Eaton HO72 Tech Thread

[AlxJ64]

I’m just a spectator here, as I don’t have any ho72 hand-on experience.

How similar are 14b and ho72 carriers? Deck height, snout bearing diameters, ring gear pilot diameter, etc.? Close enough to make the 14b carrier to work, to open up on locker options, including arb?

Guys have modified ARBs to work but it isn’t a drop in or deal. I’ll have to find pics from one guy that did it

Paging Tech Tim

 

[Tech Tim]

I have pics somewhere of an ARB Air Locker machined to fit an H054/72 ring gear (iirc Cooper was the name of the guy who did it???).

Someone posted them up on the old board.

I don't remember all the differences, but the carriers are different. The most noticeable is the bolt pattern, hence needing to machine the Air Locker.

What most people do is what has already been discussed in this thread, running the Detroit and 14B shafts.

The cool thing about the 14 bolt Air Lockers, you can get them in 35 and 40 spline versions (RD235 & RD234).

 

[06h3]

I’ve got the pics on my computer. I’ll find them and post them tomorrow. It was cooper aka 1951rover on the old board

 

[06h3]

 

[YotaAtieToo]

Just do it.

Selectable rear works as good, or sometimes better than front dig and is way faster. Our group likes to run front locked, rear open on trails. Maneuvers really well and you can kinda use rocks and trees to pivot around on.

Being able to go 40 spline easily is another advantage. If you're having shafts made, why not.

 

[gtxracer2]

Yeah, I agree. If spending cash on ARB it would be best to do 40 spline shafts at same time if you’re breaking shafts. You’re the only one I’ve seen break 3 shafts though

 

[06h3]

It is tempting!!!!

For now I’m doing the 14 bolt Detroit and shafts to do an apples to apples comparison but if I break em id consider 40 spline. It just sucks because 40 spline shafts don’t fit through stock 14b spindles so I assume the same for HO72 spindles.

 

[YotaAtieToo]

It is tempting!!!!

For now I’m doing the 14 bolt Detroit and shafts to do an apples to apples comparison but if I break em id consider 40 spline. It just sucks because 40 spline shafts don’t fit through stock 14b spindles so I assume the same for HO72 spindles.

That will be interesting to see the difference. I'm not betting on a huge difference. 14b shafts are pretty strong.

The one factor with old factory stuff is you never know what it went through. You think stuff would be bulletproof in stock trucks, but you never know. Doing a burn out in mud to drive pavement can be damn hard on stuff.

I want to say 37 spline fits in the spindles, but I'm not sure if that's a huge size difference from the 14b 30 spline.

 

[06h3]

I’m pretty confident 37 spline does. I have a buddy running 37 spline in his rear dana 70 and I’m pretty sure he runs stock spindles/hubs

 

[YotaAtieToo]

I’m pretty confident 37 spline does. I have a buddy running 37 spline in his rear dana 70 and I’m pretty sure he runs stock spindles/hubs

Billa Vista bible says 1.59 spline diameter for 14b axles. Which contradicts the 1.54 spindle id

Read another person say 14b is 1.56.

Best I can find is 37 spline is 1.59-1.62.


This is probably better information anyway, especially when comparing to your old school low spline cound stuff.

Minor Dia. (where the strength really comes from):
14FF 1.422
D80 1.490
D60/70 1.361

Clearly the 37 spline is not worth the effort or cost over 30 spline.

Also, my opinion, only based of what I've seen. Is that I would never want to bore a spindle for larger axles. I've heard of people bending spindles enough that I wouldn't want to increase the chance. Imo, 40 spline, go UB. But maybe the aftermarket chromo spindles are good too.

 

[06h3]

If I do 40 spline I should make it easy on myself and do rear steer

I just flat out love rear steer.

AlxJ64 did you find out what you machined off each side gear?

 

[YotaAtieToo]

If I do 40 spline I should make it easy on myself and do rear steer

I just flat out love rear steer.

AlxJ64 did you find out what you machined off each side gear?

You sound like me. "since I broke this one single, cheap part, I may as well upgrade to the fullest extent"

I want to try rear steer also. It would be a big challenge on a full body rig with big tires though.

 

[DMANbluesfreak]

At least on the AAM 14b (2001+), the spline OD on the shafts is 1.545".

Again on the AAM 14b (2001+), the spindle ID is 1.58"

For what it's worth, here's the section view of the modern 14b spindle. I also wouldn't feel comfortable on a heavier rig boring it for larger diameter splines. Especially considering I've bent one myself (but never broken a shaft...).

 

[DMANbluesfreak]

I want to try rear steer also. It would be a big challenge on a full body rig with big tires though.

Especially an SUV that tubbing the fenders would potentially require cutting into the cabin space.

Rear steer would be cool even to only ~20 degrees like a Quadrasteer truck. It's something I, too, would like to explore someday.

 

[DMANbluesfreak]

Back to the spindle vs. axle shaft diameter conversation - if you're taking things to these extremes... I'd say go to SD unit bearings out back and run even beefier shafts. No spindle to bore or bend, that way, and maximum splines are possible.

 

[YotaAtieToo]

Especially an SUV that tubbing the fenders would potentially require cutting into the cabin space.

Rear steer would be cool even to only ~20 degrees like a Quadrasteer truck. It's something I, too, would like to explore someday.

Yes, even the frame becomes an issue pretty quickly. I'd agree that limiting angle would be probably the most realistic way to make it work. Also running a wide axle with max back spacing would help.

There is a group of pnw snow wheelers that run Cherokees and Toyotas on 38s with 4ws. If like to see up close pics of the rear wheel wells.

Back to the spindle vs. axle shaft diameter conversation - if you're taking things to these extremes... I'd say go to SD unit bearings out back and run even beefier shafts. No spindle to bore or bend, that way, and maximum splines are possible.

I agree.

I still believe that going to a drw hub without a spacer would probably cure your problem.

I wonder if that's why you hear about more 14b spindles bent than Dana's? Most dana hubs put the wms right over the center of the bearings vs spaced out towards the end.

Although late model ford 10.5s have almost no hub stick out and have ridiculous payload ratings. They use very deep back spaced wheels though.

 

[DMANbluesfreak]

I agree. But finding a C&C Dually 14b has proved difficult at best. I could run narrower spacers, but then my tires will get into the wheel well more than they already do when flexing and it'd let my body get closer to stuff.

I will say, the 14b from the factory has a WMS between the bearings and most factory GM wheels are pretty close to zero offset. I think GM just has much narrower rear axles so people tend to run lower BS wheels or spacers like me.

 

[GLTHFJ60]

For what it's worth, here's the section view of the modern 14b spindle. I also wouldn't feel comfortable on a heavier rig boring it for larger diameter splines. Especially considering I've bent one myself (but never broken a shaft...).

Kind of interesting aside, that section view makes it seem like the spindles are rotary friction welded onto the housings. That's kinda neat.

 

[DMANbluesfreak]

Indeed. I hope to see / confirm that when I fix my bent spindle.

Even more interesting aside, the wall thickness of the tube reduces inward of the friction weld and then gets thicker when it goes into the diff housing (not shown). I know the new SD60s have this too, likely to save weight at the non-joint areas. I wonder what that manufacturing process is like.

 

[06h3]

I watched the 40 spline video from ECGS and that spindle is HUGE.



On the rear steer, I never thought of it until I saw this Green K30 crew cab truck come out wheeling in Idaho. He was on pirate I think and he lives near the rubicon if I remember correctly.

Anyways, I don’t judge rigs based on looks. Maybe it’s a personal thing since people judged my H3 for a long time but anyways, I saw this giant crew cab k30, he got the wheelbase as short as he could get it and it was still 142ish. He had 43in TSLs that looked like 35s because this thing was so big. He had rear steer and I swear that damn thing was as nimble as a TJ.

I don’t think I have ever been so impressed in my life. The thing flat out worked and it was truly amazing.

I gotta find his thread.

Anyways, I think quadrasteer trucks only had 15* of angle. I feel like that would even help! But to bring the thread back to HO72, all this money gets tied up shit to make 40 spline work it’s almost worth the extra money to get an upgrade out of it.

Sorry for the derail. Back to HO72 stuff, my grizzly shows up today. Gtx took .060 for spacing out the locker. Alx thinks he took .013 per side so .026 I gotta figure out what to do. I don’t wanna risk it being too loose.

 

[YotaAtieToo]

I agree. But finding a C&C Dually 14b has proved difficult at best. I could run narrower spacers, but then my tires will get into the wheel well more than they already do when flexing and it'd let my body get closer to stuff.

I will say, the 14b from the factory has a WMS between the bearings and most factory GM wheels are pretty close to zero offset. I think GM just has much narrower rear axles so people tend to run lower BS wheels or spacers like me.

C&c will be narrower. You want a regular dually. I'd think a gmt400 is your best bet. I'm not sure if gmt800s used 10.5 14b in duallys.

Derail over

 

[DMANbluesfreak]

C&C Dually VAN axle is what I meant. The GMT800s used the 11.5 for the dually axles in the trucks.

NOW, the derail is over

 

[arse_sidewards]

C&c will be narrower. You want a regular dually. I'd think a gmt400 is your best bet. I'm not sure if gmt800s used 10.5 14b in duallys.

Derail over

C&C is the "regular" dually. Change my mind.

 

[DMANbluesfreak]

C&C 14b pickup axles are 63" WMS-WMS. A lot of guys will use those axles under mid size rigs so the track width matches the front axle.

C&C Cutaway Van Dually AAM 14b axles are 74" WMS-WMS.

NONE OF THIS IS EATON TECH THOUGH.

 

[06h3]

Here is a video of me breaking the shaft. The ledge is VERY steep. I have another video of a buggy on the ledge and all 4 tires are spinning. Not going anywhere, rear steered passenger a tad, hooked up and went up but here’s the shaft break.

 

[06h3]

I sometimes think driving style can fix this problem.

If I hammered the gas (admittedly it would be sketchy) I could get the tires to spin. When spinning the shaft is twisting back and forth let’s say 10 degrees as it sees and unsees traction.

When going slow like I was the shaft will twist to failure.

 

[YotaAtieToo]

I sometimes think driving style can fix this problem.

If I hammered the gas (admittedly it would be sketchy) I could get the tires to spin. When spinning the shaft is twisting back and forth let’s say 10 degrees as it sees and unsees traction.

When going slow like I was the shaft will twist to failure.

Thats a fair point.

Untill you slide back while on the gas, your back tires grab traction at the bottom and really shock load something.

 

[TrailTamer]

The 14 shaft have ideal design. Can see how it step down just after spline, then neck down again. I can’t really see any on the ho72 shaft. Looks like it was cast? Can easily play a factor on their maximum strength and metal fatigue.

Can’t really go wrong switching to 14b shafts, to have easy access to stock spare shafts and aftermarket stronger shafts are ready to go when you need it.

 

[arse_sidewards]

Looks like it was cast? Can easily play a factor on their maximum strength and metal fatigue.

Nobody, and I mean nobody, casts an axle shaft. Even the most flexy cast steel (not iron) varieties are basically glass compared to (hot or cold, doesn't matter) rolled steels.

Even if the design isn't ideal it is almost certainly some sort of hot rolled high carbon alloy that's been case hardened (typically 10-20thou) and then machined.

 

[AlxJ64]

My notes say that I took 0.130" off each side, I feel like that's not right but then again its what's in the spreadsheet when I was keeping track of this stuff.