2000StreetRod
Moderator Emeritus
- Joined
- May 26, 2009
- Messages
- 10,597
- Reaction score
- 334
- City, State
- Greenville, SC
- Year, Model & Trim Level
- 00 Sport FI, 03 Ltd V8
The 2003 Explorer Limited I'm buying has 180K on the odometer and the 5R55S transmission has never been rebuilt. The only thing the seller remembers being done to the transmission since the vehicle was purchased new by her parents was fixing the overdrive when it quit working. She thinks that entailed replacing a "solenoid" about a year ago. So the transmission is about due for a complete rebuild even though I didn't detect any upshift or downshift issues when I test drove the Limited and agreed to buy it. Since I plan to increase the engine performance (forged pistons, forged rods, DOHC heads, Mach 1 intake and possibly boost) the transmission rebuild should include enhancements capable of sustaining my cast crankshaft limit of 500 fhp.
My very limited experience with automatic transmissions includes adjusting the bands on my 1958 XK-150 Jaguar about 45 years ago and my correction of an upshift flare on my 2000 Sport due to a valve body separator plate blown gasket a few years ago. I anticipate the Limited being my last project vehicle so I'm tempted to finally learn about automatics and perform the rebuild/enhancements myself. I've watched some videos and read some shop manuals and it seems the modern transmissions require a lot less special tools, hydraulic presses, etc. to rebuild than were required for my 1950 and 1956 Oldsmobile hydramatics. Because the 5R55S was used in the mid 2000 year Mustangs there is a lot of documentation on their weaknesses and how to make them more robust. There are also many more aftermarket options than there would be if the transmission was only manufactured in SUVs.
The stock input shaft seems to be susceptible to failure when engine power exceeds 400 to 450 fhp and when it fails the torque converter may also. Even some stock 3 valve Mustangs experience input shaft failure during hard downshifts or the torque converter locking during WOT. Excess engine speed flares during upshift or downshift increase the risk of failure and one work-around is to alter the tune to reduce spark advance during upshifts with torque reduction. I think replacing the input shaft with a performance part is a prudent insurance investment.
They are typically hardened steel and machined to improve oil lubrication.
Manufacturers:
Level 10 Product Code Ford-5R55 Input
PATC P/N 5R55BIS 300M billet steel (TS = 280 to 305 ksi), may require some minor machining of the stator support
Performance Automatic P/N PA27406 hardened forged 4340 steel (TS = 185K psi)
TCI P/N 579600 Vaccu Melt 300 billet steel or Vasco 300 steel, requires some minor machining of the stator support
My very limited experience with automatic transmissions includes adjusting the bands on my 1958 XK-150 Jaguar about 45 years ago and my correction of an upshift flare on my 2000 Sport due to a valve body separator plate blown gasket a few years ago. I anticipate the Limited being my last project vehicle so I'm tempted to finally learn about automatics and perform the rebuild/enhancements myself. I've watched some videos and read some shop manuals and it seems the modern transmissions require a lot less special tools, hydraulic presses, etc. to rebuild than were required for my 1950 and 1956 Oldsmobile hydramatics. Because the 5R55S was used in the mid 2000 year Mustangs there is a lot of documentation on their weaknesses and how to make them more robust. There are also many more aftermarket options than there would be if the transmission was only manufactured in SUVs.
The stock input shaft seems to be susceptible to failure when engine power exceeds 400 to 450 fhp and when it fails the torque converter may also. Even some stock 3 valve Mustangs experience input shaft failure during hard downshifts or the torque converter locking during WOT. Excess engine speed flares during upshift or downshift increase the risk of failure and one work-around is to alter the tune to reduce spark advance during upshifts with torque reduction. I think replacing the input shaft with a performance part is a prudent insurance investment.
They are typically hardened steel and machined to improve oil lubrication.
Manufacturers:
Level 10 Product Code Ford-5R55 Input
PATC P/N 5R55BIS 300M billet steel (TS = 280 to 305 ksi), may require some minor machining of the stator support
Performance Automatic P/N PA27406 hardened forged 4340 steel (TS = 185K psi)
TCI P/N 579600 Vaccu Melt 300 billet steel or Vasco 300 steel, requires some minor machining of the stator support