Compresses the 1-2-3-4 clutch piston return spring and seats the retaining ring in the bore on GM 6T40 and 6T45 transaxles during rebuild.
If you have a GM 6T40 or 6T45 apart on the bench, sooner or later you have to get the 1-2-3-4 clutch piston and its return spring back into the bore and hold them down long enough to drop the retaining ring into its groove. This listing is the three-piece DT-47799 compressor and installer set made for exactly that step: a retaining ring guide plus the DT-47799-1 and DT-47799-2 compressor halves. It is aimed at shops and serious DIY rebuilders working on the six-speed transaxle behind the Chevrolet Cruze, Malibu and Equinox, the GMC Terrain and Buick Verano and Regal. It is solid steel with a black anti-corrosion finish, weighs about 7.5 lb, and ships from the USA.
The 6T40 is a clutch-to-clutch transaxle with no bands, so every gear depends on five clutch packs applying at the right pressure. The 1-2-3-4 clutch is applied in the first four forward gears, which makes it the busiest pack in the unit. Its apply piston is a bonded piston that rides in the housing against a return spring, and the whole stack is held in place by a retaining ring. Pushing that spring down by hand while trying to line up the ring is where pistons get cocked in the bore and lip seals get rolled or cut.
The set solves that by loading the spring retainer evenly from two sides while the guide steers the ring into its groove. Piston and ring go home together and the piston stays square to the bore. That matters on this unit specifically, because the factory pistons are bonded rubber-to-metal parts and a seal lip nicked on install will leak apply oil from the first drive.
Do not pull the transmission on a code alone. Read every module for codes, check the fluid level at the correct temperature, and rule out a solenoid or calibration fix before you go inside. Our 6T40 common problems and fixes guide walks through the P2723 piston case, the 3-5-R failure and the fluid check, and the 6T40 shift solenoid symptoms guide explains which solenoid feeds which clutch so you can separate an electrical fault from a mechanical one. GEARS also advises replacing the bonded pistons on every rebuild, so plan for new pistons rather than reusing the old ones.
The tool is listed for the GM 6T40 and 6T45 family. The vehicle list on the listing reads 2017 and later Cruze, Equinox, Malibu, Traverse, Terrain, Verano, LaCrosse and Enclave, but be careful with that list: several of those nameplates used other GM transmissions in some years, and the tool only helps if the unit on your bench is a 6T40 or 6T45. Confirm the transmission by its RPO code on the glovebox or spare tire label, or by the ID tag on the case, before ordering. The 1-2-3-4 clutch housing layout is common across the 6T40 and 6T45, which is why one set covers both. If you are not sure, send us the year, model and VIN and we will check it.
Most buyers order this alongside a full kit such as the 6T40E rebuild kit with pistons and filter or the 6T40 master rebuild kit for 2012, since new bonded pistons are the parts this tool is protecting. If you are also replacing a cracked 3-5-R housing, see the 6T45 clutch drum for 2012-2021.
| Fits | GM 6T40 / 6T45 transaxle - 2017-later Chevy Cruze, Equinox, Malibu, Traverse; GMC Terrain; Buick Verano, LaCrosse, Enclave |
| Clutch | 1-2-3-4 clutch piston and retaining ring |
| Set Includes | Retaining ring guide, DT-47799-1 and DT-47799-2 compressor halves |
| Material | Solid steel, black anti-corrosion finish |
| Weight | 7.5 lb |
| Dimensions | 8.3 x 8.3 x 3.9 in |
| SST Number | DT-47799 |
| Ships | From the USA |
It is listed for the 1-2-3-4 clutch piston and its retaining ring in the GM 6T40 and 6T45. It compresses the piston return spring and guides the ring into its groove at the same time so the piston stays square in the bore.
Only if the vehicle actually has a 6T40 or 6T45. Many Traverse and Enclave years used a different, larger GM transmission. Check the RPO code on the vehicle label or the ID tag on the transmission case, or send us the VIN and we will confirm before you order.
People do, and it is the most common way the bonded 1-2-3-4 piston gets cocked or its seal lip gets cut. A damaged piston means a slip or a P2723 code shortly after the rebuild, which costs far more than the tool.
GEARS Magazine recommends replacing the bonded pistons on every 6T40/6T45 rebuild, and documents cracked 1-2-3-4 pistons that caused falling out of gear with P2723. A kit with pistons, like our 6T40E rebuild kit, is the usual pairing.
The 6T40 and 6T45 take Dexron VI. Set the level at operating temperature through the check plug, then run the transmission adaptive values learn with a scan tool so the module relearns the new clutches.
