Is an Allison 2500 enough?

[JasonHurst.studio]

Hello everyone. I’ve always read that the Allison MD 3060 was one of the best transmissions you can get on the bus, especially with a large displacement engine like the Cummins 8.3. I found a bus in great shape, but it has an Allison 2500 transmission in it. It’s a 2000 bluebird all America. 40 foot diesel pusher With a Cummins 8.3 I’m gonna do a roof raise and a full build out and the bus will not be light in any way. . Is the 2500 enough for this or should I wait to try to find a MD 3060? Thank you for all your help

 

[Albatross]

If you're going to do a roof-raise, then you can always do a tranny-swap, as that is usually much easier and quicker than a roof-raise.

 

[JasonHurst.studio]

Yeah,, my expertise is in metal fabrication so the roof raise is very much in my wheelhouse changing a very heavy very expensive transmission on a bus is not within my wheelhouse. I’m sure I can get it done, but I would much rather buy the power train in the proper spec to begin with if you know what I mean

 

[nikitis]

If you're going to do a roof-raise, then you can always do a tranny-swap, as that is usually much easier and quicker than a roof-raise.

Is it? I'm finding it to be more difficult to swap my transmission out than doing a roof raise personally.

A roof raise you just cut and weld, rivet, and paint.

A transmission swap at least in my case means obtaining a TCM, figuring out how to make it work with J1708 networks which it was never designed to do. Shortening the drive shaft, figuring out how to make the throttle not go to zero when using cruise control thus telling the transmission to not shift etc. It's pretty complex.

Unless of course you are lucky and only need to unbolt and rebolt and everything else is compatible already.

 

[nikitis]

Yeah,, my expertise is in metal fabrication so the roof raise is very much in my wheelhouse changing a very heavy very expensive transmission on a bus is not within my wheelhouse. I’m sure I can get it done, but I would much rather buy the power train in the proper spec to begin with if you know what I mean

So my opinion is that the AT2500 is better than an AT545, but not by a lot. They are newer so they will last but if you are looking to push highway speeds, it's not much better than At545.

I could be wrong but from observing people on the forums and speeds they achieve with their 2500 seems to be on par with the 545 or slightly better.

A 3060 is great and much better. And I even get the impression the 2000 is better than 2500, and 1000 is better than the 2000 for older buses. Newer buses should shoot for 3060, and older buses the 1000.

 

[Albatross]

Well apparently I am wrong, but then I also work in a machine shop, and have done a ton of mechanical maintenance, so it's the sort of thing that makes more sense to me--whereas doing precision cuts over a long length, fabbing the supports, and then getting the height just right and doing nice welds to seal everything up is more intimidating to me.


So what, I'm wrong, it's happened before, and it's sure to happen again. I'd just rather do with a repower than a roof-raise.

 

[nikitis]

Well apparently I am wrong, but then I also work in a machine shop, and have done a ton of mechanical maintenance, so it's the sort of thing that makes more sense to me--whereas doing precision cuts over a long length, fabbing the supports, and then getting the height just right and doing nice welds to seal everything up is more intimidating to me.


So what, I'm wrong, it's happened before, and it's sure to happen again. I'd just rather do with a repower than a roof-raise.

Hehe. I see yeah, it's people coming from two different directions. I wouldn't say your wrong, just trying to understand if it's just about perspective or if I'm missing something. My history I've done more metal work so it seems far less intimidating for me and your opinion on the difficulty being easier has intrigued me because I never thought about it that way. Us with plenty of metal fab experience and little mechanical experience think one way, and you guys with more mechanical experience see the metal fab as more extensive.

Again no judgement, just interesting to me. I'm likely the wrong one here if anything as I haven't done a transmission swap. I'm not scared of the bolting and unbolting. I'm more scared of the additional wiring in my case as it's not simply plug and play, and if I go to those lengths and it doesn't drive cause I screwed up the wiring, then I have quite a giant paperweight so that's where our fears come from since we're not mechanics by trade.

 

[PorchDog]

From the School Bus Fleet forum--the last comment was from an administrator on said forum---FWIW--

While both are six speed transmissions, these are completely different transmissions built in different cases with different internal parts built to handle different torque and horsepower ranges. The 2500 will handle the torque rating of 660lb on a Cummins ISB but will not be adequate for the 860lb torque rating of a Cummins ISC. My general rule of thumb is 280hp and less on the ISB, the 2500 will be adequate. A 300HP ISB and all HP ranges on the ISC gets the 3000.

Here is a link with more rating information.

http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=SA3362EN.pdf

Here is the real difference I have experienced: If you plan to keep the bus for 12-20 years, and you select the 2500 series, then be sure you have an adequate transmission jack to replace it a time or two.

3000 is a tough SOB and my first choice seeing how I cannot accept less than 15 years of good, reliable service.

 

[kromboy]

Tough call but if the engine is a 6CT and not an ISC, I would definitely go for it despite the tranny being 2500.

If you have the VIN for the bus or ESN of the engine I can look it up for ya.

 

[Albatross]

Hehe. I see yeah, it's people coming from two different directions. I wouldn't say your wrong, just trying to understand if it's just about perspective or if I'm missing something. My history I've done more metal work so it seems far less intimidating for me and your opinion on the difficulty being easier has intrigued me because I never thought about it that way. Us with plenty of metal fab experience and little mechanical experience think one way, and you guys with more mechanical experience see the metal fab as more extensive.

Again no judgement, just interesting to me. I'm likely the wrong one here if anything as I haven't done a transmission swap. I'm not scared of the bolting and unbolting. I'm more scared of the additional wiring in my case as it's not simply plug and play, and if I go to those lengths and it doesn't drive cause I screwed up the wiring, then I have quite a giant paperweight so that's where our fears come from since we're not mechanics by trade.

I'm also a kind of perfectionist, so when I start to make something (from scratch), it really, really turns into that artistic conundrum of never being good enough, or "just right".



But it's also easier for me to pick up a grab-bag of parts, and figure out a way of doing something--especially if that "something" has already been designed or engineered before, like gears. But things like "cutting straight lines" always gets to me because the perfectionist in me knows just how imperfect any straight line actually is.


And being primarily a wire-biter above anything else, adding sensors and the like is much easier for me to figure out than anything else. Especially if I know what's going on inside the magic black boxes. But yes, even that, even there, I have been known to "let the genies escape in their magic blue smoke" once or twice before.

 

[JasonHurst.studio]

I just wanted to say thank you all for your responses! This community is excellent and this is exactly the feedback I needed. I will hold out for the MD3060. The bus with the 2500 is super clean and low miles but it's just not the transmission that I want to get married to.
Thanks again for answering my questions.
J

 

[BamaBus]

The bus with the 2500 is super clean and low miles but it's just not the transmission that I want to get married to. J

Do you have a link to this bus that is for sale?

 

[JasonHurst.studio]

Sure, here you go…
https://www.facebook.com/share/p/tqG8EnKC6nxjjtyg/?mibextid=79PoIi

 

[cadillackid]

the engine looks like an 8.3 ISC and the transmisison is an MD3000 series not a 2500..

 

[JasonHurst.studio]

the engine looks like an 8.3 ISC and the transmisison is an MD3000 series not a 2500..

He swore up and down that it was the 2500. How can you tell. I knew the engine but could not tell the transmission

 

[cadillackid]

the one pic of a side view of the driver compartment you can make out the outlines of the electronic pushbutton shift pad.. the 2500 PTS requires a handle shifter... the 3000 series are fully electronic and can utilize an electronic pushbutton shift pad..

 

[JasonHurst.studio]

Ahh that’s the knowledge of experience. Thank you
I had him send me an image of the build plate with the serial numbers, but I could not decipher the model number of the transmission.

the one pic of a side view of the driver compartment you can make out the outlines of the electronic pushbutton shift pad.. the 2500 PTS requires a handle shifter... the 3000 series are fully electronic and can utilize an electronic pushbutton shift pad..

 

[BamaBus]

ISC 250 Cummins(built in '99) with a MD3060 transmission, according to the posted serial numbers. Originally from Woods County Schools in West Virginia. Do they salt roads there?

 

[BamaBus]

Is that 586,620 miles on the odometer?

 

[kromboy]

Looks like 58662 miles, there's a decimal at the end and first digit is unoccupied.

379 hours? assuming it rolled over, 10379hrs, average speed 5.65mph sounds about right for a local route.

Is that 586,620 miles on the odometer?