5R55S Shift Kit, new and ready to install. Fits the 5R55S. Ships fast from the USA.
If your Explorer, Mountaineer, Mustang V6, Lincoln LS or Thunderbird sits in gear for a few seconds before it moves on a cold start, slips the converter clutch on the highway, or keeps setting a torque converter clutch code after you already replaced solenoids, this is the kit most rebuilders reach for. It is a new Superior K5R55W/N/S shift correction package, one part number that covers the 5R55S, the 5R55W and the earlier 5R55N. It is not a pile of firmer springs meant to make the truck bang into gear. It goes after three specific weak spots: the line pressure relief valve in the pump, the converter clutch apply circuit, and the return springs on the 3-4 clutch drum piston.
Superior states the package addresses several converter clutch and shift solenoid error codes, including P0740, and that the changes help keep the solenoid block and nearby components cooler and better lubricated.
The 5R55S and 5R55W shift entirely under computer control. Transmission Digest counts four on/off shift solenoids, one pulse-width converter clutch solenoid and three variable force solenoids in these units, all fed by line pressure that starts at the pump. When the pump relief valve sticks, or the lockup circuit leaks, the computer cannot command its way around it. Sonnax explains that the line control plunger in the 5R55 pump can stick open, which exposes output oil to the pump suction and gives a delayed engagement that clears up once engine speed rises. That is exactly the start-up no-movement complaint this kit's relief valve is aimed at. On the converter side, Sonnax describes how worn bores in the TCC modulator and solenoid regulator circuit change apply pressure, causing slip, shudder or converter damage.
Check the fluid level hot and look at its condition first. Burnt fluid with friction material in the pan means clutches are already gone and this kit belongs inside a rebuild, not in place of one. For a cold-start no-movement complaint, the in-vehicle test Sonnax describes is useful: in Reverse, unplug the solenoid connector briefly to force maximum line pressure. If the engagement comes back, a stuck pump line control plunger is likely. Keep that test short, since it puts the servos and seals under high pressure. Our 5R55S no-movement diagnosis guide covers the full sequence, and the 5R55 harsh or delayed shifts walkthrough helps separate a pressure problem from worn clutches. If your main complaint is lockup, read how the 5R55S converter clutch works first.
This kit is listed for the 5R55N from 1999 to 2003 and for the 5R55S and 5R55W from 2002 on. Per Sonnax, the N ran in the Jaguar S-Type, Lincoln LS and Thunderbird, the W went into 2002-2003 Explorers and Mountaineers, and the S replaced the N in the Lincolns and Thunderbirds for 2003 and the W in the Explorer from 2004. The kit's listed vehicle coverage runs through the 2010 Mustang and Explorer Sport Trac. The three units share this kit, but most other parts do not interchange between the N and the W/S. If you are not sure which unit is in your vehicle, our 5R55S identification guide shows the external case differences, or send us your year and VIN and we will confirm. Everything else we carry for this family is on the 5R55 parts collection page.
| Fits | 5R55S |
| Part type | Shift Kit |
| Condition | New |
| Brand | Superior |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
The Superior part number is K5R55W/N/S and it is listed for the 5R55N from 1999 to 2003 plus the 5R55S and 5R55W from 2002 on. The N and the W/S share very few other parts, so do not assume anything else crosses over. Send your year and VIN if you want us to confirm.
No, that is not its purpose. It corrects a sticking pump relief valve, a leaking or slipping converter clutch apply, and tired 3-4 piston return springs. Superior describes the lockup change as an on-off style apply that fixes slip without making the engagement harsh.
Not completely. The line pressure relief valve sits in the front pump and the return springs go in the 3-4 clutch drum, so a full install means the transmission is out and apart. It is meant to be installed during a rebuild.
It can be. A pump relief or line control valve stuck open causes delayed engagement that clears once rpm rises, and that is what the K060 valve in this kit addresses. Check fluid level and condition first, because low fluid or worn clutches cause the same complaint.
Use Mercon V. If the unit is apart, replace the filter and the seals with an overhaul kit, inspect the pump gears and bore, and test the solenoid block. Finish with an adaptive relearn and a hot fluid level check.
