MY MECHANIC SAYS THE 9 BOLT REAREND ARE NO GOOD AND I SHOULD CHANGE IT TO 10 BOLT I HAVE 2;77 GEARS IWANT TO PUT THE 3'45 IN IT BUT HE SAYS I'LL BRAKE THE REAREND

 

Get a new mechanic. The BW 9-bolt is stronger than the F-body 10-bolt, the only disadvantage being less selection of gears with the 9-bolt. Mine is a 9-bolt, it's 3.23 or 3.27 (I can't ever remember). Several people have different gears in their 9-bolts, so someone should be able to tell you the ratios you can go with.

 

you might get a better reponse to this topic in the drivetrain forum

 

I second that Jethro... sounds like you need a new mechanic, along with a new "book". The 9 bolt is a lot better... also, check out your caps lock key, it can work miracles in keeping you from hollering on a message board. That can be annoying.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

 

The problem with 9 bolters is that there is limited gear availability and what is available is damn expensive. You have to ask your mechanic what he exactly meant.

If he meant availability and cost... he's right. As for strength the 9 bolter is the strongest of all three (but not much); none are any screaming hell. The later 7 5/8" 28 spline is the better of the two 10 bolters and not that bad.

For strength, you REALLY have to consider a completely different rear end...which is big bucks.

[This message has been edited by Glenn91L98GTA (edited March 13, 2001).]

 

Im sorry to tell you but you cant get new gears for the 3.23 and lower carrier. You will have to have a machine shop fab you a carrier which will be REAl expensive. Then you have to pay like $500 for the gears, the probably pay a good mechanic(with the proper tools to set up the rear end properly) about $150 to put it together. For that price you can get the 4th gen 10-bolt with disc brakes a lot cheaper that it cost to get the carrier and have a stronger rear. Plus the gears will be cheaper so you can get a new set of wheels to go along with it. Well maybey two cheap rims.
I have been on the hunt since 96 for 3.73 or 3.77 or any gear in that range for my TPI, but I gave up and just made the power in the engine haul *** with a 2.77 gear(which is the gear in the BW rears instead of 2.73)


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86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and added a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace added. Soon to have Intrax lowering springs.
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Kills:
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The Third Gen Will Never be Forgotten

 

3.27 and 3.45 9-bolt rear ends can step up to a 3.70 gear, available from a few US gear places. I've posted this several times in the Tranny/Drivetrain forum. The 2.77 rear end needs a new posi unit and gears if you want to change. They're not that expensive. If you have a friend in Australia, you can get them, as they're very common there.

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West Coast GM Shootout 2001!
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=-

 

9 bolt's and 10 bolt are pretty much the same in the strength department. If you want to step up to the pump and spend the money, call Strange and get their complete 12 bolt F-body rearend. It will save you money in the long run if you want to go any faster.

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92 Camaro Z28
350 TPI
Dart Iron Eagle heads
10.5:1 cr
Lunati L54779 cam
52mm throttle body
Ported plenum
Home made AFPR ($2)
1 5/8 shorty headers
Ram air
255 lph Holley fuel pump
2.5 inch TRUE DUAL exhaust (no cats)
Flowmaster mufflers
4.10 gears
700R4 w/2000 stall
100HP nitrous
Best time before any of these mods:
15.1 @ 91.9
Best time after mods:
12.60 @ 108.3
That is at high alt.
5600 feet Morrison, Colorado Bandimere Speedway

 

NUN,

If you have any significant torque, and a fairly heavy car that connects well, you really should take the advice of the few that have suggested the 12-bolt Saginaw or convert a Ford/Dana unit. It really isn't that difficult to install all the correct bracketry on an axle housing to mount in nearly any vehicle. I DO know that a 10-bolt doesn't hold up long in a 420+ HP truck, even with street tires.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
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