1999 CV200 (GMT530) Chevy 7.4L Allison AT545 or MT643?

[Back To Skool]

Hello all. I have searched high and low on the forum and the internet and cannot seem to find out the following info:

Would a 1999 Chevy with a CV200 Bluebird body and a GMT530 chassis (also known as B7), containing a Chevy 7.4L Vortec 7400 gasoline engine, have an Allison AT545, or an MT643 transmission paired to it?

I can tell by photos in the ad that it is a 4 speed. The most info I can come across on wikipedia is that it indeed is paired with an Allison.

I emailed the seller but have not heard back.

Any and all help is appreciated.

[rdrnek3]

It may have an at545 but it is doubtful that it would be an MT643 because of the size of the mounting flange. I know that on a DT466 the MT643 will mount right up(sae#2 bellhousing) but the AT545 is designed for an sae#3 bellhousing and use an adapter to get down to that size. I could be wrong but I don't believe an SAE#2 bellhousing is very common on gassers.

[cadillackid]

ive never seen one with a 643 but I believe it was available from what a buddy of mine said, his schools always ordered all their gasser CV's with 545s but couldve gotten a 643 as an option..

[Back To Skool]

Originally Posted by rdrnek3

It may have an at545 but it is doubtful that it would be an MT643 because of the size of the mounting flange. I know that on a DT466 the MT643 will mount right up(sae#2 bellhousing) but the AT545 is designed for an sae#3 bellhousing and use an adapter to get down to that size. I could be wrong but I don't believe an SAE#2 bellhousing is very common on gassers.

Awesome! Appreciate the insight. I always like learning more about the mechanical side of things and swap capabilities.

So, in theory, if I found a good sled with a DT466 rocking and rollin, but a crappy 545 hanging on to it, I could potentially... if I felt so inclined, swap in an MT643?

I'll cross my fingers the seller emails me back. And triple criss cross my fingers and toes that it's a 643 attached.

[cadillackid]

I’ve done a 545 to 1000 swap on a 444e abd did a 545 to 643 on my dt360, both busses are fantastic to drive now.. threads are out there on this board

[Back To Skool]

Originally Posted by cadillackid

I’ve done a 545 to 1000 swap on a 444e abd did a 545 to 643 on my dt360, both busses are fantastic to drive now.. threads are out there on this board

Been looking on these threads. Found a whole lot of chatting off topic but haven't found a good one yet with straightforward info.

I've been all over the AT545 hater threads and other pertinent rabbit holes.

So, you just may be the person to ask...I noticed you have a lot of experience on the mechanical side of skoolies.
I'm looking at a rig with stupid low miles (well under 100k) and virtually no rust from what I can tell. DT466E mated to the "dreaded" AT545. I live in Colorado, and would want to be traveling through the Rockies, yes.

From what I gather from reading the AT545 threads here, this transmission is fine if one drives one's bus accordingly and properly. But I am a bit concerned about dumping a $20k build onto a bus with a transmission that may overheat or grind up when climbing and descending these beautiful mountains. I have read about putting coolers on them, but not sure if that's something I am capable of doing.

I do my own basic car maintenance and have done things like ball joints, plus I can build a motorcycle from the frame up, so I'm not green. But when it comes to Diesel work, absolutely a newborn. Have never done anything close to an engine or transmission swap on a car. Have never welded. (going to learn for my roof raise)

Is swapping the 545 to the 643 even worth the hassle? Or to a different series altogether?
What did it cost you in the end? Money (ballpark) and time, namely?

Just wondering if I shouldn't be as concerned about the AT545 as I have previously been lead to fear it. Considering a swap as a possible future endeavor.

Could you perhaps reference the threads you favor on this topic?

Guidance is greatly appreciated, as I need to make a decision sooner rather than later.

[cadillackid]

From a financial perspective you are generally far better off to buy the bus you want drivetrain wise..

So let’s look at my 643 swap..

I wanted something that would last..
reman 643 was $650 in Missouri plus tax
I drove out to get it from Ohio since it was easy so whatever fuel my Dodge Ram 2500 hemi drank added to the price..shipping was going to be like 200

I paid somewhere around 150 bucks for a flex plate.
100 bucks in hose and AN fittings to make all new cooling lines
200 at the driveshaft shop for shorten, new U joints , balance..
miss costs in bolts hardware etc

I also did other upgrades to the bus so it’s tough to exactly sort the costs but let’s just use 1500..
much less than paying a shop and I’ve got a new trans and new parts along the way.

That’s 1500 right off the bat you can add to your target buying price for a bus.
If your target price is 2000 now make it 3500.. ive seen quite a few busses with good trans sell I’m the 3500-4000 range..

If you can build a motorcycle you can add a trans cooler to a bus, you can also swap a 545 to a 643.. they are heavy but there’s jacks chains and straps for that.. I’m a weak 145 lb dude that swapped an 800 lb trans in..

Yeah I’m one of those guys with a whole garage full of tools but I don’t have lifts or pits or such.. I do have jacks and stands and impact ..

545 in the Rockies sucks.. not gonna say you are gonna ruin it.. but 20k build sounds like it will be fantastic and prob heavy so I’d rule the 545 out. They are wonderful stop n go transmissions and they do OK in mountains that aren’t crazy steep.. I damn near burnt one up on a single hill pull on I 80 in a gasoline bus with a bad carb....

Allison 2000 swaps will give you a better trans.. you gain overdrive which if the rear gears in your bus are low will make you more set for the highway.
They also bring about the need for a lot of electronics. In the case of mine I started with a brand new high performance allison 1000 and built the electronics.. that bus is a custom. It’s tuned it’s built.. much like a custom motorcycle.. yeah it was expensive..

Another member here bought another bus and swapped everything over then sold that bus.. lots of work in labor, job got done and I’m guessing his cost was minimal..

Allison 2000 series busses show up in auctions every day.. 466e and CAT engines with them all over. That 2002-2004 timeframe are really good years for them..

Me? I build stuff for fun.. my school busses are toys.. I don’t camp or convert them. I love to build and drive much like others with classic cars.. so swapping engines trans drive lines etc is fun..

If I had been out to get the perfect conversion bus I’d have bought it vs built it.

[Back To Skool]

cadillackid, Thank you so much for that insight and info, and for taking the time! This is exactly what I needed to hear to move forward into a decision.

I'm thinking I just may have to remain patient a little while longer and wait for the right drivetrain combo. Considering what my intended uses are going to be, I do not want to be restricted to where I can go because something as silly as "I bought the one with the grandma transmission." Meaning, if I am going to be mountain driving a lot, then I should be looking for something at least half decent for climbing. Taking into account your experiences with the AT545 and others' info in other threads, this transmission might not be what I need.

And even though I may be able to pull it off, I just don't feel the added expense and time of a swap is worth it (in my case), as like you said, the "right one" is out there.

Much appreciation!

[cadillackid]

I should add that I swapped both AT545s when I did because I Brooke them..
one gave me warning so I did the swap before it died completely

The other one died 3 miles from base. Literally I was on my way home with it and no warning it died.. lucky because both of those busses travel multi 1000 mile trips..

Mountains in the east are what those are.. fairly regularly as Ohio to Florida is a common drive for me eso in winter and I like to explore Tennessee , Carolinas and such where there are mild hills..

The overheated trans was a climb on a 2700 mile trip from Oregon to Ohio in a 40 year old bus.. ( finding a rust free bus identical to one I road to school on brand new was worth that trip).. if I ruin the trans in that bus I’ll rebuild it in my garage because the AT545 sound and feel is part of driving that bus..

[o1marc]

Originally Posted by Back To Skool

I'm looking at a rig with stupid low miles (well under 100k) and virtually no rust from what I can tell.

You will soon learn that the speedometer is one of the first things to break on these old buses. They are replaced with used or new units that are not corrected for mileage. If you find a bus with "stupid low mileage" count on it not being accurate. Buses typically see 10k miles a year.

[Back To Skool]

Originally Posted by o1marc

You will soon learn that the speedometer is one of the first things to break on these old buses. They are replaced with used or new units that are not corrected for mileage. If you find a bus with "stupid low mileage" count on it not being accurate. Buses typically see 10k miles a year.

I'm kind of getting off topic and mixed up with my buses now. The low mileage was actually on a different bus than the one I referenced in the thread title. The seller of the CV200 Chevy still has not returned my messages, so I have given up on him and finding out what transmission is in there.

But, in regards to your response on the low mileage bus:
I thought of the gauges being wrong, so I asked the seller. Apparently, the engine was replaced at 30k miles due to a blown turbo, then only 50k put on it since, used as a spare ride/activities bus.
The hours did say only about 5,000.

But what flags it for me is when I asked twice if he had the maintenance records, he finally responded simply that "the bus was up to speed on inspections when we got it."

*cough *cough....ummmm, okay.

When a seller isn't straight forward to a simple yes or no question, it raises pause. If he's telling the truth, great! But if it can't be verified, to your point, it could simply be a faulty or replaced gauge cluster (in this case).



So, to anyone still wanting to know what transmission is typically in a late 90's CV200 7.4L Vortec Bus, the question remains.

[o1marc]

Originally Posted by Back To Skool

I'm kind of getting off topic and mixed up with my buses now. The low mileage was actually on a different bus than the one I referenced in the thread title. The seller of the CV200 Chevy still has not returned my messages, so I have given up on him and finding out what transmission is in there.

But, in regards to your response on the low mileage bus:
I thought of the gauges being wrong, so I asked the seller. Apparently, the engine was replaced at 30k miles due to a blown turbo, then only 50k put on it since, used as a spare ride/activities bus.
The hours did say only about 5,000.

But what flags it for me is when I asked twice if he had the maintenance records, he finally responded simply that "the bus was up to speed on inspections when we got it."

*cough *cough....ummmm, okay.

When a seller isn't straight forward to a simple yes or no question, it raises pause. If he's telling the truth, great! But if it can't be verified, to your point, it could simply be a faulty or replaced gauge cluster (in this case).



So, to anyone still wanting to know what transmission is typically in a late 90's CV200 7.4L Vortec Bus, the question remains.

This brings up the question of who is "We" when referring to"when we got it" If it's at an auction, the contact will most likely be the school maintenance garage, who would have gotten it with no maintenance records because it would have been brand new. If you're talking to people at the auction , you're talking to the wrong people as the bus isn't at their auction site.

[cadillackid]

the gasser CV200 454's ive been around all have had AT545's.. Gasoline engines produce their torque at higher RPMs and less of it than diesels.. esp in stock schoo; bus form.. while the 454 in a school; bus is virtually the same block as that in a hotrod.. they run a camp which produces some more low end torque yet not as much as a diesel.. and less high end HP.. AT545's like a few RPMs.. so gasoline engines in front of them dont generally present as many issues as diesels... climbing mountains you'll still; get your 545 hot but flat landing they work pretty well behind a gas motor..

[Back To Skool]

Originally Posted by o1marc

This brings up the question of who is "We" when referring to"when we got it" If it's at an auction, the contact will most likely be the school maintenance garage, who would have gotten it with no maintenance records because it would have been brand new. If you're talking to people at the auction , you're talking to the wrong people as the bus isn't at their auction site.

I researched the company. They do environmental cleanup. Digging bulldozers out of swamps, pulling airplanes off of highways, etc.

The guy said it was from a small local school district. The best I can gather is they passed it to him to sell because he is registered with the auction and he gets a chunk. They had a video of the bus driving in their parking lot. They do have it physically.

I'm passing on it anyway. AT545 be damned

[Back To Skool]

Originally Posted by cadillackid

the gasser CV200 454's ive been around all have had AT545's.. Gasoline engines produce their torque at higher RPMs and less of it than diesels.. esp in stock schoo; bus form.. while the 454 in a school; bus is virtually the same block as that in a hotrod.. they run a camp which produces some more low end torque yet not as much as a diesel.. and less high end HP.. AT545's like a few RPMs.. so gasoline engines in front of them dont generally present as many issues as diesels... climbing mountains you'll still; get your 545 hot but flat landing they work pretty well behind a gas motor..

Great info...thanks!

Yeah, every time I saw this one I couldn't help but think of a hot rod with a 454 in it.

[rdrnek3]

Originally Posted by cadillackid

From a financial perspective you are generally far better off to buy the bus you want drivetrain wise..

So let’s look at my 643 swap..

I wanted something that would last..
reman 643 was $650 in Missouri plus tax
I drove out to get it from Ohio since it was easy so whatever fuel my Dodge Ram 2500 hemi drank added to the price..shipping was going to be like 200

I paid somewhere around 150 bucks for a flex plate.
100 bucks in hose and AN fittings to make all new cooling lines
200 at the driveshaft shop for shorten, new U joints , balance..
miss costs in bolts hardware etc

I also did other upgrades to the bus so it’s tough to exactly sort the costs but let’s just use 1500..
much less than paying a shop and I’ve got a new trans and new parts along the way.

That’s 1500 right off the bat you can add to your target buying price for a bus.
If your target price is 2000 now make it 3500.. ive seen quite a few busses with good trans sell I’m the 3500-4000 range..

If you can build a motorcycle you can add a trans cooler to a bus, you can also swap a 545 to a 643.. they are heavy but there’s jacks chains and straps for that.. I’m a weak 145 lb dude that swapped an 800 lb trans in..

Yeah I’m one of those guys with a whole garage full of tools but I don’t have lifts or pits or such.. I do have jacks and stands and impact ..

545 in the Rockies sucks.. not gonna say you are gonna ruin it.. but 20k build sounds like it will be fantastic and prob heavy so I’d rule the 545 out. They are wonderful stop n go transmissions and they do OK in mountains that aren’t crazy steep.. I damn near burnt one up on a single hill pull on I 80 in a gasoline bus with a bad carb....

Allison 2000 swaps will give you a better trans.. you gain overdrive which if the rear gears in your bus are low will make you more set for the highway.
They also bring about the need for a lot of electronics. In the case of mine I started with a brand new high performance allison 1000 and built the electronics.. that bus is a custom. It’s tuned it’s built.. much like a custom motorcycle.. yeah it was expensive..

Another member here bought another bus and swapped everything over then sold that bus.. lots of work in labor, job got done and I’m guessing his cost was minimal..

Allison 2000 series busses show up in auctions every day.. 466e and CAT engines with them all over. That 2002-2004 timeframe are really good years for them..

Me? I build stuff for fun.. my school busses are toys.. I don’t camp or convert them. I love to build and drive much like others with classic cars.. so swapping engines trans drive lines etc is fun..

If I had been out to get the perfect conversion bus I’d have bought it vs built it.

What's the name of the company that you bought that MT643 from? Thats a dang good deal. I am planning on swapping my AT545 for a Mt643.

[cadillackid]

LKQ parts in Marshfield missouri.. they are a wrecking yard.. in 2018 they bought all of the Reamnufactured AT545s and MT643s from navistar.. you will get a unit that was rebuilt by Navistar's builder, fresh and ready to roll..



last i knew they still had a few left..

[jimburke77502]

Hey cadillackid, quick question for you(and anyone else here that would care to chime in.) seeing that you seem to know more than me on the allison trannys. Anyone ever thought of or actually re purposed one of the old bus heaters for a transmission or oil cooler? I know it would add a substantial amount of capacity, BUT would it work?

[cadillackid]

I wouldnt.. a coolant heater is designed to take 15 PSI of coolant water and you would be putting upwards of 100+ PSI of transmission oil pressure into it..

[jimburke77502]

Was just a thought, hell the things gotta be good for something. I'll only be keeping one of the three that are in my bus.