Allison 1545 Automatic Transmission Specs

HDN

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I saw this posted in the 1545 failure poll and was surprised to see it wasn't repeated here:

Not exactly the thread for this, but I'm trying to (discretely) spam this info I just found about AT 1545s:

For those 1545s with serial #s GREATER than 321-101-6535 (or retrans GREATER than 9108-0912-20), there is a newer option for the front pump. This newer option involves replacing the front pump and stator. It retains the lockup. Darpco in Dallas (likely among others) can assist with this.

Good luck!
SJ
 

HDN

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I have a 545 and I have changed the transmission fluid and filters ... it seems to be doing fine except if I don't hold the peddle to the floor when speeding up the transmission jerks when going from 3rd to 4th ....any ideas about what could be going on ?
It is my understanding that this is normal behavior for the 545 transmission. My truck and another owner's do the same thing. It just clunks into 4th gear, and the tranny takes its time shifting into third. I almost thought it was going into another gear between where it felt second and third were!

FWIW my experience has only been with the motor oil it came with. I plan on switching to ATF in the spring.
 

rustystud

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I have a 545 and I have changed the transmission fluid and filters ... it seems to be doing fine except if I don't hold the peddle to the floor when speeding up the transmission jerks when going from 3rd to 4th ....any ideas about what could be going on ?
To much "governor" pressure. Your using "modulator" pressure to counter-act the high "governor" pressure when you hold the pedal to the floor.
The governor weights could be sticking. Take it apart and clean it real good.
 

HDN

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To much "governor" pressure. Your using "modulator" pressure to counter-act the high "governor" pressure when you hold the pedal to the floor.
The governor weights could be sticking. Take it apart and clean it real good.
I'll have to get this checked out now. Although my jerk may be different from the other guy's jerk. Probably best for me to get it checked out at the local Allison shop and have them do the ATF conversion as well!
 

URSATDX

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I am planning on doing the MO to ATF conversion on my Allison 1545. I will introduce the ATF thru the check/fill tube. In order to insure a complete and thorough flush what would be the best point to disconnect the flow circuit so that the entire trans and cooling system are flushed. I’m assuming the ideal disconnect would be at the return line at the transmission. Thoughts? If this seems to be the best location, I would need to confirm the direction of flow of the MO/ATF in the system. I am ASSuming that the fluid flows from the trans to the top of the radiator out the lower radiator to the trans cooler (top) and from the cooler back to trans. If this is the correct direction of flow then I will proceed to flush until the fluid at the trans return line is all ATF and no MO. I’d then drop the pan, replace filter and gasket. Replace the inline spin on filter, run and adjust fluid level.

Suggestions on ATF types?

Any thoughts from the troops?

Much appreciated.

God Bless our Great Country!
 
Last edited:

rustystud

Well-known member
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Location
Woodinville, Washington
I am planning on doing the MO to ATF conversion on my Allison 1545. I will introduce the ATF thru the check/fill tube. In order to insure a complete and thorough flush what would be the best point to disconnect the flow circuit so that the entire trans and cooling system are flushed. I’m assuming the ideal disconnect would be at the return line at the transmission. Thoughts? If this seems to be the best location, I would need to confirm the direction of flow of the MO/ATF in the system. I am ASSuming that the fluid flows from the trans to the top of the radiator out the lower radiator to the trans cooler (top) and from the cooler back to trans. If this is the correct direction of flow then I will proceed to flush until the fluid at the trans return line is all ATF and no MO. I’d then drop the pan, replace filter and gasket. Replace the inline spin on filter, run and adjust fluid level.

Suggestions on ATF types?

Any thoughts from the troops?

Much appreciated.

God Bless our Great Country!
The return line is located directly behind the breather vent. This is the procedure we used at the transit agency to flush the bus transmissions. Just be careful ! Don't allow the transmission to run dry ! That would destroy your oil pump in a heart beat !
Since I'm pretty sure you don't have ATF on a pressure system like the transit department does, (we just put the nozzle in the transmission fill tube and pulled the trigger and out poured ATF at 20 gallons a minute) you need to run the engine in short bursts. Then top off the transmission and run it again. Do this until the fluid runs clear ATF.
 

URSATDX

Member
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Location
So Jersey, NJ
The return line is located directly behind the breather vent. This is the procedure we used at the transit agency to flush the bus transmissions. Just be careful ! Don't allow the transmission to run dry ! That would destroy your oil pump in a heart beat !
Since I'm pretty sure you don't have ATF on a pressure system like the transit department does, (we just put the nozzle in the transmission fill tube and pulled the trigger and out poured ATF at 20 gallons a minute) you need to run the engine in short bursts. Then top off the transmission and run it again. Do this until the fluid runs clear ATF.
Thanks for the response, Rusty.
Looked thru TMs for answers, but I have a hard time navigating thru them.
I do have an ATF dispenser (gun) fed from a 110 gal tank. (Own/operate a quick lube).
The tank is filled with a multi veh full syn ATF. (Specd for Allison / Allison (C-4 / TES-295 / TES-389) . I will look for a diagram of the 1545 to be sure I pull the correct line. I'll keep you posted on the results.
Thanks again.
God Bless America.

1580153467767.png
 

Sgt Jiggins

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I'd like to make one more add to this thread: after having my 1545 rebuilt the rebuilder suggested using "John Deere Hy-Gard Transmission and Hydraulic Fluid" (not just Hy-Gard Hydraulic Fluid - there apparently is a difference?) in it. I know fluids in these things come up in discussion frequently and don't want to start a battle with this information but maybe put it out there as an alternative in case people are still not happy with other options.

As always, YMMV har har
 
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