Ford 5R55W / 5R55S/ 5R55N Worn Servo Bore Fix [U.S. Patent No. 9,121,418]
Up until our kit was available, the only available fix for a worn servo bore on the Ford 5R55W, 5R55N, and the 5R55S transmissions was to have the bores bored out and sleeved. This obviously involves dropping the transmission. Not only is that an expensive proposition for high mileage vehicles, it is an undertaking that could only be done by experienced shops or mechanics.
This fix involves a Patented fix where o-ring grooves are machined into the OEM parts. The parts included in the kit are the intermediate and overdrive servos/pistons, with o-ring grooves machined into them and Viton o-rings installed and a patented assembly sleeve over those.
The bores in these transmissions reach limits of wear that cause loss in pressure to the top of the piston and that causes functionality issues in the 70,000 to 200,000 mile range depending on driving habits.
The best thing about this fix is it includes instructions on how to replace both servos without dropping the transmission on the Explorer family vehicles. This is an intermediate-to-long-term fix that has been tested and installed on all types of the Ford Explorer Series and their sister products, along with the Lincoln LS and even Jaguar S-Types with the Ford 5R55N transmission with great success. The type of work involved can be done by an experienced mechanic in 2 hours or less, and for the do-it-yourself crowd in 3-6 hours. It can be done and has been on car stands also.
The secret to the longevity of the fix is the original design accounts for a percentage of fluid loss to the reservoir, and to the underside of the piston. The loss to the reservoir causes loss in pressure to the top of the piston and the loss to the underside of the piston causes back pressure. The o-ring above the cross bore seals the bore against loss and back pressure to the backside of the piston. The o-ring below the cross bore seals the loss of fluid to the reservoir. The exposed o-ring cross sections are under very little force, around 2-3 pounds. The top of the bore is mostly concentric with the pin and the bottom is where most of the wear takes place, causing an ob-round shape. The o-rings redirect all the flow to the top of the piston where it is needed.
This fix is not a permanent fix but we consider it a intermediate to long term fix. There are vehicles out there that have had this fix working in them for over 100,000 miles! The o-rings will eventually wear out and the servo will need to get pulled and o-rings replaced. But you can do that as many times as necessary. In some cases people have gotten over 70,000 miles on one set of o-rings. Not only do we machine the o-ring grooves, we machine them in such a way as what caused most of the wearing on the OEM machining is dramatically slowed down.
This fix involves a Patented fix where o-ring grooves are machined into the OEM parts. The parts included in the kit are the intermediate and overdrive servos/pistons, with o-ring grooves machined into them and Viton o-rings installed and a patented assembly sleeve over those.
The bores in these transmissions reach limits of wear that cause loss in pressure to the top of the piston and that causes functionality issues in the 70,000 to 200,000 mile range depending on driving habits.
The best thing about this fix is it includes instructions on how to replace both servos without dropping the transmission on the Explorer family vehicles. This is an intermediate-to-long-term fix that has been tested and installed on all types of the Ford Explorer Series and their sister products, along with the Lincoln LS and even Jaguar S-Types with the Ford 5R55N transmission with great success. The type of work involved can be done by an experienced mechanic in 2 hours or less, and for the do-it-yourself crowd in 3-6 hours. It can be done and has been on car stands also.
The secret to the longevity of the fix is the original design accounts for a percentage of fluid loss to the reservoir, and to the underside of the piston. The loss to the reservoir causes loss in pressure to the top of the piston and the loss to the underside of the piston causes back pressure. The o-ring above the cross bore seals the bore against loss and back pressure to the backside of the piston. The o-ring below the cross bore seals the loss of fluid to the reservoir. The exposed o-ring cross sections are under very little force, around 2-3 pounds. The top of the bore is mostly concentric with the pin and the bottom is where most of the wear takes place, causing an ob-round shape. The o-rings redirect all the flow to the top of the piston where it is needed.
This fix is not a permanent fix but we consider it a intermediate to long term fix. There are vehicles out there that have had this fix working in them for over 100,000 miles! The o-rings will eventually wear out and the servo will need to get pulled and o-rings replaced. But you can do that as many times as necessary. In some cases people have gotten over 70,000 miles on one set of o-rings. Not only do we machine the o-ring grooves, we machine them in such a way as what caused most of the wearing on the OEM machining is dramatically slowed down.
