Glad to see you thinking about the Cummins again. On one of your earlier posts you mentioned 4.10 or 4.56 axle ratios, I think that is too low if your running a 37-38 in tire. Shoot for 1800rpm at whatever speed you cruise at.
I have been very happy with my 56 cummins conversion, it's geared to cruise at 62mph at 1800rpm. I'm using a dana 80 with a 3.31ratio with 9r22.5 tires.
If you want drive mine before you make the final decision you have an open invitation.
If we where closer I would take you up on that offer, be helpful to see how it does in a '56.
The gear ratio thing seems to just be a mess of numbers. 90% of the time I will be going 20 or 30mph (its not even 25 or 35 here, lol), so I use 20,30 and 75mph to see what RPMs I would be and what gear at a given speed.
I'd like to run an Allison transmission on it, 6 speeds helps out a lot. With one of those and 4.56 gearing with 37" tires I'm at:
20mph = 1500rpm in 2nd
30mph = 1752rpm in 3rd
75mph = 1926rpm in 6th
With 4.10 gearing it's:
20mph = 1350rpm in 2nd (or 2300 in 1st, so that's no good)
30mph = 1575rpm in 3rd
75mph = 1731rpm in 6th
From what I came across you want the RPM to be between 1300-1500RPM makes for the best MPG, 1800RPM being the top of the power torque. You don't want to go below 1300 otherwise it starts to bog out and is worse.
Now transmission choice on this effects a great deal. But after going through all the options 4.10-4.56 always seemed to put me where I wanted to be. If I go less than that I'm staying in 1st gear for basically everything. I'm curious as to what transmission you're running as well as what else, most every Cummins 4x4 owner I've come across had it at 4.10-4.56 when they had 37" tires.
The six speed allison would be great with the 4.10-4.56, I have one in the truck I drive for work. IT shifts very smooth but is not cheap.
Can you use a six speed allison on a 12v cummins?.... computer controls?
Sorry I am no help with automatics.
I'm using a fuller 5306 six speed (no overdrive) but I do have a spicer 6041 four speed aux. trans behind the six speed the first two gears are underdrive third is direct and fourth is overdrive, Its like having a 4 speed rear end.
example: 1st gear in aux trans would be like I had a 7.08 ratio rear end.
3rd=3.31 the rear end ratio that I have
no need to split the gears in the fuller, but you could if you wanted to.
Glad to see that you started a build thread. I remember all the excitement around here when you announced your plans and proceeded to do it. Maybe you could put a link to some of those early threads in this thread? It was fun reading.
Was kinda interesting going through all my topic posts to see how my understanding and what I wanted to do changed. I had forgotten how far I had come with it all, lol. Man some of my original ideas where out there, lol.
That's a pretty neat setup Rusty, whole lot of gears to choose from! I've seen an Alison used on a Cummins before, even factory from Ford on an F700 none the less. I might opt for a different transmission though as I forgot about the computer. I don't want computers on this truck, electrical motors for the windows and locks are fine, computers I just don't like on vintage.
I checked out the other transmission options as well, like the 47RE,NV4500, Getrag, ect. as well as what transfer cases work with them or can be made to work, availability of parts, cost to change things, ect. (I have a whole note book of every combination, RPMs, speeds, ect.)
There are a couple setups that can work for me, I will probably be seeing what I come across more than anything. I'd like it to be an automatic simply because it's easier to 4x4 with, however I might end up with a manual. I love manuals in my cars but in a truck it's not the same experience, just more work usually. We'll see.
The pain with the gear ratios is that 4.56 is ideal for most setups in this, but not common, and it requires a larger housing, it's split on 4.10, some have the smaller, some are larger. But I have seen them around here, hopefully I can nab a pair with disc brakes. Still waiting for that deal of what I really want to cross my way, and then this build will get real serious real quick.
Right now I'm also working on my '89 Bronco. It was my fathers and had to sit for a little bit, so I'm trying to get it driving again. The plan is to be able to use that truck while my '56 is under the knife and once it's done build up the Bronco.
I could use a couple parts if anyone has some laying around. Most of my cash is tied up but I have things for trade if need be. I could use a set of running boards, I'll have to modify them anyways to work so I'm willing to use just about anything (the short ones are killing me right now), I could also use a horn button and that spring thing that goes with it, be nice to be able to use my horn (just don't want to spend $40 on a new one and end up changing out the column or something), and maybe another wiper arm and a wiper motor. Mine just slowly goes to the side then doesn't have enough power to come back down, lol. But none of those things are critical right now, just something I figured I could work on at the moment. If you have any such parts feel free to message me, but like I said most my money is tied up at the moment and these parts aren't critical to me yet, lol.
More pictures to come... when I have something worth sharing, lol.
Electric or vacuum? I rescued the vacuum wiper motor in our '55 F500 last Sunday. Pulled, cleaned, opened carefully, cleaned, silicone grease, reassembled, tested, opened, cleaned felt air return filter, rereassembled, works really well now! I have pictures if they'd help.
Yeah I might be interested in those. I think mine is electrical but to be honest I've never checked, just didn't notice anything vacuum related on it. It's not a huge priority, after all I've yet to discover if I can stop in the rain or not yet, lol. Hard enough on dry pavement. (brakes suck... only really work in the last 1/2" of the pedal and you have to give it all your might)
I asked ND Bill if the 66 wiper stuff would work. Ain't heard back from him yet. If they do I will pack a battery out and see if they are even worth pulling the motor. I know the switch is bad but I am pretty sure the motor and trans wiper ***. Is okay.
Man a guy may get in trouble with out a period in the abbreviation of assembly in that last sentence.
Awesome truck, don't let everyone else get you down! The old 50's trucks are sweet and I dig the pickup on steroids look...I've been contemplating doing something similar with my '63 F600. It's currently Sea Foam green and all stock. I love the sound of an inline 6, but the top-end of my 262 is a bit lacking. Since my '01 F-350 Superduty burned down about 6 months ago, I've been debating making a "real super-duty" out of the F600. I would still retain the flat bed and hoist, but shorten it to about 8'-10' overall. Cummins, 7.3PSD OR maybe a 7.3IDI + Turbo, and new rear axle/tranny to match the diesel RPM/powerband... It would be the "Tonka truck" I had as a kid, now as a BIG kid!
Just thought I would throw this out as an option on your engine / transmission source. Some smaller diesel pusher motorhomes sometimes used the B block Cummins with the six speed Alison transmission and most all the wiring, ECU, etc is somewhat grouped. Most of the owners I have known take immaculate care of them. Find a wreck or burned unit. Great thread, BTW.