Anyone know how to adjust the shift points on M936A2?

[corvette9]

Seems to me the trans dose not down shift on a hill to keep the rpms up in the 1500 range. The rpms will get down to 12-1300 and lug before it will down shift. There for droping out of the power band. It shifts ok on flat roads but up hills dose not seem right. I have an allison in 2000 C 6500 Chevy truck and it down shifts like it should and stays in the power band. Will adjusting the cable at the throttle make any diff.? Any help would be great.

I did the fuel adjustment. Turned the fuel screw out 4 turns. That made a big diff. from a stand still. I think the truck pulls very well for the weight. If I can get it to go up a steep hill better I'll be very happy with it.

 

[patracy]

Yes, the adjustment is at the throttle cable. Have a look in the TM's for it:

http://www.steelsoldiers.com/forumdisplay.php?115-5-ton-and-up-TMs

That's the root section of the 5 ton TM's, we just have gotten the newer updated TMs there.

 

[wheelspinner]

Personally on pulls like that I prefer to manually select and eventually up shift.

 

[Suprman]

I have done that adjustment a few times. It increases or decreases trans fluid pressure. Its like adjusting a kick down cable in a muscle car. If you bring the cable out it will decrease the pressure and soften the shifts and by bringing the cable forward more will increase pressure. You can make it shift very hard if you want to.
Will

 

[jarhead1086]

Personally on pulls like that I prefer to manually select and eventually up shift.

I am going to try manually shifting. Mine seems to shift way too early and can't maintain the proper RPM. The shift is stiff enough, just timed wrong. It made a noticeable difference climbing hills by removing, greasing, and resealing all my hubs. I still need to turn up the juice. I never see any black smoke. I really enjoy these trucks and all the good tips from this site.

 

[corvette9]

I did move the cable foward yesterday. About a 1/2 inch. I marked the orig. location just incase. By moving the cable pivot foward you are tighting the cable.( or pulling the cable out more) I only took it for a quick ride and can not say if it made a diff. or not.

About shifting manually. I tried that. When pulling a hill I shifted right down to 1st gear and the trans did not down shift. Maybe I should look at the shifter cable. Being as heavy as it is I'm not expecting a rocket but it needs to stay in the power band. Thats all I want it to do. It's raining here today so I may have to wait till next weekend when I have time again.

 

[wheelspinner]

About shifting manually. I tried that. When pulling a hill I shifted right down to 1st gear and the trans did not down shift. Maybe I should look at the shifter cable. Being as heavy as it is I'm not expecting a rocket but it needs to stay in the power band. Thats all I want it to do. It's raining here today so I may have to wait till next weekend when I have time again.

Did you go all the way to 1st right away? If so the tranny saw the error of your ways and did not downshift as commanded. Its best to click down one at a time until you find the right gear.

 

[Suprman]

Did you check the fluid level. You have to do it in neutral with the engine running. I have also seen the wrong bolts holding the shifter into the column. They were too long and interfered with the shifter position in reverse and in first not enough for me to notice when shifting but enough that the transmission knew.

 

[Jason O]

Bringing this back up with a modulator / upshift question.

TM -24 pg5-392 shows "full throttle" shift points. My truck shifts a few hundred RPM early through each gear. Looks like this is an internal adjustment.

I understand that the modulator changes shift pressure (softer at light throttle, harder at full throttle). Downshift points are also effected - I can lug the engine in a high gear at light throttle, and "step on it" to get a downshift / kickdown.

My question - Are UPSHIFTS (1 to 2, 2 to 3 etc) at a LOWER RPM under light throttle, or at the same RPM but softer?

 

[quickfarms]

The first thing you should do is download a copy of the Allison operators manual and the mechanics tips.

When you drive a allison equipped truck you should not change the throttle position until you have reached your desired speed. When taking off from a stop you bring the RPM's up to 200 below governed.

The properly adjusted transmission should be programmed to shift at 300 rpm below governed, except the high gear that shifts 500 rpm below governed.

Manipulating the throttle can lead to the transmission short shifting and sluggish performance.

First gear in this transmissions is a granny and may be set up for manual shifting.

Downshifting the selectee lever just tells the transmission to downshift if it can.

The proper shifting of the transmission is dependent on all of the settings being correct. Unfortunately I have run across a lot if these trucks in which the transmissions are not correctly set up.

The actual shift points are adjusted by dropping the pan. Adjusting the shift points on the truck is an art. I have talked to several different Allison shops that state the best way to set up the manual Allison's is on the bench.

 

[Jeepsinker]

Just for the record, my 936 shifts all kinds of stupid if you let it too. I adjusted my cable and it did help some.