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4L80e + doubler?

muddybuddy

muddybuddy

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i found a 4L80e bout 20min away and the guy says hes askin $475 for it, but will take $400. it was rebuilt 1.5 years ago so it should be in good condition. my question is, how do i bolt a doubler up to this? i know the 4l80e is electric speedo, and my truck is mechanical, but what is the best way to go about this? im debating bout getting the computer since i could get the tranny so cheap. what are my options?
 
You sure it's a 4L80E and not a 4L60E? If it is a 4L80E you won't be doing any doubler in a K5 with it because it is way too long. Also the stand alone computer needed to run a 4L80E is about $800.00.
 
computer and harness kit and all will run about mid to high $600's from jegs. I have been thinking about this as well, but would have to go klune-v doubler because I dont think there are adapters mating to a 203, there are adapters to the 205 but are very hard to find. Something to think about though.

Remington
 
computer and harness kit and all will run about mid to high $600's from jegs. I have been thinking about this as well, but would have to go klune-v doubler because I dont think there are adapters mating to a 203, there are adapters to the 205 but are very hard to find. Something to think, I am wanting to go 4l80e also but no doubler. Just an np208.

Remington
 
Greg72 has a 4L80E and the adapter to mount the 203 but it is a TH400 adapter of some sort that is slightly modifed to work with the 203 once the front face of the 203 has been drilled to accept the adapter.
 
how wuld i not be able to run a doubler with it? the doubler is shorter than my current 208...

for speedo, would i have to get a 91 np205 and swap inputs to get electrical? or would i convert to mechanical speedo? my gues is that if i went manual valve body i could convert to mecganical, and if i get the computer id have to go electric? right?
 
damn, jus talked to the guy and its 2wd :( is it still doable? i know they make divorced 203's but they are prety rare. i guess now it would be alot more expensive since its 2wd, or could i swap the output or something to make it a 4wd?
 
muddybuddy said:
how wuld i not be able to run a doubler with it? the doubler is shorter than my current 208...

for speedo, would i have to get a 91 np205 and swap inputs to get electrical? or would i convert to mechanical speedo? my gues is that if i went manual valve body i could convert to mecganical, and if i get the computer id have to go electric? right?
Click to expand...

The t-cases may be shorter than your 208 but the trans is longer by a bunch.
 
4X4HIGH said:
The t-cases may be shorter than your 208 but the trans is longer by a bunch.
Click to expand...

uhh no its not... The 4l8e is exactly the same dimensionally as a TH400 to my knowledge. I have one in my pickup and I work on trucks all the time that have them and none of them look any larger than a Th400.

The 2wds can be done but its a bit trickier and THAT may be too long. You need to have a custom 2" spacer block made to go between the adapter and the transmission. The output shaft on the 2WD 4l80e is still 32 spline and the same size but it is 2" longer than the 4x4 one. I'm going to have the spacer made and run a 241 with a SYE in my 97 C2500, but that is a long bed single cab, not a Blazer.
 
sweetk30 said:
run the 208 and up adaptor and redrill the face of the 203 and tap the holes and bolt it on is what i have been told to do if i was to do it.
Click to expand...

Exactly what I did to run my doubler behind my 400 with out finding a 203 adapter and tailshaft. When you drill it you can even add some clockablity to it.
 
so is all i need to make it fit the 2" spacer? could i also swap in the 4wd output?

what could i do bout the speedo part?
 
speedo is driven off of the Tcase, doesn't matter. Though I bet those computer drivers for the transmissions need a VSS signal.

The 2" spacer, Th400-208 adapter, and a 32 spline input 203(not the easiest thing to find), as well as the computer to control the 4l80E.

You can convert to the 4wd output shaft if you are comfortable with transmissions. You have to completely disassemble the trans to install it(the output shaft is the very first piece you install when you are puting together a transmission).
 
4l80 has all the sensors it needs. one input speed sensor and one out put speed sensor. all in the case.

as to case lengths her ya go bell face to tail housing face.

350:21 5/8
400:24 5/16
700 to 95:23 3/8
700after 95:21 3/4
4l80:26 even

i had a 32 spline 205 with the short input mated to a fixed yoke 2x4 4l80 easy. had a 1 1/4 spacer made. gave the tail shaft 10-15 thosands play to the end of the input gear.
 
well i know the tranny doesnt need any more sensors for speed, what im asking is, how would i have a speedo since the 4L80e is vss? would i ahve to get a '91 205 to keep vss?
 
you have a vss setup. TBI needs it. You likely have a cable drive but there is a vss setup in your speedometer. Don't worry about what the 4l80E is setup with in newer vehicles, you just need the cable drive off of your tcase.
 
350:21 5/8
400:24 5/16
700 to 95:23 3/8
700after 95:21 3/4
4l80:26 even
Click to expand...

His rig is an 88 blazer so this would make the tranny 2 5/8" longer than his existing tranny.
 
As to the computer, Diesel 4l80e have a standalone computer. It may need to have the shifts adjusted but cheap for a Junkyard.
 
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