TH350 Planetary 1969-1986, remanufactured and ready to install. Fits the TH350. Ships fast from the USA.
This is the rear planetary for a 1969-1986 Turbo 350, the low/reverse planet that GM's manuals call the reaction carrier. It is remanufactured, and it fits the TH350, TH350C and the lighter TH250 and TH250C that share the same rear gear train. People shopping for it usually have a GM car or truck from that era that whines in 1st and Reverse, has lost Reverse after a broken pinion, or showed steel chunks in the pan at teardown.
The rear gear set is the reaction carrier, its pinions, and the output ring gear that is snap-ringed to the output shaft. In 1st gear the carrier is held from turning by the low and reverse roller clutch; GM's assembly steps have you line up the splines on the inner race of that roller clutch with the splines on the reaction carrier. In manual Low and in Reverse, the low and reverse clutch holds it instead, and the steel lugs around the outside of the carrier engage the low and reverse friction plates. With the carrier held, the sun gear drives the pinions and the output ring gear turns at a reduced ratio, or backward in Reverse. That makes this carrier the part that takes the full reaction torque of 1st and Reverse.
The TH350 is a hydraulic transmission without a computer, so there are no trouble codes. GM's chart also lists cut low and reverse piston seals for no engine braking in Low, so confirm the planet is damaged before you blame it.
Start with fluid level and a line pressure check in Reverse; low Reverse pressure is a valve body or seal problem, not a gear problem. Our TH350 valve body testing guide covers the pressure side, and the TH350 common problems guide covers no-Reverse causes. At teardown, spin each pinion by hand and feel for roughness, check pinion end play against a new carrier, look for blued or cracked pinion shafts, and inspect the carrier hub bushing and outer lugs.
Listed for the 1969-1986 TH350, TH350C, TH250 and TH250C in select Buick, Chevrolet, GMC, Oldsmobile and Pontiac applications. Before installing, set this unit beside your old reaction carrier and compare the number of pinions, the hub and the outer lug pattern before installing. If you are unsure, send us your year and VIN and we will check it. The full range of Turbo 350 parts is on the TH350 parts page; the front gear set's ring gear is the TH350 front input ring gear.
If you are replacing seals and soft parts while the case is empty, look at the ATP SMS-9 TH350 master repair kit and check its contents list against what your unit needs. Refill with Dexron; see the TH350 fluid capacity guide.
| Fits | TH350 1969-1986 |
| Part type | Planetary |
| Condition | Remanufactured |
| Brand | OEM |
| Reference | TH250 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Rear. It is the low/reverse planet, called the reaction carrier in GM manuals. It works with the output ring gear on the output shaft.
The listing covers TH250, TH250C, TH350 and TH350C from 1969 to 1986. Compare pinion count, hub and outer lugs to your old carrier, or send us your year and VIN to confirm.
It is listed as remanufactured. Inspect it when it arrives and check pinion end play before installing, as you would with any planet.
The reaction carrier to output ring gear needle bearing, the output ring gear to case needle bearing if rough, a new output ring gear snap ring, and the carrier hub bushing if worn.
Usually not first. Low fluid, linkage, a stuck modulator or boost valve, cut direct or low and reverse piston seals, or broken pump hub seal rings cause no Reverse more often. Pressure-test first, then inspect the gears.
GM installs the reaction carrier to output ring gear needle bearing lip side up, and the output ring gear to case bearing with the inner race lip pointing toward the rear.
