What cars came with a factory posi?
10-19-2008, 09:06 PM
#1
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Car: 1991 Camaro RS
Engine: 454
Axle/Gears: 2.73 open
What cars came with a factory posi?
I am trying to find a cheaper alternative to a 4th gen rear end swap. I don't know how to install a posi so I'm wondering if I can go junkyard diving for a 3rd gen with 3.08s and a posi.
Car has a 454 low comp engine with a very mild cam and roller rockers, TH400 or 350 and 2.73 open rear
Car has a 454 low comp engine with a very mild cam and roller rockers, TH400 or 350 and 2.73 open rear
10-20-2008, 10:55 AM
#2
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Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: What cars came with a factory posi?
Very few, if any, came with 3.08:1 and a posi. Have you considered spending $400 for a conversion locker? With those, you don't affect your backlash or anything of the ring and pinion, you just replace the spider gears.
If you're willing to use 3.23:1 or 3.27:1 gears, those are far more common with posi. Avoid any pre-87 axle. The '87 350 cars came with the Warner 9-bolt and 3.27:1 posi. Same in '88, 89 and 90. The '91s were back to the ten bolt, with 3.23:1.
For '85 the ten bolt went from 7.5 to 7.625" ring gear, and mid '89 saw 28-spline axles replace the 26 spline in earlier 10 bolts.
finding a 2.73:1 posi is also really rare. But be aware that using a 225/70R15 tire with a 3.23:1 gear gives the exact same results as a 215/65R15 with a 3.08:1 gear, so you might be okay on a 255/60R15 tire if you're on 15s, and www.tirerack.com can hook you up with some 255/55R16s if you're on 16s. If you have 17s you can run a 255/50, and you should see the trend. Also, If you have 18s that are wide enough you can use 285/40s.
If you're willing to use 3.23:1 or 3.27:1 gears, those are far more common with posi. Avoid any pre-87 axle. The '87 350 cars came with the Warner 9-bolt and 3.27:1 posi. Same in '88, 89 and 90. The '91s were back to the ten bolt, with 3.23:1.
For '85 the ten bolt went from 7.5 to 7.625" ring gear, and mid '89 saw 28-spline axles replace the 26 spline in earlier 10 bolts.
finding a 2.73:1 posi is also really rare. But be aware that using a 225/70R15 tire with a 3.23:1 gear gives the exact same results as a 215/65R15 with a 3.08:1 gear, so you might be okay on a 255/60R15 tire if you're on 15s, and www.tirerack.com can hook you up with some 255/55R16s if you're on 16s. If you have 17s you can run a 255/50, and you should see the trend. Also, If you have 18s that are wide enough you can use 285/40s.
10-20-2008, 11:01 AM
#3
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Car: seeking '90.5-'92 'bird hardtop
Engine: several
Transmission: none
Axle/Gears: none
Re: What cars came with a factory posi?
Hey, look a few threads down. 89ROC-Z claims his '89 IROC has a 3.08:1 posi and he's looking for a deeper-geared rear.
10-20-2008, 07:10 PM
#4
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Car: 1991 Camaro RS
Engine: 454
Axle/Gears: 2.73 open
Re: What cars came with a factory posi?
Very few, if any, came with 3.08:1 and a posi. Have you considered spending $400 for a conversion locker? With those, you don't affect your backlash or anything of the ring and pinion, you just replace the spider gears.
If you're willing to use 3.23:1 or 3.27:1 gears, those are far more common with posi. Avoid any pre-87 axle. The '87 350 cars came with the Warner 9-bolt and 3.27:1 posi. Same in '88, 89 and 90. The '91s were back to the ten bolt, with 3.23:1.
For '85 the ten bolt went from 7.5 to 7.625" ring gear, and mid '89 saw 28-spline axles replace the 26 spline in earlier 10 bolts.
finding a 2.73:1 posi is also really rare. But be aware that using a 225/70R15 tire with a 3.23:1 gear gives the exact same results as a 215/65R15 with a 3.08:1 gear, so you might be okay on a 255/60R15 tire if you're on 15s, and www.tirerack.com can hook you up with some 255/55R16s if you're on 16s. If you have 17s you can run a 255/50, and you should see the trend. Also, If you have 18s that are wide enough you can use 285/40s.
If you're willing to use 3.23:1 or 3.27:1 gears, those are far more common with posi. Avoid any pre-87 axle. The '87 350 cars came with the Warner 9-bolt and 3.27:1 posi. Same in '88, 89 and 90. The '91s were back to the ten bolt, with 3.23:1.
For '85 the ten bolt went from 7.5 to 7.625" ring gear, and mid '89 saw 28-spline axles replace the 26 spline in earlier 10 bolts.
finding a 2.73:1 posi is also really rare. But be aware that using a 225/70R15 tire with a 3.23:1 gear gives the exact same results as a 215/65R15 with a 3.08:1 gear, so you might be okay on a 255/60R15 tire if you're on 15s, and www.tirerack.com can hook you up with some 255/55R16s if you're on 16s. If you have 17s you can run a 255/50, and you should see the trend. Also, If you have 18s that are wide enough you can use 285/40s.
I am dead set on better gears and a posi, I just want to get them by swapping a whole rear end. Thanks for all the information, I now know what to look for.
10-20-2008, 08:55 PM
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Car: 1991 RS Vert
Engine: LO3, 305, TBI
Transmission: 700R4
Axle/Gears: 3.42
Re: What cars came with a factory posi?
I got a set of these from the same seller on EBAY:
http://cgi.ebay.com/ebaymotors/10-bo...mZ280277049558
I paid $200 to get it/them installed. Plus, about $100 for a complete install kit from Summit/Jegs.
I suppose you can save a few bucks getting a swap from the JY, but I have a nice new rear end with all new seals and bearings. I'm happy with it.
http://cgi.ebay.com/ebaymotors/10-bo...mZ280277049558
I paid $200 to get it/them installed. Plus, about $100 for a complete install kit from Summit/Jegs.
I suppose you can save a few bucks getting a swap from the JY, but I have a nice new rear end with all new seals and bearings. I'm happy with it.
10-20-2008, 08:58 PM
#6
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Car: 1991 Camaro RS
Engine: 454
Axle/Gears: 2.73 open
Re: What cars came with a factory posi?
I got a set of these from the same seller on EBAY:
http://cgi.ebay.com/ebaymotors/10-bo...mZ280277049558
I paid $200 to get it/them installed. Plus, about $100 for a complete install kit from Summit/Jegs.
I suppose you can save a few bucks getting a swap from the JY, but I have a nice new rear end with all new seals and bearings. I'm happy with it.
http://cgi.ebay.com/ebaymotors/10-bo...mZ280277049558
I paid $200 to get it/them installed. Plus, about $100 for a complete install kit from Summit/Jegs.
I suppose you can save a few bucks getting a swap from the JY, but I have a nice new rear end with all new seals and bearings. I'm happy with it.
10-21-2008, 05:40 AM
#7
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Car: 1987 Firebird Formula
Engine: 2004 LQ4
Transmission: T-5 WC
Axle/Gears: 3.42
Re: What cars came with a factory posi?
I've got a 3.27 10 bolt. Man is that thing ever tight.. Took 2 of us to turn it straight to get it into the car..
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