1953 F250 Plans
Cargo Master
Joined: Aug 2008
Posts: 2,661
Likes: 23
I've seen a 6bt Cummins with an Allison transmission in a newer F700 from Ford, so you also have the Allison option as well. (From what I remember the 4bt and 6bt are basically the exact same engine, the 4bt just has 2 cylinders cut off, so it should bolt right up as it would on a 6bt).
As far as those axles go, hubs can be changed out if you want a different bolt pattern. The 4.56 might be a bit much though, it's what I have planned for my truck but I also have 37" tires. You'll want to decide on your transmission and wheel size before gear ratio, they greatly effect it. If you gear it too low you'll have great low end torque but your first couple gears will be basically useless for daily driving and you'll top out at like 50mph. If you gear too high you won't have the torque you're looking for and be slower from a stop.
The RPM range you want on a 6bt is 1300-1800, with 1500RPM being ideal for MPG (from what I read). That's on the 6bt, but since the 4bt is identical in a lot of ways it should be the same.
Use this calculator to help figure it out:
http://www.grimmjeeper.com/gears.html
What you're aiming for is where the RPMs will be at the speeds you drive (down at the very bottom), the better your RPM range at your driving speeds, the better your MPG will be.
As far as those axles go, hubs can be changed out if you want a different bolt pattern. The 4.56 might be a bit much though, it's what I have planned for my truck but I also have 37" tires. You'll want to decide on your transmission and wheel size before gear ratio, they greatly effect it. If you gear it too low you'll have great low end torque but your first couple gears will be basically useless for daily driving and you'll top out at like 50mph. If you gear too high you won't have the torque you're looking for and be slower from a stop.
The RPM range you want on a 6bt is 1300-1800, with 1500RPM being ideal for MPG (from what I read). That's on the 6bt, but since the 4bt is identical in a lot of ways it should be the same.
Use this calculator to help figure it out:
http://www.grimmjeeper.com/gears.html
What you're aiming for is where the RPMs will be at the speeds you drive (down at the very bottom), the better your RPM range at your driving speeds, the better your MPG will be.
Thread Starter
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Senior User
Joined: Nov 2012
Posts: 225
Likes: 0
From: N,Ga
I've seen a 6bt Cummins with an Allison transmission in a newer F700 from Ford, so you also have the Allison option as well. (From what I remember the 4bt and 6bt are basically the exact same engine, the 4bt just has 2 cylinders cut off, so it should bolt right up as it would on a 6bt).
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
A 6bt is a good motor, I've got one and I love it, and it might actually cheaper than a 4bt. The 4bt's command a premium, and parts aren't as common as the 6bt. The only the thing is that 6bt is heavy, about 1100 lbs dry.
Sam
Sam
Cargo Master
Joined: Aug 2008
Posts: 2,661
Likes: 23
The NV4500 should be a good option for that then. I remember coming across something to fix before installing it though, there is this tiny little part that goes out and it tends to fall out of OD when you're driving. It struck me as an easy and simple fix, like a washer under a bolt kinda thing. Let me see if I can find my notes on it, it was a transmission I was also thinking of using. Oh, and I don't know if the 4bt has it, probably, but there is a bolt of death to fix that literally just needs a washer like clip under a bolt next to it so it can't back out. It tends to fall out sometimes and can cause major damage.
Those are the only two things I have ever heard that where "negative" about those parts, and both of those are super easy fixes that are about something that doesn't usually happen anyways. So awesome choice! lol (I spent a solid 2 years or more figuring out what powertrain I wanted in my truck, and we're thinking the same, lol)
I think the 4bt might work better for you, better MPG and all the power you'll ever want or need (and easy to get more), I have an F600 so my chassis is a lot thicker and wider and heavier duty, the only 6bt I've seen in one of these was also and F600. They are heavy and would require some strong axles and suspension. The 4bt wouldn't I don't think.
Those are the only two things I have ever heard that where "negative" about those parts, and both of those are super easy fixes that are about something that doesn't usually happen anyways. So awesome choice! lol (I spent a solid 2 years or more figuring out what powertrain I wanted in my truck, and we're thinking the same, lol)
I think the 4bt might work better for you, better MPG and all the power you'll ever want or need (and easy to get more), I have an F600 so my chassis is a lot thicker and wider and heavier duty, the only 6bt I've seen in one of these was also and F600. They are heavy and would require some strong axles and suspension. The 4bt wouldn't I don't think.
Posting Guru
Joined: May 2010
Posts: 2,068
Likes: 7
From: Moyie, BC Canada
Quote:
Something to remember as you'll get people saying it and it's annoying. Cummins isn't Dodge. A passenger side Dana axle isn't made by Dodge/Chevy with a drivers side made by Ford. Cummins makes the engine, Dana makes the axles. Car companies buy them to install into their cars. No different than the radio being made by Bose. Just a reminder because you will get the "why you putting a dodge in a Ford?" from people who don't realize this.
I used to think..."Why would they put a Cummins in a Dodge??? but they did
Something to remember as you'll get people saying it and it's annoying. Cummins isn't Dodge. A passenger side Dana axle isn't made by Dodge/Chevy with a drivers side made by Ford. Cummins makes the engine, Dana makes the axles. Car companies buy them to install into their cars. No different than the radio being made by Bose. Just a reminder because you will get the "why you putting a dodge in a Ford?" from people who don't realize this.
I used to think..."Why would they put a Cummins in a Dodge??? but they did
More Turbo
Joined: Dec 2006
Posts: 670
Likes: 6
From: south-central PA
have you decided which side you want the drive shaft on.
I agree with Mervy49 about what parts to use....
some other old school transfercase that meet your ideas are the bronco Dana 20, jeep Dana 300, or NP203 which are very heavy duty but because when comparted to a 205 they alway lose and aren't used. all can be adapted to a NV4500.
lots of old trucks have divorce mounted cases, it's more work than a swapping in a married unit.
most have a lot shorter intermediate driveshaft than mine, i did this for a total different reason. just to give you and idea......
I agree with Mervy49 about what parts to use....
some other old school transfercase that meet your ideas are the bronco Dana 20, jeep Dana 300, or NP203 which are very heavy duty but because when comparted to a 205 they alway lose and aren't used. all can be adapted to a NV4500.
lots of old trucks have divorce mounted cases, it's more work than a swapping in a married unit.
most have a lot shorter intermediate driveshaft than mine, i did this for a total different reason. just to give you and idea......
Cargo Master
Joined: Jan 2004
Posts: 2,202
Likes: 354
From: Mandan, ND
Quote:
Something to remember as you'll get people saying it and it's annoying. Cummins isn't Dodge. A passenger side Dana axle isn't made by Dodge/Chevy with a drivers side made by Ford. Cummins makes the engine, Dana makes the axles. Car companies buy them to install into their cars. No different than the radio being made by Bose. Just a reminder because you will get the "why you putting a dodge in a Ford?" from people who don't realize this.
I used to think..."Why would they put a Cummins in a Dodge??? but they did
Something to remember as you'll get people saying it and it's annoying. Cummins isn't Dodge. A passenger side Dana axle isn't made by Dodge/Chevy with a drivers side made by Ford. Cummins makes the engine, Dana makes the axles. Car companies buy them to install into their cars. No different than the radio being made by Bose. Just a reminder because you will get the "why you putting a dodge in a Ford?" from people who don't realize this.
I used to think..."Why would they put a Cummins in a Dodge??? but they did
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