Author Topic: Replacing 700r4 with a 4l80e  (Read 3900 times)

Offline Patman

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Replacing 700r4 with a 4l80e
« on: July 27, 2018, 10:22:24 AM »
Howdy again folks!

Got a question. How difficult is it to swap out my existing 700r4/4l60 with a 4l80e?

This seems to be a pretty big job but I wanted to get input from you guys before I put a whole lot of energy into doing it to find out that it’s above my pay grade.

I have a feeling that I’ll need a new trans before too long and I figure that if Ive gotta pull the trans, I should reinstall what I really want, assuming that I can afford it and that it’ll not be too technical for my little brain.

Im guessing that I’ll have to get my drive shafts shortened or lengthened and maybe a different adapter for my transfercase and probably a new transmission support/crossmember. How about the electrical side of the house? Or linkage?

As always, any help/advise here is much appreciated!

85 K10 350, 700R4, NP208, Quadrajet, Long Bed w/ 33’s
All stock except for the motor, used to be a 305.

Offline Irish_Alley

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Re: Replacing 700r4 with a 4l80e
« Reply #1 on: July 27, 2018, 12:45:43 PM »
things youll need
a TCU (transmission control unit)

4l80e

transfercase (with 32 splines, can be found behind a th400 or 4l80e and newer sm465)
it will be hard to find a 4l80e and passengers side transference since they only were around in 91

new driveshafts

it can be pricey and a tcu will range from 200-700, the trans would be another, depending on style of output shaft on the trans and thats going to effect what t case you can use.
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Patman

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Re: Replacing 700r4 with a 4l80e
« Reply #2 on: July 28, 2018, 11:15:41 AM »
Irish,

THanks for the input. I think I’ll stick with the 700r4.... Can afford the upgrade... :-)
85 K10 350, 700R4, NP208, Quadrajet, Long Bed w/ 33’s
All stock except for the motor, used to be a 305.

Offline Irish_Alley

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Re: Replacing 700r4 with a 4l80e
« Reply #3 on: July 28, 2018, 02:19:07 PM »
yeah its not really worth it, youre better off getting the 700r4 built if strength is what youre after
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Patman

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Re: Replacing 700r4 with a 4l80e
« Reply #4 on: July 28, 2018, 04:51:15 PM »
Strength and longevity is what I’m shooting for, Im pacing my self and in 5 years time and maybe 10-15 grand I’ll have a very respectable little truck to bop around in.  THe goal is to eventually install 1 ton axles and an NP205. I have a fresh TH400 but I was hoping to use that for another project. The 400 is set up as a 2wd as it is. However, if necessary, I can redo the 400 and make it 4wd compliant. That with the 205 and 1tons should set me straight. Upgrade the breaks, eventually I’ll rebuild the motor, replace the dash and the rest of the interior and I should be good to go. At least until my grandkids are ready to fight over the truck...
85 K10 350, 700R4, NP208, Quadrajet, Long Bed w/ 33’s
All stock except for the motor, used to be a 305.

Offline Irish_Alley

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Re: Replacing 700r4 with a 4l80e
« Reply #5 on: July 28, 2018, 07:20:34 PM »
205 vs 208 you wont find much difference, the military even used the 208. you also have an option of a 241(c)
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Patman

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Re: Replacing 700r4 with a 4l80e
« Reply #6 on: July 29, 2018, 03:07:25 PM »
Ive been told that the 208 was the next best to a 205. It’s good to hear confirmation on that. Looks like less work for me! I can not get the TC to shift into 4L. So I think that I’ll be doing a rebuild on it. Ive been told that these are pretty straight forward. ANy words of wisdom before I get into it?

 In the meantime, Im getting my butt kicked trying to remove the exhaust manifolds. That front bolt on the passanger side is a bear! Having a hard time grabbing ahold of it.


Thanks again Irish!
85 K10 350, 700R4, NP208, Quadrajet, Long Bed w/ 33’s
All stock except for the motor, used to be a 305.

Offline Irish_Alley

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Re: Replacing 700r4 with a 4l80e
« Reply #7 on: July 29, 2018, 09:36:36 PM »
I Can't really look at the training manual due to being on my phone. but we do have one for the 208  towards the bottom of the page
http://forum.73-87chevytrucks.com/smforum/index.php?topic=30115.0
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Patman

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Re: Replacing 700r4 with a 4l80e
« Reply #8 on: July 30, 2018, 10:09:30 AM »
Yea buddy, thats what Im talkin about! Thanks!
85 K10 350, 700R4, NP208, Quadrajet, Long Bed w/ 33’s
All stock except for the motor, used to be a 305.

Offline 87project

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Re: Replacing 700r4 with a 4l80e
« Reply #9 on: August 04, 2018, 01:54:27 PM »
On my 87 the linkage connected up with little modification,  if I remember correctly we used a np241 out of a jeep. Simply unbolted the case and reclocked it. Even my crossmember used same holes. Engine is ls6.0 with dirty dingo mounts