re-gear for 35's?

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Jul 6, 2005 | 08:58 PM

#16

Sal FX4

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Joined: Jan 2005

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From: The Woodlands, TX

Quote:

Originally Posted by jasonkola

studying those charts I think the best ratio for 33's would be 4.10 and for 35's would be 4.27. I think I heard someone mention once that someone makes a 4.27 rear gear for our trucks. I am not sure on that one though.

I would probably stay under 4.56s if i were putting on 35s, just my opinion.

But it all depends, do you want more acceleration or do you want more top end? You may want to do the math to make sure you know what it is you are getting. Check out the Yukon gears they make almost any ratio, I have those on my truck.

Jul 6, 2005 | 10:26 PM

#17

tycreek

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I don't think top end is part of anybody's equation on this forum! MPG maybe? The thing is with gears ... after 4.10's you're installer starts to be more important ... and as you get closer to like 4.8x's or higher ... heat and noise can start to be a factor in that it gets harder to avoid even with the best of the best.

And, Oh yea, my RPM's are actually just about right on and maybe a few lower than my chart with the TQ conv locked. It all depends on the tire ... one size AT might actually be larger than the calculated values and other highway types smaller etc... a worn tire can make a 2-300rpm difference.

Last edited by tycreek; Jul 6, 2005 at 10:33 PM.

Jul 7, 2005 | 12:01 AM

#18

Sal FX4

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From: The Woodlands, TX

Quote:

Originally Posted by tycreek

You're right about that! When calling around to the local shops only 2 guranteed no noise with 4.56s and they charged top dollar too. As far as top end I wasnt really talking about 100mph I was thinkin more like crusin speeds of 70-85 for highway use. You dont want to be at 3,000 rpms doing 80 mph.

Jul 7, 2005 | 12:26 AM

#19

tycreek

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Ya... on the highway at 80+ all the time ... 4.56's might be a bit much for 33's ... though I wouldn't trade up or down as I think for my uses it's just perfect!

I had the same thing ... wanted a guarantee that things would be right! Well worth it IMO...

If I stand on it I never hit 4th until I back out of the throttle. My take is that I just don't need to be hitting anything near 100mph in this rig so I back off ... not worth it for many reasons! Still have a good chunk of 3rd left in the 1/4mi.

Jul 7, 2005 | 12:57 AM

#20

Sal FX4

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Joined: Jan 2005

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From: The Woodlands, TX

Quote:

Originally Posted by BalogUK

hey, sorry to barge in, but can someone further explain that chart... ive got the 3.73 with the 31" rugged trails presently- looking to go to 35's now according to the chart, they say my rpm at 65 is 2628 (factor in 30% difference for OD), and thats 1800-1900 rpm (on my truck) so, when i look at the chart, do I want to match to the 2628, or the 18-1900? when i up to 35's so the 4.27s should be right. second question, what is prime- do you want more or less rpm?

thanks alot-
jj

you can't really use the chart because the 4th gear ratio on our trucks is 0.67:1 You need a chart where you can plug ALL the factors. Here are two:

http://www.4lo.com/calc/gearratio.htm

http://www.ringpinion.com/content/calculators/RPM.asp

I went through both calculators and plugged all kinds of factors before changing my gears.