AT545 to MT643 DT466E swap

[cadillackid]

if I remember right the governer on the 545 and 643 is interchangeable so if all of the shift points are a little high or low but were perfect on the 545 you can move the governer over easily..



governer 461 is likely what you have in both transmissions and then the valve body trim wheels can fine tiune from there.. but my guess is you'll put it in and it will work fine. having shift points a little high means less lugging of a lower horsepower engine in a big bus..

[JT20]

Thanks guys for the info!

I’ve got the MT643 to the house and unloaded, it looks good.

I’ve ordered a new rear main seal and the special tool to install it. The tool was more than the seal, oh well.

I’m still waiting on the new flex plate to come in from Colorado.

So maybe things will be here by Friday, we’ll see.

Also cadillackid mentioned a bus parts place east of where I was, it was a little out of the way but we drove over and picked up a used rear door and a front bumper. My bumper was bent pretty bad and the rear door was bent on the corners near the hinge, probably could have gotten it out, but they gave me a good price on the door.

[cadillackid]

Sweet you got it home ready to go!! Did you hit up mike and B? That place is like a candy store for me

[JT20]

Yeah I did, got the rear door and front bumper from them. Wish I had more time to look around.

[Simplicity]

Congrats on getting the tranny. Hope the install goes well and all works great.

As soon as change over how my modulator is activated, I hope my tranny starts shifting as it's designed.

Nice Navy grey color on the tranny.

[JT20]

Thanks, I hope Simplicity you get yours going good. I’m going to be replacing my modulator as well as all other sensors on the transmission.

[s2mikon]

Simplicity, What is the problem with the modulator now? Is it not activating via the ECM?

[JT20]

Originally Posted by s2mikon

Simplicity, What is the problem with the modulator now? Is it not activating via the ECM?

Honestly I haven’t checked it, it looked pretty rough on the outside, when the buss was on the road it never shifted good.

It may be a good part, I will test it and keep it as a backup. With the amount of money I’m putting into this swap I would hate for the modulator to go bad a ruin my transmission.

It’s just me being precautious.

[Simplicity]

Originally Posted by s2mikon

Simplicity, What is the problem with the modulator now? Is it not activating via the ECM?

I think that's accurate.

I've traced the connection between the modulator and relay to assure I am working with the right relay. It tones.

I've bench tested the relay, 12v to 85 and I get continuity between 85 and 87, so the coil is good. 0v at 85, I get continuity between 30 and 87a, so the switch is good.

I've tested the socket per the diagnostic manual, version 190, and all the voltage and continuity test good.

I've traced the socket to pin 56 on the ecm connector and it tones.

I have NOT tested pin 56 on the ecm with the battery connected and brake down because I'm not really confident in playing with the actual ecm. I believe all I have to do is put the + of a meter on pin 56 and the - to a solid ground.

Even if I got the ecm / electrical connection to work, I will be putting a light in my dash to verify the modulator is receiving voltage appropriately.

I'm looking at by-passing the ecm and going with a w.w. williams micro-switch or something similar. I think it's overall a more reliable solution.

[s2mikon]

You could also use a Hobbs pressure switch on the intake manifold to sense manifold pressure and ground the relay. Adjustable switches are available to allow you to set the boost pressure that you feel is about half throttle. All the wiring would be at the back of the bus. I used to use them for propane fumigation setups on diesel engines 30 years ago until CARB came down on me. I have some on my old Dodge power wagon that are 35 years old and still working. I like the idiot light idea but it still won’t tell you when the modulator takes a crap.

[cadillackid]

Originally Posted by s2mikon

You could also use a Hobbs pressure switch on the intake manifold to sense manifold pressure and ground the relay. Adjustable switches are available to allow you to set the boost pressure that you feel is about half throttle. All the wiring would be at the back of the bus. I used to use them for propane fumigation setups on diesel engines 30 years ago until CARB came down on me. I have some on my old Dodge power wagon that are 35 years old and still working. I like the idiot light idea but it still won’t tell you when the modulator takes a crap.

S2, the ECM in ther early years was terrible about working.. However again ill say please test in the real world, you cannot test the relay with the bus in neutral and engine off.. at least not the ECM feed.. it works off of the engine load factor. which is only active when the bus is being driven. speedometer sensor must be working too from what I understand.



there were a lot of issues on the earlier ECMs. so WW williams set up a Micro switch activated by the foot pedal.. my red bus still has it on from when I had a 545.. im going to take it off and send it to him since I am running allison 1000 now. its simple when you step on the pedal hard enough it activates the switch, relay and modulator.. kind of like the old electric kickdown on the Turbo 400 GM transmissions..

[JT20]

So I got everything I needed to put my transmission in tomorrow, except for the flywheel bolts. Figured I would pick them up locally.

I have been to Lowe’s, auto zone, advanced auto, tractor supply, and harbor freight. No luck, no one seems to have metric 12X1.25 in a grade 8 or 10.9

I’m dead in the water, looks like I’m going to have to order some, I’m going to check Napa in the morning, but I don’t know where else to check.

[Mountain Gnome]

Originally Posted by JT20

So I got everything I needed to put my transmission in tomorrow, except for the flywheel bolts. Figured I would pick them up locally.

I have been to Lowe’s, auto zone, advanced auto, tractor supply, and harbor freight. No luck, no one seems to have metric 12X1.25 in a grade 8 or 10.9

I’m dead in the water, looks like I’m going to have to order some, I’m going to check Napa in the morning, but I don’t know where else to check.

NAPAs are all different, but most I've seen carry these quality bolts.


I also use Ace Hardware and True Value Hardware for quality bolts.


Lowes and HD suck for hardware.

[JT20]

Originally Posted by Mountain Gnome

NAPAs are all different, but most I've seen carry these quality bolts.


I also use Ace Hardware and True Value Hardware for quality bolts.


Lowes and HD suck for hardware.

Definitely will check two different Napa’s tomorrow, I checked and there are two true values within an hour from here. So cross my fingers, one of them will have them.

[s2mikon]

What bolts are you looking for?

[cadillackid]

Farm stores are another good source of hardware.. as is a place like TruckPro.. or even amazon, I didnt realize those bolts were metric, I swear on my DTA360 they are standard 1/2" fine thread. something they likely changed when they went to 'NGD'

[JT20]

Originally Posted by s2mikon

What bolts are you looking for?

The flywheel bolts, they have been a pain to find! Still have not had any luck.

[JT20]

Originally Posted by cadillackid

Farm stores are another good source of hardware.. as is a place like TruckPro.. or even amazon, I didnt realize those bolts were metric, I swear on my DTA360 they are standard 1/2" fine thread. something they likely changed when they went to 'NGD'

Mine are 12mm by 1.25 by two inches or so. I found two bolts at one Napa that was close by. Now I’m calling places in Charlotte, which is 1.5 hours from me, but still have not had any luck.

This blows! I thought I he everything, never would have thought these bolts would be impossible to find.

[s2mikon]

Have you tried the Navistar dealer?

[JT20]

Yes but without a part number they can’t help me