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Old 04-05-2013, 08:38 AM   #1
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Re: Engine and Transmission Questions - looking at two busse

INTERESTING ENGINE,just read the pdf about it

http://www.demanddetroit.com/pdf/voc...-schoolbus.pdf

I wouldn't want it because of all the electronics of it

I don't think many older used buses would have this engine, weird that it's coupled with a A545 tranny seems to new for that tranny

Are you sure on the tranny,those power numbers are alittle high for A545

Engine brake standard,thats neat

What year bus are you looking at?

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Old 04-06-2013, 10:53 AM   #2
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Re: Engine and Transmission Questions - looking at two busse

The DT usually has a 545. You cant go wrong with that engine. Wet sleeved so you need to keep after the coolant ph and nitrites, etc. I would check gear ratio and be sure it will get you down the hwy at a reasonable speed.
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Old 04-08-2013, 05:20 PM   #3
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Re: Engine and Transmission Questions - looking at two busse

Its an acceptable transmission. Most school buses have the 545. If you are not going to be in the mountains much, it will be just fine. It doesnt have a lock up converter so going up you will have to watch tranny temp. Going down you will be relying on your brakes and not the tranny.
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Old 04-09-2013, 07:29 AM   #4
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Re: Engine and Transmission Questions - looking at two busse

Like Opus said the tranny is fine on flat ground,up and down the mountains is not it's element

Where I live it's up and down mnts to go anywhere...on flat ground it "idles" at 60 in 4th gear
.
.
.
Normally I stay in 3rd gear at 2200/2500 and thats 45/50 (narrow back roads and lots of up and down) just have to watch tranny temp
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Old 04-12-2013, 06:06 PM   #5
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Re: Engine and Transmission Questions - looking at two busse

Just know that a FE bus is going to be LOUD! 230k miles isnt an issue. Check the engine hour meter, that is far more import than miles. I think we talked about this before but I think you would be much happier if you picked up something out west. You would eliminate the rust problem and chances are you would get a bus better suited for highway use. Rear axle ratio is going to be important for you too. I am thinking that something with a 545 will have a lower gear ratio, therefore limiting highway speeds. Not positive on that though.

Sorry to be negative but I would rather be negative about what you HAVEN'T bought, than about what you have bought and wish you hadn't.
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Old 04-13-2013, 12:30 PM   #6
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Re: Engine and Transmission Questions - looking at two busse

I have limited experience with modern electronic bus engines, but I have worked on several ambulances with electronic 5.9 and the Mercedes diesel, and they are all coupled to electronic transmissions with lock up torque converters.

How likely is a person to find an electronic engine coupled to a non electronic trans?
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Old 04-13-2013, 12:39 PM   #7
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Re: Engine and Transmission Questions - looking at two busse

As far as rust, with the exception of the bus I parked in the ocean, rust has not been much of an issue with the other michigan buses I've owned.

Some blue bird buses are galvanized which is an option of you are concerned with corrosion.

There is a link in skoolie that helps you identify an at545 vs an mt643. It would be a great idea to have the photos of each trans handy so you can identify the trans on any particular bus when crawling underneath.

Also, the rear end ratio is occasionally printed on the vehicle info tag near the driver seat, and almost certianly printed in a metal tag attached to the differential cover.

Lock up torque converter, inline engine, and 4.44 or 4.10 rear end ratio is super important for fuel economy.

If you were burning diesel fuel, the wrong powertrain that gets 2mpg less than the alternative would cost an extra $500 on one trip from Michigan to California and back.
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Old 04-13-2013, 04:16 PM   #8
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Re: Engine and Transmission Questions - looking at two busse

Lapeer the electronic vs non electric tranny also is what caught my eye it just seems weird
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Old 04-14-2013, 08:45 PM   #9
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Re: Engine and Transmission Questions - looking at two busse

We just got back from a 600+ mile weekend of concerts. About 40 miles from here there are 4 buses sitting. I think they are for sale, I will find out more this week about them. Looked like a couple of them were rear engine as well.
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Old 04-15-2013, 10:08 AM   #10
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Re: Engine and Transmission Questions - looking at two busse

I'll have a friend stop and get me a number and I'll call. I dont plan on going that way for a few weeks though.
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Old 04-18-2013, 03:35 PM   #11
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Re: Engine and Transmission Questions - looking at two busse

I called the guy and talked briefly. This is what I found:

Both are BB rear engine, 5.9 Cummins. 1 has 129k on it and the other 53k.

His price on them is around $5500. That is a good price, they are from WA so should have no rust.

The guys name is Preston and his number is 406-826-2322
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Old 05-28-2013, 01:29 PM   #12
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Re: Engine and Transmission Questions - looking at two busse

The DT466E uses electronic injectors unlike my DT466 which is mechanically injected. What the difference you ask. The injectors for the E motor run about $300 a piece. Mechanical are about $50-75 each. I have an AT 545 in my bus. What a pile of ****. If you live in Kansas City and will never leave or go over 45 mph, it's fine. I accepted that transmission because to positives out way the negatives on my bus.
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Old 05-28-2013, 10:14 PM   #13
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Re: Engine and Transmission Questions - looking at two busse

Quote:
Originally Posted by lapeer20m
There is a link in skoolie that helps you identify an at545 vs an mt643. It would be a great idea to have the photos of each trans handy so you can identify the trans on any particular bus when crawling underneath.
viewtopic.php?f=44&t=1824

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Old 05-28-2013, 11:26 PM   #14
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Re: Engine and Transmission Questions - looking at two busse

A school bus is slow. It doesn't need a lock-up converter because it is rarely in a situation where it could benefit from one. An automatic uses the converter to split the gears, especially in a heavy, low-powered vehicle like a bus. Anytime there is acceleration going on, the converter would be unlocked and in use doing its job. In a big school district where the students are gathered by smaller buses into a staging area and then sent on the highway to a big school, you might find a huge transit-style school bus with a lock-up converter. I would think new, in-service buses would have them so they could pretend to meet emissions goals, but 99% of school buses wouldn't benefit from a lock-up converter.

The overdrive is the second thing. Nope, MT643 doesn't have it. Neither does the AT545. To go fast, you need to switch the rear axle gears. It's simple, but you have to be strong or smart. The rear axle is an empty shell that the differential bolts into. You have to unbolt the driveshaft and tie it up out of the way; unbolt the axles at their flanges in the middle of the drive wheels and slide them out 6"; unbolt the 12 bolts that hold the pig into the axle housing; pull out bad pig; push in new pig, sweeten to taste. There are minor intermediate details, but that's the plan, overall. The transmission doesn't play a big part, except that for your drives, the lock-up is better because you will be going down the highway a lot. Still, if it's a torque sensitive system, it might be unlocked a lot. If it's speed sensitive, you should be okay. A locked converter is about as efficient as a manual trans. If you can keep it locked.
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Old 05-31-2013, 08:24 PM   #15
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Re: Engine and Transmission Questions - looking at two busse

Good advice so far. Just an opinion from someone who has a DT466 and MT643. It is an awesome combo. I have 4.78 gears for now and am looking for 4.10 or lower (numerically), but otherwise I am in love. It actually feels like it is shifting again when the tc locks up, instant boost in speed. And I can climb mountains all day long at 50mph+ and my transmission never even hits 150*. The only combo I can think of that would top it is a Cummins 8.3 and an MD3060
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Old 06-03-2013, 02:19 PM   #16
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Re: Engine and Transmission Questions - looking at two busse

Quote:
but 99% of school buses wouldn't benefit from a lock-up converter.
I respectfully disagree with this statement. Maybe you mean a school bus being used as a city school bus that never sees a freeway. But as a skoolie used for traveling, an AT545 transmission is a pig and will cost you dollars in fuel and is nowhere near as stout as a MT643. I just finished 700 miles on my bus in 3 days. As soon as I have some extra cash, that 545 is gone. I know this trans cost me at least 15% more in fuel. I watched speed, rpm and temps the whole way. I know that at some times I was turning 500 rpms higher that if I had a lockup converter. Also, a 545 is rated for about 28-30k GVW gross and the 643 is rated at about 60-70k GVW. If someone finds a bus with a 643 trans for not much more, it will pay dividends down the road.
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Old 06-03-2013, 02:45 PM   #17
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Re: Engine and Transmission Questions - looking at two busse

hopefully CC will document changes needed bell housing, shifter mods, flex plate and or spacers for tc and the basic wiring needed
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Old 06-03-2013, 05:53 PM   #18
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Re: Engine and Transmission Questions - looking at two busse

Quote:
Originally Posted by bansil
hopefully CC will document changes needed bell housing, shifter mods, flex plate and or spacers for tc and the basic wiring needed
I will but when I buy a 643, I will try to find one that was behind a DT466. That will simplify things.
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Old 07-29-2013, 08:36 PM   #19
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Re: Engine and Transmission Questions - looking at two busse

Quote:
Originally Posted by lapeer20m
I have limited experience with modern electronic bus engines, but I have worked on several ambulances with electronic 5.9 and the Mercedes diesel, and they are all coupled to electronic transmissions with lock up torque converters.

How likely is a person to find an electronic engine coupled to a non electronic trans?
I have driven several vehicles with AT545's, an AT500, and an MT643 behind electronic diesels.
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Old 07-29-2013, 08:39 PM   #20
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Re: Engine and Transmission Questions - looking at two busse

Quote:
Originally Posted by crazycal
Quote:
but 99% of school buses wouldn't benefit from a lock-up converter.
I respectfully disagree with this statement. Maybe you mean a school bus being used as a city school bus that never sees a freeway. But as a skoolie used for traveling, an AT545 transmission is a pig and will cost you dollars in fuel and is nowhere near as stout as a MT643. I just finished 700 miles on my bus in 3 days. As soon as I have some extra cash, that 545 is gone. I know this trans cost me at least 15% more in fuel. I watched speed, rpm and temps the whole way. I know that at some times I was turning 500 rpms higher that if I had a lockup converter. Also, a 545 is rated for about 28-30k GVW gross and the 643 is rated at about 60-70k GVW. If someone finds a bus with a 643 trans for not much more, it will pay dividends down the road.
Actually, it's even further apart. Best I recall from Allison: the AT545 is rated for 26,000lbs. The MT643 is rated for a stunning 73,000lbs! The trash trucks my brother drove had 643's.

I have NEVER seen a worse match than a 12-valve Cummins and an AT545!
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