what rear gear should i run.. - Pontiac GTO Forum
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post #1 of 12 (permalink) Old 08-27-2012, 11:27 PM Thread Starter
 
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what rear gear should i run..

i have a 455/462 i am gettin ready to put in my 71 gto. Im trying to decide what kind of gear to run. Was thinking 3.73's. I am going to be street/stripping the car and will not be doing long distance runs all that much if at all. Let me know your input and experiences please I am surrounded by chevy guys haha
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post #2 of 12 (permalink) Old 08-27-2012, 11:36 PM
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Which rear end are you using? Type-C 12 bolt or a BOP 10 bolt? What are your current gears? Automatic or 4-speed?

Randy


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post #3 of 12 (permalink) Old 08-27-2012, 11:43 PM Thread Starter
 
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the car currently has an open 10 bolt 8.2 bop but i am open to ideas
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post #4 of 12 (permalink) Old 08-28-2012, 12:18 AM
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Find a Chevelle 12 bolt with 3:73 gears, the carrier breaks on BOP rear ends are 2.76 & down / 2.94 to 3.23 / 3.31 & up, what are your current gears?

Randy


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post #5 of 12 (permalink) Old 08-28-2012, 12:35 AM Thread Starter
 
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I believe 3.23s. Will 3.73s work well with the motor? Performance wise. I will be running a 400 tranny
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post #6 of 12 (permalink) Old 08-28-2012, 10:17 AM
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Performance-wise, 3.23's are a much better gear for a 455 than 3.73's. Much better. If you had a small block Chevy 327, then the 3.73 would be the gear of choice. A short gear with a 455 will limit its performance potential quite a bit without an up-side. Stick with the gears you have and add a limited slip.
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post #7 of 12 (permalink) Old 08-30-2012, 03:52 PM
 
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gears

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Originally Posted by geeteeohguy View Post
Performance-wise, 3.23's are a much better gear for a 455 than 3.73's. Much better. If you had a small block Chevy 327, then the 3.73 would be the gear of choice. A short gear with a 455 will limit its performance potential quite a bit without an up-side. Stick with the gears you have and add a limited slip.

really ...I would think 3:23 would be to high for a street /strip car ...more like a highway cruiser ... get all your ducks in a row ( tire size..what rpm you figure to run in the traps ..1/8 or 1/4 mile track.. what converter stall you have) then you can find info on line to figure your gear but in my experience you need a lower gear than 3:23's for you big block... small block Chevy's need gears in the 4's to wind them up had quite a few over the years ..just my 2cents
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post #8 of 12 (permalink) Old 08-30-2012, 07:11 PM
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Garage
For a street car you want a gear that provides cruising at aprox the torque peak (around 1500-2500) for a drag car you want a gear that gives you max rpm just as you cross the quarter mile.

You will need to estimate your MPH through the traps and then calculate the rpm to choose the gear ratio. More than likely you will want a compromise between the two.

Other variable include what converter you are running and the tire hieght. You can run a tall tire on the street and a shorter slick or drag type tire for the track to adjust your gear ratio slightly. I used to have a 65 Satelite that I ran a reletively short 14" rim and radial tire on the street and it would run, took it to the track and bolted on a set of 29" tall slicks and it just killed it. You can do the opposite.

I vote 3:55's for decent highway cruising and decent launch at the track.
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post #9 of 12 (permalink) Old 08-30-2012, 11:47 PM
 
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455 Poncho pulls 500 Ft Lbs of torque stock! But you cant' pull a ton of RPM out of a stock motor. So, lower gear because it pulls power right away, heads flow like no ones business. BOP all make torque, and Cadi. Can't build a BOP C like a Chevy/Ford, just doesn't work.

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post #10 of 12 (permalink) Old 08-31-2012, 10:17 AM
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Check out the performance years forum on gearing. A lot of info. Depends on the car and combo, what type of driving you plan on doing, and how much driving. The data pretty much shows that a big journal motor does not like being buzzed at over 3,000 rpm all day long, and that a 455 can hook up better and cut a better ET with a taller gear. Pontiacs are not Chevrolets, and don't need to be geared like one to perform. I have to respectfully disagree with ALKY, who I respect fully on the 3.55's: they are a great cruising gear if your cruising speed is 55mph. They won't cut it at 65 or higher, and in my part of the country, the slow cars are doing 75mph on the highway. At $4.50 for a gallon of premium, a high revving, slow moving, gas-chugging gear does not make sense 99% of the time. This is all, of course, Just My Opinion, gathered after driving GTO's continually for the past 35 or so years as daily drivers.....with all sorts of rear gears under all sorts of conditions...
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