440 Automatic. What gears are you running?

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1BAD72

1BAD72

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I presently have an 8 3/4, 3.23 SG in my 72 duster. I have a mild build 440 with a 727. I have never driven it on the highway in the 3 years that I own it. All of the car shows and cruise-ins are within 30 miles of my home on local roads. 28" rear tires (275/60R15). Thinking some bigger gears would increase the fun factor around town. Not planning on taking it to the track. Those of you with a similar motor/tranny set up and tire height... what gear ratio do you run? Are you happy with them?
 
I have 3.73 in mine with a 275/60/15 drag radial, car is a handful. runs 2600 rpm at 60 on the highway. Good all around gear.
 
I’ve got a mild 440, 727, Dana 60 w/3:73 gears 255/60-15’s in a 71 Duster, loads of fun on the street! Haven’t done a lot of freeway driving and as I recall was around 3300 @65mph. (Don’t quote me on that, my memory ain’t what it used to be.) Not too terribly obnoxious.
I dig em so far. Calculator says closer to 3000 @ 65. That probably is more accurate.
 
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I run 3.55's w my 383. No worries on the highway, I can keep up 65-70 mph. I wouldn't run anything lower ratio-wise.
 
I'm on the fence between 3.73 and 3.91. Probably going to need different tire compound. I'm roasting BFG's with 3.23's.
 
I gotta agree with the 3.73 gears.I've had 'um in everything from Slant Six to 472 Hemi cars. I always look at where you live and drive. I came from eastern PA.Lots of hills and twisty turny roads and barely a straight away to be found. They worked great. Now living in the desert out west 2.94 is my gear. In any direction 3 miles from home is 75 mph highways ( most run 80-90 mph) that go for miles straight and flat.Just my 2 cents.
 
Darter6 said:
I gotta agree with the 3.73 gears.I've had 'um in everything from Slant Six to 472 Hemi cars. I always look at where you live and drive. I came from eastern PA.Lots of hills and twisty turny roads and barely a straight away to be found. They worked great. Now living in the desert out west 2.94 is my gear. In any direction 3 miles from home is 75 mph highways ( most run 80-90 mph) that go for miles straight and flat.Just my 2 cents.
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SW Florida... flat and straight.
 
I've got 3.55s in mine, but the engine hasn't been in the car yet. Those gears were in my son's '67 Barracuda 383/4sp with 235-60-15 tires. I don't know if I'll like those gears with a 440/727, but I'll find out...
 
Jim Lusk said:
I've got 3.55s in mine, but the engine hasn't been in the car yet. Those gears were in my son's '67 Barracuda 383/4sp with 235-60-15 tires. I don't know if I'll like those gears with a 440/727, but I'll find out...
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Thats a short tire. I have 3.55 gears in my 80 vette with a 255/60/15. and they are nice with 350 hp and 400 tq. car accelerates and drives well. 60mph is around 3100 rpm. 100 mph is 4500 rpm.
 
threewood said:
3.55 rear ratio, 275/60R15 Nitto 555R tires. I'm at 3k RPM at 65 mph.
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295 65 d15 w/ 3:73 gear , works well w/ 440/505 alum. headed roller cammed pump gas--.
Wondering how much some real gears would make at the dragstrip tho .
 
I ran a 28x13.50r15 and now a 315/35R17 (26") with 3.91 gears. It's a blast around town, on the highway it turns the R's. 70 is about 3600 with the 26" tire, but my highway driving is usually only a few miles at a time. If I drive further, i usually only go 60-65 max to lower the rpms a little.
 
What torque converter do you have? If you currently have a stock converter, a converter swap will probably improve acceleration more than any gear change.
 
So if all you're going to be highway driving is 30 miles each way, i would go to a 3.73 gear. The car will burn the tires hard and still be under 3000 rpm at 60-65 mph. But it's your car decide what you're doing with it. I love the 3.73 gears in mine, perfect for my combo.
 
If your swapping gears in rears...here is the transmission speedo gear chart...keep that speedo in check as well.
Go to the link and use the Automatic or Manual trans link (at the top) to insert tire sizes etc for correct gear choice... cool
This will also tell you expected RPM @ speed

Thanks to Brewers web site

Mopar Speedometer Pinion Numbers
 
marksmopar1 said:
If your swapping gears in rears...here is the transmission speedo gear chart...keep that speedo in check as well.
Go to the link and use the Automatic or Manual trans link (at the top) to insert tire sizes etc for correct gear choice... cool
This will also tell you expected RPM @ speed

Thanks to Brewers web site

Mopar Speedometer Pinion Numbers
Click to expand...
Thank you!
 
thesiren74 said:
Im using 3.73s with 275 60r/15s and it's awesome! Even better when i swap a shorter tire.
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So, if I read this correctly, you like the 3.73 better with the shorter tire than the 28" tire. Since I'm staying with the same 28" tire size as you referenced would you recommend going with the 3.91? I'm assuming you already tried the 3.73 with a shorter tire and liked it better than the 3.73 with the 275/60-R15. Yes?
 
I ran a 26" tire with 3.55 gears and it was okay - a little wound up at highway speeds but not too bad. Now I have 28" Nittos with 3.91's. Pretty noticeable difference and I like it but don't know if I'd want to spend a lot of time at highway speeds. 3.73 might be a good compromise for you but it's all very subjective.
 
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