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Old 03-26-2007, 10:04 AM   #1
kev82vette
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rear end upgrades

I have a 82' and i was wondering what could be done to this rear end to make sure it will stand up to about 450-500hp. I will running a automatic but I love to do burnouts.
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Old 03-26-2007, 10:57 AM   #2
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Best thing you could do is have a ford 9in modified to go in. There are companies that do this to install them in race cars, and even to stuff them into a Jag multi link for Cobras.

The aluminum case is the weak part of the diff. No matter what gears you have, axles, or clutches, or posi unit...if it grenades, it is done, at $1200.00 a whack. (899.99 from mid america, +300.00 core +shipping)

The internals can be strengthened, but the weak link will always be the case...something lets go in there she, is DONE.

A few of my friends have been through this, with high horsepower (and abusive stuntwork, lol) They tried a multitude of things, but in the end, until they replaced it with a Strange, or a drag prepped 9 in....same result...as the Germans would say...KAPUT. (then Cha-ching at a Corvette supplier.)
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Old 03-27-2007, 05:43 PM   #3
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You could convert to an iron unit that is built much stronger with some mods it will handle it. I build the iron units but won't touch a 80-82.
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Old 03-27-2007, 08:00 PM   #4
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Are the older rears any stronger? can something be swapped in there?
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Old 03-28-2007, 04:57 PM   #5
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The older unit are a lot better then the 80-82's. They can be built several ways to add strength to them, I do custom builds a lot and can offer you some pointers on what to look for.

Here is a custom job I did. Those of you familar with these will notice there are no springs in the posi. Also the case is radiused and polished to cut down on stress risers.

You can convert to these but you'll have to get the bracket for the front.

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Old 03-28-2007, 06:30 PM   #6
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you could try these guys, it says that they only do up to '79, but i bet they could do yours too http://www.hotrod.com/techarticles/1...dup/index.html
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Old 03-29-2007, 07:49 PM   #7
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you could try these guys, it says that they only do up to '79, but i bet they could do yours too http://www.hotrod.com/techarticles/1...dup/index.html
I checked out the sight and they didn't list the changeover kit..so this would have to be custom..unless they still sell it but don't lidst it.
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Old 03-29-2007, 07:58 PM   #8
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Quote:
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Are the older rears any stronger? can something be swapped in there?
The iron units are much stronger than the Dana44. It will bolt right up to the aluminum batwing with very little modification.
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Old 03-31-2007, 11:16 AM   #9
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The iron units are much stronger than the Dana44. It will bolt right up to the aluminum batwing with very little modification.
VanSteel, in Clearwater, Fl., performs this swap-over, and will 'back-date' my '82 Dana-44 IRS for bracket-racing in the next year:
here are pictures of their work -


http://www.vansteel.com/photos/index...Thumbs&e=4&s=1
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Old 03-31-2007, 06:36 PM   #10
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There ya go. Dana 44 won't handle over say 350HP.
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Old 03-31-2007, 07:20 PM   #11
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Now, when did they stop putting in the old iron?? I have a 75. Does that have the good case or the weak case?
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Old 03-31-2007, 07:58 PM   #12
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Now, when did they stop putting in the old iron?? I have a 75. Does that have the good case or the weak case?
I understand that iron thru and including '79 (minor-differences thru the years, but basically the same ), with aluminum Dana-44 '80-'82.

The guy who installed the 3.73s in my Dana-44 a few years ago, who has lotsa experience with C3s and drag-cars, suggested not putting even sticky tires on the back of my '82, even-with the wimpy Cross-Fire, he was so scared of it:
VanSteel claims their back-dated/Dana-44 set-up is good to 650 HP with slicks, more-than-enough for my application.


Now..... if somebody would only make a spool for these cars.....

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Old 04-01-2007, 09:48 AM   #13
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63-79's used iron units. The 63&64 used a dana posi and they were weak. Most by now have been replaced with a Eaton. 65-79's used Eaton posi's.
Posi became std in 70 and there were some open diff in the earlier models. The 65-70 posi clutches were solid steel and the 71-79 were slotted clutches to try and resolve the common hammering they have. This didn't work and the clutches break under constant load.
The 65-69 cases were prone to cracking and breaking apart,again under load. The later 70-79 cases are much better as are the service cases. The current 63-79 eaton loaded cases come with heavier springs, fiber clutches, and powdered gears. Other then the bare case they are not what I'd use.
The best built 63-79 unit is a custom built one using the best parts, that is what I do. Steel bearing caps and solid sleeves can be fit to them to increase the strength as well. There is no way a $600 advertised job will have these features so do some research if anyone is looking to exchange, you may not get what you expect for the much lower cost.
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Old 04-01-2007, 01:47 PM   #14
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I can do this stuff myself...for the most part.. So what you are saying..I keep my case then what? trim it out and put the 12 bolt gears in like the custom job from the mag article? or keep my gears and just upgrade the carrier to a quality built posi-trac unit and put in steel end caps.
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Old 04-01-2007, 02:42 PM   #15
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Quote:
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I can do this stuff myself...for the most part.. So what you are saying..I keep my case then what? trim it out and put the 12 bolt gears in like the custom job from the mag article? or keep my gears and just upgrade the carrier to a quality built posi-trac unit and put in steel end caps.
How much power are you thinking of ? If you build one like the one I pictured, it will be pretty strong. It will be better then any stock rebuild for sure. Will it handle a lot of trips on the track with slicks-??? Hard to answer. The 12 bolt setup that Tom's builds is about the best vette diff out there. The one I pictured is still a 10 bolt but is a pretty good one.

I stock all the parts if you need them, just PM me. To build one you're going to need access to a surface grinder.

Last edited by gtr1999; 04-01-2007 at 06:21 PM.
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