This is a continuation of a previous thread, but Tom Parsons gave me part of the info I needed to solve my problem with the rear gears. I have since found out that indeed I do have a 4-series carrier installed. Also the ring gear is 39 teeth with an 8 tooth pinion....a 4.88 gear ratio!!!!! Holy burn-out Batman, Bubba was a drag racer!!!! Anyway, Tom or anyone, my question is this...Can I use the existing gear case housing for a 3-series carrier and new ring and pinion gears? Any advice or help is appreciated. Also, are there any venders other than Summit or Jeg's that have good prices on gears and carriers?
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Re: Differential help needed...Tom Parsons?
If I were you, I'd keep my eyes open for a 3 series rear end and buy the whole rear. You don't say what rear gear you are fater, but if you watch, you can find what you need at a decent price.
You also don't say if the rear is original to your car, but I'm assuming not if the 4 series is too low for your car. Any rear from '63-'79 will work, however, the '78 and '79 used a smaller bolt to hold the spring. Be sure to get the rear complete and you can just bolt it in, saving a lot of time and expense. -
Re: Differential help needed...Tom Parsons?
Mark-----
In order to use a 4-series posi case with 3.70:1 or numerically lower gears you have to machine the flange on the posi case. I wouldn't do it. I'd either lookk for a 3 series case or just buy a complete used or rebuilt differential. The one you have may be acceptable as a core.In Appreciation of John HinckleyComment
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Re: Differential help needed...Tom Parsons?
AHHHHH!!!
Joe, here is one of the few places I'd ever disagree with you, but Mark, DO NOT turn in your 4 series case as a CORE.
That is like turning in a dated block as a core on a Pep Boys rebuilt 350.
The 4 series case is worth more than a core, and if it is a complete running rear end, which sounds like it is, then it is worth more than any 3 series rear end, and a lot more than many, like a 3.08 or a 3.36 rear.
If you look carefully, you can find a '63-'79 rear complete for around $300, give or take.
63-79 Corvette Rear End 3:36 ratioComment
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Re: Differential help needed...Tom Parsons?
Mike-----
Not quite. It USED to be that the 4 series carrier case was more valuable than the 3 series because the 4 series was discontinued by GM years ago and was, consequently, unavailable for many years while the 3 series was available for many years thereafter. However, a 4 series Eaton (and other) case can now be purchased through aftermarket channels.
In addition, the demand for 3 series cases is FAR greater than the demand for 4 series cases. That's why I used the word "MAY" in reference to the unit being acceptable as a core. Many rebuilders will not accept a differential unit with 4.11:1 or numerically higher gears as a core for a 3.70:1 or lower numerical unit.
A rebuilt differential assembly with 3.70:1 or numerically lower gears is going to cost about $550 WITH a $300 core charge. Paying that core charge rather than giving up one's 4 series unit (assuming that the rebuilder would even accept the 4 series as a core) would be, indeed, a foolish thing to do. There's no way that the used 4 series posi case is worth that much.In Appreciation of John HinckleyComment
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I've bought several for under$100
I've bought several mid to late 1970's rears with 3.08 and 3.36 gears for under $100 on e-bay (you just have to wait for a month or two for an auction with no activity) the shipping was about $50.
Good luck,
MarkComment
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Re: Differential help needed...Tom Parsons?
Mike,
He can't use a 63-79 rear----------------he has a 59 or 60.Comment
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Re: Differential help needed...Tom Parsons?
Mark,
Yes, you can use the same case to install a 3 series posi carrier into. They are all the same up to 62 for Vettes and 64 for passenger cars (and 62-63 Chevy II). The earlier advice about just keeping the 4.88 setup that you have and looking for a 3 series complete center section is good. BUUUUUUUUUUUUT, for the 57-62 posi rears, the days of a good deal for these early style posi rears are pretty much gone.
If your case IS NOT the original (or at least not a good corrosponding dated case) one for your car, then I'd give SERIOUS consideration to searching around for some 60-64 passenger cars with a good rear. VERY PROBABLY, the 62-64 plain ole 4dr passenger cars will likely have a GOOD rear that is either 3.08 or 3.36. Then, as I mentioned earlier, I'd buy one of the new Eaton style posi units for early Chevys/Vettes, and you'll end up with a very nice posi rear. I wouldn't get concerned about your rear not having an original DANA built posi unit because it can never been seen once it is installed.Comment
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That is a whole new situation having a C1
I guess I missed that piece of information.
Now if he had that 4.88 in a black '61, I'd be interested in talking to him as a friend used to have one that way, but if I remember right, it was a Camaro rear and definitely not a Corvette rear.Comment
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Re: Differential help needed...Tom Parsons?
Tom, I think that your suggestion is a good one. The case is not original to the 59, but is casting #3743833 which is period correct. The stamp markings on the right flange is AM 1024 and the casting date of manufacture is J187 with a thick "P" cast next to it. It's a passenger car rear with posi, most likely out of a 57 Chevy BelAir with a 2.83. I think I will keep shopping to see if I can find a 3-series posi with 3-series gears to install in that case. I really don't want to spend roughly $600 for new parts when I can probably buy a good used carrier and gears or gears and posi unit only for $300 or less. Worst case scenario?.....I re-install the 4.88's and live with it until the money tree I planted last year matures!!Comment
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Re: Differential help needed...Tom Parsons?
Mark,
I know that it is NICE to have a posi case with the big P cast on it, BUT personally, I could give a flip less about that P. I prefer to just have the posi and that makes me happy. If you were fortunate enough to locate a cheap pass car rear (up to 64) with 3 series gears of your liking, and then added one of the new Eaton posi units, you wouldn't be spending $600 (unless of course you had it totally rebuilt with all new parts).Comment
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Apples and Oranges
I believe the man is talking about a C1 rear end not a C2!
TerryComment
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So we heard 3 hrs after I posted - sorry! *NM*
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Differential help needed...Let's try again - C1
Now that we know it is a C1, have you looked on eBay as usual?
Here is an early pumpkin with a 3.70 gear.
Here's another:
And another:
And a real "cheap" 4 series with a 4.11 gear:
Now if you want a non-Posi 3.36 gear:
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Re: Differential help needed...Let's try again - C
Mike, thanks for the websites. I have already added two of those ebay sites to my Ebay Watched Items page. I do have a 4.88/1 rear end with a 4-series carrier. Although the enjoyment of laying long black stripes would be fun, my wife will get real tired, real quick with my antics. Anyway, I'm going to keep watching out for a 3.73 or lower unit with or without posi. At the very least, I could transfer the existing rear end gear case and gears into my new axle housing. It's period correct, but not correct for the car. Thanks for your help.Comment
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