3 Speed to 4 Speed w/ OD 4WD Auto Tranny Swap on 1987(86.5?) Pathfinder

[Marsh]

Hi Guys and Gals!

I have a late 1986 or early 1987 2 door Pathfinder with automatic transmission. This is my first visit and use of this site. Hopefully someone here can answer some questions on an automatic transmission swap.

After I purchased this ultra clean Arizona rust free rig, I kept looking for the overdrive button that is usually found on the shifter or some where else on the dash, but to no avail. Then I thought the electric shock switch which puts the shocks in a off-road mode might also be a dual function switch turning off the tranny overdrive. No such luck….finally I was informed that 1986/87 was the year they switched transmissions from a 3 speed auto tranny to a 4 speed w/ OD. Apparently I have the 3 speed model with no overdrive, hence the reason for no OD switch on the shifter :-)

The PF has 125K miles and both the 3.0 V6 motor and tranny run great, but without overdrive the motor is running 4K+ rpm at highway speeds of 70+mph. This is hard on the motor and overheats the vehicle in Arizona's hot summer climate in no time, especially with the AC running. I've changed to a dual core all aluminum radiator which has helped to a large degree with the heat, but still the trusty Pathfinder is not a very good highway vehicle in this day and age where 75-80MPH is the norm on USA highways, especially in Arizona.

My wife just learned how to drive with an automatic and so we'd like to keep it that way until she is ready for manual. So I wondered if the later 4 speed automatic w/ OD would be a clean easy swap on the vehicle's engine and transfer case? Otherwise we just have to resign ourselves to the fact this is a local driver and not much use on the highway except for short spurts. Driving at 55mph on Arizona highways is actually quite dangerous with all the passing cars and road rage out there.

Any transmission advise on how to install the later 4 speed automatic in a 3 speed configuration would be greatly appreciated, such as years of transmissions that will work and whether it's even possible without changing the transfer case and drive shafts.

The rig is very clean inside and out and I've rebuilt critical systems to get her to be a dependable vehicle. It would be nice if she had an automatic overdrive transmission. I know there is a ton of Nissan trucks and Pathfinders with the same basic body and frame, so hoping Nissan kept the same bolt-on configuration when they went to an OD tranny.

Thanks,

Marsh

Edited February 13, 2016 by Marsh

[Kingman]

You'd need the engine wiring harness, transmission wiring harness/body harness, ECU, TCU, TPS, possibly transfer case, and possibly the cross member. There's probably a few more little extras to swap as well.

 

It'd be best to have a donor vehicle.

 

The downside is the 4 speeds are not as reliable and definitely require a large aftermarket cooler to prolong their life, unless you bought an automatic from a 2000+ Xterra or Frontier. The 3 speeds are bulletproof.

Edited February 13, 2016 by Kingman

[RCWD21]

Kingman is right about the 4 speeds being nightmares. I rebuilt the one in my 90 and it had a lot of burnt friction discs due to being over heated. Now I run a huge cooler and plan on going even bigger for this summer.

 

I also have an 87 with the 3 speed and it's toast due to pure neglect from the previous owner. When I drained it, it was burnt and felt like someone poured sand in with the fluid. So now I'm going with a manual transmission.

 

As for the transfer case they're all the same bolt pattern but becareful as the one for the manual transmission has a little cup under the input shaft to hold oil for the seal right there. The autos don't have that cup.

Edited February 21, 2016 by RCWD21