Eaton HO72 Tech Thread

[Defecater]

Sometimes the numbers are stamped on top of the third, on top of the pinion oiling slinger galley, the bump on top of the third. I've seen them there, but not always.

So I went and looked at the remnants of a 1954 chevy 3600 delivery truck today. There were numbers on top of the pinion oiling passage-

MG1217

Maybe I am just dumb, but I dont see how that number is telling the ratio unless it is a GM reference code.

Cut the driveshaft and got one wheel to turn. Did the math and it was 4.56ish

Anybody got a reference that tells what the codes on the diff are?

 

[Drummer79]

Judging by the weight ratings for those axles, I am going to bet those are medium and heavy duty axles

I wondered that too, and know so about some of those axles, but wasn't sure about some of the others.

 

[Twankie]

So I went and looked at the remnants of a 1954 chevy 3600 delivery truck today. There were numbers on top of the pinion oiling passage-

MG1217

Maybe I am just dumb, but I dont see how that number is telling the ratio unless it is a GM reference code.

Cut the driveshaft and got one wheel to turn. Did the math and it was 4.56ish

Anybody got a reference that tells what the codes on the diff are?

Truck happen to have the grille still? I'm looking for one.

 

[Defecater]

Truck happen to have the grille still? I'm looking for one.

 

[Twankie]

Price and location? If it's not rusted out it's better than what I currently have (nothing)

 

[AlxJ64]

So I went and looked at the remnants of a 1954 chevy 3600 delivery truck today. There were numbers on top of the pinion oiling passage-

MG1217

Maybe I am just dumb, but I dont see how that number is telling the ratio unless it is a GM reference code.

Cut the driveshaft and got one wheel to turn. Did the math and it was 4.56ish

Anybody got a reference that tells what the codes on the diff are?

Those aren't the numbers for the ratio; again not all of them have the numbers. It would be something obvious like 7 36 or 7 32 and it is stamped right on top of the bump over the ring. I have one around here somewhere with it and will try to snap a picture sometime this week.

 

[Defecater]

Price and location? If it's not rusted out it's better than what I currently have (nothing)

Just checked the posting and it is shown as sold now

 

[gtxracer2]

Have some Eaton H072 parts from my stash that I’d like to clear out of my garage. It’s all in the Seattle area, prefer not to ship but can if needed. I figured this group would appreciate first dibs!

Open 5.14 third, great condition
Lincoln locked diff w/welded 30 spline 14B side gears
Extra H072 case (empty)
Empty H072 case with alignment pucks for making your own housing (no bar included, pucks have 1-/1/8” diameter holes)
Box of random parts and bolts, mostly for the empty thirds
Diff cover
DRW hubs
17 spline axle shafts
30 spline 14B axle shafts

Pics below, can get more.

 

[AlxJ64]

Here is a pic of some factory numbers stamped in. You can see the upside down 7 over the 36 - this was a 5.14 with factory No-Spin when I found it. Was in a 3/4 ton SRW with the 6 cylinder, 4 speed,

 

[06h3]

How much for the 3rd with the pucks?

 

[gtxracer2]

How much for the 3rd with the pucks?

$100 shipped. It's all that's remaining, all the rest has been taken already.

 

[06h3]

$100 shipped. It's all that's remaining, all the rest has been taken already.

Damn that was quick! Glad to see there’s still some Eaton Fanatics. I’ll take it

 

[AlxJ64]

Went to a Fall Festival yesterday that is a local awesomeness. Its a conglomeration of industry from the days of the settlers, all the way up to modern brand new machinery. Ie they had folks in horse drawn carriages and a wood fired black smith on site, and yet across the way I was able to climb into a 2024 CAT 330 and move around crushed cars with it.

While wandering around I stumbled on these old log skids, which use Eaton HO axles as part of the lift and drive system.

Obviously the sign is a year old from where they dug these things out of the woods and got them working again.

 

[ridered3]

Went to a Fall Festival yesterday that is a local awesomeness. Its a conglomeration of industry from the days of the settlers, all the way up to modern brand new machinery. Ie they had folks in horse drawn carriages and a wood fired black smith on site, and yet across the way I was able to climb into a 2024 CAT 330 and move around crushed cars with it.

While wandering around I stumbled on these old log skids, which use Eaton HO axles as part of the lift and drive system.

Obviously the sign is a year old from where they dug these things out of the woods and got them working again.

That’s pretty cool!

 

[Drummer79]

Went to a Fall Festival yesterday that is a local awesomeness. Its a conglomeration of industry from the days of the settlers, all the way up to modern brand new machinery. Ie they had folks in horse drawn carriages and a wood fired black smith on site, and yet across the way I was able to climb into a 2024 CAT 330 and move around crushed cars with it.

While wandering around I stumbled on these old log skids, which use Eaton HO axles as part of the lift and drive system.

Obviously the sign is a year old from where they dug these things out of the woods and got them working again.

That's really cool. When I worked at the catfish farming company we had PTO aerators built from Eaton's as well. I should go visit and see if any are still parked on the hedgerow. They looked similar to these below.

 

[Covecrawler]

Went to a Fall Festival yesterday that is a local awesomeness. Its a conglomeration of industry from the days of the settlers, all the way up to modern brand new machinery. Ie they had folks in horse drawn carriages and a wood fired black smith on site, and yet across the way I was able to climb into a 2024 CAT 330 and move around crushed cars with it.

While wandering around I stumbled on these old log skids, which use Eaton HO axles as part of the lift and drive system.

Obviously the sign is a year old from where they dug these things out of the woods and got them working again.

Where is said festival? I’d love to try to make it next year.

 

[AlxJ64]

Where is said festival? I’d love to try to make it next year.

Rassawek Festival - huge vineyard / hunting preserve / stocked ponds / restoration shops, etc. Its right between Richmond in Charlottesville VA. Town of Columbia, even though its not a town anymore. I'm luckily only 12 minutes from the place.

Autumn Festival

Autumn Festival in Goochland, VA celebrating the season's bounty, fostering community spirit, blending nostalgia and a professional rodeo.

rassawek.com

Here is something from the trip last year.

 

[Covecrawler]

Thanks for the info on the festival.

Not sure if this info is in here,
I was reading a vintage Petersen’s 4wheel&offroad today with my son. They had an article suggesting flipping the housing and swapping the diff, and diff cover to build an offset axle for a Landcruiser, Willys or Samurai. Pretty cool tech I never considered.

 

[06h3]

Thanks for the info on the festival.

Not sure if this info is in here,
I was reading a vintage Petersen’s 4wheel&offroad today with my son. They had an article suggesting flipping the housing and swapping the diff, and diff cover to build an offset axle for a Landcruiser, Willys or Samurai. Pretty cool tech I never considered.

That is genius!

 

[06h3]

Wow. I don’t know what to say. I was swapping my 3rd into a new housing to link it, about a year ago was the last time I checked it.

Before people say 14b’s are better, I have seen one Eaton break and it was on the old sites eaton thread and he was a sled puller. Sled pullers say Dana 80 or AAM11.5 is the way to go for sled pulling. Maybe the 14b is better but if so I would assume it’s marginal and not worth an “upgrade” where a D80 would be an upgrade. I’m assuming this is from pulling the broken H3 out of the rubicon.

Anyways, I have a week to decide what my next move is. I grabbed another 5.14 3rd out of the shed or find a D80.

I may send this off to a metallurgist, when I first got it there was some pitting on the teeth and the rear end shop polished it.

I’d like to think I’d kill a 14b too because every lightweight rig that’s run an Eaton hasn’t killed one. My buddy has raced 2 KOHs on his without failure and his has too much backlash but it doesn’t seem to care.

 

[McBastard79]

In for good tech

 

[Sluggy]

So what's the average going price for one on these axles? I know of 2 of them and ones a 5.13 gear ratio and ones out of a 71 c20. Just trying to get a idea on what to offer.

 

[arse_sidewards]

So what's the average going price for one on these axles? I know of 2 of them and ones a 5.13 gear ratio and ones out of a 71 c20. Just trying to get a idea on what to offer.

$50-250, same as any other old drum brake FF rear end.

 

[06h3]

$50-250, same as any other old drum brake FF rear end.

That’s about right. I got my first one for free. A fee for like $100 then one for $200

 

[06h3]

In for good tech

I’m in for good tech too. Where are the metallurgists at

 

[AlxJ64]

I’m in for good tech too. Where are the metallurgists at

I'm not a metallurgist by trade, but have a LOT of steel fatigue and metallurgy education regarding my involvement in structural steel, along with all the "hobby" fabrication, gear work, etc over the years. I've also been involved in some pretty in depth projects regarding the mechanical rehab of some very large movable bridges with some pretty radically large gearing where the forces and wear become very evident over the years. Take all my comments with a grain of salt, as without seeing it in person I am just spitballing.

One of the pics of the failure, the adjacent ring teeth have some galling striations it appears. To me, this means the contact pattern, has been at times, less than an ideal module force (high point to high point in a rolling fashion) along the gear faces. When this occurs, it starts to "peel" at the tooth and not just apply shearing forces as it is intended to be loaded. So instead of it pushing the gear tooth straight, it kind of puts a shaving load as well as the shearing force, which if there is any stress riser (like the old pitting you mentioned) it will start to break open.

Another question I have, is how close is the ring to either the cover, or bottom of the housing? At any point could a hard rock smack possibly deformed the housing enough to tap the end of the gear teeth and shock the failure?

In comparison to the normal wear pattern, how is the failure located? Is the wear pattern more towards the outer edges of the ring gear teeth or deeper. Hows the pinion edges look also?

Theres also the chance that you've just beat the ever living Fawk out of something that is over 50 years old, and you found the point of fatigue. Pulling truck loads would seem to be more linear in application and less shock related than rock crawling your hawse ass truck in places like the Rubicon.

Edit:

Also, what's up with this? Looks like at some point the pinion was sliding off the edge of the ring? The thrust bolt adjusted correctly? How about the carrier bearings and the adjustment rings? I've put one of these together with the bearing race crooked and first hard reverse load knocked it back straight against the threaded collar and then the carrier was sloppy AF back and forth. You didn't kill a carrier bearing first and then these teeth were secondary victims?

 

[06h3]

AlxJ64 thoughts on the carrier bearing?

 

[06h3]

Videos wouldn’t load well when posting direct to the site

 

[AlxJ64]

Videos wouldn’t load well when posting direct to the site

So these bearings being spherical in nature, when they wear or start to fail, they still will function for a long time but the side effect is migration of supported components. Its easy to visualize something spinning in a bowl that is almost the same diameter of the top of the bowl. If you start to reduce the diameter of the thing spinning, it will go further down into the bowl, but it also now has room to wander some or ride at an angle or even wobble while still staying in the bowl.

My theory of failure is that the bearing on the thrust side of the carrier started to wear, fail, or wasn't happy in its place originally and something moved, and allowed the carrier to "cock back" from carrier centerline some. This also pulls the gear contact away from the pinion some. This has minimal change on the function of the load bolt as its not a lateral shift but rather a contact depth / mesh change and therefore moves the the contact point and loading of the ring gear teeth towards the outer edge. The other bearing, being spherical, doesn't care and absorbs the fine misalignment. This angle of movement away from centerline was enough to allow, and maybe only under hard load, the pinion to try and step over the end of the ring teeth. That in conjunction with the pitting and overall hard shock environment contributed to the failure. The tooth smearing and sharp edges also back up the fact that you had some carrier motion since the pinion does appear to be quite content where it is and usually any play there is very obvious, especially with the carrier out.

Thats my $0.02 on it, FWIW.

 

[06h3]

I am in an airport right now so I won’t have pics until Thursday when I get home but I believe the thrust bolt (load bolt) had a groove in it for uneven wear.