85"720 Posted July 5, 2015 Report Share Posted July 5, 2015 I want to get my trans serviced..Is there any band adjustments on this tranny or is it just the fluid and filter change?? 1 Quote Link to comment
datzenmike Posted July 5, 2015 Report Share Posted July 5, 2015 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. 1 Quote Link to comment
85"720 Posted July 5, 2015 Author Report Share Posted July 5, 2015 would it shift better or would it drive better because everything will be in specs 1 Quote Link to comment
datzenmike Posted July 5, 2015 Report Share Posted July 5, 2015 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. Quote Link to comment
85"720 Posted July 5, 2015 Author Report Share Posted July 5, 2015 I've done the filter and fluid change a while back.. I just want to know if its really important to get those things adjusted Quote Link to comment
datzenmike Posted July 6, 2015 Report Share Posted July 6, 2015 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. Quote Link to comment
85"720 Posted July 6, 2015 Author Report Share Posted July 6, 2015 Would that be the reason why my truck shifts through 1 pretty quick Quote Link to comment
datzenmike Posted July 6, 2015 Report Share Posted July 6, 2015 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. Quote Link to comment
85"720 Posted July 6, 2015 Author Report Share Posted July 6, 2015 My truck has 3.89 gears and its has L3N71B transmission so most likely thats the ways it supposed to shift then. Quote Link to comment
datzenmike Posted July 6, 2015 Report Share Posted July 6, 2015 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. Quote Link to comment
85"720 Posted July 6, 2015 Author Report Share Posted July 6, 2015 They make 4x4 automatics???? Quote Link to comment
84720FourWheel Posted July 6, 2015 Report Share Posted July 6, 2015 Not that I know of. I thought that all 4x4s were manual. Quote Link to comment
85"720 Posted July 6, 2015 Author Report Share Posted July 6, 2015 I thought the same thing.. Quote Link to comment
datzenmike Posted July 6, 2015 Report Share Posted July 6, 2015 :blush: sometimes when I get my head down.... You could run an automatic in a 4x4. To shift the trans case you would first have to slip it into neutral... probably why they didn't. Quote Link to comment
85"720 Posted July 6, 2015 Author Report Share Posted July 6, 2015 Would a 4speed auto be better for city driving?? Quote Link to comment
datzenmike Posted July 6, 2015 Report Share Posted July 6, 2015 Nope. The 4th gear is for highway cruise speeds to reduce RPMs and perhaps increase mileage. Same as a 5 speed... not needed if you primarily drive in town. Quote Link to comment
85"720 Posted July 6, 2015 Author Report Share Posted July 6, 2015 Thanks for the info Quote Link to comment
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