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Discussion Starter #1 (Edited)
Hello everyone, i'm totally new here and this is my first post. I've been lurking for awhile trying to learn what I can but finally reach a point where i'm hoping more experienced people can help me understand in seconds what might take me hours of research otherwise...


What are the pros and cons of each of the major axle makers? I am assuming that for a solid axle vehicle it's not excessively difficult to put a different make axle under your trail rig or people wouldn't be using Rockwells.. so maybe some GM corporate axles would find their way under a dodge, or some Ford Sterling ones into a GM under certain circumstances. Is there ever a good reason to NOT run what came stock?

What i'm wondering is what those circumstances are in each weight class. :) I'm mostly curious about say the 1/2ton-3/4ton category and 1 ton (light and heavy) ranges. So i'm guessing for instance that it's a battle between GM 12 bolt, Ford 9 inch, and Dana 60 rear (44 front) for the lighter. Then probably GM Corporate 10.5/AAM 11.5, Ford Sterling 10.25/10.5, and Dana 70/80 class stuff (or Dana 60 in the front which seems notably stronger than in the rear). (unless there is anything else in the running for those weight classes?)


As near as I can figure the GM 14 bolt's main advantage is that it's cheap, the Dana's is that it has the lowest rolling resistance (if that matters to you for MPG/actually does for me as usually on road), and the Ford... i'm not sure what it's advantage would be actually. Both Ford and Dana offer 3.07 ratios possible for those of us planning slow turning diesels and granny gear 1:1 transmissions with double low crawl boxes. I'm hoping the tall gears are also in low demand meaning cheaper parts.

For the lighter ones (separate 4x4 project am contemplating with 1/2 ton or 3/4 ton running gear on something as small as a jeep even) i'm even less sure other than the Dana again has the lowest rolling resistance in every case. The Ford 9 inch here though offers the numerically lowest gears for again nonoverdrive diesel vehicles running normal size tires when on the road BUT if there is nothing 2-series to match on the FWD end of things that doesn't matter unless there's some way to stick one in the front. The GM... well just probably came on it so i'm guessing in this class nobody would ever put a GM axle on a non-GM or mix brands of axles front to back as long as the ratios match?


I'm aware there are mountains of specific information on each axle here... that's the problem! :) I'm looking for just one line comments to help me decide one way or another, like "cheapest and lightest rear disc brakes for X" or "this axle is cheap in the junkyard but once rebuilt costs more" for instance. I'm actually wanting to choose a 4x4 from the axles up and design around that.

About the only must have features for me are some kind of manual locking differentials (air or cable, no electronics to short out) and a preference for numerically low gear ratios (3.07 ideally for the one ton aka like 4.10's with an OD where I gear lower in the trans instead of the axle, and for the other perhaps even 2-series if possible since street tires on a jeep or compact pickup with no OD is pretty small diameter - I don't want to tool around on mud tires on the street, sorry. :p I will literally leave the trail tires at the cabin and swap) in both cases to use cheap non-OD transmission with like a NP203/205 double low crawl box. The double box should make even a 2.29 rear gear into a 4.56 afterall with a normal crawl box and i'm hoping the axles will cost far less because nobody wants them!


PS yes i'm aware most people would encourage low axles, but this is the idea I can't get out of my head... can I just use the tall gears nobody wants to get strong parts for cheap, then gear down in the transmission and transfer case to make up the difference... the tires should only care about the ultimate gear ratio between the engine and them, not which among the trans/transfer case/axle is doing how much reduction. Or is there some other issue i'm not aware of like strength? (though i'd think a big huge pinion on a 2.29 gear would be far stronger than the tiny one I see on a 4.56 gear)

PPS things like lockers not supporting the tall gears would be an example of a 'veto trait' i'd consider valid for disregarding my tall gear interest and accepting shorter gearing. I still don't think i'd want shorter than the 3.5 range though or it will scream on the highway with normal gears.
 

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holy wall of text batman. bigger is better. lower ratio is better.cheep is better. hope that helps.
 

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To much reading.

Look at a Dana 44 front, ford 9 rear combo

And a Dana 60 front 14 bolt rear.

Ford9 ring and pinion strength is it's strong point.

Depending on your terrain, Dana 44 ford 9 can run at the smallest 35s I guess.

60/14bolt combo should run 36 smallest cause the 14 bolt hangs low unless you modify it.

A stock front 60 is stronger than a built front 44
 

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Easy concept, the stress of the parts moves. Let us know how the t-case outputs last with 3.00 gears. Or 1310 joints...
 

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I'll take a stab at it...

Is there ever a good reason to NOT run what came stock? Typically you're looking for something stronger than stock - if what you have is strong enough for your application, no reason to upgrade.

As near as I can figure the GM 14 bolt's main advantage is that it's cheap, the Dana's is that it has the lowest rolling resistance (if that matters to you for MPG/actually does for me as usually on road), and the Ford... Advantage of the Ford 9" and Dana is aftermarket support. As you say, the 14-bolt is cheap and lately aftermarket has been catching up since people are using it.

The Ford 9 inch here though offers the numerically lowest gears for again nonoverdrive diesel vehicles running normal size tires when on the road BUT if there is nothing 2-series to match on the FWD end of things that doesn't matter unless there's some way to stick one in the front. Search for 609 or "sixty nine" - combination of Ford 9" center section and Dana 60 outers for a "front axle" 9". Similar things are done for a front 14-bolt.

I'm actually wanting to choose a 4x4 from the axles up and design around that. Makes more sense to choose a vehicle that suits your needs and then upgrade components to meet specific needs. Again, if a stock vehicle suits your needs it is going to be a lot cheaper and easier than building something from scratch.

PS yes i'm aware most people would encourage low axles, but this is the idea I can't get out of my head... can I just use the tall gears nobody wants to get strong parts for cheap, then gear down in the transmission and transfer case to make up the difference... the tires should only care about the ultimate gear ratio between the engine and them, not which among the trans/transfer case/axle is doing how much reduction. Or is there some other issue i'm not aware of like strength? (though i'd think a big huge pinion on a 2.29 gear would be far stronger than the tiny one I see on a 4.56 gear) Usually cheaper to regear the axles than to regear a transmission or swap in a second transfer case. Also, a doubler is going to lower your overall setup for the trail. But it isn't going to do anything for highway travel. So if your axles aren't geared reasonably for your tires, highway travel will suffer. Pretty common for people to put on larger tires without regearing and then find that they can't use overdrive on the highway because they're lugging the engine.

PPS things like lockers not supporting the tall gears would be an example of a 'veto trait' i'd consider valid for disregarding my tall gear interest and accepting shorter gearing. I still don't think i'd want shorter than the 3.5 range though or it will scream on the highway with normal gears. You want to start with one of the gearing calculators out there - plug in tire size, transmission, and transfer case and then start looking at what axle ratio you need for speed vs. engine rpm
 

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PS yes i'm aware most people would encourage low axles, but this is the idea I can't get out of my head... can I just use the tall gears nobody wants to get strong parts for cheap, then gear down in the transmission and transfer case to make up the difference... the tires should only care about the ultimate gear ratio between the engine and them, not which among the trans/transfer case/axle is doing how much reduction. Or is there some other issue i'm not aware of like strength? (though i'd think a big huge pinion on a 2.29 gear would be far stronger than the tiny one I see on a 4.56 gear)
If you put the low gears in the transmission or doubler, then the entire drivetrain needs to be able to handle the torque. Stout transmission, transfer case, u-joints, drivehsafts. Heavier, more expensive parts. Putting the gear reduction in the axles means just the axle shafts need to be extra stout. It's easier/cheaper to build drive shafts balanced for high speed/low torque than for high torque/ low speed. This is why most modern vehicles have overdrive transmissions to increase road speed/ decrease engine speed rather than put less reduction in the axles. Heavy duty off highway vehicles often have gear reduction hubs to put the torque multiplication as far downstream as possible.
 

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Best advice I can give is to hook up with someone that wheels hard, hang out with him/her for a year, look at what people are running, ask them questions, see what works and what doesn't and then decide for yourself. I've been wheeling and building for 20 years and I can honestly say I can not easily answer all of your questions. You just need to start hanging around those that are doing it and starting asking questions and learning.
 

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Discussion Starter #8
Sorry for my wall of text, i'll try and make it more readable.

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Easy concept, the stress of the parts moves. Let us know how the t-case outputs last with 3.00 gears. Or 1310 joints...
I guess I was going off the 'reputation' of the NP205 being bulletproof so I was hoping a 33% taller ratio and higher load on the backside vs a common 4.10 wouldn't be unreasonable. If it is, i'll have to change my plan - simple. Originally it was about non-OD granny box and tall 'unwanted' Danas as a way to save money on both ends for parts then work around it.

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I'll take a stab at it...
Thank you!

The "609/69" axles are very very interesting to me, to avoid spamming the thread i'll make a separate small topic after I read more on it. Should such an axle have the GAWR/weight capacity of a Dana 60 then, since if it's still full floating, the weight should be borne by truss and Dana 60 outers and only torque load should reach the ford center? I mean would you trust a 609 under the rear of a 1 ton as well if also used for towing and heavy cargo in the back type pickup duties?

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If you put the low gears in the transmission or doubler, then the entire drivetrain needs to be able to handle the torque.

It's easier/cheaper to build drive shafts balanced for high speed/low torque than for high torque/ low speed.
When I read about Dana 61/71 axles I was wondering if that would give me the axle strength at a lower price since "nobody wants them", provided I can work around it and just gear down trans/x-case. People talk like Dana stuff is over $1000 in bad condition used! :-/ (I haven't looked yet, is early in parts choosing process still figuring what the options even are)

It makes sense why factory vehicles would have a fast drive shaft as you say, but if the used value of the axles is a big difference might heavier upstream parts pay? I mean like if it's that I could buy an axle at half price at some point the cost of stronger trans and such may be money ahead if I have enough gear to use it. Would the NP205 and it's u-joint be the weak point in an SM465/3.07 geared Dana 60&70 combination?
 
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