What engines and transmissions to avoid

[gbstewart]

geeezz, I guess I should just blow up my bus, it has t444e with a at545, I have had it for almost 5 years, put 25000kms with a few steep grade hills, never had a problem, I did replace the injectors, but it has 240,000kms on it, what am I missing here? my bus runs just fine, shift fine and get 10.5 mpg average.
gbstewart

[nat_ster]

Originally Posted by gbstewart

geeezz, I guess I should just blow up my bus, it has t444e with a at545, I have had it for almost 5 years, put 25000kms with a few steep grade hills, never had a problem, I did replace the injectors, but it has 240,000kms on it, what am I missing here? my bus runs just fine, shift fine and get 10.5 mpg average.
gbstewart

What RPM does your engine meet peak torque?

I suspect that it's higher than the 1600 RPM that the 12 valve Cummins run.

My main issue with the 545 is the needing 2000 rpm or better to keep the converter locked. The poor Cummins hates it.

Nat

[Hank's P-O-S]

Originally Posted by nat_ster

What RPM does your engine meet peak torque?

I suspect that it's higher than the 1600 RPM that the 12 valve Cummins run.

My main issue with the 545 is the needing 2000 rpm or better to keep the converter locked. The poor Cummins hates it.

Nat

The T444e makes peak torque at 1400 RPM.


I understand that people want an "easy" bus to drive, but dammit, you will never convince me that an auto. Will out live a manual.
Manuals are also like a poor mans cruise control, you can only go so slow and so fast in each gear.
Notice how the only people who drive autos are North American? Yeah, there is a reason for that....

[Tango]

545's are tough and work just fine for what they are. But if you need better mpg's , lockup and OD...the only answer is something newer.

[cadillackid]

Originally Posted by Tango

I have a "FREE" AT545 for anyone who cares to pick it up. Yes...it was a "runner" when taken out.

It was replaced with a 5th generation Allison 2200MH six speed with double OD. Great thing about the New Gens is that they can plug & play with old school all mechanical engines, unlike the previous series. A single built-in processor lets it communicate with any engine via nothing more than a throttle position sensor.

The newer automatics are full lockups and will get better mileage than a standard. And to my simple mind, Allison builds just about the best there is.

how did you go about finding and acquiring your 2200MH that fully integrates without an engine PCM? everythign I find on the 2000 series makes me think I have to buy that special $1600 TCM from destroked or have to have some inputs from an engine PCM to feed to the TCM?

not that I have any idea ow tough going from an AT545 to a 2200 will be.. but mechanics are mechanics.. I think I read where at least the 1000 series from an AT545 only required like 3/4 difference in length and a rather easy rear mount adjustment...

-Christopher

[Tango]

The ability to operate without talking to the engine is really what sets the 5th gen trannies apart. As noted, all they need is input via a TPS (throttle position sensor). As the Allison rep explained it to me, they have a single computer within the transmission that "learns" it goes. Sounds like voodoo but they work. It does need to be flashed once everything is hooked up but it is nothing like the earlier units. There are a couple of guys over on 4BTswaps.com that have been trying get some 4th gen Allisons to talk to various motors for years now with no luck. Due in part on one because the engine is a GM and they will not share any of their code with anyone. They are stuck basically trying to "hack" the code, then have to hand build a complex wiring harness to get them to work together. I guess Allison got tired of the hot-rodders complaining and came up with this solution.

I worked directly with the Allison rep at Stewart & Stevenson, but just got lucky on the timing. They had just come out.

[cadillackid]

Originally Posted by Tango

The ability to operate without talking to the engine is really what sets the 5th gen trannies apart. As noted, all they need is input via a TPS (throttle position sensor). As the Allison rep explained it to me, they have a single computer within the transmission that "learns" it goes. Sounds like voodoo but they work. It does need to be flashed once everything is hooked up but it is nothing like the earlier units. There are a couple of guys over on 4BTswaps.com that have been trying get some 4th gen Allisons to talk to various motors for years now with no luck. Due in part on one because the engine is a GM and they will not share any of their code with anyone. They are stuck basically trying to "hack" the code, then have to hand build a complex wiring harness to get them to work together. I guess Allison got tired of the hot-rodders complaining and came up with this solution.

I worked directly with the Allison rep at Stewart & Stevenson, but just got lucky on the timing. They had just come out.

ive done a lot of reading and in the past work with electronic trannies.. I built my own controlers to run the 4L60E and 4L80E in my past-hotrod-life.. the new allisons use the TPS as the main input.. (more or less as a replacement for the shift cable thats present on the AT545 / MT643). and then they ALSO have inclinometers in them (that also act as accelermoeters) to help the transmission know what you are doing.. so for instance you are going down hill and let completely off of the go pedal.. it knows you are likely trying to maintain or slow down speed so it can act accordingly .. it also knows if you are pulling a hill and back off the accelerator a little and you are in 4th or 5th gear to not immediately shift to 6th because chances are you will soon be pressing back down.. and on that incline angle at that speed level you most likely need X-gear and Y-apply of the converter .. it remembers and averages various driving conditions you put it through and adapts accordingly.. an allison shop(im told) can also "tune" it initially with your vehicle;s parameters.. weight, physical size, expected use, and personal preference.. "ie do you like hard or soft shifts overall" etc.. I havent gotten that far yet..

allison has never "given up" their communications protocols.. im not sure how the folks at Destroked were able to make a custom allison controller standalone.. but they are the only ones who claim to have one that will run an older 1000 / 2000 standalone.. they charge $1600 for their box...


im sure many are asking why I would buy an older bus just so I can put $1000s into making it "newer".. however I just like the industrial,metal,heaviness etc of older busses.. the newer IC's just feel "flimsy".. and I dont like the car-like plastic interiors of the newer Busses...

for me being DT360 mechanical and AT545.. I can EASILY turn up the DT360 a bit (20-30 Horsepower is easy without hurting anything).. and getting an O/D trans in there would be the next logical update..

I just need to find an allison guy to work with me on what I would need for a swap... (i'll put some miles on my bus before I make the swap just to see if its necessary)... and then to get me in the right direction of ordering the correct parts(adapter plates, flex plate, bell, etc).. there are many different ways to mount a TPS also.. from pedal mount to at the throttle under the hood.. ive put plenty of TPS's on old Carb'd cars in the past so I dont think i'll have an issue mounting and tuning a TPS on my bus...

this is great stuff!!!

-Christopher

[turf]

that allison 2200mh sure would be a nice upgrade!!!

i just did the math on the overdrives.

my bus is the 5.9 w/the at545. 41" tire diameter, 2600 rpms, and a 4.78 differential.

4th gear is 1:1 gives me the same speed as the at545 - 67mph

5th gear is .71:1 and take the bus up to 95mph!!

6th gear is .61:1 and approaches the sound barrier for a bus (110 mph)


wowsa!!

[Tango]

The "Prime Directive" on my build was to achieve maximum mpg & engine longevity. I started with the Cummins 4BT's "sweet spot"...the rpm range that it is most happy at and did what I could to get reasonable highway speed while staying within that range. For the 4BT, that is about 1800 RPM which is just 100 RPM's above the motor's peak torque. Peak HP is at 2100. You can wind it higher, but unless you are drag racing or pulling a sled, you won't gain anything or be doing the engine any favors. As Cadillac noted, diesels are all about producing big torque at relatively low RPM's. Torque is what moves a load. But to effectively use that torque requires the right gearing to get it to the ground. Even tire size plays a big role. You have probably been passed on the highway at 70 by a big rig hauling a big load and may have noticed the engine sounded almost like it was idling. That is what the right gearing is all about. And having more gears makes it that much easier to stay in any engines sweet spot. You may have also noticed that the trend among the new cars these days is to have trannies with 6, 8 and more gears. No more three on the tree. They are finally doing what the trucking industry has been doing for decades...optimizing the torque curve for maximum efficiency and mpg. We skoolie builders can do the same and reap big benefits.

[cadillackid]

Originally Posted by Tango

The "Prime Directive" on my build was to achieve maximum mpg & engine longevity. I started with the Cummins 4BT's "sweet spot"...the rpm range that it is most happy at and did what I could to get reasonable highway speed while staying within that range. For the 4BT, that is about 1800 RPM which is just 100 RPM's above the motor's peak torque. Peak HP is at 2100. You can wind it higher, but unless you are drag racing or pulling a sled, you won't gain anything or be doing the engine any favors. As Cadillac noted, diesels are all about producing big torque at relatively low RPM's. Torque is what moves a load. But to effectively use that torque requires the right gearing to get it to the ground. Even tire size plays a big role. You have probably been passed on the highway at 70 by a big rig hauling a big load and may have noticed the engine sounded almost like it was idling. That is what the right gearing is all about. And having more gears makes it that much easier to stay in any engines sweet spot. You may have also noticed that the trend among the new cars these days is to have trannies with 6, 8 and more gears. No more three on the tree. They are finally doing what the trucking industry has been doing for decades...optimizing the torque curve for maximum efficiency and mpg. We skoolie builders can do the same and reap big benefits.

the new car manufacturers also have the added benefit of VVT.. helps to make the engine work around your own torque / HP curve..

something I could wish for in a bus.. oh wait maybe not.. ive already had that VVT serviced on my Silverado with 3000 miles...

-Christopher

[turf]

when i saw that 110mph number i knew i wasnt doing something right.

makes sense, back off the rpms to max torque and fuel economy, and that be a sweet setup!

[Robin97396]

They're doing better than 110 with those truck/tractor races. I start chickening out at about 60.

[cadillackid]

Originally Posted by Robin97396

They're doing better than 110 with those truck/tractor races. I start chickening out at about 60.

ive never seen them hit 110 in the school bus races.. but they ruin a lot of nice busses
'

[EastCoastCB]

Originally Posted by cadillackid

ive never seen them hit 110 in the school bus races.. but they ruin a lot of nice busses
'

Our sheriff died in one.

[sojourner]

Having been a marine mechanic for over 25 years, I can testify that all manufacturers have proprietary parts and they're all high. On my DT408 the rubber connection from the aftercooler pipe to intake was over $80.00. Worth every penny though. With a split in it the bus wouldn't get out of its own way from bleeding of all its boost. After replacing it, it looked for hills to eat😀!!
Aftermarket support varies and is usually tied more to the truck market (in our case medium duty). If serviced and not allowed to overheat, most won't use their rigs enough to require a rebuild on the engine. Fortunately, the parts we'll most likely need like brakes, tires, filters, etc are easily sourced via aftermarket.
That being said, my International is the first of its kind I've personally owned and can tell you, it was worth the wait. The 408 is a bit of an oddball (a de-stroked 466) but runs like a sewing machine. Coupled with the MT643 it's near bulletproof.

[cadillackid]

Originally Posted by sojourner

Having been a marine mechanic for over 25 years, I can testify that all manufacturers have proprietary parts and they're all high. On my DT408 the rubber connection from the aftercooler pipe to intake was over $80.00. Worth every penny though. With a split in it the bus wouldn't get out of its own way from bleeding of all its boost. After replacing it, it looked for hills to eat😀!!
Aftermarket support varies and is usually tied more to the truck market (in our case medium duty). If serviced and not allowed to overheat, most won't use their rigs enough to require a rebuild on the engine. Fortunately, the parts we'll most likely need like brakes, tires, filters, etc are easily sourced via aftermarket.
That being said, my International is the first of its kind I've personally owned and can tell you, it was worth the wait. The 408 is a bit of an oddball (a de-stroked 466) but runs like a sewing machine. Coupled with the MT643 it's near bulletproof.

for the internationals and the cummins there is quite a bit of aftermarket support as the Diesel-truck guys got in on the action...

AND also dont always try to look up parts for a school bus.. as the older conventional busses like a lot of us are buying are simply a Box truck with a bus instead of a box..

an International S-3800 was the "school bus" chassis version of a 3800 truck.. so finding parts for a 3800 truck such as wheels, tires, transmissions, belts, hoses, fuel injectors, turbo parts, etc will fit the S-3800.. now things like windshield wipers and light bulbs? not so much (unless its for the hood mounted lights).. as those are parts for the Body which were many..

so for those newbies you may think your whole bus is an "international" but you may find that just the chassis was international and the bus body may be Thomas, bliuebird, carpenter, wayne, crown, superior, etc there will be a tag inside the bus above the driver seat that will tell you who made the body on the bus...

-Christopher

[Scooternj]

Originally Posted by cadillackid

so for those newbies you may think your whole bus is an "international" but you may find that just the chassis was international and the bus body may be Thomas, bliuebird, carpenter, wayne, crown, superior, etc there will be a tag inside the bus above the driver seat that will tell you who made the body on the bus...

-Christopher

Unless, of course, it *is* an International Bus (Ward, Amtran, IC Bus) But even then, I go by the model number. It's an International 3000RE, and when I talk to the local International bus dealer or questing for parts online, I use that information.

[cadillackid]

Originally Posted by Scooternj

Unless, of course, it *is* an International Bus (Ward, Amtran, IC Bus) But even then, I go by the model number. It's an International 3000RE, and when I talk to the local International bus dealer or questing for parts online, I use that information.

true that.. ive always wondered how to figure out what some of the busses are.. ie I saw a wierd looking Blue-bird yesterday.. dog-nose bus but just said blue bird all over it.. kind of a wierd shape.. so id have no idea what the chassis is on it.. it's new enough it was still carrying kids.. but in a few years its someone's future Skoolie..

-Christopher

[Scooternj]

I remember reading somewhere that when IC Bus builds the chassis for another coachmaker, they add that maker's logo instead of the International shield. It's possible it could have been a new 3800-series

[yeggs]

My general attitude is "if you can't open it, you don't own it."

So, when it comes to bus transmissions and engines, that, to me, means older, non-electronically controlled stuff. I'm no neo-luddite. Computer control has great potential, but practically as it relates to skoolies, Cat and allison are deliberately designed to be hard to work on. They want licensed, certified, lawsuit-weary techs to work on them. The result is two things: these engines and transmissions are slightly more efficient and very slightly cleaner, and are finicky and difficult to shadetree mechanic. Proprietary tools, licensed software, expensive adapters, on and on.

Cummins has a slightly better reputation... that in my experience is not deserved. YMMV. The older internationals I've monkeyed with have been pretty straight forward.

So, the question is kind of a style question: Are you a shadetree mechanic? Are you going to burn vegetable oil? Are you going way "out there"? Or do you never open the engine bay? Want to put it in "D" and go 80 on the highway without another thought?

Personally, I'd love an auto with a lockup torque converter... but the hoops I've seen folks on these boards jump through to get allison to "allow" them to use the two lockup gears on the equipment that they own is ridiculous, and doesn't work for my "way out in it" backwoods diy style. I just don't trust things I can't open if they break. Slow, dirty and old school is how I roll.