DISASSEMBLING, ANALYZING, AND UPGRADING A BUILT E4OD—8 YEARS LATER

MIKE MCGLOTHLIN

After noticing the unmistakable smell of burnt transmission fluid, a quick check of the dipstick confirmed our suspicions that something was amiss inside our E4OD. Once we pulled the drain plug, it was obvious something metallic was breaking down inside. Following a quick call to John Wood Automotive, one of the premier E4OD/4R100 builders in the transmission world, we had an appointment scheduled to get our slushbox into his highly capable hands.

Built by John Wood back in early 2011, the four-speed was initially spec’d to live behind a 400- to 450-rwhp truck. But believe it or not, it had spent the past six years flawlessly dealing with nearly 600 rwhp, 1,100 lb-ft of torque, dozens of boosted, four-wheel drive launches, and being hot-lapped at the drag strip. Throughout this time, it never skipped a beat. Had it not been for the scent of burnt ATF, there would’ve been no reason for us to even think about the transmission’s health. It was shifting and performing perfectly fine before we pulled it.

The built automatic transmission is a mainstay in the diesel world. At some point, even the toughest factory transmission needs to be reinforced in order to continue the neverending quest for more power. But, as this article illustrates, having a built automatic in your truck doesn’t mean it’s exempt from ever requiring a once-over, if not a full-on rebuild, from time to time. Although having to rebuild an “alreadybuilt” transmission is something a lot of folks don’t like to hear, in the end it’s practicably inevitable. While a performance transmission can be prepped to handle big horsepower and gobs of torque (and do so extremely well), it can’t handle the job forever—especially if you’ve added power since the last time your transmission builder was in there.