Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 01-31-2013, 06:03 PM   #21
Bus Nut
 
Join Date: Nov 2008
Location: ellijay ga
Posts: 560
Year: 94
Coachwork: b/b
Chassis: tc2000
Engine: 5.9
Rated Cap: 72
Re: How to tell AT545 from MT643, w/pix & specs

the only reson u have that type of trans is because u got a cat,, and there motor to trans bolt hole are for a cat trans,,make sure u have an allison trans,it maybe a cat trans.

keith is offline   Reply With Quote
Old 02-21-2014, 10:12 AM   #22
Skoolie
 
juliol's Avatar
 
Join Date: May 2013
Location: Monrovia California
Posts: 151
Year: 1984
Coachwork: Blue Bird
Engine: 3208 turbo Cat
Rated Cap: 78
Re: How to tell AT545 from MT643, w/pix & specs

Ok, I get it, Allison MT643 is the transmission to have, but what does it really mean that it locks up 3rd and 4rd gears, can someone explain in a driving senerio the advantage of the transmission locking up on gears? I have a cat 3208 with MT643, just started my conversion.

J
juliol is offline   Reply With Quote
Old 02-21-2014, 10:50 AM   #23
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,491
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
Re: How to tell AT545 from MT643, w/pix & specs

Quote:
Originally Posted by juliol
Ok, I get it, Allison MT643 is the transmission to have, but what does it really mean that it locks up 3rd and 4rd gears, can someone explain in a driving senerio the advantage of the transmission locking up on gears? I have a cat 3208 with MT643, just started my conversion.

J
A basic automatic transmission does not have any mechanical connection between the engine and the tires. There is no clutch, as in a stick shift.
Instead, the power is transmitted by a fluid. There is a "propeller" on the rear of the engine, and an other "propeller" on the front of the transmission. These two "propellers" are very close together, inside the unit called the torque converter. This unit takes the place of the clutch.
So the engine "prop" blows the transmission oil against the transmission "prop", which is how the power is transmitted. But oil is not solid, so there is slippage -- maybe 5 or 10 percent. This slippage becomes heat (thru friction, essentially).
So we lose some of the energy that would otherwise serve to drive the bus forward; and we get heat, which is damaging to the tranny. The slippage is typically about 200 RPMs worth.

Then somebody invented the torque converter lock-up clutch. This clutch is located inside the torque converter, and is controlled by the transmission's regular valve body (I think). It bypasses the "fluid coupling" with a solid connection, so no power is wasted as heat.
The result is better efficiency, which means more driving force to the tires, and less fuel consumed. In addition there is less wear on the transmission from the lower heat. Having torque converter lockup is most important in mountains, when a plain torque converter generates a great deal of heat, which can ruin a transmission.

You can feel and hear when the lock-up clutch engages. It is almost as if the transmission shifts gears, so it can seem as if the tranny has five or six gears.

Does this help?
__________________
The "Black Death" of the 14th century killed half the population of Europe and Asia.

Please blah, blah, blah.
The life you save may be mine. Thank you!
Elliot Naess is offline   Reply With Quote
Old 02-21-2014, 11:11 AM   #24
Skoolie
 
juliol's Avatar
 
Join Date: May 2013
Location: Monrovia California
Posts: 151
Year: 1984
Coachwork: Blue Bird
Engine: 3208 turbo Cat
Rated Cap: 78
Re: How to tell AT545 from MT643, w/pix & specs

Wow! Elliot, that is why this site is so helpfull there is people like you that takes the time to explain it as it is, thank you this really helps.
J
juliol is offline   Reply With Quote
Old 02-21-2014, 11:22 AM   #25
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,491
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
Re: How to tell AT545 from MT643, w/pix & specs

Yeah, I'm a "Wow!" kind'a guy, ain't I.
I mean... You are most welcome.

There is more going on inside a torque converter than I mentioned -- the thing is called a "torque convertor" for a reason. Otherwise it would be simply a "fluid coupling" -- which is what the first ones were, back in the late 1940s. But we don't need to know about the "converting" -- we just benefit from it.
__________________
The "Black Death" of the 14th century killed half the population of Europe and Asia.

Please blah, blah, blah.
The life you save may be mine. Thank you!
Elliot Naess is offline   Reply With Quote
Old 08-20-2014, 10:55 AM   #26
New Member
 
Join Date: Aug 2014
Posts: 4
Year: 1983
Coachwork: wayne
Chassis: b600
Engine: 370 ford
Re: How to tell AT545 from MT643, w/pix & specs

I have a 1983 ford b600 with a 370 and an Allison 545 I am at a crossroad and thinking about a engine swap as I understand this model year also offered the bus with a Detroit Diesel 8.2 and the DD 8.2 turbo. can I up engine without changing the transmission or its location. My 370 is a little long in the tooth and may be at a place of needing head work rear main leaks all the normal ailments of an older gasser etc... and the bus is of sentimental value to the family so chucking it for a newer model isn't an option. Plus we might want to head south thru the mountains and follow nascar a bit, and I am a little sketchy if it can climb up mountains well. I am not married to the DD 8.2 willing to listen to all advice on this subject I think if I do this I want to go diesel, and not a bunch of lg modifications. i would consider a more modern engine but not sure about the electronics. like the idea of keeping it simple I am a reasonable skilled mechanic but large trucks are anew area for me so I take it slow and figure it out as I go. new to schoolies but love every minute of it. And any easy way to figure out rear end gearing without taking it out?
autoqual is offline   Reply With Quote
Old 03-23-2015, 11:55 PM   #27
Bus Nut
 
Join Date: Oct 2011
Location: Snowflake, Arizona
Posts: 330
Year: 1996
Coachwork: Blue Bird
Chassis: All American Rear Engine
Engine: C-8.3-300 Cummins MD3060
Rated Cap: 40 Prisoners
The 5.9 Cummins is a very popular engine and can produce 190 HP very reliably and it usually comes with a 545 trans. I have seen some with MT643 and some with the MD3060 which would be the ideal trans for your application since it has double overdrive and lockup converter. Biggest problem converting from gas to diesel is that
the gas engine runs at a higher rpm to produce its power and a diesel like the 5.9 or the 8.3 Cummins have their max speed at 2400 to 2800 RPM. So to avoid changing
rear differential ratios you can add an overdrive transmission. As a side note the 8.3
Cummins also came in Fire trucks with a MD3060 transmission.
Dragonpop is offline   Reply With Quote
Old 03-24-2015, 08:23 AM   #28
Bus Geek
 
Join Date: Aug 2011
Location: Stony Plain Alberta Canada
Posts: 2,937
Year: 1992
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 190hp 5.9 Cummins
Rated Cap: 72
I would watch for a 5.9 Cummins, DT 466, Cummins 8.3 with a MT643, or a MD3060 behind it. NO AT 545 transmissions.

I would not touch any other engine. Not worth the time if your already doing a swap.

Nat
__________________
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."

Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization
nat_ster is offline   Reply With Quote
Old 11-03-2015, 02:23 PM   #29
Bus Geek
 
Join Date: Aug 2011
Location: Stony Plain Alberta Canada
Posts: 2,937
Year: 1992
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 190hp 5.9 Cummins
Rated Cap: 72
The 3000 series Alison transmissions are the best of the available transmissions in school buses. Most common variant is the MD 3060 double over drive, 6 speed automatic transmission.

If it has a electronic shift panel, it's got a 3000 series or better transmission.

Not all 3000 series transmissions have the electronic shift panel, but most will.

This is what you want to see.







Edit

Is a OP able to move this post to just under the OP's original post? It won't do much good 3 pages into the thread. Thx


Nat
__________________
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."

Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization
nat_ster is offline   Reply With Quote
Old 11-04-2015, 10:47 AM   #30
Site Team
 
crazycal's Avatar
 
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
Quote:
Originally Posted by nat_ster View Post


Is a OP able to move this post to just under the OP's original post? It won't do much good 3 pages into the thread. Thx


Nat
I don't think a mod can do that. Maybe someone in admin can.
__________________
I'm hungry!

You Gotta Let Me Fly
crazycal is offline   Reply With Quote
Old 12-29-2015, 09:58 AM   #31
Skoolie
 
Join Date: Dec 2015
Posts: 153
I do plan on taking it cross country. My dog, my girlfriend and I are planning on living out of it and traveling the west side of the country. Maybe Canada as well. We would like to live out of the bus for a few years doing this if we can make it work. I will be doing a pretty basic renovation as we will hopefully be able to do a lot of camping in the woods. Wood burning stove is the only real requirement I have other than a solid bus that can handle some mountain driving
EricW is offline   Reply With Quote
Old 03-06-2016, 12:45 PM   #32
Bus Crazy
 
Join Date: Aug 2014
Location: SW New Hampshire
Posts: 1,334
Quote:
Originally Posted by Elliot Naess View Post

This is quoted from the first message in this thread, which is several years old by now. I just wanted to document that the referenced link is no good any more. It's Chinese or Japenese text now, and Google translates a bit of it like this:

"Is it true that there is an annual income limit for caching? Law of the mechanism and correct debit, how to return. Caching of record let you know exactly how the future, where the influence. Caching even in part-time job is OK? Let us in the perfect preparation and mental attitude. There is the obligation to return the debt of her husband? Do you have responsibility for a debt of the secret to his wife "

Strange, and not a lot of useful.
dan-fox is offline   Reply With Quote
Old 03-06-2016, 01:07 PM   #33
Bus Nut
 
Hank's P-O-S's Avatar
 
Join Date: Jun 2014
Location: MB
Posts: 279
Year: 1997
Coachwork: Tomas
Chassis: International
Engine: T444e
Rated Cap: 54
Quote:
Originally Posted by dan-fox View Post
This is quoted from the first message in this thread, which is several years old by now. I just wanted to document that the referenced link is no good any more. It's Chinese or Japenese text now, and Google translates a bit of it like this:

"Is it true that there is an annual income limit for caching? Law of the mechanism and correct debit, how to return. Caching of record let you know exactly how the future, where the influence. Caching even in part-time job is OK? Let us in the perfect preparation and mental attitude. There is the obligation to return the debt of her husband? Do you have responsibility for a debt of the secret to his wife "

Strange, and not a lot of useful.
That's what happens when people don't pay their bills.
__________________
"...Baler twine tie downs goin' down the road
On two bald tires and an oversize load..."
Hank's P-O-S is offline   Reply With Quote
Old 03-31-2016, 01:48 AM   #34
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,491
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
It's the nature of the interweb. Websites come and go. Right now I got just "error 403" on that link. But I find that practically any information can be found with a bit of searching.

And the MD3060 seems to be the "standard" transmission these days, yes. It is a six speed, but I read that 6th gear is often blocked in school buses. These days, that would be controlled by a computer, and you would probably need to spend a few hundred at an Allison dealer to get 6th gear activated again.
__________________
The "Black Death" of the 14th century killed half the population of Europe and Asia.

Please blah, blah, blah.
The life you save may be mine. Thank you!
Elliot Naess is offline   Reply With Quote
Old 05-25-2016, 06:20 PM   #35
Bus Crazy
 
Stu & Filo. T's Avatar
 
Join Date: Sep 2013
Location: Vacaville, Ca
Posts: 1,632
Year: 1988
Coachwork: Crown / Pusher
Engine: 8.3 Cummins
I know it's not quite the same but I've got a Allison 647, what can anybody tell me about this Trans? If anything.

: Thanx:
Stu & Filo. T is offline   Reply With Quote
Old 05-25-2016, 06:51 PM   #36
Bus Crazy
 
Stu & Filo. T's Avatar
 
Join Date: Sep 2013
Location: Vacaville, Ca
Posts: 1,632
Year: 1988
Coachwork: Crown / Pusher
Engine: 8.3 Cummins
Quote:
Originally Posted by Stu & Filo. T View Post
I know it's not quite the same but I've got a Allison 647, what can anybody tell me about this Trans? If anything.

: Thanx:
Ok did find some info that stated their rated for up to 350hp.
Stu & Filo. T is offline   Reply With Quote
Old 05-25-2016, 09:08 PM   #37
Bus Geek
 
Robin97396's Avatar
 
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
I've found that tranny available used out of wrecked motor homes, but they didn't list a price. I was looking at pictures, you didn't say I had to read. Numbers, you know how bad at math I am.
This is going to take all day. What do you know about it? You bought one.
Robin97396 is offline   Reply With Quote
Old 05-25-2016, 10:26 PM   #38
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,491
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
Google is your friend. From just a couple minutes (I'm kind'a busy) it looks like the 647 is a beefed up version of the 643.

And look what else I found. This was posted by somebody on a forum, so the source is not certain, but it has the look of legit information copied out of a publication.


"Here are the complete Allison MT (since 1973) series transmission specifications, for those of you who are concerned about power and whether or not your transmission's good enough for your engine.

MT-640/643/650/653DR
Input speed: 2,200-4,000 rpm
Max input power: 250 hp (186 kW) (general purpose); 210 hp (157 kW) (transit/shuttle bus)
Max input torque: 640 lb/ft (868 N-m) (general purpose); 590 lb/ft (800 N-m) (transit/shuttle bus)
(1)3.58(2)2.09(3)1.39(4)1.00(R)5.67
Torque converter ratios: TC-380 (1.86:1), TC-370 (2.43:1) and TC-350 (3.09:1)

MT-644/654CR
Input speed: 1,800-3,000 rpmallison transmission mt653
Max input power: 300 hp (224 kW) (general purpose); 250 hp (186 kW) (transit/shuttle bus)
Max input torque: 780 lb/ft (1,058 N-m) (general purpose); 690 lb/ft (936 N-m) (transit/shuttle bus)
(1)3.58(2)2.09(3)1.39(4)1.00(R)5.67
Torque converter ratios: TC-494 (1.92:1), TC-495 (2.21:1) and TC-497 (2.70:1)

MT-647/648
Input speed: 1,800-2,600 rpm
Max input power: 300 hp (224 kW) (general purpose); 250 hp (186 kW) (transit/shuttle bus)
Max input torque: 950 lb/ft (1,288 N-m) (general purpose); 800 lb/ft (1,085 N-m) (transit/shuttle bus)
(1)3.58(2)2.09(3)1.39(4)1.00(R)5.67
Torque converter ratios: TC-494 (1.92:1) and TC-495 (2.21:1)



AT 545
(1)3.45(2)2.25(3)1.41(4)1.00(R)5.03
2400rpm-4000rpm
27.2 inches long 267lbs

235 HP 445 LB-FT"
__________________
The "Black Death" of the 14th century killed half the population of Europe and Asia.

Please blah, blah, blah.
The life you save may be mine. Thank you!
Elliot Naess is offline   Reply With Quote
Old 11-05-2016, 01:02 AM   #39
Bus Nut
 
Dapplecreek's Avatar
 
Join Date: Mar 2016
Location: near Christiansburg VA
Posts: 692
Coachwork: Thomas
Chassis: Freightliner
Engine: Cummins 5.9
Rated Cap: 44 or 66? 11 rows
So when you see "Automatic Transmission" on an auction site, what do you do? I would want to call someone and ask which transmission they have. Seems the shop would know off the top of their heads. Is this the way to handle it?
Dapplecreek is offline   Reply With Quote
Old 11-05-2016, 02:08 AM   #40
Bus Crazy
 
Elliot Naess's Avatar
 
Join Date: Oct 2005
Location: Clearlake, Northern California
Posts: 2,491
Year: 1992
Coachwork: Blue Bird
Chassis: TC-2000 Frt Eng, Tranny:MT643
Engine: 5,9 Cummins
Rated Cap: 84
Trouble is, they won't know. Nobody there will know. The model of the automatic transmission is not relevant to anything in daily use, and the transmission itself is completely out of sight.

If you are lucky, a mechanic who has worked on it may -- may -- know, but this is far from certain.

When I bought Millicent, a mechanic at the school bus yard told me she had an AT545. After I arrived home, I discovered to my delight she has an MT643.

That said....

A newer bus may have a 5-speed or even 6-speed. (The 5-speed is a 6-speed with 6th gear blocked out, to limit top speed, because 6th is a long-legged overdrive ratio.) If -- IF -- the shift selector shows 5 forward positions, then you are safe from the AT545. But I have never seen any of those gear levers. For all I know, it may have just "D". After all, school buses are made for housewives to drive.

So... exactly what do you do?

Study the weight of the bus. That is, the Gross Vehicle Weight Rating.
Look at the beginning of this thread, and you will see how much weight the AT545 is approved for by the manufacturer. A 40 foot bus is probably rated for a couple thousand pounds more.

Usually, they post a photo of the factory plate that shows the weight ratings. But it is a good idea to learn to judge the length of a bus by the number of windows -- not counting the driver's window (or the door on the other side). One window = one seat. Mind... there are variations for emergency doors, wheelchair lifts and rear-mounted engines.

Also, the listing may give the number of passengers. In school buses, they count three kids to each seat. So... 6 kids x 14 rows = 84 kids = 40 feet = probably too heavy for an AT545.
__________________
The "Black Death" of the 14th century killed half the population of Europe and Asia.

Please blah, blah, blah.
The life you save may be mine. Thank you!
Elliot Naess is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Specs and tweaking a t444e? JeffD2u Mechanical and Drivetrains 21 09-16-2018 06:34 AM
BlueBird TC2000 40ft Specs? crazycal Mechanical and Drivetrains 7 03-22-2013 05:04 PM
at545 to mt643 mounting questions adamanderr Mechanical and Drivetrains 8 02-24-2009 06:43 PM
Does a MT643 fit instead of a AT545 ????? Protecx Conversion General Discussions 1 02-09-2007 09:14 PM
Bus Specs hoser Everything Else | General Skoolie Discussions 5 11-24-2005 01:14 PM

» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:10 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.