No reverse on my M923A2

[CARMAN]

Take your external filter off (the one under hood passenger forward of trans). Cut it open and inspect pleats in filter for residue/debris.

You can also send a fluid sample off to be tested for content and condition of fluid.

It's most likely the clutches if Allison has tested it.

The governor filter is external, located on the very rear of trans, below output shaft, behind a large 7/8" or 15/16" nut. It is thimble sized filter, cleanable and reuseable.

I had a transmission fail in july 2016. When I bought the truck in july2014 it made sounds like a screech owl when upshifting. Pulled solid with no slipping. Oil was clean and clear, smelled fine. Downshifts were quick, firm, and decisive. So I proceeded to drive the truck 7000 miles before the trans failed in the forward gears one night. Never lost 1st or reverse. I replaced the entire trans with a new rebuilt one out of the can.

Be sure and use the correct oil when going back with a new trans, do not use motor oil. In cold enviroments, the motor oil is too thick and will cause failure of the transmission unless you use a heat pad on the trans pan, and let the transmission warm up 30 minutes before driving per Allison instructions.

Had just done a filter change a couple months ago. Will take it off and have a look.

 

[lindsey97]

Allison C-4 rated oil which is 10wt with correct additives. Oreilly's premium green bucket 5 gallon pail, pn 74209.

Plan on needing more than 4 gallons or whatever the dash placard says, they didn't take into account for the cooler, hoses and filter capacities.

 

[CARMAN]

Replacing a transmission can be done on your own with a Large transmission jack from harbor freight. Luckily its an A2 so the bellhousing bolts are easy to get to. Only real pain in the butt is the upper transmission mount. Everything else is pretty easy. About 90 mins and it should be out and on the ground. Going back in is the real fun part. in fact it just sucks. I would rather pull the cab off and put the transmission in than fight with one on a jack. but that is just me.

You can do it in a day with general hand tools and a decent impact gun even if you are a beginner.

Wes. I had sent you a PM. Did you get it?

 

[CARMAN]

Have you checked your governor filter on the very back of the transmission?

The truck is back in it's home. Will have to wait till next week as I work all weekend. I will check out these things and probably drop the pan. I did confront the shop with these questions and they said that if the gov. filter was clogged pressure check would not have come out ok. Truck ran great back to it's home, just no reverse. Until warm, then backs up about 5 feet and kicks out. Wish there was a 5-ton member closer I could "beer" or $$ into helping with a swap. Shop wants big bucks to swap, even with me supplying a trans. Did find a take out with low mile for a good deal. 1/4 of a rebuilt one. But...will I be doing this again in 2 years?

 

[CARMAN]

So I assume this is bad. Not a trans guy but a handful of little strips of metal in the pan.

 

[tobyS]

Looks like clutch, but I can't tell in the photo's.

 

[CARMAN]

All those little black strips are metal shards. Maybe 20 pieces. All stuck to the magnet. Other than that. Clean as a whistle.

 

[tobyS]

All those little black strips are metal shards. Maybe 20 pieces. All stuck to the magnet. Other than that. Clean as a whistle.

Do you see the gear like shape of the piece on the left? That, I think, is the inner part of a friction clutch plate. Some of the disk may still be in place in the clutch, ready to do more damage. You have no choice but to pull.

 

[162tcat]

What causes the clutch friction parts to disintegrate like this? Could this be attributed to using motor oil versus transmission fluid in the transmission?

I'm no transmission expert but an oil specifically designed for a transmission with internal clutches seems like it would support a longer healthy life better than motor oil which is designed to lube bearings.


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[CARMAN]

Big question is can I put it back together fill it back up and drive it to a better location where I can get help pulling out and putting in. Assuming those pieces are just from reverse??

 

[tobyS]

Big question is can I put it back together fill it back up and drive it to a better location where I can get help pulling out and putting in. Assuming those pieces are just from reverse??

You take the chance of more parts coming off internally and getting into gears or bearings that otherwise may be fine.

 

[CARMAN]

Anyone know if (wartimefinds) on ebay is a member here?[COLOR=#0654BA !important][FONT=&quot]
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[CARMAN]

Someone in Utah got this. Any one know who? Want to sell it?

https://www.govplanet.com/for-sale/...0,sm|1,k|mt654cr,mf|1&rr=1&hitprm=&pnLink=yes

 

[simp5782]

They paid way to much for something that may not work. I think a take out will last you just fine. I got 30k out of em. Heat killed mine

 

[tobyS]

Try C&C Surplus in south Indiana for a working take out. Don't buy one with motor oil.

 

[CARMAN]

I’m fielding all your ideas but how do I get a take out from a military truck that does not have oil? Or do you mean. Buy a take out. And before I install it. Service it and put in dex. ?

 

[Jbulach]

If memory serves me correctly, there have been more than a few on here that croaked very shortly after switching from motor oil to dextron. I will keep motor oil in mine until it’s time for a rebuild...

 

[tobyS]

I wouldn't buy a used tranny that has had motor oil in it, only one with ATF. My mechanic who had Allison certificates, says the frictions and steels act differently and while oil may work, oil reacts with the friction material negatively....so I trust him.

You probably have (only) one clutch pack that has failed. I don't think you have continued trying, running, to the point that more than one or two frictions have came apart...like the piston that puts pressure on it, melting, don't think you have done that, it's a recent problem. If there is little odor and no aluminum pellets, it's a good thing...you probably have a tranny that is well worth a proper rebuild and needs few parts. Parts may be less than $500...but you need a good mechanic that works Allison. Ask at a few truck repair shops who works on trannys (careful asking at truck stops about "tranny's"...someone might get the wrong idea).

 

[simp5782]

Anyone know if (wartimefinds) on ebay is a member here?[COLOR=#0654BA !important][/COLOR]

Wartime finds is in eastern texas, hes a real PITA to deal with and wants everything for cheap but everything he sells has a gold price.

 

[CARMAN]

Here we go.