Compresses the low and reverse rear clutch return spring on GM units so you can pull or seat the retaining ring safely instead of fighting a loaded spring.
Rebuilding a 700-R4 or 4L60E out of a Silverado, Tahoe, S10, Camaro or Corvette and stuck at the bottom of the case? The low and reverse clutch piston sits at the very rear of the case under a return spring assembly held down by a retaining ring, and you cannot get that ring out or back in until the spring is compressed. This steel, black oxide T-0151 pattern compressor is shaped for that job, so the spring comes down evenly and the ring groove opens up instead of you fighting a loaded spring with screwdrivers.
The low and reverse clutch holds the reaction carrier for manual low and for reverse. Its piston is the last thing in the case: three seals (outer, center and inner) on a piston that sits in the back of the case, with a spring assembly on top and a retainer ring holding it all in. Above it stack the clutch plates, which in the GM procedure are a waved plate, a selective spacer plate, then five fiber plates alternating with four steels, all under the low and reverse support. A worn or rolled piston seal here means slow or slipping reverse, so any full overhaul replaces those seals, and that means compressing the spring twice: once to get it out and once to put it back.
GM's overhaul procedure tightens a clutch spring compressor bridge over the low and reverse spring to remove the piston, using a disc that depends on case type: J 41420-2 for a one-piece case and J 42628 for a two-piece case. On reassembly it calls for the J 23327-1 forward clutch spring compressor bridge to compress the spring while the retainer ring is installed. This tool does the same compressing job for the rear section. Before you seat the spring, make sure the notch in the piston lines up with the parking pawl window in the case. Our 4L60E bench rebuild tools guide lays out every J-tool in the teardown, and the 4L60E common problems guide explains which failures send a unit to the bench in the first place.
The listing covers the GM rear-drive family that shares this rear clutch layout: the 250, 250C, 350, 350C, 700-R4, 4L60, 4L60E, 4L65E, 4L70 and 4L70E, plus the 4T80-E. GM changed the 4L60E case over the years, including one-piece and two-piece designs, so lay the tool over your spring retainer before loading it and confirm it seats evenly. Questions about your unit? Send us the year and VIN. The rest of our 4L60E parts are on the 4L60E collection page.
| Type | Low and reverse rear clutch spring compressor |
| Fits | GM 250, 250C, 350, 350C, 700-R4, 4L60, 4L60E, 4L65E, 4L70, 4L70E, 4T80-E |
| Function | Compresses rear clutch return spring for safe ring removal |
| Material | Steel with black oxide finish |
| Replaces | Atec Trans-Tool T-0151 pattern |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is listed for the GM 250, 250C, 350, 350C, 700-R4, 4L60, 4L60E, 4L65E, 4L70, 4L70E and 4T80-E. Seat it on your spring retainer before applying load to confirm it sits evenly.
It follows the Atec Trans-Tool T-0151 pattern. GM's procedure uses a J 23327-1 bridge with a case-specific disc for this step; this tool is shaped to do that compression on the rear clutch.
No. The low and reverse piston sits at the back of the case, so this tool is used only during a teardown or full rebuild with the gear train removed.
The three piston seals at minimum, plus the low and reverse fibers and steels. Inspect the roller clutch race and reaction carrier while you are there.
Slow, slipping or missing reverse, or no engine braking in manual low. Rule out low fluid and line pressure before you tear the unit down.
