TH350 Shift Kit 1969, new and ready to install. Fits the TH350. Ships fast from the USA.
If your Turbo 350 drops out of third once it gets hot, takes a long lazy shift into high, or keeps cooking the direct clutch after a rebuild, this is the kit most builders reach for first. It is the TransGo SK350 Shift Kit, a valve body repair kit for the GM Turbo Hydra-Matic 350. The listing is titled 1969, the first model year of the TH350, but TransGo catalogs the same kit for every 350, 350C, 250 and 250C from 1969 on, with or without a lockup converter. That covers the Chevrolet, GMC, Pontiac, Oldsmobile and Buick cars and light trucks that used the 350 through the mid-1980s.
The TH350 is a fully hydraulic three-speed. Pump pressure is set by the pressure regulator and raised under load by the vacuum modulator, and the governor on the output shaft tells the shift valves when road speed is high enough to shift. Between the valve body and the case sits a steel separator plate whose holes meter oil to each clutch and servo. TransGo does not sell this as a hard-shifting race kit. Its own instructions call it a repair kit that adds oil flow to areas of warp and wear and exhausts the cross leaks that starve clutches. For non-lockup 350s the kit supplies a new TransGo separator plate, new case and valve body gaskets, and a special gasket that goes under the reinforcing plate. TransGo says that gasket stops the high clutch leak behind many direct clutch failures. You also get new springs for the 2-3 shift valve, the pressure regulator and the governor, plus spare .250 check balls.
A shift kit cannot fix a torn modulator diaphragm or a scored servo bore, and both can cause these same symptoms. Pull the vacuum hose at the modulator. Fluid in the hose means the diaphragm has failed. Check engine vacuum too, because a vacuum leak gives late, harsh shifts that look like a valve body problem. Our TH350 valve body testing guide walks through the bench and road checks, and the TH350 common problems guide covers the bore wear that a gasket kit will not seal. A line pressure gauge on the case tap during a road test settles the question. The vacuum and pressure gauge kit reads vacuum and line pressure together.
Fits the TH350 and TH250 from 1969 on, lockup and non-lockup. How it goes in depends on which one you have, so identify the unit before you open the box:
If you are not sure which unit you have, send us your year and VIN before ordering. You can browse every part we carry for this unit on the TH350 parts page.
The kit installs with the transmission in the car. Drop the pan, remove the valve body, and stick the gaskets and check balls to the new plate with petroleum jelly or assembly gel. Use two valve body bolts in the marked alignment holes to line up the plate and gaskets. Then tighten the seven reinforcing plate bolts before you hang the valve body. With the selector in Drive, the manual valve must sit within 1/16 inch of flush with the back edge of the valve body. Pick governor springs by vehicle: two yellow for cars and light trucks, white and yellow for 4WD. You can change shift timing later without taking the governor apart. On engines with EGR, TransGo recommends a large-can modulator to stop late shifts from low vacuum. An adjustable vacuum modulator is a good companion if the old one is tired. Refill with the Dexron-type ATF GM specifies, using a new pan gasket. If you want firmer shifts than a repair kit gives a lockup unit, look at the TransGo 350C-1-2 kit instead. For harsh-shift causes after install, see our TH350 harsh shift guide.
| Fits | TH350 1969 |
| Part type | Shift Kit |
| Condition | New |
| Brand | TransGo |
| Reference | SK350 |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, as long as it is a 350 or 250. TransGo catalogs the SK350 for all 250, 250C, 350 and 350C transmissions from 1969 on, lockup and non-lockup. The 1969 in the title is the first TH350 model year, not a limit. Lockup and 250 units reuse their original plate instead of the new one in the kit.
A lockup gasket set. TransGo's instructions say the lockup gaskets are not included and list GM kit 8641953. You will reuse and modify your original separator plate and install five .250 check balls instead of four.
No. TransGo describes it as a repair and durability kit, not a high-performance kit. It firms and shortens shifts and stops the cross leaks that burn the direct clutch. For a firmer feel, TransGo points non-lockup units to its 350-1&2 kit and lockup units to the 350C 1-2 kit.
No. The kit goes in with the transmission in the vehicle. You drop the pan, remove the valve body, swap the plate, gaskets and springs, and reinstall. Governor springs can be changed without taking the governor apart.
That is one of the problems TransGo built this kit to correct, along with soft late shifts and third clutch failure. If the direct clutch plates are already burnt, though, they need to be replaced. A shift kit only stops the next set from failing.
Use the Dexron-type ATF that GM specifies for the TH350, and install a new pan gasket. Check the level hot in Park after a short drive, and do not overfill.
