Eaton HO72/HO52 vs. 14 Bolt FF

[kurk4fun]

Thanks guys for your replies to my questions about conversion from drum brakes to a disc and rotor brake setup. I am at my end. I have a bad rear drum that I need a replacement. My 1972 dually and a friend of mine are both in need. Does anyone know of a new axle setup that would be the correct width for our trucks. Or a course for a new brake drums.

[Dieselwrencher]

Great thread! I have a HO52 that has no center section if anyone is lookign for brake parts. I can check the condition of them. It is just under a Longhorn frame right now to allow it to move around. I'm getting a 72 K20 soon, and I plan to do the 13" 14bff brake swap to it.

[Theboatandcarman]

edited, please use the classified area for ads.

[rustyburbin]

Originally Posted by chewiebarker

Sorry for the ignorance, and for reviving an old thread, but if people use the heavy duty rear ends like Eaton HO52 with 4.56 gears for hot rods or drag racers, and they use transmissions like TH350s, why the heck is my 71 K20 Suburban so slow? Is it just that the 350 engine can't spin the gears fast enough? Is it just the weight? If I put a 500hp engine in it, will it then 'go fast' with little other modification? (Not that I would. I am just trying to learn how it all works together.) Thanks for any insight! - Marc

I have a 70 K20 suburban with an ho52, 4.10 gears and 35 inch coopers. I put in a ZZ4 350 (approximately 340HP at the crank) and have the th350 trans (4l80 coming this summer!) My truck scoots around pretty dang good for its size and weight. In fact I can beat up lifted ford's with the 7.3 (I know, I know the 7.3 is a bit of a dog) but still, I spank their butts!

I don't how this helps if at all... maybe just a grounds of comparison?

[trivejb]

Running a 4.56/31" Michelins in a 1968 C30 (3/4 ton) 8' stepside which weighs 4500 empty and, for what it is, performance is on par. While on the subject of the H052's does anyone have a gear whine noise problem with it. I have a very loud whine in mine. I have put 30K on it and it has never gotten any worse and never caused any other problem. Just would like to know if there was any fix for it.

[Getter-Done]

I would check for amount of backlash in ring gear to pinion gear .
If ok Lucas Oil Treatment does Miracles.

[trivejb]

Had the Lucas oil treatment recommended and on my list as soon as the weather allows. Will try that first. Can someone point me to how to check and adjust the backlash. Sounds a little complicated and something I have not done.
Thanks

[rustyburbin]

I recently did mine. You'll need a dial indicator and regular set of wrenches. You can do it without pulling out the third member but it's probably better too, I did mine on the work bench. Either way you'll need to pull your axels and disconnect your drive shaft. Here's a short video that explains the basics... https://youtu.be/Ouq67Fyt5K8

Your HO52/72 doesn't have shims it has threaded bearing adjusters (that's not what they're called) which make it supper easy to work on but be sure not to loosen one side or the other to much while adjusting the backlash because you can loose your bearing preload... set up your dial indicator like on the video and if you need to tighten the you'll need to loosen the bearing adjuster on the passenger side first about a 1/4 turn and tighten the drivers side the same amount, check the dial and repeat as necessary. It's really not that hard. Oh yeah, loosen the bearing caps a little bit so things move freely. And don't forget to move the deflection pin in a little bit too. That's the little "bolt" with the jamb nut that's on the side of the case closer to the pinion, you see it when you get into the diff, it has a brass end that rides against the back side of the ring gear.

[trivejb]

Thanks for the video and very complete description for setting the backlash. Does not sound bad and I do have a dial indicator so will tackle it soon. Will try and find an exploded view of the Eaton to determine what the " threaded bearing adjusters" are.

[K20super]

I put the late model 2500hd brakes on my ho72 I work at a machine shop and have a program written water jet them out I will try to get pictures tomorrow.

[PortalAxls]

Originally Posted by K20super

I put the late model 2500hd brakes on my ho72 I work at a machine shop and have a program written water jet them out I will try to get pictures tomorrow.

I have been thinking about doing this. Please share some pictures when you get the chance!

[K20super]

I am out of town right now I will next week

[Z28young]

I have a 72 C30 Cab Chassis dually with HO72. Will the drum brakes and wheel hubs from a 97 Chevy 3500 dually 14b work on my HO72??? I want to keep my dual wheels.

[Getter-Done]

Z28young
I think the measurement from inside bearing and outside bearing and also drum width is different.
There are a lot of threads on here that cover those subjects.
Welcome to Forum.
I will search the threads and see if I can find you an answer.

[Z28young]

Ok thanks. Yes there is a ton of info on here but I haven't found exactly what I'm looking for yet. I also found a couple of mid 80's 14 bff for sale, but was afraid to pull the trigger just yet without knowing if the brakes will swap over to my HO72.

[Getter-Done]

Z28young
Just an idea . If you have a Pu ll a P art type salvage yard near you .
And you have some spare time. It would give you good Knowledge of the difference /If you can find a 14 bolt Full Floating rear end and tear it down & take some measurements and compare it to your measurements on your HO72 It could give you the info you need.

[Ronsmith]

I've got the ho 72 in a 1962 GMC the truck only has 55,000 miles on it and I plan to put it on airbags and just make a driver out of it. I want to keep the stock transmission the stick shift but I would like to put a better gear ratio in the rear so that I can drive it on the highway and not turn so many RPMs does anybody know where a guy could find a replacement carrier and a ring and pinion to put like a set of 355 gears in there

[Clyde65]

Change it to a later model Dodge or GM 14 bolt. You will be glad you did!!

[Captainfab]

There is no such thing as 3.55 gears for a Eaton HO52/72. The highest gears that were made were 4.10's.

I agree with Clyde65. You will be far better off changing to either a 14 bolt or a Dana 60. There is all sorts of aftermarket parts support for those two differentials, whereas there is basically nothing for the Eaton.

Originally Posted by Ronsmith

I've got the ho 72 in a 1962 GMC the truck only has 55,000 miles on it and I plan to put it on airbags and just make a driver out of it. I want to keep the stock transmission the stick shift but I would like to put a better gear ratio in the rear so that I can drive it on the highway and not turn so many RPMs does anybody know where a guy could find a replacement carrier and a ring and pinion to put like a set of 355 gears in there

[Ronsmith]

Right on I knew I would have to possibly try to find a new carrier to put a gear like that in there but with no aftermarket support I guess a later model rear end is my only option I was just trying to use all the old parts does anybody know which of the Dually rear ends four-door Dodge or Chevy that might be the same width as what would have came in this truck

[slowcrawl]

Good morning,

Please help me identify this rear end.
Drum ID is 12-1/8.
It is on a 1971 k20.
My mechanic thinks it is from an older 1-ton, maybe 1966.









Slowcrawl

[jbclassix]

That's the eaton. I havent had any luck finding an aftermarket replacement drum, so have just upgraded to the bigger later brakes. That drum does look like the older version that sandwiches between the hub and wheel.

[Captainfab]

That is an Eaton HO72. If you really need to know what year it is, pull the rear covers and look at the date stamped on the edge of the ring gear. The gear oil more that likely needs changed anyway.

Lack of parts availability and what parts you can find are expensive is one of the reasons I always recommend changing to a 10.5" 14 bolt or a Dana 60.

[slowcrawl]

I am doing this work so I may be asking another stupid question.
It has a Detroit locker in it.
So would it still have the stock ring gear?

"That drum does look like the older version"
Did the h072 come on the 60-66 trucks?

Is that H oh, or H zero, 72?

If people edit their old posts and change jpg to jpg~original their pictures will work.
For photobucket links

[Bigdav160]

The locker unit is inside the differential case and the axle shafts are spliined to it. The ring gear is unaffected as it is bolted to the outside of the differential case.

I believe it's a number and not a letter.

While I don't know for sure, I think the H072 was one ton+ and not found in 3/4 ton trucks.