eaton Guru needed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mikep · 03-26-2003, 10:52 PM

Its hard to find info on these ! Ive got three carriers. Two are pretty much trhe same except for the gearing. Theyre late '58 and '60 carriers in 4.11 and 5.14 respectively . The 5.14 I have in the truck right now. The pumpkins are identical as far as I can see except for the gearing. same sort of pumpkin and all with the bronze ring gear deflection adjuster.
I was thinking about trying out the other 1962 manufacture carrier I have with 4.57 gears so I starting cleaning it up today and tearing it open for inspection and painting the pumpkin and I noticed that the back of the ring gear looked pretty clean compared to the other two and that was because.... It had no deflection pad . There wasnt a boss for one cast into the pumkin at all. Plus the ribs on the pumpkin looked a little taller than the others. Is this a different type? All the eaton pumpkins I have seen had deflection adjusters in them. Is this a different model?

Hooter · 03-27-2003, 12:09 AM

I-I-I dont Know!?

mikep · 03-27-2003, 12:58 AM

That was a bad guru answer. OK lets try this. i hear these things referred to as HO72's . I also see another designation that slips my mind a the moment. Perhaps thats what this is. Anyone know what that designation is?

breeh · 03-27-2003, 01:31 AM

HO52??? This is the lighter duty rear. Lighter than HO72 anyway.

mikep · 03-27-2003, 01:40 AM

That might be it. The only difference I can see is the lack of a ring gear deflection stop but that would probably make it lighter duty than one with a deflection pad.

69oldie · 03-27-2003, 03:56 PM

The only "MAIN" difference between a "single rear wheel" Eaton HO 7,200 and the HO 5,200 is the size of brake drums on the 67-70. That changed in 71-72. These years, the lug studs vary from 1/2"(3/4ton) to 9/16"(1 ton) and brake cylinders(because now 71-72 have front disk brakes, which required a different size brake wheel cylinder for rear)......the HO 7,200 had the 9/16" and larger drums while the HO 5,200 had the 1/2" and smaller drums. The except to this is the HO 5,200 in the K20's......these had smaller drums (BUT with "cooling fins" cast in them) BUT had LARGE 9/16" lug studs. 67-72 Eatons all had the ring gear deflector. The differental housings and 3rd member drop outs where all the same....(except of course the gear ratios and "D-lockers" options). There is also slight differences in the types of brake lines used and placement throught out these years....so not all 67-72 Eaton brake lines are interchangeable. One more thing....The 67-70 HO 7,200's brake backing plates are also NOT interchangeable with 71-72 HO 7,200's. They will bolt on but your brakes will not work properly without changing either the brake proportioning valve or changing the FRONT wheel brakes to match...this is also true for the HO 5,200. I am NOT an Eaton expert by any means...........These are the differences I have encountered through my years of experiance with the 67-72 trucks ONLY. I hope this helps you out.
Take care!
Jim "69oldie"

breeh · 03-27-2003, 08:14 PM

69oldie, not an Eaton expert, huh!

mikep · 03-27-2003, 08:23 PM

Variations of this same differential unit go back to 1952 and were a lot more common in the 60- 66's than in our trucks it seems. I managed to pick up an eaton single speed rear axle manual from 1955 on Eaby today. When I get it I'll scan in PDF files for anyone who wants them.

**COBALT** · 03-27-2003, 09:08 PM

I'd love to get those.

The only thing I'd add is that there's a rumor going around that the HO52 only came with 3/4 ton coil sprung trucks, while HO72 (7,200) only came with 1 ton leaf sprung trucks. I can squash that right now with my 3/4 ton 7,500 GVW truck with 9/16" studs and the larger brake drums. The 7200 lb axle under my truck was stock under a coil suspension.

69oldie · 03-27-2003, 11:29 PM

Cobalt,
I have seen Eatons HO 5,200's that were under leaf springs as well. This is definitly a first for me to hear of a HO 7,200 on a 3/4 ton 7500 GVW truck. What year is your truck? Does it have front disc brakes or drum? Are the front tire wheel studs matching 9/16"? What size drums are they? Are you 100% sure it is 100% original? You got me curious now!!!
Let us know!
Thanks
Jim "69oldie"

mikep · 03-28-2003, 12:40 AM

A little side note. My 7500 GVW 68 3/4 ton truck has 1/2" studs all the way around.

**COBALT** · 03-28-2003, 02:13 PM

I'm going to go recheck this just to make sure. I might be smoking something, but here's my configuration:

1969 3/4 ton coil sprung truck. The GVW is 7500, and it has the aux. springs option and heavy duty coils option, with drums front and back.

Before I rebuilt the front and back suspension the front-end had never been worked on, and the rear-end had never been unbolted from the trailing arms. I am the first person to do any serious work on this truck outside of the engine being replaced.

I'll go get my calipers and measuring tape and get back to you. I swear the last time I measured the drums and studs they were larger than they were supposed to be, but that was 2 years ago...

03-26-2003, 10:52 PM	#1
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	eaton Guru needed Its hard to find info on these ! Ive got three carriers. Two are pretty much trhe same except for the gearing. Theyre late '58 and '60 carriers in 4.11 and 5.14 respectively . The 5.14 I have in the truck right now. The pumpkins are identical as far as I can see except for the gearing. same sort of pumpkin and all with the bronze ring gear deflection adjuster. I was thinking about trying out the other 1962 manufacture carrier I have with 4.57 gears so I starting cleaning it up today and tearing it open for inspection and painting the pumpkin and I noticed that the back of the ring gear looked pretty clean compared to the other two and that was because.... It had no deflection pad . There wasnt a boss for one cast into the pumkin at all. Plus the ribs on the pumpkin looked a little taller than the others. Is this a different type? All the eaton pumpkins I have seen had deflection adjusters in them. Is this a different model? __________________ No truck :-(

03-27-2003, 12:09 AM	#2
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	I-I-I dont Know!? __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

03-27-2003, 12:58 AM	#3
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	That was a bad guru answer. OK lets try this. i hear these things referred to as HO72's . I also see another designation that slips my mind a the moment. Perhaps thats what this is. Anyone know what that designation is? __________________ No truck :-(

03-27-2003, 01:31 AM	#4
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	HO52??? This is the lighter duty rear. Lighter than HO72 anyway. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

03-27-2003, 01:40 AM	#5
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	That might be it. The only difference I can see is the lack of a ring gear deflection stop but that would probably make it lighter duty than one with a deflection pad. __________________ No truck :-(

03-27-2003, 03:56 PM	#6
69oldie Never too many LONGHORNS! Join Date: Dec 1999 Location: Los Angeles Calififornia Posts: 423	The only "MAIN" difference between a "single rear wheel" Eaton HO 7,200 and the HO 5,200 is the size of brake drums on the 67-70. That changed in 71-72. These years, the lug studs vary from 1/2"(3/4ton) to 9/16"(1 ton) and brake cylinders(because now 71-72 have front disk brakes, which required a different size brake wheel cylinder for rear)......the HO 7,200 had the 9/16" and larger drums while the HO 5,200 had the 1/2" and smaller drums. The except to this is the HO 5,200 in the K20's......these had smaller drums (BUT with "cooling fins" cast in them) BUT had LARGE 9/16" lug studs. 67-72 Eatons all had the ring gear deflector. The differental housings and 3rd member drop outs where all the same....(except of course the gear ratios and "D-lockers" options). There is also slight differences in the types of brake lines used and placement throught out these years....so not all 67-72 Eaton brake lines are interchangeable. One more thing....The 67-70 HO 7,200's brake backing plates are also NOT interchangeable with 71-72 HO 7,200's. They will bolt on but your brakes will not work properly without changing either the brake proportioning valve or changing the FRONT wheel brakes to match...this is also true for the HO 5,200. I am NOT an Eaton expert by any means...........These are the differences I have encountered through my years of experiance with the 67-72 trucks ONLY. I hope this helps you out. Take care! Jim "69oldie"

03-27-2003, 08:14 PM	#7
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	69oldie, not an Eaton expert, huh! __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

03-27-2003, 08:23 PM	#8
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Variations of this same differential unit go back to 1952 and were a lot more common in the 60- 66's than in our trucks it seems. I managed to pick up an eaton single speed rear axle manual from 1955 on Eaby today. When I get it I'll scan in PDF files for anyone who wants them. __________________ No truck :-( Last edited by mikep; 03-27-2003 at 08:25 PM.

03-27-2003, 09:08 PM	#9
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I'd love to get those. The only thing I'd add is that there's a rumor going around that the HO52 only came with 3/4 ton coil sprung trucks, while HO72 (7,200) only came with 1 ton leaf sprung trucks. I can squash that right now with my 3/4 ton 7,500 GVW truck with 9/16" studs and the larger brake drums. The 7200 lb axle under my truck was stock under a coil suspension. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

03-27-2003, 11:29 PM	#10
69oldie Never too many LONGHORNS! Join Date: Dec 1999 Location: Los Angeles Calififornia Posts: 423	Cobalt, I have seen Eatons HO 5,200's that were under leaf springs as well. This is definitly a first for me to hear of a HO 7,200 on a 3/4 ton 7500 GVW truck. What year is your truck? Does it have front disc brakes or drum? Are the front tire wheel studs matching 9/16"? What size drums are they? Are you 100% sure it is 100% original? You got me curious now!!! Let us know! Thanks Jim "69oldie" Last edited by 69oldie; 03-27-2003 at 11:38 PM.

03-28-2003, 12:40 AM	#11
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	A little side note. My 7500 GVW 68 3/4 ton truck has 1/2" studs all the way around. __________________ No truck :-(

03-28-2003, 02:13 PM	#12
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I'm going to go recheck this just to make sure. I might be smoking something, but here's my configuration: 1969 3/4 ton coil sprung truck. The GVW is 7500, and it has the aux. springs option and heavy duty coils option, with drums front and back. Before I rebuilt the front and back suspension the front-end had never been worked on, and the rear-end had never been unbolted from the trailing arms. I am the first person to do any serious work on this truck outside of the engine being replaced. I'll go get my calipers and measuring tape and get back to you. I swear the last time I measured the drums and studs they were larger than they were supposed to be, but that was 2 years ago... __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

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