Six steel governor weights and six springs to move the 1-2 and 2-3 shift points on a TH350 after a gear swap, tire change or engine build.
Put 4.11 gears or a set of 33-inch tires under a Turbo 350 and the shift points stop matching the engine: it either short-shifts and bogs, or it hangs in first and screams. This governor recalibration kit (part A44681-4K, the K018 pattern) lets you move the wide-open-throttle 1-2 and 2-3 points without touching the valve body. It contains six steel governor weights, six calibration springs, two new weight pins with E-clips, an O-ring and a square gasket, and it also fits TH350C, TH400, 700R4/4L60, TH250C and 3L80 governors.
The TH350 has no computer. The governor is a small spinning valve driven by a nylon gear off the output shaft, and it sends the valve body an oil pressure that rises with road speed. When governor pressure overcomes the shift valve springs and the throttle-related pressures pushing back, the transmission upshifts. GM's own manual notes that TH350 shift points vary with rear axle ratio, because the governor only knows output shaft speed. The weights are what make it speed sensitive: centrifugal force swings them out and raises governor pressure. Heavier weights build pressure at a lower road speed and bring the shifts sooner; lighter weights let the engine run further up before it shifts. The springs tune the curve between the 1-2 and 2-3 points rather than doing the heavy lifting.
The kit cannot fix a mechanical fault. GM's diagnosis chart ties a no 1-2 shift to a sticking governor valve, a loose or worn driven gear, blocked governor feed passages or a scored governor bore. A shifts-cold-but-not-warm complaint can be a governor gear roll pin that sits too short, and a gear stripped all the way around usually means the case pin is missing. Part-throttle shift feel is set by the modulator and valve body, not the governor. Our TH350 common problems guide covers the modulator and worn bores that get mistaken for governor issues.
Log full-throttle shift rpm and road speed in first and second with a tach, and compare it to where your engine makes power. If the transmission shifts on time but slips through the change, you need a pressure fix, not a governor change; see the TH350 valve body testing guide. Pull the governor and look at the gear teeth and the weights. If the gear is chewed or the valve sticks in its bore, fix that first, because a worn governor gives erratic shift timing no matter what weights it has.
The kit is listed for the TH350 and TH350C 1969-1986, TH400 1965-1992, 700R4/4L60 1982-1993, TH250C 1980-1985 and 3L80 1992-1993. On a TH350 the governor cover is held by a retainer wire and sealed with an O-ring, so use the kit's O-ring there; the square gasket is for the bolted covers on other units. The model and year code is stamped on the TH350 governor cover, which helps when you are not sure what is in the car. Send us the year and VIN if you need help, and see the full TH350 parts collection.
The governor comes out on the car. Pry the retainer wire off with a screwdriver, ease the cover out without bending it, and slide the governor straight out of the case. Drive out the weight pins, swap one weight or spring at a time, fit the new pins and E-clips, and make sure every weight swings freely. Check the bore and sleeve for scoring while it is out. Reinstall with a fresh O-ring, top off with Dexron-type ATF, and road test at wide-open throttle, adjusting in small steps. Expect a few rounds; it is trial and error by nature. If you are building the whole unit, do this on the bench along with a TH350 overhaul kit, and pair it with a firmer StreetFighter valve body if you want harder shifts as well as relocated ones.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Usually not. A no 1-2 shift is most often a sticking governor valve, a damaged governor gear, blocked feed passages or a valve body problem. Inspect the governor and fix any mechanical fault before recalibrating.
Lighter weights let the engine rev higher before the shift; heavier weights bring it sooner. Use the weights to get close, then fine-tune with springs, changing one thing at a time and testing at wide-open throttle.
Only somewhat. Part-throttle shift timing and feel are mostly controlled by the vacuum modulator and valve body. The governor kit is mainly for setting full-throttle shift rpm.
No. On a TH350 the governor is behind a wire-retained cover on the side of the case and slides out with the transmission in the car. Have a new O-ring and some ATF ready for the top-off.
The kit is listed for TH350/350C, TH400, 700R4/4L60 (1982-1993), TH250C and 3L80 governors. Those units use a bolted cover, which is what the square gasket in the kit is for.
