[navymark08]

Hello all,
My Cummins 4BTA powered Jeep Wrangler project has been in planning for a long time, and the work will begin shortly. Before it does, I really need your advice and expertise with the choice of axles. This is similar to the other active thread, but I want to introduce fuel economy into the equation.

My Jeep will be primarily street driven, but I want it to be a dual purpose rig. So far I have the motor and a NV4500 transmission. The transfer case will be an Atlas II but I have yet to buy it since I don't know if I will have a driver's or passenger's side differential.

I intend on running nothing smaller than 35" tires (like a BFG AT) for the street (since all I can find are 4.10 ratios) and interchanging between 37" swampers for the trail. So far at a junk yard, I found a really nice Dana 70 (I believe) rear end with disc brakes and 4.10 gears. I also found a million other 1 ton rears like sterlings and other Dana 60's/70's with drum brakes (not very desirable in my opinion) and some nice axles from a newer Dodge Ram 1500. If I go with the disk brake 70, I would opt for a Dana 60 front axle.

This issue has been on my mind for weeks and I can't decide! :rasta: As much as I want my Jeep to be totally bada$$, will I really need a Dana 70 rear and Dana 60 front? Yes, I want reliability and durability, but wouldn't that come at a cost to my fuel mileage with all that weight? Those are some HEAVY axles! I think there needs to be a compromise here...

Let's face it, most of us swap in the 4BT for it's economy and torque. I am no different - I want the economy everyone else talks about - around 30 mpg or higher! Would this motor be powerful enough to move these heavy axles and tires with ease or would it simply bog it down and use more fuel?

My other thought was to use 1/2 ton stuff like the Dodge Ram 1500 axles I mentioned (Dana 44 front, Chrysler 9.75 rear). I figure this would still be strong but would be a lot lighter too.

So in the end, how much will the added weight of heavy duty axles affect economy? Please, if you have any suggestions, comments, or advice to offer me I would greatly appreciate it - I'm starting to get sick of arguing with myself! uke:

Thanks for reading my post and thanks in advance for your help.

Respectfully submitted,
Mark H

 

[scout4bta]

My Scout 4BT is running D44's, 33" tall tyres with 3.73 gears with PowerLoc's. Atlas transfer case, 4.33 gears.
Breakage so far:
1. Lets see, the first breakage was the rear diff, gernaded the the spider gears, open diff pulling up oleander stumps with a real short chain. First gear low range , just let it idle. This is farm equiptment right?
2. Front drive shaft at the weld, wheeling. (Stock factory shaft)
3. Rear drive shaft u-joint at the diff, powering over some bumps in 2 hi.
4. Front passenger side u-joint broke, took out stub axle and inner axle.$$

Go with D60 front and rear, that should be all you need.
IF you keep in on the street and don't tow you can get away with a D44, IMHO.

A D44 is at it's limits with a gas motor and 35's.

 

[JimmieD]

What Scout4BTA said!

It's a little over 100 lbs difference between a D44 and a D60 so at most you're only talking about maybe 300 lbs total difference? Those aren't make or break numbers for fuel mileage. 4BT torque through Atlas gear reduction is a whole lot of applied torque on your axles.

 

[navymark08]

Thanks a lot for the input so far - it is much appreciated. I don't know how much my stock dana 30 and dana 35 weigh, let alone 44's, but I've heard before that dana 60 fronts were on the order of 500+ lbs. People on Pirate 4x4 are usually mentioning that these are REALLY heavy parts.

Is there an effect of unsprung weight (weight under the springs) on economy? At least wider, heavier axles would give me more stability and a lower center of gravity.

keep 'em coming...

Mark

 

[Diesel Durango]

hmm, more axle discussion, good stuff.

If you can get a 70 rear, go for it. stock D60 30 spline full float aren't all that desirable IMO. The shaft size isn't much larger than a D44, the only thing they have going for em is full float, that is a good thing though. if you can find a D70U that's even better, they have a smoothe bottom to begin with.

all weight has an effect on economy, but i really don't know how much. more weight downlow will also help with stability.

If you want to keep a somewhat narrow stance, H2 wheels look pretty good, i could probably dig up a picture of H2 wheels on a YJ with 35's if you want. H2's came with 35" BFG A/T's too and lots of people upgrade to the standard 24's, so they can be found for reasonable prices sometimes.

H1 wheels will work as well, but aren't quite as :grinpimp:

 

[52wrench]

How about a Ford 9"? Not as heavy as a 1 ton but probably better than a D44plus you can get just about any setup you want for it in terms of axles and gears. It might be a good compromise.

 

[dubvee]

I vote for portals.

 

[Diesel Durango]

How about a Ford 9"? Not as heavy as a 1 ton but probably better than a D44plus you can get just about any setup you want for it in terms of axles and gears. It might be a good compromise.

the 9" is a great axle ( i have one in my grand cherokee) but if he thinks he may move up to a 60 front I would probably go 60/70 rear to start with for the right bolt pattern. I haven't seen a cheap way to convert 5x5.5 to 8x6.5. It's easy to convert a 44 front to 8 lug with 3/4 or 1 ton stuff.

 

[52wrench]

I agree, overkill up front is always better and cheaper than finding out later that what you considered overkill really wasn't.

 

[navymark08]

How about a Ford 9"? Not as heavy as a 1 ton but probably better than a D44plus you can get just about any setup you want for it in terms of axles and gears. It might be a good compromise.

I vote for portals.

Ha. Portals. That'll be the day.

I seriously considered the 9" a while back but decided that since the bolt pattern wouldn't match my front and that it's a c-clip axle which makes it kind of frowned upon. Aside from that, I wanted something wider than the stock 60" wms of my jeep axles and the Ford 9 is normally 58" or less.

Guys thanks again for the responses - you're making me feel better about my choice to run the 70 rear and the 60 front! That'll be :grinpimp: This thing would be a total monster with those axles.

Any other comments and suggestions are still welcome!

 

[Diesel Durango]

uhhhh what kind of 9" were you looking at? maybe you are thinking of the ford 8.8? the ford 8.8 generally run 58.5" or so wide.

9" axles are semi float and non-clipped. they came in a variety of widths from 58" up to 65" or so i'm pretty sure. 9" axles can be built to handle pretty much whatever you can throw at them. There's a reason you find them in the back of A LOT of dragsters. It's just a matter of how much money you got The aftermarket is pretty much never ending.

It does get expensive but they have a really nice strength/weight ratio. the housing is all steel too so you can weld directly to it very easily. a 9" housing itself can be carried around pretty much effortlessly.

I'm running a 9.25 in my Durango and we'll see how it holds up. If i start blowin R&P's it will be upgrade time. not sure what i'm going to run, depends on if i want to convert to 4wd at the time or not (I probably will).

 

[JimmieD]

I run the Dana 60HD which has a much stronger ribbed case, full float axles and all the good stuff. Found under RV's or D-200-HD Dodge trucks. Like everybody else, Dodge offered standard weight rating D200 3/4 tons, and HD rated 3/4 tons. The higher GVW got the Dana 60HD axle in rear. Most often 4.1 ratio which is perfect with an o'drive 5 speed. Mine's 2WD.

 

[beck]

I guess this all means my stock Chevy 10 bolt (1/2 ton 2 wheel drive) is toast!
I just spent $515 for a total rebuild on it too.
I'll run it until is blows.

 

[52wrench]

No c-clips on Ford 9", they have bearing plates on the outer ends, bearings pressed on to axle, pumpkin is removable from housing. If you decide to get one, get the big bearing one they put in the 3/4 ton trucks. I'm replacing my 8.8" with one but my rig will be pretty much a highway queen. Probably don't really need it but I like going to junkyards

 

[navymark08]

what's the weight difference between a Dana 60 or 70 rear and a Ford 9" rear?

If I found a nice big bearing 9" then I'd probably feel inclined to get the high pinion third member from Currie or TruHi9 - and that costs serious money. I'm not sure if I'd want to put that much money in an axle like that. Would it be worth it? It seems like a cheaper and easier solution would be to get the 60 or 70 rear.

 

[Diesel Durango]

there is a HUGE difference between a 60/70 and a ford 9". I don't have numbers but I'd imagine it's a very large difference.

cost wise, they are all probably close to the same when it comes to buying and setting up how you want them. Getting a Hi-9 while cool is not where i would start trying to upgrade a 9". first thing to do is get a nodular third member and disc brakes. I have ford 8.8 disc brake hardware on mine, but it's 5x4.5 pattern.

this is just my observations, I don't have any numbers on me. they are out there though.

none of them are a bad choice, but if you go with a FF 60 with 30 spline shafts it sounds like alloys aren't that expensive and are a very worthwhile upgrade. a lot of people have blown 30 spline 60 shafts with 37's.

edit: there's a 9" bible out there, i think it's by Mr. N over on pirate, i'd check around for it. it will tell you what BB 9" axles came in and how to identify them.

 

[JimmieD]

I'd agree that the cheapest and most effective, most bang for the buck, is the Dana 60. Only reason I happened to use the HD model with ribbed case reinforcement etc. is because I had one leftover just waiting. You can find D-60's on Craiglist for as little as $100 every now and then, but that's for a rear of course. Some even come with Dana Power Lok installed which is a good anti-spin diff. I had a friend give me a Power Lok for it but unfortunately I'm currently too stupid to know how to install it:rasta:

Supposedly the D-60 only weighs about 125-150 lbs more than a Ford 9", Chrysler 8 3/4" or Chrysler 9 1/4" rear. From manhandling one alone, I'd say that's about right.

 

[Diesel Durango]

If you go for a pig of a rear end, the 14bolt is another very good option. They can be found with 4.56's/detroits/discs brand new for very reasonable prices, i forget how good, i wanna say 800? maybe? that's government surpluss and never run axles. Detroits are cheap too because of the 2-piece carrier setup.

they can be shaved pretty well too, but they are still big axles.

I'm happy with my 9" in my jeep. I kind of wish i had a full width one to match the HP44 for the front, but with wheel adapters from 5x4.5 to 5x5.5 i'm at 64.5 anyways. I currently run 35" BFG Krawlers, but I will move up to 37's at some point down the road and i don't plan on changing axles.

 

[4BTFJ40]

No c-clips on Ford 9", they have bearing plates on the outer ends, bearings pressed on to axle, pumpkin is removable from housing. If you decide to get one, get the big bearing one they put in the 3/4 ton trucks. I'm replacing my 8.8" with one but my rig will be pretty much a highway queen. Probably don't really need it but I like going to junkyards

The 9" Never came in anything rated over 1/2 Ton that I know of. The big bearing alxe can be identified by the size of the wheel bearing studs. The larger 7/16" studs signify the big bearing housing. "Big Bearing" refers to the larger size wheel bearings (and bearing housings, etc) that were used on more demanding applications. You want the big bearing rear because the "small bearing" rear can't use standard bearings and any shaft over 28 spline. Most commonly "Big Bearing" rears were found in Trucks and High-Performance applications.