Building a rear axle... tube thickness?

[DirtyMJ]

I'm building a D44 rear. Okay, I'm not yet. But I will. Maybe. Once I finish the front one. But the plan was to have a little fun and make it full float and high pinion, then see if it simply fails horribly and I wasted a bunch of time.


So, given it's 1/2 ton crap at best, what thickness of axle tubes are really necessary? 3x1/2" tubes are convenient, given what my donor is. But really, that seems over-kill. And I'm trying to watch my weight, because that'll probably be the only hope for keeping things alive.


So, what's typical for a stock D44 rear? 3x - 3/8"? 5/16? 1/4"? Or, they're 2.75" X something?

Should I just use the 3x1/2" tubes, and not worry about it? I was planning on a truss of sorts at least - if only for the upper link brackets.

 

[Lincoln]

1/4 wall is what a lot of D44's came with. One problem is it can be dented when hit hard on something. I think 3"x.25 is plenty if you're planning a good truss.

.375" wall would provide much more protection against dents. The dents make an easy place for a bend to start, but again with a good truss it shouldn't be an issue.

.5" wall is good but like you said a little more heave. You probably wouldn't need a truss unless the rig is heavy and you are going to go fast.

The truss is important though and even more important with a floater. In a semi float app the axles actually help with bending resistance and in a floater the shafts don't help much at all. 10 years or so ago bent housings after a floater conversion were fairly common. Most were 2.75x.25" tubes and the bent on the outter ends between the springs and the backing plate.

 

[DirtyMJ]

They actually make full float kits? Hmm. Bet they're expensive.


Truck won't go fast or weigh much (I hope). It's just a D44, so it internally wouldn't have chance doing either.


I calculated the approximate weight savings and strength differences. I'll just use the 3x.500 tubes. I'd rather have any excess weight in the axles than anywhere else.


I'll just bend a single peice of tube only over the pumpkin for a link tower.

 

[CanMan]

I would go with 3/8". A nice tube type truss would be good.

Both DOM.

Axle tube material.

http://www.onlinemetals.com/merchant.cfm?pid=13000&step=4&showunits=inches

Truss material.

http://www.onlinemetals.com/merchant.cfm?pid=7793&step=4&showunits=inches

 

[Lincoln]

Sounds like a good plan.

If you are doing a floater kit just put 14 bolt spindles or get some Rockcrusher spindles (to use front 60 hubs for the smaller bolt pattern) and run 35 spline shafts. Spools are not available right now but Alloy USA is supposed to have them in the works. The other choice for 35 splines is an ARB.

 

[Rockslut]

Sounds like a good plan.

If you are doing a floater kit just put 14 bolt spindles or get some Rockcrusher spindles (to use front 60 hubs for the smaller bolt pattern) and run 35 spline shafts. Spools are not available right now but Alloy USA is supposed to have them in the works. The other choice for 35 splines is an ARB.

All good points but, the high pinion gears wont live long unless this rig will be uber light. Why put 35 spline shafts in it and then guarantee that the weak link will be the gears?

I bet this axle would live a decent life if not reverse cut.

 

[DirtyMJ]

The gears will be reasonably matched in strength to chromo 30 spliners like this. Maybe. Anyways, that means I can run cheap/avaliable D44 spindles/hubs/brakes all from a waggy axle. Apparently warn makes (hopefully still does) 30 spline drive flanges for D44s. Have to bore out the spindles though, whatever.


If I use the 3x.500 tubes it makes life easier as I will only have to buck down one side. The other side will either have to be pulled/cut out and replaced with some tube harvested from one of my waggy D44s. But that's easier than pulling both.


Then I just have to make the weld on adapters for the spindles. We'll see if I remember how to use a lathe.

 

[JeepFreak21]

All good points but, the high pinion gears wont live long unless this rig will be uber light. Why put 35 spline shafts in it and then guarantee that the weak link will be the gears?

I bet this axle would live a decent life if not reverse cut.

What size tires are you going to run on this HP44 rear? How do you plan on keeping the R&P from :explosion ?
Billy

 

[DirtyMJ]

That's a detail I wasn't going to worry about until I had it done.



Nah. I want to do some serious dieting with this truck. Or another one like it. Or just start with tube... Can I get it down to 3200? Or less? Will that be light enough? I sure as hell don't know! But I don't worry about it too much. Insanity comes easily. I'll try 37 MT/Rs, on single beadlocks. If I keep breaking stuff I'll sell the axles as a pair (maybe for good money, maybe not). But the idea is if I build it using D44 parts that I have lying around, over-all cost will be reasonably low. Okay, so I'm out a R&P, spool (already have), gear setup kit, custom shafts, drive flanges, and a hell of a lot of time and effort. Would it make more sense to build a HPD60 instead? Hell yes. But with a bare housing going for about $1200-1600 around here, I'd rather not cut it up then change my mind about the project (which happens a lot). If the entire axle works other than it isn't strong enough, I will cross that bridge. If it works but is weak, I can always sell it. Somebody will buy anything.

 

[rehab]

HP gears are not made for runing in reverse. that means that instead of runing on the drive side of the gear, it is driving on the coast side (considerably weaker) which makes for a big pop and metal flying from the housing when you get on it.

 

[RWKHausSupply]

If your going through all this and retubing. Why not just get a Rockjock Center section? For like 400$ (if you call the right shop) you can have a HPD60 center for not much more then the D44.

Just a thought lol

 

[DirtyMJ]

I thought about it. But then I'd talk myself into building a pair (I'm hard on front end components).

I don't want an aluminum centre section anyways. I guess I could look at the other options. Shipping would probably kill me.

 

[RWKHausSupply]

wouldnt do alum either. Look at the Rockjock III I dont even think they make a alum one any more?

 

[Rawbrown]

I'd go aluminum alot fast than HP 44 out back. what all will fail? lots.
outer pinion bearing will burn up from lack of lubrication and excessive pressure thus allowing more deflection in the gears. Then there is the possibility also of a broken pinion shaft from the excessive side loading/deflection of the gear. Of course you just might lose a few gear teeth first from the deflection.
why does everyone get queasy with the thought of aluminum? have you seen those things... if I could afford it, I'd take one in a heart beat. A housing that you could pick up with one hand that can handle 40"s... un yeah. I've built those... they are awsome.
back to the D44...
1/4 wall is pleanty in a rear axle unless you go FF then you need 3/8" wall. thats on a 3200# rig. I run a OEM D44 out back and the last time I weighted my jeep was in march. 3500# Thats no doors/hatch/glass except for the windshield. 35"s, D30/D44 with Jack and spare mounted but no tools. Cage is welded in as well. but now I'm gonna step up to 37's so that all needs to change. retubing a D44 front and gonna run Dodge D44 parts. out back is going to probably be a 33 spline D44. I don't think 35 spline is necasarry. I'd rather bust a shaft than a gearset. but if you want to go HP, then you either need to build a RJ 60, Prorock 60 (which I don't like as much) or go true hi9.
Or keep the LP D44 and build it up.