Overdrive Assembly: Description and Operation

New Hydraulic Plungers
Hydraulic pistons with improved seals were introduced progressively in type J, J/P and P overdrive units during model year 1988.

The new seal consists of a heavy O-ring, replacing the existing O-ring and Teflon sealing ring. The seal is made of a more durable material and reduces the risk of fluid leakage.





Affected Overdrives
The modification is effective from the following type, part and serial numbers, see table above.

Reconditioning
When reconditioning type J and J/P overdrive units incorporating the earlier design hydraulic pistons and it is noticed that the Teflon rings are worn, the pistons should be replaced by the new type pistons P/N 6814454-2 and new O-ring seal, P/N 6814455-9.

NOTE: If slippage occurs when engaging or dis-engaging, or when reversing, the clutch plate should be replaced or a service kit installed. Service kit P/N 271183-6, should be installed to correct the fault on overdrive units not bearing one of the listed part number listed above.