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Old 09-27-2018, 11:45 AM   #1
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allison 2500

Do these have the lockup? Looking at a full size with DT466 that's suppose to have one of these. This could just be my lucky day.
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Old 09-27-2018, 09:00 PM   #2
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Originally Posted by pcdreams View Post
Do these have the lockup? Looking at a full size with DT466 that's suppose to have one of these. This could just be my lucky day.
Lockup AND overdrive.

I've got a bus with a 466/2500 and its SWEET.
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Old 09-27-2018, 09:16 PM   #3
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The 2500 comes in 5 and 6 speed models with both lockup and overdrive as EastCoastCB has stated. They are basically the same transmission with a software unlock. Both 5th and 6th gears are overdrive. Here's the ratio chart.

First 3.51 : 1
Second 1.90 : 1
Third 1.44 : 1
Fourth 1.00 : 1
Fifth 0.74 : 1
Sixth 0.64 : 1
Reverse -5.09 : 1

Even better, here's the spec sheet on them: https://www.allisontransmission.com/...rsn=877fbf1c_2
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Old 09-27-2018, 09:24 PM   #4
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Quote:
Originally Posted by Pizote View Post
The 2500 comes in 5 and 6 speed models with both lockup and overdrive as EastCoastCB has stated. They are basically the same transmission with a software unlock. Both 5th and 6th gears are overdrive. Here's the ratio chart.

First 3.51 : 1
Second 1.90 : 1
Third 1.44 : 1
Fourth 1.00 : 1
Fifth 0.74 : 1
Sixth 0.64 : 1
Reverse -5.09 : 1

Even better, here's the spec sheet on them: https://www.allisontransmission.com/...rsn=877fbf1c_2

the 2500 camew in 5 speed up until 2006.. from 2006 on it is capable of 6 speed with a 4th or 5th gen TCM and software changes.. no school bus is produced wuith 6th unlocked.. several forum threads are open about the procedures for 6th.. the pre-2006 models were 5 speed only models unless you change the TCM, harness and the valve body... the upgrades arent cheap... the pre 06 models simply had the rotating assembly and clutch pakcs for 6 gears but werent set up to ever utilize them...



-Christopher
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Old 09-27-2018, 09:27 PM   #5
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the 2500 camew in 5 speed up until 2006.. from 2006 on it is capable of 6 speed with a 4th or 5th gen TCM and software changes.. no school bus is produced wuith 6th unlocked.. several forum threads are open about the procedures for 6th.. the pre-2006 models were 5 speed only models unless you change the TCM, harness and the valve body... the upgrades arent cheap... the pre 06 models simply had the rotating assembly and clutch pakcs for 6 gears but werent set up to ever utilize them...
Thanks for the clarification - I knew about the upgrades, just wasn't able to pull it from the recesses of my brain ;)
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Old 09-28-2018, 08:47 AM   #6
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I've got the Allison AT545 in mine. Put her in gear, and she starts crawling at idle, and responds well in nearly all situations, except at the "line" between 2nd and 3rd - coasting at around 22MPH on a slightly bumpy, horizontally flat road with little to no fuel, the tranny "shudders" as it rapidly switches back and forth between 2nd and 3rd; I think this is related to the "bouncy" rear-end as torque is loaded and unloaded into the system in these specific conditions. That said....

I don't use my bus to carry a load of kids, stopping at every street corner, trying to give them a safe, smooth ride. Mine is now a highway vehicle, and I want an overdrive. I was thinking of the Alison AT3020 (I think it was called), but now I realize there is the AT2500 also. Can anyone say anything about the differences, strengths and weaknesses of these units?

I am really thinking of selling my AT545 while it is still in great condition while I can still get some cash out of it, and installing an overdrive unit. After crossing the country with the AT545 at 2500RPM, I think I could get so much better fuel mileage in my 5.9L Cummings (don't they call this motor "the sipper?"). I drove manual tranny vehicles most of my life, and I am always wanting to reach down and upshift to pull the low-end torque out of my motor, but this tranny only understands high-end horsepower, and, as the owner's manual states, is designed to keep the RPM's high for an extended period of time, for city driving.
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Old 09-28-2018, 10:15 AM   #7
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Good luck selling the 545. I offered my fully operational unit for free and got no takers. Not even as a core. Called a couple of heavy duty tranny shops and they passed on it too. Went as scrap.
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Old 09-28-2018, 12:57 PM   #8
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When I upgrade my transmission I'll have a fresh reman 545 up for grabs... I bet I'll end up scrapping it.
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Old 09-28-2018, 01:13 PM   #9
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There is a trend here. A couple of the big tranny shops I offered it to free said they don't even work on 545's any more (?).
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Old 09-28-2018, 05:12 PM   #10
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Quote:
Originally Posted by Mountain Gnome View Post
I've got the Allison AT545 in mine. Put her in gear, and she starts crawling at idle, and responds well in nearly all situations, except at the "line" between 2nd and 3rd - coasting at around 22MPH on a slightly bumpy, horizontally flat road with little to no fuel, the tranny "shudders" as it rapidly switches back and forth between 2nd and 3rd; I think this is related to the "bouncy" rear-end as torque is loaded and unloaded into the system in these specific conditions. That said....

I don't use my bus to carry a load of kids, stopping at every street corner, trying to give them a safe, smooth ride. Mine is now a highway vehicle, and I want an overdrive. I was thinking of the Alison AT3020 (I think it was called), but now I realize there is the AT2500 also. Can anyone say anything about the differences, strengths and weaknesses of these units?

I am really thinking of selling my AT545 while it is still in great condition while I can still get some cash out of it, and installing an overdrive unit. After crossing the country with the AT545 at 2500RPM, I think I could get so much better fuel mileage in my 5.9L Cummings (don't they call this motor "the sipper?"). I drove manual tranny vehicles most of my life, and I am always wanting to reach down and upshift to pull the low-end torque out of my motor, but this tranny only understands high-end horsepower, and, as the owner's manual states, is designed to keep the RPM's high for an extended period of time, for city driving.



OK.. so you can buy a fully reman AT545 for aboiut $550 so that doesnt bode well for you selling a somewhat Busted AT545 for much..


yours is doing the 2-step Dance.... thats a sign its getting pretty low line pressure at low RPM... line pressure drops it downshifts.. then the RPM goes up because the 2-3 gradient is enough the engine rpm spikes... that spins thye pump faster and now it upshifts.... slow-down the engine RPM. and it drops pressure again... you get the shudder..



you can put a line pressure gauge on it to be sure.. but its on its way to being a great anchor for someone's Boat...



you want to upgrade? go with a BUILT 1000 or a 2000 series swap... its gonna be some work.. you can read my thread 'RedByrd Transformation' top see what it takes to upgrade from a mechanical transmission to a 6 speed overdrive.. I chose a brand new performance built 1000 for my build.. others have bought a working pull for a 2000 from their engine from a bus. which saves some coin..



going to the 3060. is going to require some mechanical work in extra frame mounts, a new shifter.. plus the electronics.. and the sheer weight of stuffing it up under the bus..



to stay all mechanical you can go 643 which is heavy. and no overdrive but its darn near bulletproof ... on a cummins 5.9 you'll need an extra support for a 643 to go in as well.. as well you may need a new flywheel housing..



for those with a navistar DT-360/408/466(e). just pull the SAE3 ring, swap the flexplate, bolt up a 643 and roll wheels...





can you save your 545? you can drop the pan, swap the filters both internal and external and see if you get lucky.. but most likely you will find lots of metal materials on your pan magnet (and your VSS sender) which usually is the reason the line pressure is next to nothing at idle...



-Christopher
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