I overshot neutral into Reverse

[Clark19]

I was driving my M923A2 out of my driveway in 2nd gear and accidentally moved the gear shifter up.... all the way to Reverse.
I overshot gears 1 to 5, then past neutral...into Reverse.
The tires locked up on the pavement, the engine did NOT stall, and I then dropped it back to neutral and to forward gears.
Now the Allison Transmission sounds bad, does not go into gears higher than 1st or 2nd.
I stopped, & put it into Reverse and backed up the 5 ton for 30 yards, hoping that would back out the damage or locked gear, in case something in the trans is still wanting to go to Reverse.
That did not help.
Now when I idle & sit in neutral, the transmission bucks backwards into Reverse.
Also, when I am coasting down a hill in neutral, the transmission is NOT free flowing, it has lots of noise and drag, as if something in the transmission is holding it back....and the trans has a winding sound in neutral & the 5 ton gets slower and slower.
Please help.
I hope I did not destroy my trans.
I hope there is an easy fix.

 

[98G]

Suboptimal.

Lindsey97 has a transmission new in the can....

 

[simp5782]

It blew a band. Rebuild it or replace it.

 

[98G]

Be aware, if your shifter is working correctly it won't allow this. You can shift from lower forward hears to higher forward gears, but it won't let you go past N until you mash the button.

 

[snowtrac nome]

No bands in that trans, I have seen this before and found the teeth stripped out on the back set of clutches. its pretty easy to pull the back cover off the transmission and replace the clutches, however on a 5 ton you may have to remove the t-case to get enough room to work.

 

[Clark19]

I have been driving this M923A2 back and forth, from reverse to forward gears on my back acreage for 30 minutes.
It now has no more bad sounds, no grinding, and is smooth from reverse through neutral, and into forward gears.

However, it will NOT go ABOVE 1st GEAR into any higher gears.
Maybe I broke a linkage in the trans fluid pan area?

 

[winfred]

it likely just self clearanced the offending noise making metal being driven, thats why it stopped making noise and its now being run though the bearings seals and pistons, id suggest stopping trying to walk it off and begin the removal/repair process

 

[cucvmule]

Agreed

 

[74M35A2]

I used to shift to neutral when rolling up to a stop. Will probably stop doing that now for the remainder of my auto trans life in vehicle, after reading this.

 

[simp5782]

I used to shift to neutral when rolling up to a stop. Will probably stop doing that now for the remainder of my auto trans life in vehicle, after reading this.

Shifter has a lock and should not go into reverse unless you pull the lock up. Itll go 1-5 to neutral without using the lock

Sent from my SM-G965U using Tapatalk

 

[Clark19]

This pile of metal bearings, steel and copper is what I removed from my transmission oil pan. This is what happens when Reverse is selected when going forward at 10 miles per hour.
My trans still has first gear, neutral and reverse.
It does not have gears 2 through 5.
I also removed and verified the govonor was functional, and cleaned all the valve control body parts under the transmission.
I looked in the view port into the center of the trans body and it was clean.
I also looked into the tail of the trans into all the screw out parts and it was clean.
The metal was falling out of the trans onto the valve body right where the tail of the trans and the main trans body come together....above the trans name plate.
My plan is to keep the trans mounted in the M923A2 and just access the destroyed trans parts from the tail end of the trans.
My plan is to support the trans by putting blocks of wood under the trans body onto the heavy metal bracket under the trans.
Then I will disconnect the propeller shaft towards the transfer case..... then remove the bolts from the bracket holding up the tail of the trans and the 14 bolts holding the tail of the trans to the main body.
Hopefully then I can pull out the tail trans parts in bunches, and get into the center back of the trans where the broken parts were falling onto the valve control body.....right above the trans name plate.
The TM 9-2320-272-24-4 has great step by step instructions of how to remove the rear cover of the trans and low planetary carrier parts....on pages 5-364 to page 5-383.
However, those instructions have the trans out of the vehicle with the rear of the trans up, and gear parts removed as gravity is keeping it all stable.
Here are my questions:
1. If I remove the rear of the trans while it is still horizontal in the truck, will all the parts fall out in a heap on my floor.
2. With the rear trans cover off, will I be able to pull out the parts one by one or in bunches connected together, so I can acces the broken parts in the back center of the trans?
3. Is the above a good idea or am I going to create a disaster on my garage floor?
Clark

 

[simp5782]

This pile of metal bearings, steel and copper is what I removed from my transmission oil pan. This is what happens when Reverse is selected when going forward at 10 miles per hour.
My trans still has first gear, neutral and reverse.
It does not have gears 2 through 5.
I also removed and verified the govonor was functional, and cleaned all the valve control body parts under the transmission.
I looked in the view port into the center of the trans body and it was clean.
I also looked into the tail of the trans into all the screw out parts and it was clean.
The metal was falling out of the trans onto the valve body right where the tail of the trans and the main trans body come together....above the trans name plate.
My plan is to keep the trans mounted in the M923A2 and just access the destroyed trans parts from the tail end of the trans.
My plan is to support the trans by putting blocks of wood under the trans body onto the heavy metal bracket under the trans.
Then I will disconnect the propeller shaft towards the transfer case..... then remove the bolts from the bracket holding up the tail of the trans and the 14 bolts holding the tail of the trans to the main body.
Hopefully then I can pull out the tail trans parts in bunches, and get into the center back of the trans where the broken parts were falling onto the valve control body.....right above the trans name plate.
The TM 9-2320-272-24-4 has great step by step instructions of how to remove the rear cover of the trans and low planetary carrier parts....on pages 5-364 to page 5-383.
However, those instructions have the trans out of the vehicle with the rear of the trans up, and gear parts removed as gravity is keeping it all stable.
Here are my questions:
1. If I remove the rear of the trans while it is still horizontal in the truck, will all the parts fall out in a heap on my floor.
2. With the rear trans cover off, will I be able to pull out the parts one by one or in bunches connected together, so I can acces the broken parts in the back center of the trans?
3. Is the above a good idea or am I going to create a disaster on my garage floor?
Clark

Ha. Um. pull the transmission out. it only takes about an hour to get it out of the truck. It will save yourself. Plus you want to rebuild that thing in the clean environment. You are probably going to cause more problems than it is worth. A harbor freight transmission jack will reach high enough to get it out.

Going back in is the fun part.

and if you have never taken a transmission apart then you are in for a rear treat once you get into it.

I have a spare core transmission that wouldn't cost much with all good internals it just has a busted bellhousing.

 

[Jbulach]

What Simp said. The transmission needs to be taken completely apart cleaned and rebuilt, including the converter and thoroughly flushing the cooler and lines to get all that junk out. Best bet would be to replace the trans and converter

 

[snowtrac nome]

Looking at those parts you might be better off with a good used transmission, Allison parts are expensive if you find a broken drum it will be big bucks those parts are more than just stripped splines I see snap rings and big metal parts.

 

[74M35A2]

I'm always of the take that it is currently not working, so you can't make it that much worse. A dozen donuts walked into an Allison service center close to you yields way more info than you could imagine, likely including a tech that will gladly take the job for cash under the table.

 

[snowtrac nome]

The answer to this question is yes it can be done it is a bit more work to do it on the side, I have done it so I know it can be done we wont discuss the language used in trying to line up all the splines.

 

[Clark19]

How much does the rear cover on the trans weigh?
Do I need a jack for it, or just muscle it down?

 

[The HUlk]

Sorry to to hear about your trouble, what a bummer thing to have happen. You may be able to drive it somewhat but I’m thinking there’s major damage. And metal shavings worked all through it from driving it broken. The converter is probly full of metal as well. I’d say the shortest path by far to getting your truck roadworthy is to source a useable transmission with torque converter and swap it. Then deal with the carcass of the old transmission IF it’s salvageable which at this point is questionable.

1. If I remove the rear of the trans while it is still horizontal in the truck, will all the parts fall out in a heap on my floor.

I’ve witnessed multiple automatic transmissions being rebuilt and much of the disassembly/reassembly process is done from the bell housing end. Because of this I would say there is no need to worry about ALL of the parts falling out. In fact I believe it’s safe to say that there are parts that should at least be inspected and more than likely need to be replaced that you will not be able to remove without removing the transmission and tearing it down from both ends.


2. With the rear trans cover off, will I be able to pull out the parts one by one or in bunches connected together, so I can acces the broken parts in the back center of the trans?

Again, you’ll need to tear it down from both ends to get access to all that needs inspection.


3. Is the above a good idea or am I going to create a disaster on my garage floor?

I’ve been in a few transmission shops in my day and they all looked like a disaster happened. ATF everywhere, etc.

 

[snowtrac nome]

How much does the rear cover on the trans weigh?
Do I need a jack for it, or just muscle it down?

the rear cover is light the gust inside are what is heavy but every thing will come apart in small pieces and go back the same.

 

[Jericho]

Best of luck with your tranny troubles Now it seems reasonable for a detent from N to R , but i must say there is no such monster on my shifter, I never even thought about it until some of you mentioned it , Now I wonder ?! will have to look into it !