the plates and the valve bodies and other components you listed.

The ATSG book is correct. They are not interchangeable.

When using this unit in factory PCM apps I always try to match up the tranny electronics and PCM. I have not ran one like you are. But I don't think this is the source of your temp issues either.

What the book is telling you is that the new parts are not compatible with the old units.

I would think it is related to the efficiency of the converter your are running.


01-01-2008, 07:41 PM
Alright, I won't worry about that, thanks guys.
Next I should get the filter out and see whats in it and go from there.
Maybe try a different cooler set up, right now it's got an aluminum tube and fin IIRC 3/4" thick 11"x11" 8 pass with 5/16" ends with adapters up to 3/8" to the trans. And it's covered by the grille a lot so maybe a long skinny cooler.

Vince @ FLT
01-01-2008, 08:52 PM
The electronics's in the first gen of the 4l80e had issues. The epc was changed, the internal wiring harness was changed (due to leaky plugs), temp sensor relocated to the manifold switch from the valve body, shift solenoids known for failures(updated), epc exhaust hole added in the valve body, change of the epc design, separator plate changes, accumulator housing changes and so on. The later electronic components can be used in the earlier applications. The key with the 4l80e is to make sure you do not mismatch the internal hard parts because of the changes in the lube circuit in the trans. The late harness and electronic will service all years. The first year or so(can't remember year change) the internal harness was changed to what we currently see because the internal to external plugs leaked oil from the trans. When this change occurred the external harness had to be rewired eliminating one of the wires which IIRC it was for the temp senor. With this the style of plug changed for both the internal and external plugs. The temp sensor now used is in the manifold switch. Make sure if your vehicle harness was converted and that the wiring all appears to be good. The plug was spliced in about maybe 1' from the case connector in the wiring loom. When we updated the harness there was not a change in the computer just so you know. I have a question. Are you using the cooler in the radiator along with the external cooler? The reason I ask because your 98 trans is using the center lube system. The rear line of the trans is the return line from the cooler. This should be connected to your external cooler. Also do you have the proper fitting in the rear cooler line port in the case? This is the one that should have an extension tube that feeds into the center support where a seal is located. If you do not have this setup you might have a loss of lube/cooling capabilities. Just an idea of things you should check. As far as the reference material in the ATSG guide, look at when it was written. Most of those books are outdated from a builders stand point. Most changes in the units I use my seminar books for the tech facts of the changes. Good luck and I hope I added some history info for you here. Vince

01-02-2008, 11:08 AM
Vince, I have only the external cooler connected, my temp sensor to the gauge is on the front cooler line, I put it there because I wanted to see max temp not average. I've posted before that it runs through the gears and might get up to 220* but as soon as the tcc applies it will drop sometimes up to 60* and stay there while locked up. And it drops 60* in a few seconds.
I'm sure I have the correct fitting in the back, I posted the pics of the two fittings that ended up in the sticky somewhere here.
My ATSG book is from 2003.
The reason I ask about the electronics is because along with all the changes was the change that eliminates the pressure spike for the cleaning cycle of the epc. My ECM is putting out that signal because a pressure gauge will jump up every 10 seconds. The mechanical changes made to the seperator plate and accumulator housing eliminate parts that were supposed to I guess absorb this pressure spike.
I just want to be sure that having the pressure jump up every ten seconds with a seperator plate and accumulator thats not designed for this is not causing any problems.
Thanks for the info.