July 2002 Archives - Transmission Digest
Getting a Handle on Half a Dozen Speeds

In the 1993 model year GM introduced the T56 six-speed transmission in the F body cars (Camaro/Firebird). The transmission was designed and manufactured by BorgWarner Automotive and was an evolution of the earlier T5 design. Larger and capable of handling more torque and horsepower, this trans became an instant hit with performance enthusiasts, race teams and hot rodders.

EEC-IV and EEC-V Systems – Odd Behavior

EEC-IV and EEC-V systems sometimes may exhibit odd behavior such as erratic shifting, OD or engine light blinking, nonsense or unrelated codes, with no apparent cause.

July 2002 Issue

Issue Summary:

Fluid foaming in the 41TE may be caused by the cooler bypass valve in the case under the pump.

Delayed bang engagement on the Honda Civic HX may be caused by several reasons, one of which is a stretched steel belt slipping in the pulleys.

After replacement of a turbine-speed sensor, Ford/Mazda CD4Es may experience a persistent gear-ratio error.

We also have included a special conversion procedure for Mazda-to-Ford ID

Isuzu NPR/GMC Tiltmaster

The Isuzu NPR Commercial Truck and GMC Forward Tiltmasters use an exhaust-brake system that assists in engine braking during downhill coasting while the trucks are carrying heavy loads. This system is used instead of the familiar Jacobs Vehicle System known as the “Jake Brake.” When the exhaust brake is activated, it restricts the flow of exhaust with a flapper valve in the exhaust pipe similar to that of a heat-riser assembly (see Figure 1). When the flapper valve closes, exhaust pressure increases, causing air intake to decrease. This increased backpressure and slower air intake reduce torque transfer to the geartrain, producing the desired on-demand engine braking needed during downhill coasting with a payload.

Centerline 101

The axis or centerline of an engine is the imaginary line around which the rotating mass revolves. The torque converter also has a centerline. Torque-converter rebuilders will tell you how important it is to maintain this centerline and to keep all surfaces perpendicular to this line. Transmissions also have a centerline. Most technicians learn early on the importance of good bushings and good bushing surfaces. Good bushings and their mating surfaces help to maintain a proper centerline to prevent seal and sealing-ring leaks.