Transmissions and Drivetrain Need help with your trans? Problems with your axle?

Just swapped rears and I am not happy.....

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Old 09-04-2006, 08:48 PM
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Car: 1985 IROC / 1986 SC
Engine: 305 TPI / 2.8 MFI
Transmission: 700R4's
Axle/Gears: 3.27 Posi / 3.42 Open
Just swapped rears and I am not happy.....

I spent all weekend swapping out my old 10 bolt open rear for a 9 bolt 3.27 posi. It was a HUGE pain in the *** but I got it done. Before, from a dead stop, I could fry the passenger tire at will and had NO traction, now I can hardly break them free and it seems like I have excellent traction. My problem is that when I power brake and do a burnout it only leaves one tire mark, the passenger side. I tried to do a donut but couldnt get it to do it. The rear was bought used and it seemed nice and tight, everything looked good and checked out fine. I opened my door and watched during a burnout and it looks like the driver side tire is trying to turn, but just isnt. But like I said, when I do take off hard, my traction is much better than before. Is the posi unit just worn out and working, but not at full strength?
Old 09-04-2006, 08:53 PM
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Car: 89 RS
Engine: 305
Transmission: th350
Sounds like a worn out posi.
Old 09-04-2006, 09:25 PM
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Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
sounds like you should swap the gear lube first and see if that helps or not. otherwise you'll need the posi cones shimmed to get the posi to work again. what was your old gear ratio? 3.42/3.73? ??
Old 09-04-2006, 09:25 PM
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Car: Trans-am
Engine: LT1
I just got a nine bolt 3.27 rearend but need to know for sure if a posi.
could you look at by post label "please please look at my pig " and tell if this is a posi. there picture of it thanks
Old 09-04-2006, 09:30 PM
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Car: 1985 IROC / 1986 SC
Engine: 305 TPI / 2.8 MFI
Transmission: 700R4's
Axle/Gears: 3.27 Posi / 3.42 Open
Originally Posted by xpndbl3
sounds like you should swap the gear lube first and see if that helps or not. otherwise you'll need the posi cones shimmed to get the posi to work again. what was your old gear ratio? 3.42/3.73? ??
Old ratio was 3.42. I did NOT add posi additive as everyone says not to with the cone type posi. Gear lube was replaced and new gasket was installed (still available at GM contrary to what some people say). I definately have better traction, just seems weird that it is only leaving one strip of rubber.
Old 09-04-2006, 09:33 PM
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Car: 1984 Z28
Engine: SLOW carbed ls
Transmission: TH400 with brake, 8" PTC converter
Axle/Gears: moser 9" 4.11
you'd need the posi re-shimmed. and your lack of launching is due to the drop in gear ratio from 3.42 to 3.27 gears. There are articles you can search for to learn how to shim the posi or have some shop do it for you.
Old 09-04-2006, 10:01 PM
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ALL friction based posi's, including the cone type, should have posi additive in them.
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