8 3/4 lowest gear ratio available
- Thread starter Pouria
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72Fourspeed
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They make 5.38s. Probably lower, just never had any.
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Gear ratios available on the 8-3/4" axle through the years include: 2.76, 2.93, 3.23, 3.31, 3.55, 3.73, 3.91, 4.10, 4.56, 4.89, 5.17, 5.57.
http://www.mymopar.com/Mopar8_75RearEndGuide.htm
http://www.mymopar.com/Mopar8_75RearEndGuide.htm
Pouria
Active Member
I have non O/D 4 speed A833! The gears available from the old era are no more used by the modern cars. I think I can get better millage with something like 2.2:1 gear and nicer highway cruise. In case there is a stroker big block behind the story, I believe a higher gear is the winning point. Do you think so?
toplescuda
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Thats not all the ratios. Cause I have a set of 6.14 gears for 8 3/4
72Fourspeed
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I vaguely remember a 3.03 vicinity ratio available at one time. Won't swear to it, but seems like it.
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The reason that 2.76 is the tallest ratio offered is because as the ratio gets taller, higher....The pinion gear gets bigger. The 2.76 is the biggest that fits in the 8 3/4" case.
Pouria
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As a highway cruiser, I have to observe the speed limit of 75mph but when there is no police I may want to satisfy my soul by going as high as 150:headbang: but actually, I am thinking of the 512CID stroker motor along with the highest gear to achieve reasonable millage. I would like to see the monster rev around 2500 @ 75mph.
HT413
Semi Pro Bowler
Pouria, I see that you are from Tehran. Just curious, how much does fuel cost over there? One idea would be to use the 2.76's and fit the largest diameter tire that you could find. I'm running 30" Mickey Thompson ET Streets; the tall tire makes my 4.10 gears feel a bit more like 3.91's or maybe even into the 3.80's.
Pouria
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Yes I am from Tehran. The fuel is 1.15$/US Gallon, seems very cheap but the average income here is less than 400$! Yes, using tall tires would be another consideration to increase the final ratio and I would like to use 16" wheels. Maybe 245/40-16 would be my choice.
Try this calculator, it's been posted here a few times, you can input your trans and rear end ratios then tire size and see the rpm at a given speed.
http://vexer.com/automotive-tools/speed-rpm-calculator
http://vexer.com/automotive-tools/speed-rpm-calculator
lewtot184
Well-Known Member
a 2.76 gear with a 28" tall tire is 75mph at 2500rpm.
Pouria
Active Member
I'll love it then.
Thank you all for the useful info. Now, how can I tell my own gear? How should I know if I have a sure-grip or not? It is the original gear of my 1973 Charger 340 Rallye with 727.
Another question is, how strong are the stock gears? Can a 2.76 gear handle the high pressure of a 512 stroker motor? What about the trany? my 727 has already been swapped with an A833 out of a 70 Challenger. By the setup I am planning to build, I have a high toque motor at one end and a high gear at the other end that doesn't let the car start moving easily. Everything in between will be under extreme pressure and load, could that make any problem?
69clone
Well-Known Member
Jack up the rear so the wheels are off the ground. Start spinning one of the wheels if both wheels start spinning the same direction you have a sure grip if they spin opposite directions you have a one legger.
If it's a stock rear which I assume, you'll want aftermarket internals.
If it's a stock rear which I assume, you'll want aftermarket internals.
Pouria
Active Member
Wooow, I didn't know that! I try this next time I go to the garage and post the result!
Which aftermarket vendor is more reputable and has 2.76?
Last edited:
lewtot184
Well-Known Member
they're not made anymore but when they were produced they were plentiful.
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