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1985 720 3 speed automatic


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There are...


kick down switch adj.

inhibit switch adj.

vacuum diaphragm rod adj.

manual linkage adj.


but all of these rarely need attention unless they, or the transmission is removed..


There is a brake band adjustment but you must use an accurate torque wrench for this. With oil pan off, loosen the lock nut. Carefully and accurately torque the band servo piston stem 9 to 11 ft. lbs. Now loosen the band servo piston stem exactly two turns. While holding band servo piston stem from turning, tighten the lock nut to about 14 ft. lbs.

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Depends on how it shifts and runs now. If it won't shift out of 2nd and the fluid is brown and burnt from neglect, abuse and towing... probably not. That was the factory settings for a proper running 3N71B.

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The proper adjustment is critical to 1-2 and 2-3 shift quality. If the shift quality is poor then try an adjustment. If your transmission is running and up and down shifting normally, then it's fine. Check it and adjust if needed at the next fluid change in about 30-50K miles. If it acting up then I would check the adjustment.

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Not likely. Your truck has a 4.11 differential. This is a perfect gear for hauling a heavy load with but when your truck is empty, and just a light / medium throttle the auto senses this and is designed to up shift. It doesn't lug in second because the torque converter has a built in 2 to 1 slip at low speeds. Next time floor it and you'll see that first pulls over a much longer range, but only if needed. 


There is no diagnostic for shifting too soon. It's designed this way. If light throttle and light load the transmission up shifts as soon as possible.


My '74 710 has a, (had) a 4.11 in it. When driving off a stop you can easily miss the first shift at about one car length. The shift to third feels more like into second and I used to wait and wait and thought there was no third gear. 



Your '85 also has a locking torque converter. At speeds above 45 or so the transmission locks out the torque converter and any slippage, and directly couples the engine to the transmission. This drops the engine about 3-4 hundred RPMs by eliminating any slippage. This both improves the mileage (slightly) and allow the transmission to run cooler.

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Sorry, thought it was 4x4.


Floor it and it should take longer to shift. There is a vacuum line from the intake that goes to the transmission so it can sense the load on the engine. Heavy load, carb open, vacuum low and the transmission delays the up shift. Ths is what the modulator valve does. If it's faulty it may allow up-shifts early.

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