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Grand Wagoneer 4 Speed Install
I presently own a 1986 Jeep Grand Wagoneer. This vehicle gets used and abused on a regular basis. Besides being my primary transportation, I use this truck to tow heavy trailers (sometimes in excess of 10,000 lbs.) and do some mild four wheeling. So far the only real modifications have been the installation of a Tensen 12,000 lb. 2-speed winch, extra leafs in the spring packs, and 235/85/16 tires. It still had the stock AMC Mod. 20 rear and Dana 44 front axles with 3.07 gears, and a Chrysler TF 727 transmission. I was on my third transmission, which was starting to slip, when I decided to upgrade everything. I located a J-20 pickup with T-18, NP 208 transfer case, Dana 44 front and Dana 60 rear axles. The Dana 60 included a bonus of a factory posi. I describe the axle swaps on another page, but will explain the transmission swap now.
What you need from the donor vehicle:
Transmission, transfer case, bellhousing, flywheel, and all spacers and adapters. Be sure to use a T-18 with the shortest input shaft and spacer, as the longest spacer causes the transfer case to interfere with the gas tank.
Transmission mounts and also try to get the crossmember. There is a slight difference, but the Wagoneer one will work.
Pedal assembly including clutch linkage.
Floor shifter cover plate, shift lever boots, and transmission and transfer case levers.
Driveshafts
Steering column from a standard shift J-truck.
I started by removing EVERYTHING having to do with the original transmission. This included the transmission, transfer case, flywheel, driveshafts, tranny mount, crossmember, shift linkage, kickdown linkage, cooling lines, and tranny cooler if equipped. Next remove the brake pedal and mount. This isn't all that easy. There are a few A/C vent parts and some wires that will need to be unhooked to get to the pedal mount. Unbolt it and gently remove it, being careful not to damage any of the miles of wiring under the dash. While you are doing this is a good time to swap steering columns. All connectors should attach to the new column if it came out of a compatible year J-truck.
You will have to lift the front carpet to access the floor shifter plate. Even though the Grand Wagoneers never came with a standard transmission that I know of, they still have the removable cover on the transmission hump left over from the Cherokee days. Remove the plate. You will have to scrape lots of sealing goop from the screw heads to remove them, then pry the plate off with a screwdriver or pry bar. I also removed the plate which covers the clutch rod hole in the firewall.
Now you can start the assembly process. I started by putting the pedals into place, then installing the flywheel, clutch, pressure plate, then the transmission. I jacked the transmission into place, bolted it to the block, then bolted in the crossmember. The position of the crossmember depends on which length spacer came between your T-18 and bellhousing. Now lift the transfer case into place and install the nuts. Attach the reverse switch wiring and the transfer case low range indicator plug.
Next I installed the clutch linkage. This was a simple procedure. The mechanical linkage bolts to the bellhousing with two bolts and to the frame with two more. Luckily the frame mount bolts to the same threaded holes that the auto shift linkage used. Hook the release arm to the throwout arm, attach the spring to hold tension, then run the clutch rod through the floor to the clutch lever. Attach to the clutch lever and the linkage pivot.
I put the top cover on the transmission then installed the floor plate. Next I ran the transfer case lever through the floor and attached it to the pivot mount on the floor plate. The next step was to reinstall the starter and front driveshaft. Measure for the rear driveshaft and have it shortened, and install it.
You will need to trim the carpet for the new levers on the floor, and also remove the hi-low shift lever from next to the seat, if equipped.
At this point you should be ready to start the Wagoneer and test the clutch. Adjust the linkage if necessary. Go for a test drive if everything seems to be operating correctly. The first thing you will notice is that it feels like a real truck. It will feel like it has more low end power, especially if you used a T-18 with the 6.32:1 first gear. This is a great swap if you plan to tow a trailer often. The engine will run cooler, you won't have to worry about the transmission slipping, and you will have the benefit of engine braking when slowing down or going down hill. I use my GW to tow heavy loads very often, and I'm glad to have the 4-speed every time I do. My heaviest load with this setup so far was over 15,000 lbs. gross. I didn't have any problems, even when going up steep hills.
By: James Alton
