TH400 Master Rebuild Kit 1968, new and ready to install. Fits the TH400. Ships fast from the USA.
1968 is where the Turbo 400 settles into the design most builders know: the switch-pitch converter option of the early Buick, Olds and Cadillac cars was gone, and the same basic three-speed went on to back GM cars, muscle cars, pickups, vans and motorhomes for decades. If your 1968-up TH400 now slips when it shifts, hangs in 1st, takes a second to grab Drive or Reverse, or has dark fluid that smells cooked, this master rebuild kit gives you every wear part for a full overhaul in one box.
Getting both bands matters on a 400. The front band applies in manual Second for engine braking, and the rear band applies in Reverse and manual Low, so a glazed rear band left in a fresh build can still leave Reverse soft or slipping.
Nothing in a TH400 is computer controlled. The vacuum modulator reads engine load and moves the throttle valve, which raises line pressure under load; the governor reads road speed; and the shift valves in the valve body decide when to apply each clutch and band. The detent (kickdown) solenoid is the main electrical part. That means shift quality depends on clutch packs that are still thick, seals that still hold pressure and a modulator that is not leaking. A master kit renews all three, which is why it fixes problems a fluid change or shift kit alone will not.
Start with the cheap checks: correct fluid level, a modulator that has not pulled fluid through its vacuum line, and correct linkage adjustment. Then pressure-test the unit. Our TH400 valve body testing guide explains how to tell a sticking valve from worn clutches, and if the pump is noisy or pressure is low across every range, read the TH400 pump failure guide before you order, because a damaged pump needs replacing along with the kit.
This kit is listed for the TH400 from 1968 on; the kit maker builds it for 1968-up units and offers a separate kit for 1965-1967. That covers the TH400 in GM passenger cars, Chevy and GMC trucks and vans, and the many non-GM applications that used the same transmission. Truck, motorhome and heavy-duty variants can differ in clutch count and hard parts, so check your clutch pack count during teardown, and send us your year, vehicle and VIN if you want us to confirm it first. Owners of a 1965-1967 switch-pitch unit should use the 1965-1967 TH400 master rebuild kit instead. See all parts for this transmission on our TH400 page.
If you want firmer, quicker shifts, install a TH400 shift kit while the valve body is out, and replace a scored pump with a TH400 pump. Our TH400 wear points guide lists the upgrades worth making during the job.
| Fits | TH400 1968 |
| Part type | Master Rebuild Kit |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes. The 1968-up kit includes both the front band and the rear band, along with frictions, steels, seals, gaskets, filter, bushings and an adjustable modulator.
No. This kit is for 1968 and later units. The 1965-1967 transmissions, including the switch-pitch versions, use our separate 1965-1967 master rebuild kit.
It is built for 1968-up TH400 units, but heavy-duty truck and motorhome versions can use different clutch counts. Count your clutch packs during teardown or send us the year, vehicle and VIN before ordering.
The modulator sets line pressure from engine vacuum. An old diaphragm can leak, causing harsh or late shifts and fluid loss through the vacuum line, so it is replaced with every rebuild.
Have about 3 gallons of DEXRON on hand. A dry transmission and empty converter take roughly 10 to 11 quarts plus the cooler and lines. Finish the fill by the dipstick at operating temperature.
Measure all four endplays, inspect the thrust washers and needle bearings, and check the pump and pressure regulator bore for wear. Those hard parts cause most comebacks after a rebuild.
