The 5R55E, 5R55S, and 5R55W are derivatives of the C3/A4LD units. The 5R55E was most closely related to the A4LD, but electronically controlled and wasn't especially problematic, typically having normal wear issues common to any transmission over time. The 5R55S and 5R55W units use a much different case, gear train, and valvebody design, and as with any modern unit, it's susceptible to valve and valve bore wear and those are replaced with improved aftermarket components. Some common failures specific to this unit are:

• Plastic front lube/drainback valve that is prone to melting and restricting lube is replaced by aluminum

• Center support wear allows it to move in the case causing damage to other components and is addressed by machining the center support to allow a steel ring to be installed to stop wear and act as reinforcement.

• Overdrive piston return spring snap ring tends to pop out of its groove potentially causing a catastrophic failure and a locking ring that essentially acts as a solid ring stops this failure

• Apply pressure to the intermediate and direct clutches is fed to supports that ride in the case with only tight clearance holding the oil pressure. Wear and case flex open up the clearance causing poor apply pressure. Spring loaded tubes and seals keep a constant seal to the supports, especially under heavy loads that flex the case when apply pressure is needed most.

• Original design used two narrow rear case bushings that were prone to premature wear in these heavy use transmissions. A one-piece bushing with increased surface area has proven far more durable.

Again, there are plenty of other components replaced in these units that are normal to any later automatic transmission; the list above is specific to this family of transmissions. Our experience at PowerSource is unmatched, so feel free to contact us via the Chat option or call us on the toll-free line and we'll be happy to do more than read a script to you; we have actual building and repair experience.