My M936A2 is doing 53 in 5th gear at 2200 rpm.

[1 Patriot-of-many]

Any thoughts on what the issue would be? Thought my truck wasn't shifting into 5th, but it sure is, my top speed is about 53 or so at 2200 rpm. Vehicle seems sluggish to get to speed but I'm basing that on driving other 5 tons that weigh half.

 

[RustyM923]

Are you counting the shifts?

53mph at 2200 is 4th gear.

It's likely that you're hearing/feeling the torque converter lock if you're counting the gears. You should "count" 6. The converter locking really feels like a gear shift.

Try bumping the lever a bit more towards neutral and see if it shifts to 5th. It probably just needs adjustment.

 

[1 Patriot-of-many]

I'm not following... I count 4 shifts/decrease in RPM's from a stop in 1rst. I don't know much about transmissions. Perhaps I should post a video tomorrow. Thanks for the reply.

 

[camoyj7]

Check your shifter. When mine in in drive it looks like it's in neutral. Like Rusty said 2nd or 3rd gear you will feel the torque converter lock up and it feels like a shift.

 

[RustyM923]

I'm not following... I count 4 shifts/decrease in RPM's from a stop in 1rst. I don't know much about transmissions. Perhaps I should post a video tomorrow. Thanks for the reply.

Try this. Start in 1st. Run to 1800 rpm and manually shift to 2nd.

Run second to 1800 rpms and manually shift to 3rd.

Run 3rd to 2000 rpms and manually shift to 4th.

Run 4th gear up to 2000 rpms and then gently push the shifter a bit further towards Neutral. It'll shift to 5th.

I'll bet a carne asada burrito with guacamole that your shifter linkage needs to be adjusted.

 

[1 Patriot-of-many]

Thanks a bunch Rusty, it isn't going into 5th like I thought. Just tried that, see what you mean by the lockup now. Still no joy, though there is quite a bit of slop in the 1-5 notch where there isn't any in the others. Gonna have to have a look at the linkage and adjustment when the ground dries up, it's been raining nonstop all week. Where does the modulator fit into all this? What does that do? Modulate of course LOL.

 

[tie6044]

Are you going by speedometer or GPS?

 

[1 Patriot-of-many]

Are you going by speedometer or GPS?

Speedometer, same shifts in 1-4 as 1-5, same speed and I can tell I'm not going faster than about 50.

 

[1 Patriot-of-many]

Shifter linkage is adjusted properly, no fifth gear. What would prevent it from shifting into 5th anyone besides linkage which I just ruled out? Shifts fine into reverse, all gears except 5th.

 

[RustyM923]

What happens when you have it in 1-5 and you're going 50mph...then nudge it even more towards "N"? Does it actually disengage and free wheel?

 

[1 Patriot-of-many]

Yes it pushes into neutral. i tried numerous times your suggestion. I just adjusted the modulator cable, I can't make heads nor tails of the TM instructions on adjusting the modulator cable so shooting in the dark as far as that. Yeah the shifter linkage is definitely adjusted properly, starts in neutral all postions lock in separate of each other. Guess the last thing would to be to disconnect the linkage, manually shift the lever on the transmission in the 1-5 detent with the brakes applied of course, then take it for a spin to completely rule the linkage out. Is there a troubleshooting guide anywhere on the MT654? Next stop is the friggin shop. ERRRR.

 

[1 Patriot-of-many]

Any Moderator can you change this thread title to "Anyone ever have an MT654 not shifting into 5th?"

 

[162tcat]

It sounds like it needs to go to the allison shop. Open the wallet.

 

[1 Patriot-of-many]

It sounds like it needs to go to the allison shop. Open the wallet.

Wonderful...... I can't believe no one else here has encountered this problem.
Would it be cheaper to have a shop swap motor and trans from another truck than pull out the trans and fix it?

 

[Suprman]

Take it to the Allison dealer have them diagnose it. Then at least you know what you are dealing with. It could be a simple fix.