Rear end rebuild - Pontiac GTO Forum
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post #1 of 24 (permalink) Old 11-07-2011, 07:49 PM Thread Starter
 
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Rear end rebuild

I am in the process of restoring my 67 GTO. I have had the engine rebuilt, the car painted, and the interior done. I need to focus now on the rear end and suspension/ brakes. I am thinking of starting with the rear end. Should I rebuild the original dif or by a new one? I am working with a limited budget and am trying not to piss off the wife anymore than I already have.

My engine has a somewhat aggressive cam,
Gross Valve Lift
.488 Intake, .491 Exhaust
Duration @ .006 Tappet Lift 274 intake 286 exhaust

I have a 2400 RPM Stall torque converter, Headers, MSD ignition, Turbo 400 and Automatic trans.

I am looking for a powerful street car. I am mostly driving around normal. Not street racing or anything. What gears would you suggest and what posi would you go with.

Check out the link below for progress.

Thanks

Picasa Web Albums - Kevin Kaney - 67 Cabra
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post #2 of 24 (permalink) Old 11-07-2011, 08:19 PM
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What's wrong with the differential in the car? Many of these units go for 100's of thousands of miles without issue with preventive maintenance: change the lube every now and then and check the rear axle bearings. A good performance gear ratio for the street is what your GTO probably came with : 3:36. That was the standard ratio for TH400 GTO's in '67.
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post #3 of 24 (permalink) Old 11-07-2011, 09:19 PM
 
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Shane Doss

66 tempest
64 el camino
02 mullis dragster
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post #4 of 24 (permalink) Old 11-08-2011, 08:41 AM
 
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or go to a 3.55:1 for a little more "off the line" with that cam.....



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post #5 of 24 (permalink) Old 11-08-2011, 08:01 PM Thread Starter
 
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No Safty trak. I spin the right rear tire for days. Really thats the only reason. But while It's open I figured thats a good time to make any needed changes.
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post #6 of 24 (permalink) Old 11-09-2011, 03:52 PM
 
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add a posi carrier once you check the gear ratio.
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post #7 of 24 (permalink) Old 11-09-2011, 03:55 PM
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You may have a Safe-t-track, just a worn out cone clutch. They can be rebuilt. What I'd do: pull the cover and inspect it. If it is an open rear end, and you like the gear ratio, you can get any number of good posi units brand new that will "bolt in" to your unit. Have a reputable shop do it if you're not feeling confident about it, though. It HAS to be "right". As for new inner bearings, if quiet, I'd leave them alone. They can last forever, nearly, and are bound to be better than brand new Chinese replacements.
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post #8 of 24 (permalink) Old 11-15-2011, 10:38 PM
 
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I have an auburn in mine and with 500+ HP, it still lives.
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post #9 of 24 (permalink) Old 11-15-2011, 11:07 PM
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If your rear is otherwise good and has the ratio you want, then the quick path would be to just install an aftermarket diff unit (like the Auburn).

Even if you want to change ratios and need to buy gears, you'll likely spend less money going that route.

Bear

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post #10 of 24 (permalink) Old 11-17-2011, 09:09 PM
 
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I had my mechanic rebuild the rear a couple years ago...it spun a wheel like yours...new bearings... cleaned up & painted...plus an Auburn unit. Works great!
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Undercarriage, Frame, Transmission and Differential Discussions.

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