John Wood Transmission (cont.)
The Stage One transmission from John Wood consists of upgraded clutch packs for each individual gear, his custom built and tuned valve body, a billet triple-disc torque converter, steel overdrive planetary, and a billet input shaft, along with some other modifications he's designed himself that he'd rather keep hush-hush about. All these upgraded pieces would be more than enough to support and plant all the power we'd be making in this little truck, all while improving efficiency and hopefully even improving fuel mileage. We should note that John offers a couple different stages of transmission builds from standard overhauls for stock trucks, all the way up to transmission outfitted with full billet pieces to withstand up to 1,200 horsepower.
After getting our stock transmission removed from the truck, it was easy to see where all our problems had been coming from. Metal filings in the transmission pan, a couple of metal parts clunking around in the factory torque converter, and even a pretty serious leak coming from the pump in the front of the transmission told us this stock tranny had definitely had enough and was ready for retirement.
With the new John Wood Stage One installed in the truck, we decided we'd be best off replacing the factory transmission cooler with a new one while we were at it. With all the metal particles floating around in that factory transmission pan, we didn't dare risk the chance of having those same metal filings left in original trans cooler and lines find their way into our newly built transmission and potentially causing problems. We replaced the cooler with a factory unit we picked up at the Ford dealer and made sure to flush the lines before bolting them back up to the transmission. We also installed a PML Transmission pan, which offers some added fluid capacity, added cooling fins, and a much better look.
After the first few miles of driving the truck with the newly built transmission it was easy to
understand why those factory transmissions are referred to as `slush boxes'. Man, the improvement in shifting quality, converter lock-up and just overall drivability is incredible. Between the calibrations John puts into his valve bodies and the tuning from DP Tuner, you'd be hard pressed to find a better operating transmission. Shifting strategies are some of the best we've ever seen in an aftermarket upgraded transmission. The shifts are crisp and firm, but not harsh. Quick and tight, all while keep the jerk and clunks between shifts and lock-up non existent. Not only are our transmission temperatures running cooler due to the increased efficiency of the triple disc converter, we did see a pretty significant improvement in our highway cruising fuel mileage. We never thought we'd see the day where a diesel powered truck with over 230,000 miles on it would see 20-plus mpg, but this one will do it, no problem.
When we first purchased the truck, we made sure to get it on the local SuperFlow dynamometer at Custom Auto in Idaho Falls, ID so we'd have some baseline numbers to compare with our numbers after all the upgrades we finished up. So once the new transmission was in and we could finally plant the horsepower we were making, we headed back over to Custom Auto for some dyno testing. After everything was said and done, the list of aftermarket parts we've bolted onto the truck came up to a pretty solid performing 450 rear wheel horsepower, not too shabby for an old worn out truck, huh? Especially considering that in stock form it put down a measly 181hp. That's around 275 added horsepower, measured at the tires, where it counts.