Convert to 6x6

[Deezl Smoke]

We can do the ratio math with any constants you wish. If 46" tires, then we need your proposed top speed, and max engine rpm. If you have an overdrive, what ratio it is. Or we go with what axle ratio and get the needed tire size.
As i recall, those boyce planetaries have disk brakes. Awesomeness level at 11.5.
The 5 ton meritors are 6.44:1. Similar to the planetaries, they are double reduction. Lots of rotating mass.
I'd bet the majority of buses run mid 5s rear gears.

[cadillackid]

gears in stock busses vary widely.. for one busses are sold with many different circumference wheel / tire combos.. the most standard is 22.5" with an 11R tire. so around a 41? 42? if its an older pre-overdrive bus a 4.78 or 5.13 gear seems pretty common... (most of these busses were designed to move kids about town... and not so much road trips)... we have seen busses with gears in the 6's. and ive seen full sized busses with 4.10's before.. mid 5's gets more common as you get into the newer Overdrive transmissions.. as a means of still getting decent take-off torque and highway speeds..



me personally.. id probably build for an 11R22.5 or 11R24.5 tire..



something like this
https://commercial.firestone.com/en/...e_index=281565


you can likely find that in almost any commercial tire store.. 11R24.5 is a 44... so close to a 46..


-Christopher

[NWOleman]

Yeah Cadillac kid that is basically the tread I would want to run. Top speed, 65 would be nice so I would want to shoot for 63-65 top speed. Well where would I want to run the 12v cummins, 2000-2200rpm max and it's got the at545 but would like to run the 643 I think it is. I don't know anything about overdrives for commercial vehicles. Also sounds like a 2.5tonbtransfer case from a duece would be the tc I would want according to deezl.

[EastCoastCB]

Originally Posted by NWOleman

Yeah Cadillac kid that is basically the tread I would want to run. Top speed, 65 would be nice so I would want to shoot for 63-65 top speed. Well where would I want to run the 12v cummins, 2000-2200rpm max and it's got the at545 but would like to run the 643 I think it is. I don't know anything about overdrives for commercial vehicles. Also sounds like a 2.5tonbtransfer case from a duece would be the tc I would want according to deezl.

If it were me I'd start with a much more badass drivetrain than a 5.9/545 if building what you're talking about.

[NWOleman]

Probably should have but I jumped on a bluebird that only has 30k on the motor. I'm fine with the cummins it willl make enough for me. As far as the tranny I have found you can get the 643 pretty cheap. As far as axles I doubt I would find what I want in a stock bus so I don't think I went to far wrong, maybe though!��

[cadillackid]

+1 on either beefing up that 5.9. and going to a 643 or finding something with a bigger motor..



overdrives.. starting in the mid 90s you could get allison MD3060s. which were 6 speed (4 + 2 OD) automatics.. they were typiocally sold as 5 speeds in school busses.. with 6 gear unlocked and enabled you get a final ratio of 0.65. in year 2000 the 1000/2000 series overdrives came into existence.. at the time they were 5 speeds. with a 0.71 in the 1000 and a 0.75 in the 2000.



the MT-643. was a Beffy and stout 1:1. 4 speed auto with lockup.. to swap one in place of an AT545. theres likely some parts you'll need that ive heard are tough to get for the 5.9 cummins.. the AT545 is an SAE3 bell the MT643 is SAE2.. the converter bolt pattern is larger as is the offset from bell to converter hub..



an allison 1000/2000 can be built to take as much as you want to throw at it... and it can have an SAE3 bell.. comverter bolt pattern and offset matches an AT545.. but you have electronics to deal with..



ive done a 545 to 1000 swap and a 545 to MT643 swap.. both on international engines.. which I got lucky in that the parts for the 643 swap were still available on the used / reman market.. I dont know for a cummins 5.9.. I know the 5.9 elecgtronic 24 valve were built with allison 2000's



with the big axles and conditions you are looking at driving in.. i would want something that i could build to lock-up in 2nd gear.. or go with a full manual.. something with a lot of gears including 1 or 2 OD.. maybe a 7 speed? couple with a 2.71 transfer case you'd be able to pretty much crawl the off road..

-Christopher

[NWOleman]

Are their any divorced overdrive units like they run in pickups or overdrive units you can install on the back of the tranny or transfercase like a us gearvendors setup?

[NWOleman]

Also I don't want any electronics on the transmission if at all possible. That's one of the reasons I want the 12 valve cummins, it pretty bare bones as far as electronics.

[cadillackid]

there are.. im not sure if one can go on a transfer case setup or not.. I know a friend in texas has a spicer. and then a divorced aux trans.. i'll have to ask what is trans is.. the engine is a DTA-360. and i think his axle is S190.



-Christopher

[Tango]

NOTE: The 5th gen Allison 2000's do have an internal "computer" but will work with an all mechanical engine. That is what I have in mine. An ally 2200MH 6 speed, double OD connected to a one wire Cummins 4BTAA. All that is needed is a TPS (Throttle Position Sensor).

[NWOleman]

I could live with that probably. How reliable are they?

[Deezl Smoke]

Ok, fwiw, with the 12v i seriously dont think you'll be at all happy trying to get 65mph. The bus has the aerodynamic efficiency of a brick barn. Ad to that the 4x4 tall stance and anything over about 50 will start gobbling power at an unreal pace.
A common rail 24v 5.9 would be bare minimum. That 12v would sell here in 5 minutes or less for huge money. I have 2 of them in equipment roght now. Had a 92 dodge with one as well. Great, reliable engines, but very limited in power potential for us blue collars on a budget.
The 5 ton 6x6 900 series had two engine options. The 8.3 cummins turbo, and the 855 (14L) cummins natural. The 8.3 is an awesome platform. Its used in trucks, generators, water pumps, farm and construction machinery, etc.

There are a few 2 speed divorced tmanual transmissions out there. They can be run either direction, making them direct in one gear and either under or over in the other, depending which shaft is driven vs. drive.

As mentioned above, a manual trans with a couple ODs may be something to look at.

[NWOleman]

It doesn't seem like it takes much to get 300-400hp out of a 12 valve Andy 500-600 ft lbs tq with minor mods. Seems like that would be enough? Me being a greenhorn which trannys are manual that we were talking about? Like I said, trying to learn here and pick everyone's brain. No critism from me, just feedback. Thanks for all your guys input!!

[cadillackid]

Tango - all allisons will run with just a throttle.. thats the minimum needed.. the old 3060s from the mid 90s had just a throttle on mechanical 466s, and 8.3 cummins often.. the 5th gen TCM's are a little better at learning but they are a pain to do any pattern updates because allison introduced protected parameters which cost $$ to get unlocked.. im running 4th gen TCMs in mine.. fully tuneable.. you can assign 'wire inputs' and 'databuse' inpiuts.. so you could use TPS as the main input for transmission shift patterns but also assign a kickdown wire to always drop it down a gear if the RPM wouldnt be maxxed.. you can assign retarder wire as output so if you downshifted at certain speeds it would autio apply.. the possibilities are nedless even on a mechanical engine..



its not EMP proof if that is what your desire to build is... if you use an electronic engine the trans and engine will integrate even moreso and can be programmed to be super efficient and effective..



-Christopher

[cadillackid]

all of the allisons are automatics.. the spicers and eatons i mentioned are manual sticks
-Christopher

[Deezl Smoke]

Best not instal a egt (pyrometer) at those hp ratings.
The cool thing about manual transmission in this size of project is there are many dozens of choices and can be bought for pennies. The only wires would be a reverse light and maybe a temperature sender.
I have an 18 speed in my peterbilt and a 10 speed in my freightliner. The 18 i believe has 3 overdrives, but i have to get the tag info again and recheck that.
I also have a straight 7 speed spicer in an off road sterling truck. It has a 12.?:1 1st gear. It drives like a pickup stick shift. No splitters or other controls on the stick, just shift it. They're solid transmissions, and easily mated to most engines. There are many ratio configurations available in the truck trans world. But dont be intimidated by that. They are easy to identify. Many brands have ratio and other specs on their websites.

[cadillackid]

why would you not want a pyro at thiose high HP raitings? first thing i did was install one when I started to power-add to my 444E..I at least want to watch my pistons melt.. lolol
-Christopher

[NWOleman]

Yeah I assumed a typo or a touch of sarcasm about the pyro!😁

[Deezl Smoke]

Originally Posted by NWOleman

Yeah I assumed a typo or a touch of sarcasm about the pyro!😁

Sarcasm...d kinda like hauling a poorly secured load. Best to just fold the mirrors in and not know whats going on back there.

[NWOleman]

Been there! Don't look back till you get there and everything is cool!