 Getting the vehicle high enough...  Getting the vehicle high enough in the air is critical for this type of project. STC technicians don't have the luxury of being able to lift vehicles with heavy-duty hoists, yet they're experts in doing transmission swaps on 1-ton trucks like ours or any other heavy tech procedures you can think of. This heavy-duty floorjack and jackstand setup was all Jose used to raise the truck for our project. |  |  |
 Jose removes the 15 bolts...  Jose removes the 15 bolts for the trans-fluid pan in a slow, deliberate sequence and lowers it gradually from the front lip to drain the fluid. Do this any other way and you'll have a tranny-fluid mess on your hands. The OEM torque converter is equipped with a drain plug. Fluid must also be removed from the converter before the transmission is extracted from the truck. Although the transmission had been serviced only a month before we performed this exchange (and the truck was driven approximately 1,500 miles in that time), the fluid removed from the pan and converter was burnt, an indicator that the transmission had been slipping badly. | | |
Some of the common problems for E4ODs are (forward-clutch) center-support failure, flat-spotted sprags, coast-clutch failure, slipping torque converters, and extremely sloppy First-to-Second and Second-to-Third gear shifts. While we're fairly certain that the first two internal maladies were among our tranny's issues, there's no doubt whatsoever that the other three (failing coast-clutch, roasted converter, and late gear shifts/slipping) were at the forefront for transmission concerns to be addressed.
While we were aware of the lack of snap, overall sogginess of our truck's transmission (up- and downshifts) and the total lack of any sort of engine-braking capability on deceleration, the trans was still somehow getting the job done whenever we climbed or descended big grades with a load in tow. That being the case, we admit that we put up blinders to any real problems. We were diligent about the service routine and assumed the low-miles gearbox was theoretically in the same good shape as the engine. It was wishful thinking on our part.
Bill Sanders of STC Performance Truck and RV gave us the reality check about our transmission when we visited his Norwalk, California, facility so that lead technician David Rangel could install BD's exhaust brake and TorqLoc torque converter lockup system.
Diesel engines are torque monsters and generate their power in the lower rpm range, usually between 1,500-2,500 rpm. Stock '94-'95 E4ODs like ours don't have the type of low-rev line pressure needed for performing well under severe-duty conditions. The transmissions end up failing because of this, in addition to weak sprags (an E4OD has three of these "one-way" clutches, which allow a part to rotate in one direction, while holding locked in the opposite direction), the bushing for the forward-clutch's center support, and other internal components' overall inability to live under the stresses imposed by the engine's torque output as it works hard against a payload.