Tranny shifting

[Hasdrubal]

M1009 owners,how does your tranny shift?..mine has always shifted rather high,rpm wise.I understood this to be normal,still I find myself letting off the accellerator pedal at 30 and 60 kmh so vacuum will be higher allowing it to shift sooner.On the tranny there is a vacuum line that goes to a solenoid?a small screw is in there.What range of adjustment does this provide if any?

 

[85-m1028]

you can make adjustments up to 10mph earlier, I'm pretty sure you screw it in clockwise

 

[Taz]

You can also adjust the vacuum valve that is on the passenger side of the injection pump. There are two bolts. Loosen them and rotate the valve in the slots. I can't remember which direction does what. It will alter when vacuum gets to the modulator on the transmission. I had to do this on my M1031 as it wouldn't shift into third when cruising at 30 mph.

 

[Hasdrubal]

Yes,it was the transmission vacuum valve,on the IP.Several of our M1009's had the same symptoms.Just disconnected it,connected vacuum pump direct to transmission line.Wow,what a difference,shifts at low rpm now,very smooth.Cant believe I drove this long with this BS,but the other trucks were all the same,my friend said thats how they are,you learn something new..

 

[redline300]

Yes,it was the transmission vacuum valve,on the IP.Several of our M1009's had the same symptoms.Just disconnected it,connected vacuum pump direct to transmission line.Wow,what a difference,shifts at low rpm now,very smooth.Cant believe I drove this long with this BS,but the other trucks were all the same,my friend said thats how they are,you learn something new..

I realize this is a VERY old post but hoping someone can show me pictures of how to do this mod? Connecting the vacuum pump directly to the trans line. My m1009 is shifting hard and always has. Also, lately I have to get the rpms super high, then let off the gas, to get it to shift.

 

[Tow4]

Just disconnect the vacuum lines from modulator/regulator that is on top of the engine. One is from the vacuum pump and the other is from the transmission. Hook them together by-passing the modulator/regulator.

The transmission will now up-shift almost as soon as the truck starts moving. My M1028 is in third by the time I'm going 10mph. Not a big problem with the axle ratio I have. Maybe an issue with the 3.08 ratios in the other CUCVs. You can always manually down shift if you need to.

 

[redline300]

Just disconnect the vacuum lines from modulator/regulator that is on top of the engine. One is from the vacuum pump and the other is from the transmission. Hook them together by-passing the modulator/regulator.

The transmission will now up-shift almost as soon as the truck starts moving. My M1028 is in third by the time I'm going 10mph. Not a big problem with the axle ratio I have. Maybe an issue with the 3.08 ratios in the other CUCVs. You can always manually down shift if you need to.

Ok, here is a question then....what mph should it be auto shifting at? Mine shifts at 20 and 35....