Please help me identify this rear end

[derotoreut]

This rear end is in my '69 C20. I have no idea what it is, or if its the stock rear end. There are no tags on it that I could see. Any help is appreciated.

I would also like to know the ratio. Without opening the pumpkin can I tell by rotating the wheels? With the trans in neutral I turned one of the rear wheels two full times around and the driveshaft turned over four times.

[treveiger]

I think I have the same rear end so saving. Also wondering if people want them want them lol.
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[68lngbed350]

Looks like a "corporate" rear if Im not mistaken. My 68 3/4 ton
has the identical pumpkin with rear coils as well. I was told
they only came with 4.11 or 4.57 cogs. I cant confirm this.
I think eaton made them. Also known as either ho52
or ho72. I think???

[special-K]

Yeah,HO52 in 20 series and HO72 in 30 series,it's known as the Corporate rear or in GM parts books as "Non-Dana",and HO52s go came in 4.10 and 4.57 ratio. Both the 52 and 72 are the same in single wheel version until you get to the brakes and wheel bearings. The dual rear is just narrower. The differential is made by Eaton. You should be getting a bit past 4 to a bit past 4.5 spins from the driveshaft to one spin of the wheel. Is the truck a 4spd or auto? Chances are,if it's an auto it's a 4.10 and a 4.57 if it came with auto.

[Jessechop]

Thats a Eaton with a H072 center section (load bolt on the side of the pinion gives it away) The H052 and the H072 are identical rears except the H072 has a load bolt. Both center sections interchange fine, as I have the H072 carrier in my H052 rear.

To determine the ratio jack one rear wheel up (assuming it dosnt have a locker) and mark the driveshaft and the wheel that is in the air.Truck in neutral and spin the wheel 2 full turns while counting the mark on the drive shaft. If the drive shaft turns a little more than 4 turns, it is the 4.10, 4 and a half turns 4.57's and so on.

Now if you jack one wheel up and you cant turn it with out the other one being in the air, i.e. they both go the same way when turned then you have a locker, or boud up spider, etc. Do all I said but only turn the wheel one time to get your ratio

[derotoreut]

So it sounds like normally H052 came in C20's and H072 came in C30's? So did someone swap this rear end?

Originally Posted by Jessechop

Thats a Eaton with a H072 center section (load bolt on the side of the pinion gives it away) The H052 and the H072 are identical rears except the H072 has a load bolt. Both center sections interchange fine, as I have the H072 carrier in my H052 rear.

So do I have the H052 rear with H072 carrier? What does the load bolt do?

Originally Posted by Jessechop

To determine the ratio jack one rear wheel up (assuming it dosnt have a locker) and mark the driveshaft and the wheel that is in the air.Truck in neutral and spin the wheel 2 full turns while counting the mark on the drive shaft. If the drive shaft turns a little more than 4 turns, it is the 4.10, 4 and a half turns 4.57's and so on.

So I need to keep one wheel on the ground? I did it with both wheels up in the air and got one turn of wheel to about 2 turns of drive shaft.

Originally Posted by Jessechop

Now if you jack one wheel up and you cant turn it with out the other one being in the air, i.e. they both go the same way when turned then you have a locker, or boud up spider, etc. Do all I said but only turn the wheel one time to get your ratio

I'll try this again and let you know. Also this may seem like a crazy question, but I haven't ever messed with a rear like this... How do I get at the brakes?

Also, since I haven't had this truck long I should probably change the rear fluid. What do I need to do, and what gear fluid and gasket do you recommend?

[Jessechop]

So do I have the H052 rear with H072 carrier? What does the load bolt do?

Yes, assuming you have a 3/4 ton. The load bolt was there for pinion deflection. Apperently some one at GM or Eaton decided in a 1 ton the pinion could deflect and break. Couldnt imagine it, but thats what it is for.

So I need to keep one wheel on the ground? I did it with both wheels up in the air and got one turn of wheel to about 2 turns of drive shaft.

You need to keep the other wheel from turning backwards. If you only turned the wheels 1 turn you need to multiply your result, i.e. 2 turns of the drive shaft x 2 = 4 which would be the 4.10. Or you can redo it by turning the wheel 2 full turns as I previously mentioned. The reason for the 2 turns is the spider gears need to turn 2 times for one full revolution of the ring gear.

If it had a locker/spool the spiders are then out of the equation and one turn of the wheel would then turn the ring gear one full turn

I'll try this again and let you know. Also this may seem like a crazy question, but I haven't ever messed with a rear like this... How do I get at the brakes?

Also, since I haven't had this truck long I should probably change the rear fluid. What do I need to do, and what gear fluid and gasket do you recommend?

To get to the brakes you need to take the wheel off, then remove the 8 bolts that hold the axle in. Then you can pull the axle. Behind that there is a nut with a lock ring. That would need to be taken off, then you can get to the brakes. It is pretty much the same way you would service drum front brakes, or for that matter remove a front brake rotor from a GM type car or truck. The axle is basically your dust cap. Hope that made sense the way i explained it.

For fluid I use just run of the mill 80w-90, for a gasket I use ultra grey. the bolts that hold the rear cover on are threaded all the way into the housing, so put some sealer on them when you put them back in. If you plan on removing the cover to change the fluid, you can check the ratio then.

My "guess" on the entire thing is your truck originally came with 4.57's as most C20's did. Most C30's had 4.10's. Thus the carrier was swapped out some where to take advantage of the 4.10 gears, thats exactly what I did to mine. 4.10's with a 245/60/18 isnt too bad on the road, about 2800-2900 at 60 mph

[derotoreut]

Originally Posted by Jessechop

Yes, assuming you have a 3/4 ton. The load bolt was there for pinion deflection. Apperently some one at GM or Eaton decided in a 1 ton the pinion could deflect and break. Couldnt imagine it, but thats what it is for.

Yes I have 3/4 ton, TH350 trans.

Originally Posted by Jessechop

You need to keep the other wheel from turning backwards. If you only turned the wheels 1 turn you need to multiply your result, i.e. 2 turns of the drive shaft x 2 = 4 which would be the 4.10. Or you can redo it by turning the wheel 2 full turns as I previously mentioned. The reason for the 2 turns is the spider gears need to turn 2 times for one full revolution of the ring gear.

If it had a locker/spool the spiders are then out of the equation and one turn of the wheel would then turn the ring gear one full turn

Ok I did this with pass side wheel off ground and trans in neutral. Spun tire 2X around and got a little over 4X on drive shaft. Definitely not 4-1/2X, so it looks like 4.10 ratio.

Originally Posted by Jessechop

To get to the brakes you need to take the wheel off, then remove the 8 bolts that hold the axle in. Then you can pull the axle. Behind that there is a nut with a lock ring. That would need to be taken off, then you can get to the brakes. It is pretty much the same way you would service drum front brakes, or for that matter remove a front brake rotor from a GM type car or truck. The axle is basically your dust cap. Hope that made sense the way i explained it.

Sounds good thanks. I haven't checked out the rear brakes yet, but I need to.

Originally Posted by Jessechop

For fluid I use just run of the mill 80w-90, for a gasket I use ultra grey. the bolts that hold the rear cover on are threaded all the way into the housing, so put some sealer on them when you put them back in. If you plan on removing the cover to change the fluid, you can check the ratio then.

I was gonna remove rear cover because it's leaking a little bit. Not much though. Thought I would replace gasket and fluid.

Originally Posted by Jessechop

My "guess" on the entire thing is your truck originally came with 4.57's as most C20's did. Most C30's had 4.10's. Thus the carrier was swapped out some where to take advantage of the 4.10 gears, thats exactly what I did to mine. 4.10's with a 245/60/18 isnt too bad on the road, about 2800-2900 at 60 mph

Looks like its got a 4.10. I'm running 265/60/15's on front and rear. I attached a picture.

[Jessechop]

Nice looking truck for sure. 4.10's would be what you have.

On the gasket scrape everything off and just use a bead of ultra grey, I have never had luck with a rear end cover gasket.

I have never seen a 265/60/15, maybe you have 255/60's? Those are a pretty common size. If you did have 255's you would be looking at about 3100 rpms at 60mph. Which isnt great, but isnt the end of the world either

[derotoreut]

Sorry, my mistake... 275/60/15's is what I have.

[Longhorn Man]

I've owned 2 3/4 tons with the deflector bolt, and seen planty more. I am believing less and less that the bolt deal is an HO72 only item.

[derotoreut]

Originally Posted by Longhorn Man

I've owned 2 3/4 tons with the deflector bolt, and seen planty more. I am believing less and less that the bolt deal is an HO72 only item.

How can I be sure then what rear end have?

[Longhorn Man]

regardles if the thirdmember, the rearend is a corperate rear with an eaton dropout third member. We know the axle is a 3/4 ton due to the small drums and coils, a C/30 couldn't be had with coils and even the single rear wheel ones had larger drums.
Since you confirmed that the truck is a 4.10 gear, and it has a TH350, I see no reason to think anyone has messed with it.
I say HO52 Eaton diff

[motovate]

I just found this Thread and it answered a lot of my questions. I was trying to figure out what I had for a Rear End in my 1971 Chevy Morfidite. This looks just about like what I have - except the truck has leaf springs? Any idea if that is close to stock - leaf springs??????

I believe the body is off a 1/2 T but the frame is all leaf spring and I believe was 3/T. Has a non syncro low first gear and a 205 transfer case. Came with a truck bed and a 400 small block but I put a flat bed on it - and a 350 in it - had to add my own little bit!

Any way thanks for the info this cleared up that it is at least an Eaton with a load bolt, 8 stud wheel's and I'm guessing it's a 4.11 ratio running 32" tires.

I didn't realize it was made of pieces when I bought it but it seems to be a pretty good truck.

LBM

[soxplayer]

I have one of these in a 67 Forest Service Truck. Ratio is 5.13:1. Not exactly freeway rated. Just want a complete record in case somebody else stumbles on this thread later on.

[Stocker]

Originally Posted by motovate

This looks just about like what I have - except the truck has leaf springs? Any idea if that is close to stock - leaf springs??????

I believe the body is off a 1/2 T but the frame is all leaf spring and I believe was 3/T. Has a non syncro low first gear and a 205 transfer case.

As far as I know, all 4x4s came with leaf springs.

My '72 K20 has an Eaton diff with the load bolt. I'm 99% sure it's original -- the truck was five years old when I bought it, and everything appeared to be original.

[motovate]

Originally Posted by Stocker

As far as I know, all 4x4s came with leaf springs.

My '72 K20 has an Eaton diff with the load bolt. I'm 99% sure it's original -- the truck was five years old when I bought it, and everything appeared to be original.

Thanks - maybe my truck is more stock then I thought - I think the front is a Dana 44. It has disc brakes on the front - I guess that's stock???? It also has a steering stabilizer that looks stock but everywhere I look there is not a listing for a 71 with a steering stabilizer (Dampener) I can match one that looks like it- double eye - but it's odd there is not one listed.

LBM

[Mike Bradbury]

This site might help.
http://coloradok5.com/axleguide.shtml

[Blazer1970]

Originally Posted by motovate

Thanks - maybe my truck is more stock then I thought - I think the front is a Dana 44. It has disc brakes on the front - I guess that's stock???? It also has a steering stabilizer that looks stock but everywhere I look there is not a listing for a 71 with a steering stabilizer (Dampener) I can match one that looks like it- double eye - but it's odd there is not one listed.

LBM

The '71 came stock with a disc brake Dana 44. They also came stock with a steering stabilizer like what you describe.

[special-K]

Originally Posted by Mike Bradbury

This site might help.
http://coloradok5.com/axleguide.shtml

They don't even list the HO series axles there. Seems odd for a GM 4wd based website. Especially since they showed all those non-GM axles.

[motovate]

Originally Posted by Blazer1970

The '71 came stock with a disc brake Dana 44. They also came stock with a steering stabilizer like what you describe.

Thanks - at least now I know what to get for brakes - It must be basically stock not as I thought.

Thanks.

LBM

[bollybib]

My dos centavos.

There should be a code stamped on top of your carrier on the input shaft side. The first two letters will identify what series it's for (10,20 or 30), the ratio, and if it had positraction or not. The codes are listed in the Chevy Truck Parts Catalog. Mine is JU (Series 20, 4.10, no posi). Pic of mine showing code below.

The Service Manual for 1969 calls the "load bolt" a "ring gear thrust pad". Fig. 34 on page 4-17 is for both 5200 and 7200 lb. axles and shows the load bolt for both.

I'd suggest you get both the Service and Overhaul Manuals for your truck. Also, the Parts Catalog can be very useful. I don't know how I'd manage without the Manuals even with the excellent advice available in this site.

If you are considering overhauling your brakes, you might want to look at my project thread, link below. I wrote about my experience with brakes like yours.

Nice truck have fun with it !

[motovate]

Thanks - good info - also good write up on brakes - I'll save this one also.

LBM

Originally Posted by bollybib

My dos centavos.

There should be a code stamped on top of your carrier on the input shaft side. The first two letters will identify what series it's for (10,20 or 30), the ratio, and if it had positraction or not. The codes are listed in the Chevy Truck Parts Catalog. Mine is JU (Series 20, 4.10, no posi). Pic of mine showing code below.

Attachment 754126

The Service Manual for 1969 calls the "load bolt" a "ring gear thrust pad". Fig. 34 on page 4-17 is for both 5200 and 7200 lb. axles and shows the load bolt for both.

I'd suggest you get both the Service and Overhaul Manuals for your truck. Also, the Parts Catalog can be very useful. I don't know how I'd manage without the Manuals even with the excellent advice available in this site.

If you are considering overhauling your brakes, you might want to look at my project thread, link below. I wrote about my experience with brakes like yours.

Nice truck have fun with it !

[abrahamseven]

I did not mean to hijack this thread but it is exactly what I need, I too have a 69 3/4 ton with the HO 52 my question is , what is the adjustment procedure for the load bolt or adjusting screw for the ring gear thrust pad? Mine had been messed with and there is no procedure in the service manual. I loosened the lock nut and tightened the bolt snug and backed it off one full turn then tighten the lock nut.. I turns freely and makes no noise. If anybody can give me some information I would appreciate it,

steve

Attachment 754126

"The Service Manual for 1969 calls the "load bolt" a "ring gear thrust pad". Fig. 34 on page 4-17 is for both 5200 and 7200 lb. axles and shows the load bolt for both."

[tripleD]

Does anyone know where to get parts for the H072/H052 rear ends im needing spider gears and pin for mine!