HO 52/ HO 72 question

[wrangler94]

Originally Posted by Sheepdip

From what I understand, and I could be 180 out, but seals and bearings are scarce but are a few still out there to be sourced, ring and pinion are no longer available.

If you need a total rebuild start looking for a 73-87 cab n chassis DRW 14 bolt parts truck. A cab n chassis will measure 63" WMS to WMS and 40" center to center on the spring perch's. The Dually Pickup rear ends will not fit, they are about 8"+/- to wide

Cab n Chassis will bolt right in with a couple of easy modifications on the shock mounts and flexible brake line.

Read This: https://67-72chevytrucks.com/vboard/...+brake+14+bolt

You're right about ring an pinions being basically unavailable. I'm not positive anymore but I think I saw on an offroad forum that I'm on that maybe someone was making gear sets for them again. In the rock crawling world people still love these axles, and do everything they can to buy and save them, for posterity of nothing else. They have all the strength, if not more, than a 14 bolt. Drop out third member like a Ford 9 inch, and better ground clearance. There is a whole thread that's basically a plethora of information about these axles, but I'm not sure on the rules for linking another forum in here, so I won't do that unless I'm told it's allowed.
I do know that some 14 bolt parts can be swapped into these axles, maybe even brakes, but I'd have to go back and read up on it again.

[wrangler94]

I will just give a short recap on the axle.
-Axles were used from 1947 to 1972.
-The difference between the HO72 and HO52 is the factory load bolt.
-Axle shafts are 1.5in coarse 17 spline. Many argue whether if they are stronger or weaker then 14 bolt shafts.
-14 bolt axle shafts and the drop in (detroit, grizzly) locker fits in the HO72. There are some exceptions, on some older open carriers they are a tad narrower and do not let the 14 bolt locker unlock. Some have fixed this with washers between the carrier or machining a few thousandths off the side gear. I machined .008 off each side gear for a total of .016 and it now locks/unlocks like it should.
-some carriers are a few thousandths tight and the 14 bolt shaft wont fit. Bore it out a few thousandths to fit….it seems newer (closer to 1970 HO72s have larger IDs and 14 bolt shafts fit with ease
-14 bolt disc brake kits work
-Diff covers, I have found mine on ebay. Some guy makes a HD diff cover. Ruffstuff made a short run of them
-Some did come with factory 17 spline detroit lockers
-Factory gear ratios are 4.10, 4.57 and 5.14. Supposedly there is an elusive 5.86 and if I can get my damn hands on one I would.
-No gear sets are available from the aftermarket
-pinon bearings are expensive.
-Pinion shaft is BEEF at almost 2in in diameter with zero neckdown.
-Ring gear size is 10 1/8 (some conflicting info on this but its between 10 and 10.5)
-Yoke is 1350
-I havent weighed an Eaton HO72 but they are much easier and lighter to move around compared to a 14 bolt.
-Ground clearance is better when comparing unshaved 14 bolts to unshaved Eatons.
-WMS is 63 or 65in and determined by the hub
-2 types of pinion bearings, ball bearing and tapered roller bearing, the tapered roller is better.

If it was me, I wouldn't even consider getting rid of the Eaton. for one, for the originality, for two, they were one of the best axles ever built. If brakes are why you'd consider ditching it, do the disk brake swap. Kits are available for a 14 bolt and they work for the Eaton.

[54blackhornet]

I miss the Texas firefighter ?

[Dan Castilleja]

Originally Posted by Sheepdip

From what I understand, and I could be 180 out, but seals and bearings are scarce but are a few still out there to be sourced, ring and pinion are no longer available.

If you need a total rebuild start looking for a 73-87 cab n chassis DRW 14 bolt parts truck. A cab n chassis will measure 63" WMS to WMS and 40" center to center on the spring perch's. The Dually Pickup rear ends will not fit, they are about 8"+/- to wide

Cab n Chassis will bolt right in with a couple of easy modifications on the shock mounts and flexible brake line.

Read This: https://67-72chevytrucks.com/vboard/...+brake+14+bolt

By 8" to wide, are you referring to the axle mount pads,

[67 twins]

Originally Posted by wrangler94

You're right about ring an pinions being basically unavailable. I'm not positive anymore but I think I saw on an offroad forum that I'm on that maybe someone was making gear sets for them again. In the rock crawling world people still love these axles, and do everything they can to buy and save them, for posterity of nothing else. They have all the strength, if not more, than a 14 bolt. Drop out third member like a Ford 9 inch, and better ground clearance. There is a whole thread that's basically a plethora of information about these axles, but I'm not sure on the rules for linking another forum in here, so I won't do that unless I'm told it's allowed.
I do know that some 14 bolt parts can be swapped into these axles, maybe even brakes, but I'd have to go back and read up on it again.

14 bolt brakes are an easy swap onto the HO52. Backing plates are a direct bolt on. Hubs need to be reamed for the larger studs that's about it. There are threads on here about it.

[Sheepdip]

Originally Posted by Dan Castilleja

By 8" to wide, are you referring to the axle mount pads,

Dually pickups used the wider Dana 70 and the Cab n Chassis used the narrower 14 Bolt.
They look very similar but are not, the spring mounting perch's on the dually pickups are also a wider dimension than the cab n chassis.

The 8+/-" to wide is referring the WMS to WMS... not sure on the spring perch dimension difference but it is different.