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Old 11-23-2019, 11:34 AM   #1
Mini-Skoolie
 
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Swap MT643 into a T44E?

I have a 1999 Thomas 7 window Vista bus.

Has the T444E and of course the I have the Beloved At545 currently (A freshly rebuilt one to boot)

The rear end is 4.78 gearing.

currently the engine limiters are still set and speed set to 55mp max uphill or downhill.. I am getting about 2500 -2600 or so at 55mph, but again when the limits are reset I will see... I have an appt with the IH dealer to unlock the motor and also unlock my cruise control so it will work. I had to wait on tags...the appt is set for monday 11/25/19


I want to swap in an Mt643. I am aware of the differences in bell housing sizes, but what I do not know is will an MT643 bolt up to a T444E? I am looking at the bellhousing and i I can see there is an adapter between the engine and trans... but unsure if I just remove it and then bolt up the MT643 or do I have to source another adapter?

Anyone know what parts I would need to source and if this is a feasible swap?

I've got mechanical skills, I can weld, and I got plenty of money...

also appreciate any pointers on where to find a trans (as I have no core maybe I should go new) Also on another forum seems the MT643 with a PTO WILL work vs a regular MT643 without so I think I would want the PTO... never know what I might hook up

thanks in advance

oh and the bus is NOT going to be used in the mountains... we do plan on towing a sailboat (weighs in about 3500lbs with trailer)

My goal speedwise is a comfortable and quieter 60mph without screaming at 3200 revs. I have no desire no delusions to achieve ludicrous speed and hit the fast lane... 60 comfortably and cruising is the goal... slow up a hill is fine as we are retired and in no hurry... it is a road trip bus, not a tiny home
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Old 11-23-2019, 12:04 PM   #2
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Originally Posted by RolesvilleMarina View Post
Anyone know what parts I would need to source and if this is a feasible swap?
Yes, Christopher AKA CadillacKid has done a 545 to 643 swap. Not sure of the specific thread, but he's walked through the steps and equipment needed a few times. Hopefully he'll chime in.
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Old 11-23-2019, 12:51 PM   #3
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Quote:
Originally Posted by RolesvilleMarina View Post
I have a 1999 Thomas 7 window Vista bus.

Has the T444E and of course the I have the Beloved At545 currently (A freshly rebuilt one to boot)

The rear end is 4.78 gearing.

currently the engine limiters are still set and speed set to 55mp max uphill or downhill.. I am getting about 2500 -2600 or so at 55mph, but again when the limits are reset I will see... I have an appt with the IH dealer to unlock the motor and also unlock my cruise control so it will work. I had to wait on tags...the appt is set for monday 11/25/19


I want to swap in an Mt643. I am aware of the differences in bell housing sizes, but what I do not know is will an MT643 bolt up to a T444E? I am looking at the bellhousing and i I can see there is an adapter between the engine and trans... but unsure if I just remove it and then bolt up the MT643 or do I have to source another adapter?

Anyone know what parts I would need to source and if this is a feasible swap?

I've got mechanical skills, I can weld, and I got plenty of money...

also appreciate any pointers on where to find a trans (as I have no core maybe I should go new) Also on another forum seems the MT643 with a PTO WILL work vs a regular MT643 without so I think I would want the PTO... never know what I might hook up

thanks in advance

oh and the bus is NOT going to be used in the mountains... we do plan on towing a sailboat (weighs in about 3500lbs with trailer)

My goal speedwise is a comfortable and quieter 60mph without screaming at 3200 revs. I have no desire no delusions to achieve ludicrous speed and hit the fast lane... 60 comfortably and cruising is the goal... slow up a hill is fine as we are retired and in no hurry... it is a road trip bus, not a tiny home
You won't see any appreciable improvement in MPH's without regearing. Maybe a couple mph but nothing notable. If you're at redline doing 55 increasing the hp won't make you do 60 at redline. It will just get you to redline faster.
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Old 11-23-2019, 01:16 PM   #4
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Are you sure about the gearing? I have a 96 T444E with an AT545 and 4.78 gears. I travel 65 MPH at 2600 RPM.
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Old 11-23-2019, 04:45 PM   #5
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I am not sure until I get the motor unlocked.

65 MPH at 2600 would be fine...
as we will likely do 60 still

the main reason for the 643 would be the lockout converter of course

what I am unsure of is the adapter I can see between the motor and the trans... so does this get removed and a different adapter go in, or does this adapter (which obviously reduces bellhousing size) simply be removed and a 643 installed?
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Old 11-23-2019, 04:48 PM   #6
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I understand your frustration, my bus is governed at 55 as well, but with a 6.18 rear and gov at 2500RPM but at 55 I'm not but around 2200ish RPM....

East coast, I don't think he meant by "unlock the motor" that he meant upping the HP but taking off the rev limiter.
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Old 11-23-2019, 05:10 PM   #7
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I understand your frustration, my bus is governed at 55 as well, but with a 6.18 rear and gov at 2500RPM but at 55 I'm not but around 2200ish RPM....

East coast, I don't think he meant by "unlock the motor" that he meant upping the HP but taking off the rev limiter.
More hp or removing the rev limiter aren't going to help this situation.
Running at 55 at 2600 rpm is the problem. doesn't sound governed to me it sounds limited by gearing.
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Old 11-23-2019, 05:58 PM   #8
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More hp or removing the rev limiter aren't going to help this situation.
Running at 55 at 2600 rpm is the problem. doesn't sound governed to me it sounds limited by gearing.
No.. the rev limiter is set at 2500... the speed limiter is set at 55mph...
I also have factory cruise control that needs to be "unlocked"
am fully aware of this part and am not trying to get it "unlocked" meaning more HP.

but until I get the limits reset I have no idea what my "max" is... and I am aware that I can give the trans more power than it "needs" and will spin off the rest as slip and heat...

so unsure until monday (11/25/2019) what is what.

I am certain my rear end is a 4.78..


but still not sure about this adapter for the trans

and now another post on FB forum a guy is saying later AT545 were electronic? the modulators were changed?

i thought At545 and Mt643 were both mechanical?
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Old 11-23-2019, 06:21 PM   #9
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More hp or removing the rev limiter aren't going to help this situation.
Running at 55 at 2600 rpm is the problem. doesn't sound governed to me it sounds limited by gearing.
"More hp or removing the rev limiter aren't going to help this situation." Didn't indicate it would, just was saying I didn't think he was referring to HP when he was talking about unlocking the engine..
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Old 11-23-2019, 06:27 PM   #10
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"More hp or removing the rev limiter aren't going to help this situation." Didn't indicate it would, just was saying I didn't think he was referring to HP when he was talking about unlocking the engine..
You are correct... not worrying about HP... it is a 190hp

I do have presets for speed and revs... 100% sure of this..
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Old 11-23-2019, 06:34 PM   #11
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rolesville - the MAX RPM the T444E can handle is 2600 RPM.. its governed there because you will destroy the engine above that.. diesel engines arent like cars, they arent designed to rev up to 4000,5000 or higher.. the consumer diesels in cars and ford trucks may go higher, but these engines are TRUCK engines.. if I were to reprogram your REV limiter to 3000, you would soon be back here asking about how to replace a T444E because it would break..


what size are your tires? 225/70R19.5? 55 is likely the mnax with those tires and a 4.78 gear.. the MT643 wont give you any more speed, just a Locking converter..

if you want more speed you need to look at swapping in an Allison 2000 series that gives you a 5th gear.. an overdrive gear..



I swapped out an AT545 and swapped in an Allison 1000 (6 speed but similar to a 2000) into my red bus.. search for a thread titled 'The RedByrd transformation' to see my chronicles of that swap... I bought all brand new parts but the swap is the same as if you source used parts from a junked bus..



the other option is you swap in an MT643 and then also swap your rear end for one with a Numerically Lower gear, ie a 4.10, 3.90, 3.54.



let us know the size of your Tires, that helps us come up wioth a good approach for you.
-Christopher
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Old 11-23-2019, 06:38 PM   #12
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You are correct... not worrying about HP... it is a 190hp

I do have presets for speed and revs... 100% sure of this..

yes your computer has presets for speed and revs.. the revs as i mentioned in my previous message are set there because the the Rdd-line..Not to exceed..


the speed limiter can be removed, but your engine still wont rev above 2600..


if you are hitting 55 and with your foot to the floor you watch your revs drop way-off.. then increase as you slow down then decrease, removing the speed limiter may very well help you.. but if at 55 you are running near pegged on 2600 the whole time, removingthe speed limiter wont help much
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Old 11-23-2019, 06:41 PM   #13
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by the way if you are anywhere near Ohio i have the program that can reprogram your computer for cruise / speed, and bump your Horsepower up...
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Old 11-23-2019, 07:05 PM   #14
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yes your computer has presets for speed and revs.. the revs as i mentioned in my previous message are set there because the the Rdd-line..Not to exceed..


the speed limiter can be removed, but your engine still wont rev above 2600..


if you are hitting 55 and with your foot to the floor you watch your revs drop way-off.. then increase as you slow down then decrease, removing the speed limiter may very well help you.. but if at 55 you are running near pegged on 2600 the whole time, removingthe speed limiter wont help much
Correct... I should point out I drive a big truck, am NOT new to diesels, but as for a mechanic I mostly do boats.

with this in mind I am also aware when I say "rev limits" and "speed limits"
its the internet... I will not of course be setting them above my max no.

currently this is what is happeneing... I reach 55 and my revs will decrease..
I am unsure what the engine is set at

Tire size I think are 27 inch... but I am going off my head, prob wrong... its dark and raining so cain't check... but they are all new so they stay till I get my $ outta em lol
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Old 11-23-2019, 07:10 PM   #15
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by the way if you are anywhere near Ohio i have the program that can reprogram your computer for cruise / speed, and bump your Horsepower up...
I wish.. I am well aware of both you, and your skills and exploits mate
I've lurked here for a good bit before we bought our bus..

other than the AT545 it has everything we wanted

I have a 650 Vstar motorcycle in the back (using the wheelchair lift to deploy and stow) and we plan to tow a small sailboat (22 ft, 3800 lbs total)


Speed was never the issue or want.. comfortable cruise at a decent RPM...

i would like to have the lockout... but also could keep the AT545 and regear is an option

dunno... still researching.. and still have to go to IH dealer to get the cruise unlocked... again the limits, dunno but won't exceed of course

I live in NC now, near raleigh.. but am from UK originally so cheers mate
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Old 11-23-2019, 10:28 PM   #16
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My bus has 190hp and a 545. At 65 mph I'm at around 1700 rpm +/-. I've got 3.42 in the rear. Its VERY nice gearing. I can have conversations with passengers at highway speeds without even shouting.
My 545 was a fairly fresh reman when I got the bus so I'll live with it.
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Old 11-24-2019, 06:35 AM   #17
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My bus has 190hp and a 545. At 65 mph I'm at around 1700 rpm +/-. I've got 3.42 in the rear. Its VERY nice gearing. I can have conversations with passengers at highway speeds without even shouting.
My 545 was a fairly fresh reman when I got the bus so I'll live with it.


my 545 is also a fresh reman
and I am not opposed to re-gearing it vs transmission swap
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Old 11-24-2019, 06:42 AM   #18
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Originally Posted by EastCoastCB View Post
My bus has 190hp and a 545. At 65 mph I'm at around 1700 rpm +/-. I've got 3.42 in the rear. Its VERY nice gearing. I can have conversations with passengers at highway speeds without even shouting.
My 545 was a fairly fresh reman when I got the bus so I'll live with it.
How bad is your take off and up hills with that rear end?

everything I know is a trade off

and we are pulling a small sailboat, but inside the bus is just two of us and its not "loaded" down with stuff as its not our "home" just a road trip vehicle
and in no hurry
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Old 11-24-2019, 06:42 AM   #19
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Regearing would be my first move. Or maybe tires depending on the size and age of what you have. I've got 10R's. 11R's will get ya a couple more mph if you have 10R or smaller. I've GOTTA get some 11R's on mine since its got a 5" lift, just because! lol

The 643 swap is on my "someday" list. It would definitely be a nice upgrade but won't buy an speed. May as well use up that 545. Mine's actually nice to drive and I don't notice the slipping TC like on other buses I've had.
I'd shoot for something like 3.70 to 4.10 for the rear and fullsize tires if you don't have em. That's gonna make it smoother, quieter, and will get you more mpg and mph out on the open road.
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Old 11-24-2019, 06:50 AM   #20
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How bad is your take off and up hills with that rear end?

everything I know is a trade off

and we are pulling a small sailboat, but inside the bus is just two of us and its not "loaded" down with stuff as its not our "home" just a road trip vehicle
and in no hurry
That whole "takeoff" thing is sorta overplayed on this forum. My bus has great manners taking off, cruising the interstate, whatever.
School buses come with SUPER low rear ends due to the kind of driving they're purchased to do. Some like me get lucky and get highway gearing due to how the bus was used by the school but 90% of buses come with stop and go super low gearing that's far from ideal for interstate travel and highway miles.

If you're anywhere near FL come take my bus for a spin and see for yourself.

How heavy is your sailboat?
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