Allison Transmission

Just got back from KS and spent some time with an ag operator that runs the same tranny as the 900 series trucks in big 3500 gallon spray rigs. He's running C4, and said he has 6400 hours of hard pulling on one of his 120 foot liquid sprayers without a hitch, just changes the fluid and filters every 12 months.

That's good news.

I just pulled out the biggest mother of all palm tree stumps here in El Paso today with my 923 you can imagine. But that was today. Yesterday, 21,750 pounds of empty truck just hopped up and down on the street and we broke chains, straps, you name it. Bottom line: get the stump soaked, I mean SOAKED, before you pull it out. There are limits to every machine.

Hmm, you guys are certainly not helping me.....now I want a 923 even more

I have like 53 big palms, maybe I should try that!,, Surely my wife wouldn't miss one
I did pull out a buried humvee the other day after some desert swamping after a rain, but that was pretty anticlimatic.

For all around driving, I sure like the 923. It's like driving a car compared to the older stuff.

I like the Allison in my 923 overall, but mine needs a little work. It leaks some fluid and the shift points are not consistent.

Here's a weird one. I thought the Allison in that truck was five speeds but here's what mine does.

When I put it into 1-2 it shifts up twice. Then I get another shift out of 1-3, 1-4, and 1-5. That sound right or is there something wrong with it?

Beerslayer said:

I like the Allison in my 923 overall, but mine needs a little work. It leaks some fluid and the shift points are not consistent.

Here's a weird one. I thought the Allison in that truck was five speeds but here's what mine does.

When I put it into 1-2 it shifts up twice. Then I get another shift out of 1-3, 1-4, and 1-5. That sound right or is there something wrong with it?

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no it's fine. your feeling the torque converter locking up and thinking it's another gear.

It could be the modulator on the left side of the trans. Mine shifts 1, 1/2, 1/2/3, 1/2/3/4 thru 1,2,3,4,5. The modulators stick sometimes if they've been sitting a long time.

Whenever I drive mine, I run it thru all gears, 1 thru 5 starting with 1st, just to work everything. The biggest problem with all of these trucks is sitting.

jwaller said:

no it's fine. your feeling the torque converter locking up and thinking it's another gear.

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Let me explain further and see if you still thing that is the case.

If I start out in 1-2, the transmission shifts up at about 1700. Then accelerates further and 'seems to shift' again at about 1600. The other gears do not do that.

Are you suggesting that the torque converter is slipping up until that point?

Thanks for your comments.

BS

Beerslayer said:

Let me explain further and see if you still thing that is the case.

If I start out in 1-2, the transmission shifts up at about 1700. Then accelerates further and 'seems to shift' again at about 1600. The other gears do not do that.

Are you suggesting that the torque converter is slipping up until that point?

Thanks for your comments.

BS

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yup, thats what torque converters do, they slip until locked up.

jwaller said:

yup, thats what torque converters do, they slip until locked up.

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Standard torque convertors always slip. Special locking convertors lock. Don't confuse stalling and locking, not the same thing.

For what it's worth, mine shifts until I get the rpm AND the speed of the truck up enough to where it shifts through. I have 7 speeds forward in the "D" pushbutton selector setting. I can hover all day in 1st gear, if I don't give it enough juice to get going. I still have not figured it out yet, but the tranny is a workin'. It actually gave me an alarm with the beeper when I hooked up to one of the palm tree stumps and gave it about 7/8 throttle in Mode 1, gear 1 before one of the aforementioned chains shattered.

Is that a 923A2? I didn't know 923's had pushbutton mode controlled transmissions. I thought they all had the old T-shifter.

Stalwart said:

Standard torque convertors always slip. Special locking convertors lock. Don't confuse stalling and locking, not the same thing.

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nope, they are 2 different things altogether. I have built transmissions for the last 15 years. I'm pretty sure I know how the converters work.

Got a call back from the Allison dealer this morning. The problem with the shifting was due to the wrong shift cable bracket. They modified the bracket to fit properly and adjusted the shifting and it works fine.

I see that the early 900 series trucks had an MT 500 series transmission. This one has an MT 654 which was most likely put in during the Red River overhaul.

Comments on the quality of the "Red River Overhaul" after 5 years and 3000 miles:

1. Front Driveline carrier bearing nut loose.

2. Rear Output Pinion Yoke Seal Leaking [this one probably from sitting or is original equipment].

3. Engine idle was set at 500 RPM, too low according to specs.

4. Transmission shift points not adjusted properly, impossible without modifying or replacing bracket. Transmission was shifting at 1650 RPM, way below spec.

5. Tool box mounting bolts were loose causing rattle that sounded like something was ~really wrong.

Overall, it looks like a rebuilt engine and transmission was slapped in there and the truck was shoved out the door without much care being taken to make sure it was up to spec. It would have been up to unit maintenance to make sure it was setup properly and that didn't happen either.

Don't get me wrong, I am not nitpicking or complaining about the great truck I got for $4510, it does seem to me however that the units that get these "overhauled" trucks are not getting such a great deal.

So, buyer beware. Just because it has pretty paint on it and low hours/miles, doesn't mean much. It can still fall apart before it makes it out of the GL yard.

Beerslayer - Which Allison Dealer did you use....? For future reference in case I need to see one for my -A3. Thanks.

You either love or hate the allison.

Has anyone as of yet ever had to replace the Allison Trans or have it rebuilt? What kind of price would we be looking at, or would it be cheaper buying another truck?

originalstarhauler said:

Has anyone as of yet ever had to replace the Allison Trans or have it rebuilt? What kind of price would we be looking at, or would it be cheaper buying another truck?

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I was told that to rebuild one is around $2000-2500.

Beerslayer said:

So, buyer beware. Just because it has pretty paint on it and low hours/miles, doesn't mean much. It can still fall apart before it makes it out of the GL yard.

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Accurate. Got a nice deuce with 5000 miles and torque rod came apart not long after(not to mention numerous wheel seal problems), got a 923 with 5000 miles it's putting oil into the coolant then spitting it out the overflow tube when hot....(oil cooler no doubt)

I just pulled out the biggest mother of all palm tree stumps here in El Paso today with my 923 you can imagine.

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I'll see your palm stump and raise you a double oak. The M927 lives for this kind of stuff.