Can anyone tell me the factory gearing for a '70 Dart Swinger 225 w/ BBS and a 904?

or a good way to find out?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

If you want to drop the rear end cover, you can count the number of teeth on the pinon and ring gear and divide them by each other. Ratio is usually stamped on the ring gear as well.

Otherwise, jack up the rear, and then put a mark on the driveshaft and take note where the mark is. Put tranny in neutral, then turn a tire by hand one full turn, and count how many turns the driveshaft you marked goes. If the driveshaft goes about 2.5 turns, you got the 2.45 gears, if the driveshaft goes 2 3/4 turns, then you probably have the 2.76 gears, etc etc. Less precise method but with the known availible ratios you can tell easily enough.

if the rear hasn't been swapped it is almost assuridly has a 2.76.

The factory usually stamps the ratio on the housing flange, take a wire brush to the area shown to see if you can find the numbers.
DD

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I jacked up my car and did the wheel turn thing. My driveshaft doesn't even go around twice! What is ratio is that - 1.75 !?! This is on a '64 dart. I could not find the factory stamp. Is it on the top or bottom?

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

Are you sure both rear wheels are off the ground and the tranny is in neutral? The lowest number ratio I've seen is 2.45

Yes sir. I checked the tranny. It wouldn't turn (easily) if it wasn't in netrual, right?(engine compression). Also I was doing the rear brakes, which is why I had the rear wheels off of the ground. I can't believe it either, but I don't know what I'm doing wrong. The driveshaft turns 2x for 1 1/4 turns of the passenger rear wheel.
Help!

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"Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of Him to whom we must give account."

If you check the early 80's RWD cars they will very commonly have 2.76,2.45, and the dreaded 2.26:1 ratio....(talk about a slug...)


You might try it from the driver's side wheel, you can also turn the driveshaft and have someone count it up on the tire also...

The standard ratio for grocery getter Mopars and automatics are 2.76:1.


-D.Idiot

With a non sure grip rear, you have to make sure BOTH rear wheels turn one revolution. If one wheel is on the ground, turn the other wheel 2 turns, and count driveshaft revolutions. With a sure grip they will automatically turn equally.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225