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Old 08-23-2022, 04:43 PM   #1
Mini-Skoolie
 
Join Date: Aug 2022
Location: Virginia Beach
Posts: 57
Year: 1994
Chassis: 3600
Engine: dt408
1994 Thomas vista swap

Ello I am Brandon, I bought a 1994 IH Thomas vista with a DT408 based on the advice of knowledgeable Freind of mine with a AT545 trans, My rear end is 5.38 and my top speed at 2600 revs is barely 55mph based on the rear end..

looking at options of swapping out the rear end, and whether or not an MT643 swap coupled with rear end ratio is the ticket???

bus has air brakes !!
~Thanks ��

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Old 08-23-2022, 07:49 PM   #2
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,848
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
for something like that i wouldnt plan on having a 70 MPH cruiser unless you are going to swap to a 6 or 7 speed standard trans, or an overdrive electronic allison (1000,2000,3000)..



my DEV bus has a DT360 with an MT643 and a 4.78 rear.. if I redline it (2800 on a 360) i can get 68-69 MPH out of it.. and it DRINKS the fuel doing it..



if I run it at 60-62 (2200-2400 RPM) it is happy as can be..



now that said, when both air conditioners are on.. its a dog.. even with them off.. climbing hills even mild ones.. it slows down some.. and its only a 7 window short bus.



if you want a fast cruiser you would have to gear to at least a 4.44 (assuming you have 11R22.5 tires).. to even get to run it at 65 without it redlining.. the taller rear end will reduce your torque.. it will slow down more on hills and be slower to accelerate..



the DT408 is a bit more torquey than the 360 so you do have that going for it! its a great engine! all the mechanical DT's are some of the best engines ever built.



if you kept your 5.38 and went to a 7 speed where one is an overdrive gear you would have higher top speed and also plenty of gears for choosing in between for torque and speed...


if it were my bus id probably put an overdrive 2000 series in it and make the throttle inout work with a mechanical linkage box.. but thats me.. an MT643 and regear is certainly something that would imporve the driveability over its current setup alot.. but everything has a tradeoff....


my DT360 bus is night and day differemce t odrive ever since i swapped the 545 for a 643.. but its no faster.. the MPG did go up a bit because im making power and not heat... my engine fan rarewly ever runs even in hot weather.. whereas before with the 545 it was running constantly on the highway because of the trans heat in the coolin g system...
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Old 08-23-2022, 08:36 PM   #3
Mini-Skoolie
 
Join Date: Aug 2022
Location: Virginia Beach
Posts: 57
Year: 1994
Chassis: 3600
Engine: dt408
Okay I gotcha, I appreciate that, I know a guy who swapped aat545 with a 2000 Allison but said it was extremely difficult, and do u know a way I could atleast get to 65 while cruising? 2600 revs im at like 53mph and I know I shouldn’t push pass 2600…. My Freind who swapped his said his vista is like a Cadillac now haha he gets 65mp at 2200 revs just chillin
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Old 08-23-2022, 08:38 PM   #4
Mini-Skoolie
 
Join Date: Aug 2022
Location: Virginia Beach
Posts: 57
Year: 1994
Chassis: 3600
Engine: dt408
And i plan on traveling around the west coast and I know some places it’s 80mph and I can’t be going 40 mph I could probably get pulled over or somthing for that
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Old 08-24-2022, 07:33 AM   #5
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,848
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
if they are stopping people for driving 40 MPH on mountain grades then you dont need to be there...



I swapped an allison 1000 6 speed into my IH 3800 bluebird with a T444E, night and day difference.. best thing ever.. its like a new bus.. i did that swap 5 years ago.. and the obly thing left to do is swap my rear end from 3.54 to 4.10 to bring my 6th gear RPMs up... im just waiting on parts.....
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