Ford 10R80 Piston Compressor Removal Tool A75N18

This is the A75N18 pattern piston compressor for the Ford 10R80 ten-speed. Every clutch pack in that unit sits behind a piston and a return spring assembly held by a retaining ring, and the spring load is high enough that prying at the ring with a screwdriver either bends the ring, scores the drum bore, or lets the whole spring pack come off the bench at you. The compressor sits over the drum, picks up on the spring retainer, and takes that load off the ring so it lifts out with snap ring pliers.

It is the same tool you need going back together. You set the spring pack and retainer in, compress, drop the ring into its groove, and confirm the ring is fully seated all the way around before you release. That last step is where 10R80 rebuilds get ruined: a partly seated ring will hold on the bench and then walk out of the groove under line pressure, which shows up as a pack that will not hold and a unit back on the lift.

Fits the Ford 10R80 used in the F-150, Mustang, Expedition, and Ranger, and it carries over to the GM-shared 10L80 family that uses the same drum architecture. Manufacturer part number A75N18. Sold as the single compressor tool; snap ring pliers are not included.