I have an 88 IROC b2l with the 9 bolt rear. It's getting tired and needs some serious help. Would it be better to trade it and the 2.77 for a 10 bolt from an 84 TA with 3.23? Both are rear disc.

 

The 9 bolt is a stronger rearend than the 10 bolt. The parts are usually cheaper and more plentiful for the 10 bolt, but I would stick with the 9 bolt.JMHO

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82 Z28 350, Ported #882 Heads, Performer RPM cam and intake, hedman headers,650 Demon carb,
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Future plans: Dart headed, Roller cammed 383 in early '01


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock http://www.bassettracing.cz28.com

[This message has been edited by Basett Racing (edited December 26, 2000).]

 

thanks for the help basset. one more question though. who sells a lower rear gear for the 9 bolt. i'd like to go for a 3.55 to 3.73 since this thing is a daily driver, about 60+ miles per day.

 

Lowest gears available for the 9 bolt are 3.70's and they won't fit on your 2.77 carrier. You need a 9 bolt with 3.27 or 3.42(3.45?) gears to install the 3.70 gears. The gears are also getting hard, not impossible, to find and are ezpensive.

The 9 bolt is a better and stronger diff but the 10 bolt has much more available to build it up. You can build a 10 bolt to be stronger than a 9 bolt.

Sorry I can't remember Dan's Ultimate 10 bolt buildup page at the moment.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
454 Big Block buildup now in progress for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857 altitude corrected to 11.163
Best MPH on a time slip: 117.87 altitude corrected to 126.10
Altitude corrected rear wheel HP based on power to weight ratio: 476.5
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

Dan's 10-bolt buildup page is linked in the tech articles on this site.

A 2.77 9-bolt rear end is basically a paper weight. Nobody makes gears for it, and replacement posi's are non-existant. You're better off replacing it with a 10-bolt, unless you're lucky like me and find a 3.45 and a 3.70 9-bolt. 82-88 have the same rear disc brakes, and are 26 splines, so its a direct swap. 89-92 have larger rear brakes and 28 spline axles.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

these rears must be pretty strong because this thing saw numerous nitrous passes by the previous owner, running 7.40s in the 8th mile. yeah it was a big kit, 225hp i think. thats why i have it now. that much juice with stock pistons and crank left it floating upside down. anyways, i found the 10 bolt 3.23 rear disc rear at a local junkyard for 200 bucks! and can get a 3.73 centersection for it for a little more. sounds like this is probably the best route. thanks

 

7.40's on a 9 bolt? Damn.
Are you sure it isn't a Ford 9" ?

 

1/8th mile, Not 1/4

I thought the Same thing.

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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

My best 1/8 mile when I still used 3.27 geared 9 bolt was 7.601

 

I traded my '82 10 bolt, in favor of an '89 9 bolt. I think it's the best. Ofcourse, it has discs and posi, and the ten bolt had neither. But the only problem I had, was the brake lines are metric. So I got adapters, and ran new lines. I love it, and recomend it to anyone.

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'82 Firebird, dead stock, 9 bolt disc rear, over 200,000 miles and still going strong, more to come...