Hey guys, getting ready to swap out my rear;). I currently have a Olds 12 bolt with a 10 bolt carrier non posi YUCK. Even better I have Mark Jones 505 BB in there. Needless to say I have been tearing up the "tire" all over the road. And while that is fun, I would rather tear up both;). So, that being said, I found a rebuilt 67 rear with a 2.73 posi for 600.00. My question is, is this a good price to pay? It includes brakes drum to drum. All new seals and bearings. Whats the verdict?? BTW I have a 69 chevelle...it will fit right?



Thanks all,

Tim

Your call but you'll probably want to go to a 3 or 4 series carrier for a better gear than 2.73.
So add in a gear set and a posi carrier to your expenses.
Check with Freddie or Tom for prices.

I like the gear ratio. I have a 2.73 in my limited slip. Whats the difference in the carriers?

2 series carrier fits 2.73:1 & down
3 series carrier fits 3.08:1 to 3.73:1
4 series carrier fits 3.90:1 & up

Ahh OK. Well the seller says that the carrier that is in it now will fit a 2.73 and a 3.08 (is this possible?). Its an eaton posi, brand new carrier new seals and bearings. Just talked to him to clairify.

I clarify my posting by adding the Eaton carrier numbers:
ED32088 2 series 2.73:1 & down
30140PM1 3 series 3.08:1 to 3.73:1
EDB30174 4 series 3.90:1 & up

Not aware of any 3 series gears that fit a 2 series carrier but here are 4 series gears that fit a 3 series carrier -there made with a thicker ring gear.
So to answer your question ,it can't fit both the 2.73 or the 3.08 -that's 2 different carriers.

Is it possible to use the spacers that some people use when using a 3 series carier and a 4 series gear? Mine has the thick gear as mentioned to run 4.10 on a 3 series but I've heard of people using spacers.

If it's a Chevy 12 bolt then it won't fit 2.73 AND 3.08. The 2.73 works on a 2 series differential and the 3.08 works on a 3 series. What you have now is not a limited slip, it's a standard or "open" differential. Limited slip is the correct term for "posi", which is Eaton's trade mark name for their limtied slip differential. The '67 12 bolt will fit your car, but it is 1 inch narrower over all. If you like the 2.73 gear and don't ever intend to change it then this will work for you. If you plan on changing the gears then you will need a 3 series differential.

Great info, thank you for clairifying. I never knew the limited slip was a posi. I had always heard an open carrier refered to as limited. OK, so since the guy was wrong about the carrier, how can I tell for sure hes actually selling a 12 bolt? He has the cover off to show me all the new insides.

Tim

Check the casting numbers and axle tube stamping. You can check the carrier and count the bolts holding on the ring gear.....If the last 3 cast numbers end in 939 I'd buy it....if they end in 124 take a tape and get some measurements for us here on the site. You really need to determine if 2.73 is going to be your desired final drive ratio prior to purchase. The carrier and gears are items you don't want to be replacing on a new rear for cost reasons.

I think im going to stick with the 2.73. I like the ratio. Ill find out the casting soon. But all the other 67 rears go for around 1000 that I see. If I do decide later on to get the 3.08 Id still be under the 1000's...or no. The only thing I dislike about the 2.73 is the gear changes are sloppy. But the motor has so much power, it dosent much matter.

Tim

A Chevy 12 bolt has 12 bolts, 3/8 with 9/16 heads, in the ring gear. The O rear end has 12 bolts in the cover, but only 10 in the ring gear.

Ok casting code ends in 124. What is the significance of this? Everything else looks good.

The 124 tells us that your rear is a 12 bolt casting ,not an O type and:
1967 Chevelle-Late NF3917124 or 1968-Early 1969 Chevelle NF3917124
See a date code ?

Ok. Date code is e88. Also it has an x above the nf number. It has 939 stampped on the inside of the housing.

May 8 ,68

So this is a 68 then. What about the 939 on the inside? Or the x above the nf number. Any significance? I know this is a true 12 bolt now, but some are more rare than others, didnt know if these numbers had anything to do with it.

Tim

Foundry 'stuff'.
The casting date and casting number are the ones to go by.

Ok. Good enough for me. Oh, btw I called Jegs today to ask for sure that they didnt sell a 3.08 for a 2 series carrier. And in fact they do. Unless they were wrong too. It is a 2 series eaton unit, and that is what i told them at jegs. Confused on that one.

TIm

Looks like the 2 they show for car/truck is what they gave you:
http://www.jegs.com/p/Eaton/Eaton-Posi-Differentials/750876/10002/-1
The truck carriers - Jeg's 362-19587-010 is show as 12 bolt truck on Summit's site
http://www.summitracing.com/search/Department/Drivetrain/Section/Differential-Rear-End-Components/Part-Type/Differential-Carriers/Brand/Eaton-Torque-Control-Products/Axle-Model/GM-8-875-in-truck/?Ns=Rank|Asc

Here's the 2 currently available from Eaton for the 8.875" car rear
http://www.summitracing.com/search/Department/Drivetrain/Section/Differential-Rear-End-Components/Part-Type/Differential-Carriers/Brand/Eaton-Torque-Control-Products/Axle-Model/GM-8-875-in-passenger-car/?Ns=Rank|Asc

I've never seen a 3.08 for a 2 series 12 bolt, and I don't see one listed at Jeg's either. As far as I know they don't exist. If you find one or a part number let me know because I want to see it.

So then this one will work?

So which one what would work ?

Oh, just looked at it. Didnt get the model number carrier when I was there. I asked the rep if there was a 3.08 gear set that would fit the 2 series carrier. Not a carrier that would fit both ratios. My mistake for any confusion, Just now learning all this. Ill call the rep tomorrow and ask the part number for the gears he quoted.

Thanks
TIM

Ok. Date code is e88. Also it has an x above the nf number. It has 939 stampped on the inside of the housing.

Are you sure the date code isn't e86 or e66? Sometimes 8 & 6 are hard to differentiate...........It would make more sense to have a XXXX939 housing casting number with a May 1966 date code.

Could have been 66 or 86. But the last 3 on the nf was 124. It had the 939 stampped on the inside. The posi stock number which I don't think is correct is:et or Ed30208. Couldn't find ant such number searching for it.

Sorry, I missed that.........

Could have been 66 or 86. But the last 3 on the nf was 124. It had the 939 stampped on the inside. The posi stock number which I don't think is correct is:et or Ed30208. Couldn't find ant such number searching for it.
Sure that's not ED32088 ?

Sure that's not ED32088 ?

Shure could be. To explain, there is a language barrier between me and the seller. I really only believe what I have already seen. Which was enough for me to buy it. Sorry for any confusion. I will eventually correct his misinformation and clear this up...for all of us! I'll check out that stock number and see what that turns up.

Ok after a good ammount of research here and elsewhere, I'm about certian it's a 2 series. Now if I understand it corectly, the 2 series has a 1 13/16 thick plate where the ring gear goes. And the 3 series is like 2 1/8 I think. Has there ever been any talk of adding a spacer to a 2 series to fit a 3 series gear?

Yeah ,it can be done bit it's not usually recommended by many -me included.

Ok just curious. I think I'll stick with the 2.73:).

Tim

Ring gear spacers are trouble. I can send you pictures of broken parts caused by ring gear spacers. The thickness of the ring gear flange is about the same on the 2,3 and 4 series differentials. The location of the flange is where the difference is.

Ok good info. Btw, someone here asked the length of the rear end. He measured it to be approx 55.5". This sound right?

Tim

yes it will work. since it is a '68 it has the longer axles just like you 69. not a bad price imho.....

What is the over all width? The '65 to '67 12 bolt is 60 inches and the '68 to '72 12 bolt is 61 inches.

60 from where? The axle or the very end of the housing?

Tim

Where the wheels bolt on.

Well from where the wheel bolts on, which I assume you mean the wheel studs? I got around 62" roughly.

Yeah ,depending on how/where you measure ,you can get different results.
Same goes with the source of info ,some sites show different widths than others.
http://carnut.com/specs/frear.html
http://www.chevellestuff.com/tech/rear_end_widths.htm

Your's is still a 68.

Measure to the outer brake drum surface, where the wheel mates to the drum. Not to the ends of the studs. This will be 60 inches for '65 to '67 and 61 inches for '68 to '72.

Oh, ok. I dont have the drums on there now. Just the drum "back plate" for lack of a better term. Ill see if I can put them on and measure.

Tim

ok, measured 61" exactly. And the NF number is 3917124. Must be a 68 for sure.

Well ,according to the casting date you posted previously it is.

Well its interesting. I just did a search on here and found the difference in the 939 and the 124. I found the number 939 stamped in the inside of the case, but that must have just been random numbers or whatever. The actual casting number is the 124 which is the long (late) version of the 67 and used in some 68's as well according to what was posted. And the 939 was the early 67 (short version), 60". Mine was born May of 68, so it makes sense. I THINK I have it figured out now, and everything checks out. I appreciate everyones info. Please correct me if Ive got something wrong!

Tim

Hey guys, did some research on the 3.08 for the 2 series. Granted that gear is no longer avaliable, aparentely according to a shop, it used to be and can still be found in some rear ends. It is a thicker ring gear. Has anyone heard of this?

Tim

I've been building rear ends for about 27 years and I've never seen one.

Hmm. Ok. I'm gettin mixed info.

Thanks

Tim

Hey guys. Update, I have the rear end, and as you guys know I was looking for possible ways to put a 3.08 gear in this 2 series carrier. And let me first say that I am more inclined to believe you guys, the techs, the catalogs ect. when you say that there is no 3.08 gear for the 2 series eaton. But the guy that I bought the rear from, now says that he found a 3.08 gear out of a 68 12 bolt open rear, and says that it will fit. He has been building rears for years, so I wanted to at least look at the gear set he proposes to fit. But how could I really tell if the gear fit my rear end? He says the gear is curently on a 2 series carrier, same year rear ect. Im guessing the gear would be thicker? I hate to beat a dead horse, but he insists that hes got the gear set and it fits ect ect. I just think that if he did, and it does exist, someone on here would have heard of it. In any case, I think Ill go look at it. Cant hurt. I shall report back.

Tim

It probably has a spacer on it. If it has a spacer then I would pass. The spacers just cause trouble. There isn't much difference between a 2.73 and a 3.08 anyway.

Get the number off it.

Get the number off it.

Will do. Would it be located on the ring, pinion or both?

Tim

Depends on MFG but usually on both.
The #'s off the ring gear should do.

Ok, Ill get that from him before I go out there. BTW, is there a link or the like to a blown up pic of an Eaton carrier? I didnt install the right side axle, and was turning the pinion with the rear cover off so I could watch the gears go round n round:). Well when I did that, something like a cup washer fell out. Think it came from a spider gear?

Tim

Pardon the thread drift, but this thread addressed something I have been hoping would work.

I have a '69 Chevelle with an 8.2" 10 bolt and am in search of a new posi diff. Other than being approx 1 inch narrower, is there any other difference between a '67 and a '69 rear end?

My current wheel/tire combo rubs on my fender lip and I would like to add rear discs which would push them out even further. An extra 1/2 inch on either side would solve my problem.

Suggestions?

There is a thrust washer behind both of the pinion gears in the Eaton Posi. These washers fall out easily when the cross shaft is removed. Be sure that there is a washer behind both pinion gears. If one is missing then you are taking a chance of ruining the case or breaking the gears. The washer can be a pain to get back in place sometimes, but it will go back in if you get it in the right position.

Your call but you'll probably want to go to a 3 or 4 series carrier for a better gear than 2.73.
So add in a gear set and a posi carrier to your expenses.
Check with Freddie or Tom for prices.

Is Freddie or Tom out there? I found out that I have not a 2.73 gear but a 2.56! Counted 41/16. So that being said, I am in the market for either a 2.73 ring and pinion for a 2 series or a deal on a 3 series carrier and a 3.08 gear set.

Tim

I'm pretty sure that I have at least one 2.73.

Can you pm me and let me know what the price is?


Thanks,

Tim

I'll try to remember to look for it when I get back to the shop. There is a good chance that I'll forget, so sen me a reminder. biggearhead@bellsouth.net

Another quick question. I know this is a 68 rear, but someone welded on plates where the spring cups used to be. What is the best way of securing the rear spring to the plate?

TIM

Tim see if you can find the clamp and bolt set up off a 66. Most of the vendors sell them.