Eaton rear end questions...

[BlackhillsHD]

I just bought a 70 K20. It has the Eaton rear diff with the locker and 4.10's. From what I have been reading on here its pretty rare. Now with the bad news, the ring gear is rust pitted and kind of worries me. I have found very few parts available for these rears, and when I do they want some serious money for them. Should I just swap it out for a 14 bolt that I know I can get parts for? Thoughts?

[special-K]

The rear itself is common in pre-72 trucks all the way back to in the forties. You can get a rear for the taking to next to nothing,then take the parts you need from it. The dual wheel C/30 differentials are the same.

[BlackhillsHD]

Im not so much worried about the hard parts, but when the only bearing kit I have found is $750 from Randy's ring and pinion. I can buy 14 bolt stuff all day long for 1/4 of that. I am just wondering if there is some special reason to keep the Eaton?

[special-K]

I just go to Napa for that stuff. I prefer keeping the good ole Eaton. There's no better rear that's been made since,so I just keep mine rolling so far. The 14-bolt is way heavier with less ground clearance,yet if any heavier duty it's not enough to matter. You'll have to move spring perches and shock mounts to use a 14-bolt. I have yet to have a reason to necessitate any of that. That's all I'm saying. As far as ring & pinions go,I gave my answer. But,the only ones I've ever had fail (1 in 40+ years) was due to lack of proper care.Keep the lube up and it'll last and last.

[BlackhillsHD]

OK, thanks. I guess I am just more familiar with the 14. I think I will put some disks on the old Eaton and run it until it gives me reason to do otherwise. Thanks for the input. My expertise is on slightly newer vehicles

[special-K]

Some off road guys love'em. Lots swap them out for 14-bolts. I'm doing like you,just run it until I have a reason to do otherwise. Heck,I have three No-Spins in waiting. I should start gathering rears for spare parts. I plan an axle swap on my '72 GMC K2500. It now has 3.54:1 Dana 44/Dana 60 Power Loks. I bought a set of 4.10:1 K/30 axles,so it will get the Dana 60 front axle but I'm using an Eaton w/No-Spin for the rear instead of the 14-bolt.

[flyingtim01]

I'm with Special-K on this one. My '71 K-20 has an HO52 and 12x2 brakes, and I'm going to hang on to it. The only issue with finding brake parts are getting ahold of drums. Can't seem to locate anything new, or NOS for that matter. However, wheel cylinders, hardware kits and shoes are readily available and reasonable.

The axle itself was used in trucks up to 1.5 ton, if memory serves, the only difference being larger brakes. I also had a '51 Chevy 3800 wrecker with this style rear end in it. I don't recall which denomination it was, but it had 5.14's in it and lasted 50+ years of hard abuse hauling cars and trucks around with no issues or noise.

Seems like for each issue someone comes up with, there is a solution: if you can't find drums, convert it to disc with some Cadillac parts. If you want to upgrade the axles, you can use shafts and side gears (and a locker) from a 14b. Its also a pretty popular axle for the pulling crowd, guys regularly put 500+ hp into those axles in stock configuration with very few failures.

[joemacho]

isnt there a conversion kit to switch your drums brakes to disc on these eatons...

[special-K]

Yes,at least there was. I tried to google them and it doesn't look good.
http://www.google.com/url?sa=t&rct=j...3U9pixazH9O4vQ

You can convert to 14-bolt brakes easily,as well.

[BlackhillsHD]

www.ruffstuffspecialties.com offeres brackets for the Eaton. That is what I have ordered. They are very similar to the 14 bolt brackets, except they dont need spacers. And if you ever need to upgrade to the 14 bolt all the stuff is the same so you wont have to buy it over again.

[special-K]

Well,it would have originally been an HO52 being a 3/4t. It could have been swapped or even the HO72 brakes could have been swapped to the HO52. Most HO72s were the narrow dual wheel cab & chassis rear. One difference is on the nose section/driver side in front of the axle the HO72 has a side deflection adjustment for the pinion. I wish I had a picture. Do you see anything like that? Do you know what size the brakes were? I can't recall exactly what the HO52 K/20 brakes were,but I believe the width was only 2" and they were taller than most,like 13". The HO52 brakes are at least 2.5",I believe.

[Stocker]

Originally Posted by special-K

One difference is on the nose section/driver side in front of the axle the HO72 has a side deflection adjustment for the pinion.

Based on prior discussion, some HO52s also have that bolt (mine does). IIRC, all HO72s have it.

It's visible in this pic:

[special-K]

Yeah,some HO52s have that,so it's not a definitive telltale. But,that and the bigger brakes would be*. Now,a 2wd HO52 will also have wider brakes,but not the same as a 1t/HO72.

*Unless there was some mix matching going on. The housings are the same and so are differentials.

[maxwoof]

If it helps, my 62 K-20 has the HO72 with 12"x2" brakes. C-20 brake shoes will not fit - they are smaller in diameter and wider. I belive that the 1/2 ton K series trucks of this vintage had HO52 rears with 11"x2" brakes. I find that searching parts on rockauto.com is helpful to determine what you have. They list 12"x2" drums that's as well.
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[maxwoof]

Based on my shop manual (for my 62), it looks like the 3/4 tons came with the HO72. It is a full floating axle, and the housing is two piece in that the pinion carrier unbolts (like yours). The HO52 in 1/2 tons is not full floating and it does not have a separate pinion carrier.

I think these are bullet proof also. All I had to do to mine was to replace all the seals. I think it will last forever.
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[Trekster]

I think the H052 and H072 are pretty much the same full floating Eaton axle. The difference might be the brake size. I am running an early '70s Eaton H052/072 with 4.10 gears in my 1950 1 ton. I just picked another one up and I am going to try and put disc brakes on it.

[obijuan]

for what its worth, the gm 14 bolt rear disc brackets are the same as eaton brackets. no need to hunt for eaton specific. its all the same basically, but the eaton hubs use smaller wheel studs than the 14 bolt. that may be an issue with installing 73-87 k20 rotors.

[ChrisWhewell]

For drums, try this number into oreilly's or autozone, etc.

89058328

http://www.rockauto.com/en/moreinfo.php?pk=533722

[Guildrum]

Not to hijack someone else's thread, but I have a question about these axles. I am in the planning process of a custom 1959 one ton apache. Yeah, they didn't make one tons (so I've read) in '59, but that's why I have a donor frame from a '68 C30, and that's what makes it custom I'm planning to just sit the '59 body on the '68 frame to give the truck a lower, leaner stance. The rear end on the '59 does have the side pinion adjustment bolt and I'm assuming it's an 072. The donor truck does NOT have the side bolt, and from what I read here, that makes it a 052. I have yet to crack into either of them to see what the innards look like. My choice of transmissions is either a Muncie SM420 that I believe was the original tranny on the '59, or what looks like a Saginaw that's on the donor truck. Since the SM420 is all but indestructible, if the innards look good I'm probably going to go with it.

Now, the question: would I be better off using the 052 that's in the donor truck (meaning no axle swap necessary), or should I keep the 072 mated with the SM420? Bear in mind that I have no real idea what the gears in each rear end is, just that both of these trucks spent a good life hauling hay on the farm and the only components in the drive train that has been swapped out with either one was engine upgrades.

[Stocker]

Welcome to the boards!

All HO72s have the pinion bolt, and some (but not all) HO52s have the pinion bolt. So there's a chance you have two HO52s. I believe the third members are the same whether HO52 or HO72. The difference is in the brakes, and possibly some difference in axle bearings but that might need to be researched. Plenty of threads here about Eatons. Also, the tallest gears you are likely to find inside an Eaton is 4.10s. Might be worth looking inside each diff to see what condition they are in. That's also an opportunity to count teeth and see what ratios you have.

[Guildrum]

Thanks. The brakes are my biggest worry, because on the '59 the brakes are pretty much clapped out, but in the donor truck they're in good shape. If the third member is interchangeable, though, that means a no-sweat swap if needed! I have yet to get both trucks side-by-side to do a straight across comparison. One truck is at my work while the other sits in my garage, so any comparing I do right now is by picture and memory.