Please verify Differentals 72-3/4 4x4

[NITRO]

Greetings, it is brake time and I am not sure what drums, shoes, rotors to ask for as in size. I am going to do a complete overhaul on the brakes. From what I understand this rig is pretty much stock, except for the engine, it has a later model 350, not sure what year.
The numbers on the rear differental says: 3-365
The numbers on the front differental says: 44-5F
I have no idea if they mean anything.
thanks

[1969 GMC]

You will have to measure your rear drums as they came in a few different sizes.

Your front axle is a Dana 44, you will be able to get everything you need from the parts store.
Rear axle, you should be able to, but there's a chance you might not.

[Americanrider]

Nice 72 you have there. What part of Oregon?
The front pads for your Dana 44 should not be any problem to find. Your Rear end is a Eaton HO52 Axle. It's best to take your old rear brake stuff with you when buying parts. Some parts books will show a couple of different axles like Dana 60's and Eatons, since both came in the trucks. This way you know your getting the right brake parts the first time.

[JIMs70GMC]

3 different rear brake sizes for these trucks. Definetly better to what you have with you. The fronts are the same for all the 3/4 ton dana44 disc brake front ends, used from 71 until the early 80s in GMCs, little bit earlier for the chevys(77-78).

[NITRO]

Thanks guys, that helps a lot. I live in Gresham which is about 30 min drive south of Portland. I actually grew up in this house in the pic. My parents built the house on a 24 acre farm. I will keep you posted on the progression of this truck...yea..I love these years style of trucks...too bad they dont make em like this anymore..

['71c204x4454]

Welcome to the board from a fellow Oregonian!

[RainFade]

If you have trouble finding the HO52 brake parts or the price gives you sticker shock keep in mind that disc brake brackets for a 14 bolt will work on the 52 quite nicely

[4x4Poet]

If the rear H052 brakes are 11"x2-1/2", all the parts stores carry everything, though expect special orders. If 12"x2" and the drums are beyond spec, expect to find that the 12" drums are no longer available. That would make it a good time to go rear discs to forever end unavailability problems.

Blackbird's sells H052 disc kits:
http://www.blackbirdscustomtrucks.com/

Praise Dyno Brake sells upgraded shoes, springs, and pads. Pricey, but top grade stuff, IMO:
http://praisedynobrake.com/

[budbeater]

How strong are the HO52's? That is the axle that I have under my 71, and with future planned upgrades I am wondering if I need to be on the hunt for some 1 ton gear.

David

[BobS]

The H-052 is the same axle as the 1-tons had minus the bigger brakes and pinion load bolt, they're at least as strong as a 14-bolt.

Bob

[special-K]

Originally Posted by BobS

The H-052 is the same axle as the 1-tons had minus the bigger brakes and pinion load bolt, they're at least as strong as a 14-bolt.

Bob

YUP!!You just don`t hear about them in 4wd mags`cuz they don`t mess with old stuff.You might say they`re a well kept secret.They overlook the Dana60 rear,too.Yet,it seems the only front axle worth salt is the Dana60 according to them.

[1969 GMC]

Originally Posted by special-K

YUP!!You just don`t hear about them in 4wd mags`cuz they don`t mess with old stuff.You might say they`re a well kept secret.They overlook the Dana60 rear,too.Yet,it seems the only front axle worth salt is the Dana60 according to them.

I agree with you on the fact that they overlook info on the H0 axles. The only time I saw a little blurb about them in Petersen's 4 wheel & off road (when I used to subscribe to that) they gave just about every kind of misinformation that they could (12" ring gear, blah blah).

However the D60 rear isn't really overlooked. It came under more trucks than just about every other axle besides the 14 bolt. GM, Ford, Jeep (fullsize trucks), Dodge, IH, Stude, the list goes on and on. And some cars, too.

The reason it's not popular are the advantages other axles have over it.
Its easier to swap gears in a 14 bolt.
Detroit locker is cheaper for a 14 bolt.
Smaller ring gear and axleshafts than a 14 bolt.
It came in too many variations (17, 30, 35 spline...6 or 8 lug...FF or SF...SRW or DRW...coil or leaf sprung) and sometimes the BOM are hard to read, so parts may be hard to get.
For less weight and more strength, you can modify a Ford 9 inch.

[CyberRanger]

OK, this is a fun subject (not!).

As I understand it, the Dana 60 (D60) in the 4x4s had 11"x2½" rear brakes. The Eaton's (H052) had 12"x2" rear brakes. The part stores' books for these trucks are all hosed up & always have been (even 20 yrs ago), so you can't go by what the part store says you have in the rear (& sometimes front). The numbers they'll give you for small parts kits, spring kits, actuators, adjusters, wheel cylinders, brake shoes, etc. may or may not be correct.

Your best bet is to take the parts you need to replace to the parts store with you. Verify that the part they give you matches the parts you have. I've done this several times on my own truck & several other '71s & '72s. Its a major pain in the butt, but you have to do it. Make sure you can get ALLyour parts before buyin' any, b/c if you don't you may get stuck with a pile of parts that won't do you any good b/c you can't get everything you need to finish the job.

4x4poet is correct in that if you have 12"x2" drums you're SOL. Eaton stopped manufacturing parts for the axles years ago & some parts just aren't available. The H052 is a seriously stout axle (maybe the strongest light truck axle ever made) & its a bummer they cannot be made to keep running. Some bearings, ring & pinions, carriers, etc. just cannot be obtained, except used & those are usually not in any better shape than the ones you already have. Some parts, like shoes, wheel cylinders, etc are available thru the part stores & aftermarket, but major components just aren't available, to my knowledge.

If someone had some 7 or 8-figure amount of cash layin' around they could make a fortune by buyin' up the patents, tooling, rights, etc to these old axles from Eaton & start makin' replacement parts for 'em & sellin' refurbished or repopped version of 'em on the aftermarket.

[budbeater]

Wow, this is really a good news/bad news affair then. I have one of the best rear axles made, but replacement parts are almost non existent for it. I started a brake job on mine last night and had to stop when I realized that I didn't have the tools for the job ($10,000 worth of tools and an 1800sq/ft shop and I don't have the tools, damn). I also found out something ominous, the right rear drum is leaking something, it doesn't look like gear oil so I am assuming that the reason why I can't stop anymore is that my brake cylinder gave up the ghost. Now I am worried that I can fix it.

While we are on the subject: What can I do about the open diff in this thing? I have seen pictures on the board where people are installing what looks like a mini spool. Called what? Get it where? Locker? Posi?

Budbeater

[1969 GMC]

The only option you have is to track down a No-Spin (Detroit Locker) for one. There might be one or two on the parts boards at the moment, not sure.

[special-K]

I found all brake parts,including drums,bearings,seals,and studs at my local parts store.I haven`t gone in the center section,yet.I keep record of part numbers(somewhere) when I see what a hard time the parts guy is having coming up with them.I agree,tote the parts in.There are two wheel cylinder configurations(coil/leaf?)and I ended up with(on second try)what was listed as 2wd on my 4wd.

[budbeater]

Well, it looks like I have to jump feet first into this adventure, so... I am going to take the time to get part numbers, take photos and measurements etc. If someone did this for our various axle configurations it would make a great FAQ thread!

budbeater

....later that day

I just went in to get my truck inspected for state registration and I failed the safety inspection because of my rear brakes. It looks like the pass. brake cylinder is leaking. Now I am up against a wall. I am seriously considering the disk brake conversion mentioned earlier in the thread. This issue here is price. What have you guys paid for the whole stock rebuild ie drums, pads, seals, cylinders?


Where can I find a shop manual, or some other "step by step" to take me through this? I have done rear disks and rear drums on cars, but not a floater type axle. I basically need to know what tools and procedures I need to take everything apart.


Up to my eyeballs in axle lube

bbeater

[4x4Poet]

Originally Posted by 1969 GMC

I agree with you on the fact that they overlook info on the H0 axles. The only time I saw a little blurb about them in Petersen's 4 wheel & off road (when I used to subscribe to that) they gave just about every kind of misinformation that they could (12" ring gear, blah blah)...

I think 4x4 mags ignore the H052s because none of their adverts offer upgrade parts for them. (Capt Obvious, here )

For less weight and more strength, you can modify a Ford 9 inch.

Gotta disagree with that statement. I don't know if the housings are comparable wall thickness and diameter, but I'd guess the H052 is larger diameter and thicker wall than a 9-inch. The ~10 inch ring gear is obviously stronger and the Eaton's pinion is also supported fore and aft of the gear teeth by bearings. With the ring gear deflection load bolt and drop-out third member, it makes for a strong R&P setup. From my experience, there's no slop at an H052's R&P.

I bet 35-spline 9-inch axles are as strong or stronger than 17-spline H052 axles, but then you have a cost issue to buy 35-spline axles with matching diffs. I suspect 9-inch FF hubs have smaller bearings, but that's just a guess. Also, do 9-inch come with 8-lug hubs? No doubt not cheap.

Both my 3/4 ton trucks with H052s had mucho miles, yet the R&Ps look like their nearly new. Little wear and tear. I think one can only ruin an H052 by running oil too long, too little, or contaminated.

The 17-spine axles do show wear at the splines which adds the only slop in the H052s that I can find. Easy fix with inexpensive, used axles with no spline wear.

Impressive axle, IMO. GM blew it by going to the 14bFF. If GM had stuck with the H052, all GM 3/4 ton light trucks would have lighter rearends and we H052 users would have access to many lockers and lots of cheap parts. Well, at least reasonable.

Well, I obviously like the Eaton axles, but I talk too much...

[4x4Poet]

Originally Posted by CyberRanger

OK, this is a fun subject (not!).

As I understand it, the Dana 60 (D60) in the 4x4s had 11"x2½" rear brakes. The Eaton's (H052) had 12"x2" rear brakes.

...4x4poet is correct in that if you have 12"x2" drums you're SOL.

I have two truck with H052s. One has 12"X2" brakes. The other has 11"x2.5" brakes.


And you're wrong! This is a FUN subject!




j/k

[4x4Poet]

I recently rebuilt my K20 pickup's (Edit: it's a '72) 11"x2.5" Eaton H052 brakes:

$10.70 NAPA BRK H7017 All-In-One Kit (shoe brake springs-both sides).
$17.88 NAPA BRK H2508 Adjuster Kit (with new levers and springs). Left, no right
$17.88 NAPA BRK H2509 Adjuster Kit (with new levers and springs). Right, no left
$5.27 National NAT2081 H052 Hub Seal ($10.54 for two at Bearing Sales).
$62.00 Carquest BDR 8847 Brake Drum ($124 for two. Finished & balanced. Made in USA!)
$33.00 H052 Wheel Cylinders. (lost the part #. $66 for two. Supposedly, coil and leaf spring wheel cyls are different. My old ones were coil spring wheel cyls on a leaf spring rear. Maybe a PO backing plate swap? )
~$30.00 Brake Shoes.
~$3.00 E-brake Lever Springs.

Note: I lost the brake shoe part # & cost. They were Carquest premium shoes for ~$30 for all four. The e-brake lever springs were also available for a few bucks.

Sub total for basic brake rebuild with drum replacement: ~$280 (good comparison for disc brake kit cost)

Wheel studs are also available (I won't replace max'd out drums without installing new studs):
$3.14 Carquest DOR 610-190 Wheel studs, '71/2 H052 9/16" ($50.24 for 16)
Sub total with stud replacement: $330.24

Tapered hub bearings are also available. A bearing sales store can even cross ref the original barrel bearings to superior, tapered bearings and races. IIRC, costs less than $50 to do both sides (4 bearings w/races).
Sub total with bearing replacement: $380.00

$3.86 Fel-Pro 55350 H052 Axle Flange Gasket, metal, 8-hole. (7.72 for two)
The metal axle flange gaskets should be reusable, but Fel-Pro 55350 (Future No. 15-1504) should be correct. I think they match 14-bolt gaskets because the package lists the application as "Chev. TK, GMC, 8 Mounting Bolts, Series 20, 30, 1973-95." Since 14-bolt axles can be used in an Eaton after swapping in 14bFF side gears, that makes sense.

Grand total for going all the way: $387.72

A couple extras:
$5.89 (BTB) Fel-Pro RDS5088 H052 Diff Cover Gasket (thick & rubberized, too)
$3.87 (BTB) Fel-Pro RDS5090 H052 Carrier Housing Gasket (paper thin to keep side gears aligned with axle centerlines)

I copied off my receipts and used a calculator, but since I've been know to make mistakes, I take ZERO responsibility for whether these parts are correct for H052 11"x2.5" brakes. You're on your own.

[1969 GMC]

Originally Posted by 4x4Poet

Gotta disagree with that statement.

At that point, I was referring to other axle's advantages over the D60...not the H0's.

[4x4Poet]

Originally Posted by 1969 GMC

At that point, I was referring to other axle's advantages over the D60...not the H0's.

I totally missed that. Sorry 'bout that.


See, I do talk to much...

[budbeater]

Well I decided to up-mod to rear disks. Thanks for the link to blackbird custom trucks. I placed my order for a kit yesterday. When I start I will put together a new thread with pictures from start to finish on the rebuild.

That brings me to a question. (4X4Poet you posted alot of info about part numbers for a rebuild so you might know this.) I am going through a NAPA dealer for my axle seals and bearings. Is there any upgrades that I can do in the seals and bearings department that anyone is aware of? Does anyone have part numbers?

Thank you, swearing and sweating to come soon.

Budbeater

[roger0080]

Nitro did you ever get the rear apart? Was it 12x2 drums you have?

4x4 Poet, thanks for the detailed info. You don't say what years the HO52's are from.
I am going to venture to say that one of those was switched from a 4WD Drum setup to the 2 WD drum setup of 11x2-1/2.
Could you/Do you know if the backing plates are the same/same size on both those vehicles???
The GM parts manual says that ALL the 4WD backing plates are the same part numbers.
My 71 K20 Eaton uses 5/16" brake line.
Does your 11" HO52 have 3/16 or 5/16? I wonder if that is the difference in the wheel cylinders for 2WD vs 4WD

This thread answers a lot of questions just after I started this thread:
http://www.67-72chevytrucks.com/vboa....php3?t=174664

Guess I learned that 12x2 drums are non-existent.

Looks like I'll be looking for a 2WD Eaton donnor vehicle...

Thanks if anyone can answer the questions.
-Roger

[4x4Poet]

Originally Posted by roger0080

...4x4 Poet, thanks for the detailed info. You don't say what years the HO52's are from.
I am going to venture to say that one of those was switched from a 4WD Drum setup to the 2 WD drum setup of 11x2-1/2.
Could you/Do you know if the backing plates are the same/same size on both those vehicles???
The GM parts manual says that ALL the 4WD backing plates are the same part numbers.
My 71 K20 Eaton uses 5/16" brake line.
Does your 11" HO52 have 3/16 or 5/16? I wonder if that is the difference in the wheel cylinders for 2WD vs 4WD...

Guess I learned that 12x2 drums are non-existent....

I added the year above. It's a '72 K20 pickup, but it's a hodgepodged truck, so it could have an H052 or parts of an H052 from anywhere. You may be right about my '72 K20 having swapped backing plates to get 11"x2.5" brakes. Maybe someone was running away from the 12"x2" brakes. When I ordered the brake parts, I gave the vehicle app and also told them it's got 11"x2.5" brakes.

With that info, the wheel cylinders were different and the rear brake hose did not match. Carquest books said that the wheel cylinders that did work (after returning the ones that didn't match) were for coil spring trucks even though my '72 K20 pickup obviously has leaf springs as did all 4x4s. The difference is one has symmetrical wheel cyl mounting bolt holes and one has asymmetrical mounting holes. So whether the backing plate has symmetrical or asymmetrical bolt holes or slots drives what wheel cylinder is used. According to my local Carquest, asymmetrical are for coil spring trucks.

I don't know for which model they ordered the rear brake hose that turned out to be correct. I think they made a mistake on the first hose they gave me because the correctly fitting hose matches my K10 burb's rear brake hose and my Classic Industries catalog lists Skyjacker SS hoses as being all the same part # for all 67-72 4x4s. I have one of their rear 4x4 SS brake hoses which matches the correct hose Carquest finally gave me. Anyway, don't take my word for it. Just be wary.

The 12" brake backing plates are definitely larger diameter because on both 11" and 12" brakes, the brake drum double lip fits over the backing plate lip to make something of a overlap fit without touching, of course. More importantly, there's the symmetrical vs. asymmetrical wheel cylinder bolt hole/slot differences. For the same year, maybe all 4x4 backing plates are the same if all 4x4 H052s originally have 12"x2" brakes. Maybe all 2wd are the same. Don't know.

Don't take my word for the lack of availability of new 12"x2" drums. I haven't tried to source them in years. I'd definitely convert the rear to discs if I had 12"x2" brakes in need of refurbishment to avoid future parts availability concerns. My K20 burb has 12"x2" or 12x2.5" (I forget, but the hub lines up) drums from another vehicle app that a brake shop turned part of the lip off of to help them overlap with the backing plate. Don't know the app. This was in '94 way before I knew one could convert the H052s to discs. The 12"x2" drums are fine for now since they have Praise Dyno Brake shoes mated to them.

My '72 K20 pickup's hard brake lines are 3/16" (EDIT: Wrong! They're 1/4"). The fittings take a 7/16" wrench. I haven't looked at my '71 K20 burb's H052 hard lines. The fittings for the H052 hard lines on my '72 K20 fit both the "symmetrical" and "asymmetrical" wheel cylinders. I know, because I had a few threads of the fittings started with the wrong wheel cylinders before I noticed the bolt holes didn't line up. I thought I was being smart to start the threads before tightening the cyls.