Marsh

Hi Guys, I'm a newbie here and just posted a new subject (after searching) for info on a 3 speed to 4 speed auto tranny swap. LIke Kingman said above, I've been told the 3 speed auto is stronger and more bullet proof than the 4 speed w/ OD. However, I have a super clean-rust free 1987 3.0V6 w/125K miles and would like to keep it as an automatic daily driver for my wife who just got her drivers license. The problem is it runs it at 4K+ on the Arizona highways which is hard on the engine and cooling systems, especially in the summer. I installed an all aluminum 2 core radiator w/ tranny cooler which has helped with extreme heat, but when I run her for any length of time at highway speeds in the summer, she starts to get hot with the AC on (a must). So my post is asking basically the same question as this one: can I do a direct swap of the 4 speed AT w/ OD right onto the current 3 speed transfer-case and driveshafts? Is the OD activated by a simple switch which would require me to change the shifter? I've done a lot of work with the computer troubleshooting the fuel and ignition systems (needed new injectors) and I don't believe the CPU has anything to do with the transmission shift in an 87, I'm pretty sure it's vacuum activated like the older model cars. So I don't think there's a need to change the CPU and wiring. Unless, of course, the 4 speed has electronic shifting and needs the later CPU, but this would surprise me on late 80s cars, since most used the vacuum shifting system during that era. A 5-speed manual adaptation is out until my wife can learn manual, so the 4 speed AT w/ OD is our only consideration at this point. Any help on direct swap would be appreciated. If it's too much work, we 'll just keep her as a city daily driver, which is pretty much what we use her for anyways. Just nice to have OD when we're on the highway when our Jeep GC is broken down. Cheers, Marshall

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