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post #1 of (permalink) Old 10-24-2007, 08:20 PM Thread Starter
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OT tow rig gearing

Hi

So I have a 2000 Dakota Quad cab with the 5.9L, factory tow package, 3" body lift and 33" tires and what I think is 3.73 gears...

I'll be pulling a Jeep on a trailer more frequently and right now it's a bit of a dog accelerating on on-ramps and up hills. Buying a big diesel or bigger truck isn't an option at this time.

I'll be set as much as I can be in other safety measures such as brakes, etc...upgraded truck brakes and brakes on both axles of the trailer...please no lectures...

What gears would you recommend for my situation? 4.10? 4.56? higher?

Thanks!
Patrick

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post #2 of (permalink) Old 10-24-2007, 09:03 PM
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all the other stuff aside, what size tires were on it originally?

the ratio between the stock gears and tires should remain the same once you add the new tires.....if that makes sense....do the math...or post it and we can all do it together

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post #3 of (permalink) Old 10-25-2007, 06:10 AM Thread Starter
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original tire size was 31"

Thanks!
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post #4 of (permalink) Old 10-25-2007, 07:47 AM
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Jeep Horizons :: RPM vs Gear Ratio Chart


looks like you need 4.10's to regain the original ratio

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post #5 of (permalink) Old 10-25-2007, 06:46 PM Thread Starter
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what would be the advantages/disadvantages going with taller than original ratio?

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post #6 of (permalink) Old 10-25-2007, 07:13 PM
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higher RPM's for a given ground speed.

could mean less MPG.....could mean you are out of your peak power band.

advantage is more toque at a given RPM.....same as with your jeep...more gear = more crawl

could be good, could be bad.......depends on where that engine is mean to run.....i'm not familiar with that

i wouldnt go higher than 4.27 if you drive on the street

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post #7 of (permalink) Old 10-25-2007, 08:40 PM
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The theoretical matching ratio would be 3.98 - 33*3.74/31. If you put in a 4.10 it would be geared about 3% shorter than stock - 4.10/3.98. Your truck would perform almost exactly as it did before you put the big tires on. If you put in 4.27 gears it would be about 7% shorter than stock, which would definitely be noticable.

Would it be possible to borrow a pair of 31" tires for a few hours? You could put them on, hitch up the trailer and have a good idea of what 4.10 gears would do for you.

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post #8 of (permalink) Old 10-25-2007, 09:34 PM
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I have 4.10's and mine pulls fine. I find the whole scnario funny.

Ya only go around once, best to enjoy it the first trip.
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post #9 of (permalink) Old 10-26-2007, 06:38 AM
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Quote:
I find the whole scnario funny.
Yeah, well, you're just easily amused.

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post #10 of (permalink) Old 10-26-2007, 09:58 AM
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my diesel has 4.11 gears in it with a 4 speed automatic and 33" tires. it does 83 MPH at 2500 RPM.. which is as fast as I am willing to spin the cummins.
I think your little truck could use 4.56's with the gas engine. This would also help you compression brake down hills so you don't overheat the tiny brakes on the truck quite as fast.

now for the manditory lecture...every year I have to replace the enormous brake pads on my truck and I have gone through 3 sets of rotors on the front Dana-60 in the past 4 years. these brakes are easily twice the size of the dakota stuff.

It's not what you have. It's what you do with what you have
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