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Re: Rear End Upgrade

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fasterthanu

Guest
Re: Rear End Upgrade

I have a 76 vette, with a 3.08 rear end. To my surprise, I didn't know that it came with positraction =) Have any of you done a rear end swap? Now, since it has positraction, I can still just buy the ring and pinion gear corrcect, and put it in and it will still stay posi? It it a rough job? Anyone go from a 3.08 gear up to a 3.73, or even 4.11? Big difference? I have dual quads, full race cam, high reving lifters, hooker super competition headers/sidepipes, and a newly upgraded 700R4 trans =) So, even with 4.11, will be okay on expressway =) Anyone upgrade from 3.08 to 3.73, or 4.11 with 700r4 trans? My cam kicks in at about 3200rpm, so I am sure I am losing alot because I am not getting rpms up quickly enough....
 

a69vette

Well-known member
Joined
Jun 20, 2001
Messages
264
Location
Valrico, Fl.
Corvette
1969 Triple Black Convertible: 2014 Crys Red Conv
I've made the change. But I went the other way. The car came with a 4.11 from the factory with the M21 transmission. At 3500 rpm I'd be going a little less than 70mph. My change was a little different than what you are wanting to do. I change the entire rear end. I now have a numbers matching 3.36 rear end. At 3500rpm I'm going about 85 mph. WOW, what a difference for me. The 350 hp is put to good use. There is a link in the "tools" section of the website here that can calculate what all your changes would be. Check it out. Good luck in what you decide to do. I've enjoyed my change.

Rick
 

barrier5

Well-known member
Joined
Dec 27, 2001
Messages
126
Location
janesville wi usa
Corvette
1982 bright blue coupe
I'll be able to tell you next week,have a 3.73 going in monday.I'm having a complete carrier installed,was going to do it myself but got a really good price on installation so I'm having it done.From what I hear,it's not like setting up a 10 or 12 bolt.Besides having a 2.72 gear ratio the carrier wouldn't work with the 3.73s
 
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hotrodd

Guest
I used a 2.72 carrier to change to 3.73.With a 700R4 that turned out sweet.2250 R.P.M. at about 75 MPH. Good gear for my cam comes in at 2500. really woke old sparky up!
 
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Dave L.

Guest
If you go to 4:11,you would have to also change the carrier{what the ring gear bolts to}Probably your best bet is to change out the whole carrier and pinion assy. Checkout > www.ikerds.com
 
B

Big Fish

Guest
I'm with you in not wanting to do the rear end yourself. These things are best left to the pro's who have the right tools and experience to properly shim them. There is a guy in Beloit Wisconsin who re-did my 3:08 to a 3:55. Can't tell you how it worked out yet, still working on the frame off restoration, but this is all the guy does is vette rear ends, and he actually did mine cheaper than I could buy the parts for. At my request he installed some good used parts. Check out his web site: http://corvetteperfection.com/corvetteperfection001.htm
 
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hotrodd

Guest
I just used a motive ring and pinion.I didn't have to space it,any lower and you have to.Hope that help's.
 

barrier5

Well-known member
Joined
Dec 27, 2001
Messages
126
Location
janesville wi usa
Corvette
1982 bright blue coupe
OK ,just got the car back,quite the difference with the 3.70 gears ( Richmond ) . Still need to get the speedo right but I figure 1700 at 55 now,was running about 1250 before.Will post more when I get the right speedo gear in.
 
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fasterthanu

Guest
cool, definently let me know. Hows she off the line? Big difference?
 

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