Which Bus Decision

[Pine Sap]

For several months I have been looking for a used school bus for my conversion. I have narrowed down my interest to a shorter length bus and there are 2 available that I am considering:

1) 1991 International/Thomas with a DT 360 engine, model C185, horsepower 185, MT 643 Allison transmission. 213,723 miles. 41 passengers (6 passenger windows).

2) 1995 Carpenter Short Bus. Navistar T444E engine. Allison transmission but don't know which version just yet. 230,000 miles. I have requested additional info from the seller. Also, a 6 window bus.

Considerations would be, of course gas mileage, and the ability to occasionally pull an F150 pickup.

I would greatly appreciate your input on the pro's and con's of these buses. As far as I can see, mechanical condition withstanding, the buses seem fairly comparable?

Cheers,
Norm

[Twigg]

Both sound like decent prospects from the brief descriptions. What are they asking for them.

In the end, condition sells a vehicle so are they equivalent?

My inclination would be to look long and hard at the first one. That's a very good drive-train in a shorter bus.

[brokedown]

This might easy.

All other things being equal, if bus #2 has an Allison AT545 transmission, get bus #1. The 643 can lockup in top gear and will be night and day better at pulling a load and operating at highway speeds.

[PNW_Steve]

I agree with Josh.

Also, I believe that the DT360 above would be a mechanical engine and is a wet sleeve engine. Both plusses from a maintenance standpoint.

[Pine Sap]

What does 'The 643 can lockup in top gear' mean? Lock up, its a good thing? Thanks!

[brokedown]

If you have a gear that "locks up", you are mechanically connecting the engine through the gears to the axel and ultimately to the back wheels.

In a non-locking gear, the torque converter is moving fluid that strongly suggests the back wheels should turn, but you can think of it as driving a manual transmission but never letting the clutch all the way out. Power that could be pushing you up a hill gets wasted inside the transmission doing not very useful things like wearing out your transmission parts and generating heat.

The MT643 locks in top gear, tha AT545 does not lock in any gear. Some of the bigger 6 speeds units lock in 5th and 6th gears.

[Tango]

Also...without lockup, you have no engine braking. Not that big a deal in most of Kansas. A very big deal in hilly or mountainous areas.

[Twigg]

The AT545 is very common in school buses, because for the job they do it's almost perfect. Lock-up and overdrive are not required in neighborhoods and short stretches of 4-lane, and neither is big torque handling if the bus has less than 200 hp.

Millions of those transmissions were sold, and if they stick to their job they are cheap, and very rarely fail.

The problem we have is that we want vehicles that will handle hills and highways, often towing. The AT545 is not designed for that and does not do it very well.

[johnbloem1974]

I can attest to that. My AT545 did OK for 2 years of going from Texas to Montana and various other places in the West. Finally crapped out last week. Lots of Highway driving with a vehicle in tow. I knew it was a matter of when, not if it would crater out. Upgrading to an MT643 now. Hopefully be back on the road before the weekend...

John

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[Pine Sap]

Originally Posted by Twigg

Both sound like decent prospects from the brief descriptions. What are they asking for them.

In the end, condition sells a vehicle so are they equivalent?

My inclination would be to look long and hard at the first one. That's a very good drive-train in a shorter bus.

-----------------

- Fixed price for the Carpenter at $5,700.00 with the interior insulated and paneled.

- Bidding going on for the International.

- As to condition, no first hand info but they seem approximate by sellers reports and photo's. I would need to travel to pick up either one........or have it shipped?

Thanks Twigg!

[Pine Sap]

Originally Posted by johnbloem1974

I can attest to that. My AT545 did OK for 2 years of going from Texas to Montana and various other places in the West. Finally crapped out last week. Lots of Highway driving with a vehicle in tow. I knew it was a matter of when, not if it would crater out. Upgrading to an MT643 now. Hopefully be back on the road before the weekend...

John

Sent from my SM-G950U using Tapatalk

Sorry to hear of the need for replacement. Can you do that work yourself?

Hope to hear soon which Allison is in the Carpenter. Seller isn't certain where to look on the vehicle. I suggested a metal data plate fixed to the body or transmission?

[Pine Sap]

Originally Posted by brokedown

If you have a gear that "locks up", you are mechanically connecting the engine through the gears to the axel and ultimately to the back wheels.

In a non-locking gear, the torque converter is moving fluid that strongly suggests the back wheels should turn, but you can think of it as driving a manual transmission but never letting the clutch all the way out. Power that could be pushing you up a hill gets wasted inside the transmission doing not very useful things like wearing out your transmission parts and generating heat.

The MT643 locks in top gear, tha AT545 does not lock in any gear. Some of the bigger 6 speeds units lock in 5th and 6th gears.

Info is very much appreciated! Thanks, Brokedown!

[johnbloem1974]

Originally Posted by Pine Sap

Sorry to hear of the need for replacement. Can you do that work yourself?

Hope to hear soon which Allison is in the Carpenter. Seller isn't certain where to look on the vehicle. I suggested a metal data plate fixed to the body or transmission?

Thanks! I could if I was in the right place, but since I'm stuck during travelling I'm having a shop pot it in...
Most transmission data plates will be on the passenger side. Here's what it looks like:


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[Pine Sap]

Originally Posted by PNW_Steve

I agree with Josh.

Also, I believe that the DT360 above would be a mechanical engine and is a wet sleeve engine. Both plusses from a maintenance standpoint.

Knowing next to nothing about diesel before beginning this search, that further confirms what I have learned. And, is partially why I came to favor earlier, pre-experimental-emissions control and mechanical injectors over electronic this and that. Thanks Steve!

[Pine Sap]

Originally Posted by Tango

Also...without lockup, you have no engine braking. Not that big a deal in most of Kansas. A very big deal in hilly or mountainous areas.

Really! Like having the bus in neutral?

[Twigg]

Originally Posted by Pine Sap

-----------------

- Fixed price for the Carpenter at $5,700.00 with the interior insulated and paneled.

- Bidding going on for the International.

- As to condition, no first hand info but they seem approximate by sellers reports and photo's. I would need to travel to pick up either one........or have it shipped?

Thanks Twigg!

$5700 seems high to me, even though shorties command a premium.

The other one is the better bet anyway, providing the condition is okay. If it's an auction, and not an eBay auction, you will pay what the market thinks it is worth ... don't get into a bidding war with another buyer. Only the sellers win those.

[Pine Sap]

Very helpful!

[brokedown]

Originally Posted by Pine Sap

Really! Like having the bus in neutral?

Not quite that bad, but when I was going down the mountains in my bus I'd put it in 2nd gear to try to keep my speed around 55mph, and it would spin around 1700rpm. For reference, when accelerating, my bus shifts to 3rd at 25mph.

[Twigg]

Originally Posted by brokedown

Not quite that bad, but when I was going down the mountains in my bus I'd put it in 2nd gear to try to keep my speed around 55mph, and it would spin around 1700rpm. For reference, when accelerating, my bus shifts to 3rd at 25mph.

Agreed.

The transmission fluid provides some "drag", but zero positive engine braking.

This means you have to be very cautious while driving a long down-grade.

Set a target speed, brake to 10 mph under then allow the bus to coast until it hits 5 mph over. Then brake again to 10 mph under. Rinse and repeat to the bottom.

Riding the brakes could easily deplete the air. Go too low and the emergency brake will apply, something you really do not want to happen.

Those truck escape lanes are there for a reason and getting pulled out of one will ruin your entire day.

[brokedown]

I'm "fortunate" to have hydraulic brakes, so no worries about air running out! I had some concerns about things getting too hot but never felt any fade. Between the transmission and the general process you described I was able to keep things under control through the hottest part of the year in the highest part of the US.