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Old 12-16-2013, 12:04 AM
95ram 95ram is offline
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Gear change RPM difference

Can someone tell what the rpm difference would be going from 3.5 to 4.10 gears for an AT and assuming all things the same.
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Old 12-16-2013, 08:34 AM
Jagsdiesel Jagsdiesel is offline
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At 70mph you'd be roughly 481rpm higher with the 4.10
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Old 12-17-2013, 05:01 AM
95ram 95ram is offline
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Originally Posted by Jagsdiesel View Post
At 70mph you'd be roughly 481rpm higher with the 4.10
481 is pretty precise for "roughly." 35" tires and 3.5 gears is killing me. I tow more often now and most of it is below 70 MPH. That's more of an RPM increase than I would have thought. Right now at 70 MPH I'm at 1700-1725RPM. The guys with stock size tires and 4.10's must be screaming at 70MPH. IIRC, with 265/75's I was at 2000RPM at 70MPH. Right now at 55-60 mph I have to tow with OD off or my RPM's are to low. I just towed 8K back from Dickinson, ND and at 65 MPH it seemed like it was lugging going up the hills. It felt a lot better at 70 MPH but then I could watch the fuel gauge going down on every hill. Thanks Josh.
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Old 12-17-2013, 12:03 PM
Jagsdiesel Jagsdiesel is offline
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Maybe a middle of the road 3.73 would be a good option. Be like a third gen with a 48re.
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[left]04.5 Cummins drag truck. 1197rwhp fuel only. 9.93 1/4 fuel only at 6540lbs. How many can say that!!!
6.37 1/8 fuel only. New personal best 4/14/12
2011 Mega cab laramie.


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Old 12-17-2013, 12:34 PM
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cumminsmannow cumminsmannow is offline
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My old dodge (06) ran 2,000 rpm at 65mph with 285's on it with 3.73's. Anything above that and it started chugging fuel bad. But when i switched to 35's i could do 70ish with the 3.73's and keep it at 2,000 rpm.


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Old 12-17-2013, 12:44 PM
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Takedown95 Takedown95 is offline
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Heres a couple files with a majority of the dodge trans in them. You can select gear size, tire size...etc. It's a handy tool.

Wheel speed calculator.zip

gear selection.zip
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Old 12-17-2013, 10:07 PM
95ram 95ram is offline
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Thanks guys. I've thought about going to a smaller tire, but the ground clearance is nice since the township doesn't feel the need to plow my road.
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Old 12-18-2013, 08:38 AM
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cumminsmannow cumminsmannow is offline
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If you tow alot it would be easier and cheaper to drop to a 34" tire. It may not be a big difference but would help a little and reduce rolling resistance. The 1/2" lower ground clearance isnt gonna hurt you that much in the snow.


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Old 12-18-2013, 11:51 PM
95ram 95ram is offline
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Quote:
Originally Posted by cumminsmannow View Post
If you tow alot it would be easier and cheaper to drop to a 34" tire. It may not be a big difference but would help a little and reduce rolling resistance. The 1/2" lower ground clearance isnt gonna hurt you that much in the snow.


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I'd agree I'd I didn't live in the middle of no where but I've also thought of going to a taller tire. Most of the winter I'm pushing snow with the front bumper. I've got to be to work before the plows come on the county roads and I blow our township road out more often than they plow it.
I've thought of going to 3.73's with the 35's but wasn't sure if it would be enough of an RPM drop since 75% of my towing is done at 60MPH.
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Old 12-19-2013, 07:05 PM
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If you are thinking about an even taller tire and you only tow at 60 i would jump all the way to 4:10's if you are going to do a change.
Or for the money you could have the best of both and put a gear vendors under drive to use while towing and leave your stock ratio alone for cruising on the highway at low rpms


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