48RE Shift Kit 2003-2010, new and ready to install. Fits the 48RE. Ships fast from the USA.
When a 48RE behind a Cummins keeps coming back with a burnt direct clutch, slow 2-3 shifts under load, a late or mushy lockup, or line pressure that will not rise the way it should, the problem is often worn aluminum bores in the valve body rather than the clutches themselves. This is the new Sonnax Sure Cure kit, part number SC-48RE, the shop-level fix for that wear. It does more than firm the shifts. It puts oversized valves into reamed bores so the valve body holds pressure again, then adds the seals, pilots and thrust washers that 48RE rebuilders replace every time.
The 48RE valve body sets line pressure with a pressure regulator valve, a throttle valve and a line/TV pressure plug, and it routes converter and lube oil through a switch valve. After years of heat and diesel torque those bores wear oval, oil leaks past the valves, and the unit loses line rise exactly when the truck is towing. Sonnax replaces the pressure regulator with a lube-regulated oversized valve, and installs an oversized throttle valve kit, an oversized four-spool switch valve and a new pressure plug assembly. A sleeved detent bore with a matched ball, a new manual valve and an enlarged TCC release orifice in the separator plate round it out.
Put a gauge on the line pressure tap and road test it. Pressure that starts in range but will not climb with throttle, or drops when the converter locks, points at valve body wear. Rule out a failing governor pressure solenoid or transducer first; our 48RE harsh or delayed shifts walkthrough covers the order to test them in, and the Ram 2500 Cummins shift problems guide covers the TTVA and governor codes that mimic a worn valve body.
This listing covers the 48RE from 2003 through 2010. Sonnax states the SC-48RE kit fits both the early TV-lever-style units and the 2005-and-newer 48RE with the throttle valve actuator motor. It fits 48RE valve bodies only. A real 48RE body has extra holes in the upper and lower separator plates and a passage in the transfer plate that 46RE and 47RE bodies do not, so check yours before you start. Send your year and VIN if you are not sure. Other 48RE options, including the TransGo kits and complete valve bodies, are on the 48RE parts page.
| Fits | 48RE 2003-2010 |
| Part type | Shift Kit |
| Condition | New |
| Brand | Sonnax |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. Sonnax lists the SC-48RE for the early TV-lever 48RE and for the 2005-and-newer units with the transmission throttle valve actuator. It does not fit 46RE or 47RE valve bodies.
Yes. The oversized valves go into reamed bores, so you need the Sonnax reamer tool kits and the VB-FIX fixture listed in the instructions. Many owners have a transmission shop do the valve body work.
The oversized throttle valve kit, four-spool switch valve, lube-regulated pressure regulator valve, line/TV pressure plug, detent sleeve and ball, manual valve, 3-4 accumulator spring and seals, checkball, boost valve spring retainer, intermediate shaft pilot and plug, output pilot bushing, two 6-tab thrust washers and two turbine shaft seals.
No. It restores pressure control so new clutches last, but burnt clutches and bands still need replacing. Install it during the rebuild.
On TTVA trucks, turn the key on with the engine off for 30 seconds, then off, so the actuator resets. Then verify line pressure with a gauge and check the ATF+4 level hot in Neutral.
