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Old 05-11-2013, 05:02 AM   #1
74 stepside
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Gear Ratio Opinions

Ive got 2 different 12 bolt rears. 3.40 and 3.73. Truck has a mild built 350 with 700R4 trans and 295/50/15 rear tires (26" tall). Which gear ratio would be best?
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Old 05-11-2013, 07:43 AM   #2
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Re: Gear Ratio Opinions

With that small a tire 3.40s would be good. They are almost 27" tall, have them on my car...
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Old 05-11-2013, 02:23 PM   #3
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Re: Gear Ratio Opinions

3:73s will make you go fast but use a lil more mpg than the 3:42.
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Old 05-11-2013, 02:40 PM   #4
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Re: Gear Ratio Opinions

3.40 and even then you will be turning too much rpm on the freeway
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Old 05-11-2013, 05:42 PM   #5
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Re: Gear Ratio Opinions

Not with an OD tranny.
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Old 05-11-2013, 05:44 PM   #6
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Re: Gear Ratio Opinions

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Originally Posted by b454rat View Post
Not with an OD tranny.
I missed that. Yeah go with the 3.73s then
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Old 05-11-2013, 06:47 PM   #7
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Re: Gear Ratio Opinions

I vote for 3.73.

That's what I have in my truck with the overdrive and I love it.

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Old 05-11-2013, 06:48 PM   #8
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Re: Gear Ratio Opinions

I'd try 3.73's with that wide a tire the extra rpm would not hurt or may help a bit.
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Old 05-11-2013, 11:37 PM   #9
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Re: Gear Ratio Opinions

The few times I have come across these trucks at wrecking yard with an OD trans they all had 3.73 rear ratio.
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I'd try 3.73's with that wide a tire the extra rpm would not hurt or may help a bit.
What difference does the Width of the tire have to do with gear ratio?
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Old 05-12-2013, 12:16 AM   #10
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Re: Gear Ratio Opinions

3.73 it is...thanks guys.
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Old 05-12-2013, 12:33 AM   #11
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Re: Gear Ratio Opinions

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Originally Posted by wraprail View Post
The few times I have come across these trucks at wrecking yard with an OD trans they all had 3.73 rear ratio.


What difference does the Width of the tire have to do with gear ratio?
The wider or heavier the tire a bit more rpm can help. On a friends C10 switching from 235/70/15 to 275/60/15 made a difference in acceleration, and took a couple mpg off the cruising. Then sometimes it doesn't make a difference, and I have seen it both ways.
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Old 05-12-2013, 09:37 AM   #12
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Re: Gear Ratio Opinions

It makes no difference in the gear ratio at all...but it may have some effect on how the truck drives/feels. Wider and heavier tire/wheel combinations can put more load on the entire drivetrain, under-powered vehicles will notice this more.
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