Introduction

For many of today's fourwheelers, there is no longer any question about the automatic transmission's suitability for trail use. It allows the driver to concentrate on the trail, makes stalling impossible, and provides smooth starts on any terrain. In short, it is the perfect transmission for technical fourwheeling.

Although modern auto trannies are extremely reliable, there are many ways to improve them for trail use. Likewise, there are many ways to abuse them. The biggest enemy of an automatic transmission is heat. Heat breaks down the transmission fluid and wears critical parts such as the clutch bands and the clutch plates. Slow crawling exacerbates the heat problem, especially if the vehicle is under-geared for its tires. These issues perfectly described Project YJ's early years. Add the fact that the fluid was only changed twice in 8 years and it is no surprise that its transmission began slipping under moderate to heavy acceleration. An overhaul was in order.

We contacted AutoTrans Inc. to find out what we would need. AutoTrans Inc. is one of Canada's premiere transmission wholesalers. They're a multi-line supplier of parts, consumables and tools to the automotive and industrial transmission repair industry. They are one of the largest remanufacturers of transmission hard parts in North America and have a large remanufacturing division for torque converters: domestic (stock and enhanced versions), import, industrial and racing. They are also the first company in North America to rebuild electronic components for the automotive transmission industry. To say that they could supply us with what we needed is an understatement of mammoth proportions. If you're at all interested in automatic transmissions, you should definitely talk to AutoTrans Inc. Their website has lots of information including a message board to talk about all things related to auto trannies.

AutoTrans Inc. supplied us with an overhaul kit with new gaskets, seals, bands, clutches and pressure plates. They also talked to us about how we use our vehicle and decided that the factory torque converter (TC) was not up to the task to driving 35" tires. Instead, they built a custom torque converter featuring a kevlar clutch, an extra bearing to replace the factory bushing so the converter uses bearings through-out, stronger pads, and a hardened steel spline. By the way, even if we weren't running bigger tires, they would still recommend changing the torque converter because it is extremely difficult to thoroughly clean any metal particles or other contaminants out of the TC. And having a clean TC is necessary when re-building your transmission because if you don't, the TC will immediately pump any foreign material into the nearly rebuild transmission, thereby shortening its life. To prevent future heat problems, they provided a transmission cooler to augment the factory unit that was built into the radiator.

AutoTrans Inc. provided us with clutches, bands, gaskets, seals and everything else we needed to overhaul the transmission.

To preserve the tranny once it was rebuild, AutoTrans Inc. also suggested an auxiliary cooler.

AutoTrans Inc. built us a heavy duty torque converter that could handle the rigors of off-roading and large tires.

Another method for reducing heat is to reduce the amount of time the transmission requires to shift gears. Whenever an automatic transmission shifts gears, it uses its clutches to allow some slip during the transition. The longer the transition, the longer the clutches slip and the more heat they produce. A longer slip time also means less power getting to the wheels during that period. The solution to this is to install a shift kit. The purpose of the kit is to firm up the shifts by shortening the transition time. The end result is more power to the ground, faster shifts, and less heat. When it came to finding a shift kit for our Jeep's TorqueFlite 999, Trans Go was our first and last stop. They invented the high performance transmission shift kit and have been providing transmission performance products for over 35 years. The kit for Project YJ offered us a range of modifications from the basic level which improved the shifts and increased the transmission lifespan; to the race level which allowed us to switch the transmission to full manual control with very harsh shifts. While the Rock Monkey in us wanted to use all the options, the daily driver role of Project YJ dictated that we stay with the basic modifications.

The TransGo high performance shift kit. (TFOD-518-500-618)

It came with a video, excellent instructions, springs, valve balls, drill bits, gaskets, and everything else required to modify our transmission's characteristics to our liking.

With all the parts in place, we needed to find a qualified transmission mechanic to show us how everything went together. That was the easy part: Wayne "Fozzy" Foster, our favourite transmission and differential expert, volunteered for the job.