The Stovebolt Site Forums The Shop Area Engine Shop Ring and pinion for 49 3600

Hey all, I read this thread

ring and pinion options


So i began looking around.

I have found many sights that sell 67-72 ring and pinion sets,

So I need a little clarification.

On the 67-72, would the rear axle have the same bolt pattern on the outside, would the model be a C15, k15???

I also want to clarify that a ho52 and ho72 can interchange ring and pinions. My 3600 has the stock rear axle, and I thought the the 4.11 would be a better choice, but using the stock housing.


Thanks for the help.

The model would be C20 or K20. The 3rd member is a direct interchange, the '4.10 ratio was used '68-'72 om 3/4 ton. No need to swap the ring and pinion, as the entire 3rd member bolts right in.

I googled 3rd member, apparently some asian pop group lost their third member,

more seriously, the third member is the part that retains the pinion portion? the front part of the rear differential?

By '72 some of the 3/4-ton trucks had Dana axles instead of the Eaton. Make sure you're getting gears for an Eaton if you order.

Also, if you find a place where you can order the 4.11 gears for an Eaton please make sure to post it here. I don't believe they are available new anywhere. Or at least none of the people I know who have looked have been able to come up with them.

Unless you’ve stumbled onto the Holy Grail Sam, the only option you have is to find, as Bill pointed out, a ’68-’72 3/4-ton with the Eaton HO-52 4.10 gear. Believe me when I say that I’ve beat this horse to death. No one makes a replacement gear set for that center section, not GM or any aftermarket supplier whether it’s the early model or the later one.

Even though from the outside the center sections look the same, inside they are different. I’ve had my original 1950 center section and a late model 1970 center section apart side by side on the bench. The ring gear, differential case and cover and differential gear set will interchange but the differential carrier, pinion and it’s bearing are different.
So the later one will, as Bill already noted, bolt directly in because the spacing and splines are the same but you can’t interchange the pinions in the differential carriers.

In the parts books you will find all kinds of wonderful gear ratios that will make your mouth water, but the only gear that will fit your housing is the 4.10 from the C-20’s in ‘68 & ‘69. Then starting in ’70 the C-20 and K-20 both used the Eaton HO52 exclusively and offered a 4.10 ratio. In ‘71 you a 3.54 was offered in the K-20 but it was not the Eaton HO52 axle.
On to ’72 and the C-20 and K-20 could be found with a 3.54, a 4.10, a 4.11, a 4.56 and a 4.57 the 4.10 and 4.57 being the only ones that were an Eaton HO52

And how do you know you’ve found a 4.10? Pull the cover and count the teeth, look at the ratio number stamped on the ring gear, or check the SN located on the top of the center section, passenger side.
Here are a couple of pages taken while I was making the exchange in my 3600. http://www.pbase.com/dennygraham/eaton_ho52

So there you go, all you ever wanted to know about the Eaton HO52 4.10 availability. That is, till someone else comes up with something new.
Denny Graham
Sandwich, IL

There were some posts a while ago with suggestions of where to look to get a 4.10 pumpkin. I understand that one of them was a business that seems to have some in stock. Otherwise you end up in a searching mode for a long time.

Since it hasn't been mentioned, it is sometimes referred to as a "pumpkin". That is becuase the differential assembly attaches through the front of the housing and has a general shape resmbling a pumpkin when it is removed.

The American Classic web site has an axle decoder, but it has not been working for sometime. I used to reference it a lot for the 3/4 and 1 ton 4.10 codes. I wrote down all the 4.10 codes one day to have for my file. They actually showed a 4.11 (not 4.10) HO52 available as early as 1964.

Year Code Ratio
1964 MA, MD 4.11 3/4 ton
1965 HW " " "
1966 JU " " "
1967 HW, JU " " "

1968 and after was listed as a 4.10 ratio.
I don't have a Chevrolet by the Numbers book, I think they are out of print. But I know Bill does and it sounds like Denny has one also. Can you guys confirm these codes and ratios for '64-'67?

Thanks for the extended explanation Denny. This info is probably harder to come by then you realize, having gone through it all your self.

Also, the pictures you took are fantastic! All this takes time to document and post so thanks for doing it. It's a huge help.

This is the best that I can do guys, it’s taken out of the “Catalog of Chevy Truck ID Numbers 1946-1972” so I wouldn’t guarantee that it is complete or all correct. But it should get anyone that is searching for a gear for their 3600 or 3800 in the ball park.

The ‘64 series 2000 MA, MD, was a 4.11, not an Eaton HO-52
The ’65 series 2000 HW, was a 4.11, not an Eaton HO-52
The ’66 series 2000 HW, JU, was a 4.11, not an Eaton HO-52
The ’67 series C-20 HW, JU, was a 4.11, not an Eaton HO-52

The ’68 series C-20 HW, JV, was a 4.11, not an Eaton HO-52
The ’68 series C-20 OT, NA, NB, WI, OW, OY, was an Eaton HO-52
The ’69 series C-20 HW, JU was a 4.11, not an Eaton HO-52
The ’69 series C-20 NA, NB, OT, OW, OY, TF, was an Eaton HO-52
The ’69 series C-30 IE, LJ, LZ, MR, NZ, RN, was an Eaton HO-72
The ’70 series C-20 TAA, THU, THW, TJU, TLN, TMZ, TNA, TNB, TOT, TTF, TWI, was an Eaton HO-52
The ’70 series C-30 TIE, TIH, TLJ, TLX, TLZ, TMR, TNZ, TRN, was an Eaton HO-72
The ’70 series K-20 TPW, TPX, was an Eaton HO-52
The ’71 series C-20 TAH, TAJ, TJA, TJB, TIP, TJS, 2G, was an Eaton HO-52
The ’71 series C-30 TAK, TAL, TAP, TJK, TPZ, was an Eaton HO-52
The ’71 series K-20 TKY, TKZ, was a 4.11, not an Eaton HO-52
The ’71 series K-20 TJH, TJJ, TKB, TKC, TKK, TKL, TKS, TKT, was an Eaton HO-52
The ’72 series C-20 RAH, RAJ, RJA, RJB, RKK, RKL, RKS, RKT, RJP, RJS, RKB, RKC, was an Eaton HO-52
The ’72 series C-30 RAK, RAL, RAP, RJK, was an Eaton HO-52
The ’72 series K-20 RKY, RKZ, was a 4.11, not an Eaton HO-52
The ’72 series K-20 RJH, RJJ, was an Eaton HO-52

Denny Graham
Sandwich, IL

Thanks Denny, looks like the '64 to '67 4.11 were Dana 60.

I have always heard the pumpkin term, did not think of it last night,

A place I have found has the ring and pinion portion used, from old h052 and ho72 rear axles in 4.11, 4.57 and I forget the third. He has not responded to email yet, nor Voicemail. So Holy grail could be right. This is actually for a friend 1953 3600. I like stock slow.

Denny, thanks as always. I wish everyone was as detailed.

I think you will find posts on here that suggest installing a used set may be a bad idea. I think they are hard to adjust properly once they have a wear pattern.

And Sam, one more time, if he is selling you a 4.11 it is not for an Eaton HO52 axle, it's a Dana. This Eaton axle did not, never, ever have a 4.11 gear ratio.
DG

Since I have not received a response, I am considering that option a dead end. I see what you mean about the 4.10. As I said before, I am happy with my stock 3/4 ton.

I wonder what it would take to mfg a 4.10 for the 3/4 ton rear axle? Do you think there would be enough buyers?

Or for that mater I wonder if you could make a 3.73 or similar. I imagine it would have to be a run of them, and they would be high dollar.

All ready beat ya to the punch Sam, several years ago I e-mailed out to all of the aftermarket gear seller and manufacturers asking the same question. I didn't get one responce back from any of them. They simply aren't interested in a run of a thousand which they could probably unload in a few weeks.
Denny Graham
Sandwich, IL

I suspect the price in the small quantities would be so high everyone would swap to a 14-bolt or Dana 70.

A 1000 part run would not be a small order for a gear grinder. I know I'm not the only one so I'll say it, most purists, are not going to change out a great, dependable, easily serviced Eaton HO52 or HO72 for a Dana what ever.

The problem comes in finding an investor willing to take the chance. A thousand parts would no doubt run well into the hundreds of thousands. I truly believe that once the word had got out that you could move them within weeks. There are easily 1000 three quarter and one ton trucks out there who’s owners would sell their kids to get a 3.73 or 3.55 gear in their other wise stock truck. I’d bet we get a few dozen hits a week right here on the Stovebolt forums of guys looking for the 4.10 swap and we're only one small segment of the GM restoration picture. I’d have no problem spending what ever it took to find a good road gear for mine and I’m an old retired dude with very little income. It would open up a whole new world of use for that old truck. If I could roll along at 65 or 70 on the toll/free ways you can believe me and the old gal would be taking a bunch of trips across country. Now days I just hate to think about running it any distance with the engine screaming at 2800 and still only barely pushing 55mph. That makes for a nice drive in the country on the two lane blacktop but a real pain in the ars on the interstate.
Denny Graham
Sandwich, IL

Looking at gear sets on Randy's Ring and Pinion it seems they range from about $200 to about $450 for the Dana 70-HD. I chose that one because its the right size for an Eaton replacement and figured the price would reflect high volumes.

I'm sure the retail price for a limited run for the Eaton rears would be at least the high side of that and possibly quite a bit more.

Just guessing but based on the pricing of limited market items like Cadillac 500 parts I would expect the price for these gear sets to be more like $600 to $1,000. Realize I say that with no real idea what it would take to make them.

What Randy's Ring and Pinion calls an installation kit for the Eaton is priced over $500. That's shims and seals and bearings and I suspect all stuff you really want once you spend a fist full of cash on that shiny new ring and pinion.

As an old truck guy you're going to be over $1,000 maybe $1,500 or more into that rear.

I'm not a purist, I've already put a GM 14-bolt in one of my 1-tons and have two Dana 70HDs stashed in case I decide to do another one. My total cash out to acquire all three was only a couple hundred.

To me its similar to the 8-lug disk conversion that is often talked about. Yeah there are a bunch of us who would like to buy that kit, but not nearly enough to be attractive to someone who has invested in the facilities required to create and market it.

If I said I could deliver that ring and pinion for $600 but needed 500 customers to make a $200 deposit before I'd commit to the production run, do you suppose I'd receive very many checks? I suspect getting money committed up front would be the key to making this happen.

I scratched that post, I thought I had found the grail, but it was only a french castle catapulting Cows.

I think I am going to find a scrap pumpkin, and then pul the ring and pinion and work with some fabricators to make some 4.10's or lower if possible. They would be pricy, but worth it in my opinion, especially if you can keep the rest of the truck stock.

The VCCA magazine has had ads in the past for folks who wanted gear sets made. They were not the HO52s but for some fairly old Chevs. I think I have seen this more than once. I guess that they have the numbers and contacts to pull it off.

Keep us posted. I would love to be able to tell people there is a gear set available at whatever ratio, and it only costs x dollars.

I know of a couple of places that can do this type of stuff, You just have to have a blank to either copy, or use to re-engineer in this case the faster unit.

I will let you know my progress on this.

Just to follow up, I went to car-part.com ( the hyphen is important ) and lucked out. I found an Eaton carrier with 4:11 gearing from a 1972 C30 at a salvage yard a few hours from my house. I was cautious but measured everything and it seemed identical to the stock unit. It was not cheap - $400.

It bolted right in, was to a tighter spec than the original unit (lash, mesh and everything was adjusted well)and after a few test drives it seems to be working great.

I snapped a few pictures while I was in the process of cleaning it. Here is the original in the rear end so you can see the bolt pattern and so on.

http://i289.photobucket.com/albums/ll204/unclewes13/carrier0.jpg
http://i289.photobucket.com/albums/ll204/unclewes13/carrier01.jpg
http://i289.photobucket.com/albums/ll204/unclewes13/carrier4.jpg
http://i289.photobucket.com/albums/ll204/unclewes13/carrier3.jpg
http://i289.photobucket.com/albums/ll204/unclewes13/carrier2.jpg

Thanks for all the help guys!

Wes

Hi all, found your post and am jumping in a few years later hoping someone has some new suggestions.

Have a 1950 Chevrolet 3600 3/4 ton pickup with an 4.57 HO52.

Thanks much for any input.

Not much has changed. Here are several sets of 4.10s from salvage yards. $100 up. I used this search criteria:

1971 Chevy Truck-20 Series , 1971 down to 1967
Carrier
Rear Axle