1963 rear end gears change to 3.08
Does anyone have a suggestion on a good gear manufacturer of replacement rear end gears. The car is used for normal road driving just want to lower rpm's . Thanks
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Re: 1963 rear end gears change to 3.08
Joe has it correct, these are the only gears you want to use today. I would get them while you still can.Comment
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Re: 1963 rear end gears change to 3.08
Tim keep in mind that the pinion flange will have to be replaced as the original 63/64 gears had a coarse spline, new gears have a fine spline. they do reproduce the flange.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: 1963 rear end gears change to 3.08
My question is WHY 3.08 On a sb with normal torque and hp, driving in town will be difficult a 3.36 is much better I have a 60 270 HP with a 3.36 and sometime I would like a 3.55 as it can be hard to get moving 3.08 are great for touring I have them in a 67 BB 390 and road use is great still a little difficult around town howeverFounder - Carolinas Chapter NCRSComment
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Re: 1963 rear end gears change to 3.08
True Jimmy, and I have a 3.08 in my '64 FI with the close ratio Muncie (only one available in '64), just try launching that on an, even slightly, uphill grade from a stop. But still, a great road gear, just limit your stop and go around town driving.......
Big Tanks In the High Mountains of New MexicoComment
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Re: 1963 rear end gears change to 3.08
Tim,
What gear are you running now in the car? The standard factory gear if I am correct is wide ratio trans with 3.36 (250 & 300hp) and close ratio trans with 3.70 (340 & 360hp).Comment
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Re: 1963 rear end gears change to 3.08
According to the Black Book, the only manual transmission choice was an M20 (close ratio) in 1963. And many different diff ratios were available, including 2,259 with 3.08 positracs, G81. There was also the special order G91 special highway axle ratio 3.08, and 211 of those were made.Big Tanks In the High Mountains of New MexicoComment
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Re: 1963 rear end gears change to 3.08
Yes, but I meant to say you had no choice, the transmission was a close ratio for SHP and a wide ratio for the base engines, 250 and 300 HP. You could not get a much easier to launch wide ratio if you had an SHP and a 3.08, like one of mine.Big Tanks In the High Mountains of New MexicoComment
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Re: 1963 rear end gears change to 3.08
Thanks all for the information. I should have given more info on the car. My 63 is a 250hp car 4 speed coupe (top flight Denver nats). When running on the highway at 65mph turning close to 3000rpm , also is gets a little warm (200) when running distance. I do live near 7500 alt. in the Colorado Rockies so that contributes to the heating. It does have a new Dewitts Rad is not sure what else I do to rid that problem. Thought lowing the rpm may help.Comment
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Re: 1963 rear end gears change to 3.08
Timothy, it sounds like you have a 3.70 rear end ratio, like I have in my '64 365 HP 327. I also live near 7500 feet. 200 degrees is not unusual for mine going up hills, or in stop and go driving in the summer, although it is usually near 190 cruising. I also have a DeWitts. My thermostat is a 190 degree one, not sure what you have, but I don't think lowering the rear end ratio is going to make it run much cooler, but you will get much better gas mileage. How does it do in stop and go driving around town in the summer? Is your carb jetted and adjusted properly for your altitude? Are you sure your temp gauge is reading accurately?Big Tanks In the High Mountains of New MexicoComment
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Re: 1963 rear end gears change to 3.08
The base axle ratio for 250 HP/ WR 4-speed was 3.36 and a 3.08 was available in both open and Positraction versions. Revs at 60 for each would be about 2600 and 2350, respectively with OE equivalent 760 rev/mile tires. At 65 with a 3.36 revs should be about 2766.
Assuming your speedometer reading is correct, someone might have installed a shorter rear gear. I doubt it, but you should verify accuracy of the speedometer with a portable GPS or modern car before you proceed. Also verify the tach accuracy with a test tach, and you can count driveshaft revolutions for one wheel revolution and check the stamped data on the bottom of the carrier housing to see if it's original, but that doesn't mean the internal parts are.
You should also verify that the trans is a wide ratio. If so, the 3-4 shift at 3000 will drop revs to about 2100 and 2400 if a close ratio. Also check the VIN derivative on the case to see if it is the original St. Louis installed transmission.
The 250 HP engine has the greatest low end torque of all the '63 engines and will easily handle a 3.08 with a WR 4-speed, but if it currently has a 3.36 you're only dropping revs about 10 percent, so it may not be worth it unless you do a lot of highway driving.
DukeComment
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