Eaton HO72/HO52 vs. 14 Bolt FF

[Captainfab]

The H(oh)52/72 was used from '55-'72 in 3/4 and 1 tons.

The highest gear available in the HO52/72 is 4.10's. In my experience 4.57 is the most common.

It is my understanding that the HO72 has the adjuster bolt as seen as in the pic.

[1990JEEPXJ]

First post here after lurking a while here and on Pirate regarding my HO72.

I have a question that I have not seen addressed anywhere yet. My axle is from a 56 3800 truck. Has 5.14 gears and slide on drums that are 14” diameter. Yes 14”.

Only issues I have with them is that they are not self adjusting and there are no provisions for a parking brake. I’m sure they will stop awesome but no parking brake and not self adjusting sounds like a pain. Sounds like I may need hubs/drums from a newer model?

I would ideally like to go to discs for simplicity but that would require a newer housing

And this will not be in a big old truck. It’ll be swapped into my Jeep Cherokee

[Captainfab]

If you are wanting to use that HO72 only because of the 5.14 gears, I would strongly suggest considering regearing a 14 bolt or a D60.

[Richard2112]

That's good advice to regear a 14 bolt. I have recently changed my HO for a '85 14 bolt FF and parts are much easier to find should I want to edit something. The pinion bearing is larger on the 14 bolt FF after 85 or 86 I believe. The rest is the same.

[1990JEEPXJ]

My axle is also locked and I got it for less than $250 and have an extra 4.10 HO52 third and spare shafts. So if I sell off my extra stuff I’m out maybe $100 at this point.

If I can gear and lock a 14 bolt or Dana 60 for that much I’d be all over it.

I was curious if anyone had seen brakes like are on my axle and what they did with them.

[RedRoad]

Im interested in your extra 4.10 third.

FYI you can use regular 14bolt disk brake brackets on an eaton. I would use a driveshaft ebrake or the eldorado calipers for flat land parking brake.

[1990JEEPXJ]

Originally Posted by RedRoad

Im interested in your extra 4.10 third.

FYI you can use regular 14bolt disk brake brackets on an eaton. I would use a driveshaft ebrake or the eldorado calipers for flat land parking brake.

Can’t use 14 bolt brackets on an eaton with slip on drums. The offset of the hub to the backing plate would be incorrect from what I understand.

[RedRoad]

Originally Posted by 1990JEEPXJ

Can’t use 14 bolt brackets on an eaton with slip on drums. The offset of the hub to the backing plate would be incorrect from what I understand.

Would the Cab/Chassis (dually) brackets work?

[rustyburbin]

Originally Posted by Aaron Burkemper

I want to buy an OEM locker unit for the 52 under my 71 C20. Does the locker unit determine the ratio?

I know this is an incredibly old thread but I just thought I'd chime in... I have an old timer 4x4 shop owner who has some new old stock drop in Detroit lockers for the eaton. I got one from him for 100$ before we were buddies so I'm sure he'd do the same for someone else. I love it by the way, it was a great improvement and didn't effect my 70 K20 Suburban's road manners enough to be an issue.

Message me if you or any other reader I'd interested in one and I'll do my best to work something out for ya.

[Peanutbutter]

Hi, are you familiar with the bigger HO axles, 11000, 15000 and 17000. I have a 1966 C80 with Napco conversion, looking for 7.20 ring and pinion but still haven't determined which differential I have. Napco used their housing with GM carrier, the carrier is completely round opposed to oval. I think its the 11 or the 15 but not sure, one thing I can tell you is the ring gear is 12 1/4 inchs in dia. Do you need pics to see what I have?

[Peanutbutter]

Maybe this will help, others may be able to use this info.

[rideblue00]

Following...

[Getter-Done]

Has anyone swapped a H072 from a 1965 C-30 to a 1967 C-30 Cab and Chassis?

[abig84]

Originally Posted by Getter-Done

Has anyone swapped a H072 from a 1965 C-30 to a 1967 C-30 Cab and Chassis?

I would think they would be pretty close in width, I kicked out the ho72 from under my 52 for a 80s 14 bolt. Have to move perches and shock mounts, u-joints look different too but haven't got that far

[Captainfab]

I would think it should be a direct swap. Personally I would go with either a 14 bolt or a Dana 60 or 70 before I would bother with a Eaton HO52/72.

Originally Posted by Getter-Done

Has anyone swapped a H072 from a 1965 C-30 to a 1967 C-30 Cab and Chassis?

[Getter-Done]

Just got a measurement on both.
It’s 47” plate to plate on my 67 and 46” on the other.

[Captainfab]

That is not an accurate to measure a differential's width. You must measure WMS to WMS (Wheel mounting surface). That is the dimension that matters. Not all brakes are the same width and not all backing plates are the same.

Originally Posted by Getter-Done

Just got a measurement on both.
It’s 47” plate to plate on my 67 and 46” on the other.

[Getter-Done]

Originally Posted by Captainfab

That is not an accurate to measure a differential's width. You must measure WMS to WMS (Wheel mounting surface). That is the dimension that matters. Not all brakes are the same width and not all backing plates are the same.

Thanks
After Re measuring the backing plates they are the same.
Yes I need to pull the wheels off mine to get a good measure.
I think I will just get the pumpkin out and let the rest go.
Thanks for your help.

[Getter-Done]

Originally Posted by abig84

I would think they would be pretty close in width, I kicked out the ho72 from under my 52 for a 80s 14 bolt. Have to move perches and shock mounts, u-joints look different too but haven't got that far

Thanks for the info.
I have a 14 bolt waiting in the wing.
It is funny how this stuff happens.
I was walking thru the pick a part and this one jumped out in front of me.
I will probably just get the pumpkin out of it.
The whole thing may follow me home

[Getter-Done]

Originally Posted by Getter-Done

Has anyone swapped a H072 from a 1965 C-30 to a 1967 C-30 Cab and Chassis?

Thanks CaptinFab and abig84 for the info.
I came home with just the chunk.

Here is my Numbers I have to share maybe some helpful info someone could use later.
The H072 rear axle I pulled the chuck from today was a 36/8 tooth (4.5 ratio).
It is anybody's guess if it was original.

The vin tag was Gone so No id but(from what I had to go by) it was 64-66 Chevy C-30 with 6 cyl. and sm465 with parking brake on the rear of the trans.
The main info I found out is that the axle housing would be a direct swap to my 67 cab and chassis C-30.
The measurement to the center of each spring perch is 40".
Both trucks have 2 1/2" wide springs.

From the same Pick a part 6 months ago.
There was a 71 GMC 2wd V8 Fleet-side truck (Flint plant).
I pulled the chunk from it was 32/8 tooth (4.0 ratio). this is the one I will use in my truck.

I also bought the doors from this truck. It still had the Blue I.D. sticker on the door.
In the 5th spot was an O or 0. I looked at the Vin decoder that bruceman1968 has on this site.



This makes me think that the O was maybe for that 4:11 ratio rear chuck.
Hope this info helps someone.

[Tdbengry]

Does anyone know what size these bolts are on the h052?

[Getter-Done]

Originally Posted by Tdbengry

Does anyone know what size these bolts are on the h052?

1/2 diameter threads. Has 13 threads per inch and is 1 3/4 inches long.
Take 3/4 wrench or socket.
1/2x13TPI and 1.75 inches long

[Tdbengry]

Originally Posted by Getter-Done

1/2 diameter threads. Has 13 threads per inch and is 1 3/4 inches long.
Take 3/4 wrench or socket.
1/2x13TPI and 1.75 inches long

Thank you very much for the timely reply, I'll head to the hardware store. I took mine out to inspect and have no clue where I put them 😅

[Getter-Done]

Originally Posted by Tdbengry

Thank you very much for the timely reply, I'll head to the hardware store. I took mine out to inspect and have no clue where I put them 😅

They also have lockwashers.

[Tdbengry]

Originally Posted by Getter-Done

They also have lockwashers.

Okay, I've got the bolts in everything tourqed in spec, including the rear cover axles and pinion. But now I cant move the pinion by hand, the wheels run opposite of each other. Any ideas?