Advice Needed! Trying to rebuild my LJ78 with 1UZ Engine (1 Viewer)

Joined
Sep 17, 2020
Messages
23
Location
Calgary, AB
Hi everyone,

I am new to this space and trying to get some help from more seasoned land cruiser owners/car experts regards to rebuilding my LJ78. I purchased my LJ78 without an engine or transmission and I am considering to do a 1UZ swap into it. As of right now, I have an 1UZ engine, with complete wiring, ECU, and A340E transmission. But the part I am stuck on trying to find the best option (trying to keep the cost to a minimum) for my LJ to keep the 4x4 capability. From the research I've done in the past week I believe these are my options with my current knowledge on this subject (not in any order);

1: I can pair my 1UZ + A343F (stock LJ78 trans) + LJ78 transfer case
*with this pairing, I am not sure if my Lexus LS400 ECU will pickup and link well with LJ78 transmission and T case (there is a person I can get the stock ECT from along with stock wiring, but with that being said I am not sure if Lexus ECU will pick up the stock ECT and would that require me to get a different after market ECU... or does it not matter)
2: 1UZ + A340E (The transmission that my 1UZ current is attached to) + T100 transfer case
*I've read that this is a very viable option as well since I can find A340F transmissions from T100's and certain year of 4Runners and Tacomas that has the 3.4L 5vz engine

I am not just considering these two options... this is just what I've come up with weeding through countless threads and websites. I am completely open to different ideas or even a manual swap if that is possible while trying to do this with a budget. Anything will be seriously appreciated.

Once I can get my LJ78 rolling, I would love to travel the road with it and make it my everyday rig!

Again, thank you so much for reading this! Cheers
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,817
Location
Victoria, BC, Canada
 
Hi everyone,

I am new to this space and trying to get some help from more seasoned land cruiser owners/car experts regards to rebuilding my LJ78. I purchased my LJ78 without an engine or transmission and I am considering to do a 1UZ swap into it. As of right now, I have an 1UZ engine, with complete wiring, ECU, and A340E transmission. But the part I am stuck on trying to find the best option (trying to keep the cost to a minimum) for my LJ to keep the 4x4 capability. From the research I've done in the past week I believe these are my options with my current knowledge on this subject (not in any order);

1: I can pair my 1UZ + A343F (stock LJ78 trans) + LJ78 transfer case
*with this pairing, I am not sure if my Lexus LS400 ECU will pickup and link well with LJ78 transmission and T case (there is a person I can get the stock ECT from along with stock wiring, but with that being said I am not sure if Lexus ECU will pick up the stock ECT and would that require me to get a different after market ECU... or does it not matter)
2: 1UZ + A340E (The transmission that my 1UZ current is attached to) + T100 transfer case
*I've read that this is a very viable option as well since I can find A340F transmissions from T100's and certain year of 4Runners and Tacomas that has the 3.4L 5vz engine

I am not just considering these two options... this is just what I've come up with weeding through countless threads and websites. I am completely open to different ideas or even a manual swap if that is possible while trying to do this with a budget. Anything will be seriously appreciated.

Once I can get my LJ78 rolling, I would love to travel the road with it and make it my everyday rig!

Again, thank you so much for reading this! Cheers
You can't use the T100/4Runner t-cases, as they are made for a centered diff in the rear axle (equal length rear axle shafts). The Landcruiser split case (what LJ78 came with) has the drive shaft offset to one side to match the rear axle.

I've only read on this as well, but my understanding is you can take the output shaft from the LJ78 A343f and put it into the 1UZ A340E. This will let you mate it to the landcruiser split transfer case. Probably best to take the two transmissions to a trans shop and have them do it. It's quite involved.

I've heard it's also possible to move the critical sensors needed by the 1UZ from the A340E into the A343f. I forget what this all involves. Might require machining and some swap of parts between the two transmissions.

A third option might be looking into stand alone engine management systems that can run the 1UZ with the A343f.

Final and best option would be going manual transmission. This is well documented in the 1UZ swap world. Find all the LJ78 manual transmission parts and buy the custom adapter parts for 1UZ to R151.
 
Joined
Dec 22, 2015
Messages
835
Location
Whitefish, MT
If you can source the other parts like clutch pedal and shifter, the manual swap would be well worth it to not have to mess with piecing together the two autos. Adapting the engine to the transmission should be quite simple, bell housings and flywheels are readily available on eBay.
 

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