4L80E/NP205 swap

[1968vetL-71]

I have a rod and all those brackets off a 91 R3500 crew cab. I can check when i get down there this weekend. I'll post a pic.

[wildwilly4x4]

I made a relocation bracket that bolted into the stock holes, then the pivot mount bolted to it just a lil farther back...like 1.75 inches or so. I just made it out of flat bar stock and drilled holes in it. Also had to add a little length to the rod coming off the steering column.

I also ended up swapping in a steering column from a 700r4 truck because my th400 column would not allow me to shift all the way down into manual low.

[bilfman]

Like he said, a little fab work moving the stock frame mounted part of the linkage back about 2" and I just used all the th400 stuff. It does not shift into low, but I don't really need it in my application. I have heard a company Lokar makes some shifter goodies for these types of things.

[bilfman]

Probably have some work coming my way! A buddy of mine just purchased a 91 square 1 ton crew 4x4 ,454 tbi with the 4l80e/np205 combo. Truck looks pretty solid in the pics but the owner says some serious play in the front end. So it will be a 16 hour trailer job to get it home. .....the work never ends😱 I'll post some pics when it arrives!

[chris989]

I did relocate the mount back ~2.5 inches. ( the same distance i moved the cross member)

The issue i have is the pivot points are ~2" different in height. As it rotates it is to the extremes of falling out of the frame mount. I am off to the junk yard this morning to look for a few different arms. I think i must have something completely wrong. Must have been mixed up somehow when i sold my 400.


Chris

[redneckwheelman2]

Originally Posted by chris989

I did relocate the mount back ~2.5 inches. ( the same distance i moved the cross member)

The issue i have is the pivot points are ~2" different in height. As it rotates it is to the extremes of falling out of the frame mount. I am off to the junk yard this morning to look for a few different arms. I think i must have something completely wrong. Must have been mixed up somehow when i sold my 400.


Chris

if the 4l80 was from a 92+ chevy then the shifter arm on the trany is differnt it sits off center of the hole. just need to get the one off the 400 and it bolts right on. the 400 is centered on the bolt and the one from the 90's chevys are like an inch or so offset

[chris989]

Originally Posted by redneckwheelman2

if the 4l80 was from a 92+ chevy then the shifter arm on the trany is differnt it sits off center of the hole. just need to get the one off the 400 and it bolts right on. the 400 is centered on the bolt and the one from the 90's chevys are like an inch or so offset

Yesterday i grabbed the U shaped bracket for the trans, a new pivot arm/bar from a 1990 burb. I think it was a 700r trans but it looked like the one in diagram i posted earlier. I hope to get it in there today. I could not find any 400 turbos in the whole yard.

[redneckwheelman2]

as long as it fits on it i think it would work. my 80 came out of a 90s chevy i have. and since the frames are so wide the shift linkage rod is 2 times the length with different angles to it. i think they used the long shifter linkage on the tranny to clear the driveshaft on the ifs trucks. but im pretty sure the 400 rod thats on the truck would be the same as the 700r4s.

whats everyone doing for the front driveshafts?
mines not long enough. with it fully extended it will almost make it to the axle

the rear im just moving the axle back an inch and a half since im switching to 64s out of my donor truck and i have a flatbed so wont be able to tell the difference.
i did notice the rear drive shaft from the 400/208 is identical length to the one from my 92 chevy with 4l80/241 so got a spare rear atleast now

[chris989]

Originally Posted by redneckwheelman2

as long as it fits on it i think it would work. my 80 came out of a 90s chevy i have. and since the frames are so wide the shift linkage rod is 2 times the length with different angles to it. i think they used the long shifter linkage on the tranny to clear the driveshaft on the ifs trucks. but im pretty sure the 400 rod thats on the truck would be the same as the 700r4s.

whats everyone doing for the front driveshafts?
mines not long enough. with it fully extended it will almost make it to the axle

the rear im just moving the axle back an inch and a half since im switching to 64s out of my donor truck and i have a flatbed so wont be able to tell the difference.
i did notice the rear drive shaft from the 400/208 is identical length to the one from my 92 chevy with 4l80/241 so got a spare rear atleast now

My rear shaft would have been the perfect length because with my lift it was a little short. I went with a JB conversion SYE so i am making a new rear shaft. The front is getting lengthened and all new parts too. It certainly adds to the swap price.

[redneckwheelman2]

yes it does, i was looking at the spare driveshafts i have laying around. one from the donor 92 and one from a 96 suburban i got my vortec heads from the one from the sub would work but id have to delete the double cardan joint, one from the 92 is close to the right length but is pretty well toast at the slip yoke part of the shaft due to years of not being greased and used for snow plowing for atleast 4 years.
the ifs shafts have less slip yoke then the shaft on my 87's

i dont think i can delete the double cardan without vibration but i might try it once i get the truck up and running. since ill have till about november till ill need 4 wheel drive.

[chris989]

OK,, I tried to install my new rod and u bracket and it feels like the u bracket is clocked ~90 degrees off. Is it possible the transmission shop could have installed the shifter shaft in the wrong orientation? I have never looked inside a 4l80


In Park the holes in the u bracket for the shift rod is 1/7 o-clock looking at the face.
In 1st it is 10/4 o clock looking at the face.

It does shift through all gears but it has the linkage so low it interferes with the exhaust. If i try to flip it 180 it hits the floor pan. It feels like it need to advance 90 degrees and it wold work.




PARK


1st

[redneckwheelman2]

ill go snap a pic of my 400 bracket on my 80. i dont have the linkage together yet but bracket is on

[chris989]

Originally Posted by redneckwheelman2

ill go snap a pic of my 400 bracket on my 80. i dont have the linkage together yet but bracket is on

that would be great, the part numbers for a 400 are different than a 700r

[redneckwheelman2]

400 and 80 shifter. (reference for the slotted fitment)

edit first

edit park

[redneckwheelman2]

this is the right orientation i think. i think i had the 80 bracket backwards in my other picture.

[chris989]

thank you,
they look like what i have, I tested it and i believe it will work with the 400 bracket, It just does not clear my exhaust. The new headman headers sit real high compared to most that hang low. I will need to change my new mandrel bent exhaust. If it makes to much of a mess of my exhaust i will switch to a cable or make new brackets to gain some space.

Thanks again,
Chris

[chris989]

redneckwheelman2,

Thank you for the help but today i decided to scrap the rod linkage and will install a Lokar cable setup.

I got everything to shift but it fall directly in the way of the exhaust. I spent the morning fabrication new pivot points by sleeving the rods and rotating them to new positions and it shift nicely clocked about 90 degrees.

The issue is it still interferes with my exhaust.

Thanks again for all you help. I will post a pic of the lokar setup when it is finished.

Chris

[345HP87SSAC]

Nice post!!

[Duck1]

Originally Posted by bilfman

Those two are not used with the TCI . If you play around with the shift firmness and shift aggressiveness you can have it shift just how you like it. Hope that helps
Posted via Mobile Device and yeah it shifts through the gears pretty quick at light throttle.
Speedo is not one of those two , should be on the tailshaft.

4WD units only have the front sensor