2 speed rear end
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    Question 2 speed rear end

    I have a 1 Ton Dually rear, and I was thinking about a 2 speed rear end.

    So, what is the smallest 2 speed rear end made for a truck?
    I think I once seen a 1.5 ton with split rear, I just can't remember where.
    I want something I can still get parts for, and that is adaptable.


    Please, I need more beef than a Lincoln Zephyr Columbia 2-speed.
    Loki

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    Default 2 speed rear end

    International offered Eaton 2-speed rear axles as an option for their 1-1/2 ton chassis-cab trucks from 1962 until they stopped production in 1975. They used a 5-hole Budd wheel bolt pattern, with 17" and 20" split-rim wheels. They were available with three gear ratios; the highest was 5.14/7.15.

    I believed they were geared to pull full loads at about 55 mph, with the engine turning around 3000 rpm.

    I've got a 1500, that I'd love to re-power with a diesel, but I haven't figured out how to overcome the low gears... The two-speed axles are designed to be an underdrive split, unfortunately, and not an overdrive. Wheel choices are also rather limited (Dodge chassis motorhomes had 19.5" tubeless tires with the 5-hole Budd for awhile).

    I've never seen any other "small" trucks with the two-speed axle, but they may be out there...

    Good Luck, Mike Richards

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    Default Great!

    Thanks!

    Do you think I could swap out the ring, and pinion to 3.54 & 3.08 ???
    I would like to go up to 2.05 but I don't know if that would be too steep.
    I have seen people swap wheel hubs so they can fit their old rims to a new axle, so I don't see much problem there.

    Having a locker with a two speed rear would do wonders.
    Loki

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    Like was already said you have a 5.XX limitation with a two speed rear that's why they aren't practical for diesels.

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    Detroit Section Caretaker Grigg's Avatar
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    I used a small Rockwell (Meritor) in a 1 ton truck I had, it came form a small Freightliner and was rated at 15,000 lb, a model RS-15-120. It is only a single speed, but did have ratios choices from 3.31 to 7.17, and an optional air operated differential lock. I just checked and I don't think they offer a two speed center section for this axle housing, only larger ones.

    You can search, but by the time you find a two speed axle that has favorable gear ratios the axle will be several times larger and heavier than you need or is even practical.

    Grigg
    1948 Chevrolet 6400 (2 ton) updated with a Detroit Diesel Silver 4-53T and Roadranger RTO-6610 --click for all my pictures--
    "First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-

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    Default Dreams Don't always work.

    Can't say I didn't try!

    It seems like a good ideal if I could get what I want.
    I figured I could work with the extra size, and weight because I keep the truck on the road most of the time.

    I only have a 2wd setup but if I can't get taller gears than a 5.xx then I don't want it!!!

    I guess a 3.54 is the best I could hope for in a ring, and pinion change. I want better fuel mileage, and higher speeds on the highway.
    Loki

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    Isuzu reliability tester carcrafter22's Avatar
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    Why not install a gear vendors overdrive or something similar? I have seen people get entire setups for under $1K used and in good condition. Do you already have an overdrive trans?
    Randy
    1967 F100 isuzu 4bd1t 60mm turbo procharger d1sc, big shied injection pump, 100% injectors - currently building AWD chassis for it
    2001 Jeep Grand Cherokee isuzu 4bd1t, he351 turbo 370cc pump, 100% injectors, 4l85e trans, bw4401 transfer case, clayton long arms 4.5" lift - For sale

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    Default Yup!

    I am installing a NV5600 while we speak.
    Once heard of a browning 3 speed gear spliter but I have never seen one.
    I have seen the gear vender's overdrive unit, and I have seen a
    fuller aux-trans at $5 grand.
    I have never seen any at $1000.
    Any transfer case has a high/low setting: not what I really want.

    Will research, splicer, eaton, dana, ford, rockwell, and some military surplus before I call it quits. If I find anything I'll let you know.
    Loki

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    I stand corrected. Today I checked out a 75 F600 with a 370/4 speed that has a 2 speed rear with 5.36 low and 3.90 high ratios. I do not know what make or model of differential this was, but far too big to put under a pickup.

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    Default numbers, and letters

    I have been trying to learn the call numbers for all the American made 1-1/2 ton trucks. I feel like I'm using the ole hunt, and peck method.

    I learned the IHC 1200 is a 1 Ton so I thought the 1300 was a 1-1/2 Ton.
    So what is the 1210, and the 1310?

    Every thing I have found in a 1-1/2 Ton comes from the 1930-50. That 1975 IHC that came with the 17" wheels sounds real good.

    I once had a Green 1966 3/4 Ton GMC 4X4 V6 Napco that came with a set of 17" split rims. Split Rims scare me! There is just too much that can go wrong.
    Loki

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    What are you trying to accomplish?
    What tire size, OD ratio if any, and rear axle ratio do you have or want, and or how many RPM's at what speed are you shooting for?

    There are lots of gearing options and combinations out there, but without a clear goal no one can help you figure what might work.

    Grigg
    1948 Chevrolet 6400 (2 ton) updated with a Detroit Diesel Silver 4-53T and Roadranger RTO-6610 --click for all my pictures--
    "First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-

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    Default Here's the Skinny

    I am driving across country in a p-30 Grumman bread-truck: Chevy utilimaster class. Transmission swapped to an NV5600.
    Engine 4BT
    Transmission NV5600
    Present rear 4.11
    Want 3.08
    Wheels 16"
    Tires 245
    2WD
    RPM Topping between 3500 & 4000
    OD 0.73 if I remember right: Maybe 0.75
    Max speed 85-MPH

    I am moving my belongings from New York City to Oklahoma.
    My first trip across America taught me that all the re-fueling stops were at the bottom of a HUGE hill.

    Here is my biggest problem: entering the on ramp while building up enough speed to SAFELY merge with oncoming traffic, trying to match the speed of traffic, and NOT get Myself Killed!!!

    Mirrors can only do so much.

    Misconceptions’:
    I am not trying to build this truck for racing.

    Traffic often flows at 80 MPH: however, the big hills tend to slow traffic down to around 70 MPH.

    Yes I tried to do U-Haul, Rider, Penske, Ect. $2500 to $3500, and they have more games than Parker Brothers. Web out the horror stories, and problems just for a look see.

    I figured to spend that money on my truck, and make a few trips back, and forth.

    So, I fix this: I change that: I read, and research a little more, and I do what I can.

    Bypass filters
    Amsoil
    Maybe an Airdog

    I have been researching a propane injection system to run in addition to the Diesel fuel that operates the engine. Propane is so cold that it would actually become an intercooler at the flip of a switch.

    With the huge flat nose front on this rather large stepvan, I plan to use some kind of air scoop to force more air into the intake system for better breathing.

    Yes, it already has a turbo.
    No, as of yet, I do not know what PSI it is now producing: ask me again later: I am shooting for 40 PSI on this stock motor.

    Wanted:
    More Power
    Better Fuel Mileage
    Faster Acceleration
    Matching traffic flows

    A 1-1/2 ton 2 speed rear might be a little farfetched: but maybe, just maybe it might be just the extra trick I have been looking for to add one thing without losing another.

    My truck is not a $30,000 cream dream Dodge Ram with $20,000 worth of extras, and all the comforts of home.

    I have been swinging a wrench most of my life, and a small 2 speed axle seems like a plausible option: maybe not.

    After I have exhausted all avenues of operation, I will go, and ask another.

    Questions:
    Is this dream cost efficient?
    Is it practical?
    Is it plausible?
    Can I find what I am looking for?
    Will it cause more problems than benefits’.

    I must take all this into consideration before I even think about picking up a wrench.

    I don't usually work on something this big. This is why I am here asking for help, and trying to learn from anyone who is available.

    If everything works, and I actually do the do, I promise to post the photos on this forum, and tell the tell.
    Last edited by Prankster; 05-05-2009 at 09:36 AM.
    Loki

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    Thanks, that's a lot of help.
    Basically you want a long distance box truck, will be loaded half the time, and need to make the best of the little 4BT.

    Your NV5600 has a high gear ratio of 0.73
    Tire size (outside diameter, or better yet twice the effective rolling radius when loaded) I'm guessing is about 30"??

    If you have a Dana 70 or 70HD rear axle you can get gears as fast as 3.54, also 3.73 and slower
    If you have a GM 14 bolt then you can get 3.42, 3.73, and slower.

    With the above info and this link you can calculate speeds and RPM and plug in the variables and see what works best.
    http://www.onlineconversion.com/bigger_tires.htm

    If you don't find a suitable combo then consider a gear splitter and or auxiliary OD that bolts on the back of the transmission.
    http://www.gearvendors.com/
    http://www.usgear.com/home.htm

    To address some other things:
    I hope you rarely if ever need 3,500-4,000 rpm, and not for long at that.
    If you want reasonable economy try for 1,800 rpm at cruising speed, and you may find that with a load you need more RPM, perhaps 2,200 rpm might be a start for when you're loaded and on the highway.

    Will you have enough power to go 70 or 80 with a load, or even empty pushing all that wind? If you want better economy consider 60-65 loaded and a little faster empty if you must.
    Ideally you'd be running loaded in direct drive, and return in OD turning fewer RPM at essentially the same speed.

    Can you get 40 PSI boost and will your stock turbo survive? Is that much necessary, what do you gain by it, and at what expense?

    If you would like to merge with traffic easily you need some power, but perhaps more importantly you need good shifts, nice evenly spaced gears.
    Ideally each shift results in a small RPM drop all the while keeping the engine above peak torque (about 1,600?) and without having to really wind it up on the top side. About 20% shifts seems to work out pretty good, that gives you around about 500 rpm drops when shifted at 2,400 or so, depends on a number of variables, so run the numbers in the gear calculator for your transmission gears.

    I think if you lower your expectations a little and realize you might not always be able to go as fast as you want or merge as quickly as you would like you'll be OK with what you have. Otherwise a 6BT should be a good step toward driving faster and burning more fuel.

    Grigg
    1948 Chevrolet 6400 (2 ton) updated with a Detroit Diesel Silver 4-53T and Roadranger RTO-6610 --click for all my pictures--
    "First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-

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    I have driven empty 24 footer stepvans on the interstate at 65 mph. To me this is about near the maximum safe speed for one of these big old box trucks with 1970's designed technology. You have to be alert to whenever a semi is starting to pass you because the wall of air that it's pushing slams into the side of the van which can cause you to do a slight adjustment with the steering wheel. These trucks were really designed to be short range, local town to town, high cubeage, low cargo weight type vehicles. I think running at around 65 - 70 mph in OD is going to be your best reasonable speed. Just stay alert and let the faster traffic pass.
    BobS

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    Default PS. mistake

    My max speed is 65 MPH, and I would like to go 85 MPH when it is needed: but, I would think I might need a tail wind.

    BobS, You are right about speeds over 65 being too fast. Sometimes I have trouble safely keeping it up to 65, and needing to slow down. I just want to have a bit more power to pass up the crazy drivers, and get out of their way when needed.

    I am sure you have had problems with them too!!!

    I get 20 MPG, and I am happy with that. However, this little 4BT is still bone stock, and I bet I could squeeze out a little bit more. It's those hills that has been driving me CRAZY! I fuel up at the bottom, and dangerously climb to the top while trying to merge with traffic, and accelerate fast enough to match the speed of traffic.

    Grigg thank You!
    Bob, Thank you too!
    Bindermike Great info, Thanks!
    AverageF250, also, a big thanks to you!
    carcrafter22, if you can point me to a great deal: I'm on it.

    Tomorrow I will check out the local truck grave yard for some info on a parts quest.

    Wish Me Luck!
    Last edited by Prankster; 05-05-2009 at 08:00 PM.
    Loki

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    A couple more options. The Dana 80 in a 3.31 ratio or a 1st Gen CTD with the Dana 71 with 3.07 r&p. I think 3.07 is too high in that rig, if your looking at getting up to speed to keep from getting run over. Also, it's a brick, with the aerodynamics of a brick, I don't think you should dwell too much on this. Get on moving and be done with it. I have driven these with the gasser engines in them, 65mph with any wind is a complete pipe dream... And passing truck traffic is a white knuckle event.
    1989 D250 CTD, 727HD, D70/3.07, BHAF, DIY Cold air, Tuned VE, 4" exhaust

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    Default Parts Finder

    SDstriper:

    You Ain't kidding about the white knuckles!
    You are also right about this stepvan having the aerodynamics of a brick!
    A gust of wind can toss this truck into the next lane in the blink of an eye.

    I'm still working on a better suspension: air bag asist, and, Stiffer shocks.

    How good are these trucks at pulling a trailer?
    Loki

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    Default F600 2 spd axle

    Quote Originally Posted by averagef250 View Post
    I stand corrected. Today I checked out a 75 F600 with a 370/4 speed that has a 2 speed rear with 5.36 low and 3.90 high ratios. I do not know what make or model of differential this was, but far too big to put under a pickup.
    Do you have any more info on this axle, is it available, are you sure of the ratios ?

    Thanks Richard

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    Welcome. THis is an old thread. I drove a dump with this setup and you don't want those gears under a pickup. You should b able to find this rear withouttoo much trouble.
    True self-esteem comes only from what your dog thinks of you.

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    Default Two speed rear axles

    Responding from an older info sight but am wondering how Loki made out with his "bread truck" project with finding a two speed axle? It seems the idea of a two speed axle is under utilizied? Wouldn't you have a ten speed setup if you had the two speed axle with a 5 speed transmission? Flexibility in regulating rpm,power and fuel economy could be much better accomplished? Dave

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    Dave, I agree, however, the rear axle makers don't.

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    Detroit Section Caretaker Grigg's Avatar
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    As I posted in the early days of this thread from my research you won't find a modern 2 speed axle rated for anything less than 15,000 lb, usually larger. Modern ones having favorable gear ratios..
    Or if you do find a smaller 2 speed like from something in the 50's and earlier they will have ratios around the 5.xx, 6.xx, and 7.xx range at best, so not much use even before you look at the old brakes and parts availability.

    While a 2 speed axle sized for a pickup truck may sound great I think there would be very little if any market because of the complexity of shifting it. Though not "that difficult" it is probably above a lot of pickup truck buyers who can't even or don't care to drive a manual transmission.

    More reasonable options these days are good 6 speed manual or a small Roadranger 10 speed if you have the room and desire for one.

    Grigg
    1948 Chevrolet 6400 (2 ton) updated with a Detroit Diesel Silver 4-53T and Roadranger RTO-6610 --click for all my pictures--
    "First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-

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