Just as the title states, the Ford 5R55 Transmission has four versions. Ford 5R55 can have an N, S, or W behind those numbers.
Although the 5R55N is very similar to the W or S models, only a few parts are interchangeable.
We receive numerous calls about these where someone has rebuilt the transmission, yet still experiences the same symptoms. The most common problem we see on these units is the excess wear on the case or valve body.
Transmission case premature wear occurs on the overdrive and intermediate servo bores. Apply oil comes up through the servo pin bore and through the hollow pin applying the servo. This requires the pin to seal in the servo pin bore, as well as the release oil that both servos require. Over time, the number of apply and release wears out and the pin can no longer seal properly. The overdrive servo bore will usually have more wear due to it being used for second and fifth gear. As the servo leaks, which will result in a pressure loss, it lacks the pressure to hold the band completely applied or release it fast enough to prevent the band from being burned up.
These issues can be repaired without replacing the case. Drilling the servo bores and installing a “cesleeve” to compensate for the wear eliminates the need to replace the case. The brass sleeve has proven to be more durable then the aluminum case, giving you more stability. You don’t want to use a “used case” as the possibility of the bores being worn in is very likely.
The valve body can also have excessive wear, most often seen on the TCC (torque converter clutch) modulator bore, or main regulator bore. In this case, the high duty cycle of use wears down the bore reducing clutch and servo pressures. Although the PCM (power control module) will try to compensate with an adaptive strategy, the excess wear will cause gear ratio or slipping codes.A valve body repair or update kit will usually correct these problems.
Gear ratio error codes are very common on these transmissions due to servo pin bore wear occurring at a very low mileage, in some cases.You can have a gear ratio error code without having an electrical code (solenoid), but it is unlikely that you will have an electrical circuit code without a gear ratio error code.
These are just a couple of most common problems seen on these transmissions, but not all these problems may have this problem. If you have any version of the Ford 5R55 transmission and are having problems with it, don’t hesitate to bring your vehicle into The Transmission Shop to get it checked out. Having a proper diagnostic by qualified techs will eliminate the guess work and save you major expenses in the repair, rebuilding, or replacement of these transmissions.