# Need advice on rear axle ratios.............



## Pomatomus salta (May 3, 2016)

looking at 2 GMC sierras -one has a 3.08 rear axle ratio - the other 3.42....which would do better in the sand ? I know the 3.08 would give slightly better mpg's but I'm more worried about cooking the tranny or digging in the tires due to excess speed/torque? any help appreciated , thanks


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## spydermn (Apr 26, 2009)

You will not run into issues with a 3.08 unless you are driving like a dune racer. The 3.08 will make it feel less powerful and give much better gas mileage. Me I am a butt dyno junkie, so I make everything as fast as I can afford to, I am stupid like that


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## Guest (May 31, 2017)

Measure the diameter of the tires. The rule of thumb is that the optimum gear ratio ( theoretical - get as close as possible ) is Tire Diameter in inches X .12 = Axle Ratio. So, 33" tires would be 33 X .12 = 3.96 ( 3.73 or 4.11 ).


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## Pomatomus salta (May 3, 2016)

wound up getting a silverado with 3.42 rear..guy in the dealership surf fishes and he suggested 3.42....it also has an auto locking rear diff (eaton) ..also an auxilliary tranny cooler on the model I chose,,,should be a nice surf fishing vehicle..


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## buster (Nov 16, 2006)

Either gear ratio would work fine on the beach.Towing is the difference.I have a 2014 Silverado with 3.42s and its good all around.Dont need to air down unless the beach is really chewed up.One note is that if its a newer truck then make sure you turn traction control off before going on beach or you wont be happy.


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## Pomatomus salta (May 3, 2016)

buster said:


> Either gear ratio would work fine on the beach.Towing is the difference.I have a 2014 Silverado with 3.42s and its good all around.Dont need to air down unless the beach is really chewed up.One note is that if its a newer truck then make sure you turn traction control off before going on beach or you wont be happy.


just curious / what happens if u don't ?


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## stiab (Jul 3, 2015)

Pomatomus salta said:


> just curious / what happens if u don't ?


You get stuck, or at least I did. I had not been stuck on the beach in at least 25 years, and had pulled out dozens of buried trucks with my 350 c.i. Tahoe. But then it got hit from behind and totaled and I went with a newer 4.0 Nissan, and got stuck first time on beach at Ramp 44. Later learned I had to hit the button to turn VDC off, and since then the Nissan has performed wonderfully on the beach.


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## buster (Nov 16, 2006)

Yes you will probably get stuck.The truck gets "confused" because its trying to prevent wheel slip.Very weird feeling...i forgot to shut off one time and knew instantly what the problem was.


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## Pomatomus salta (May 3, 2016)

Good info . thanks...just looked at the truck ..there's a button for trac control OFF...guess i'll have to remember to turn it of.


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## Hikes run (Aug 9, 2015)

Very interesting read guys. I recently picked up a 2011 ram 1500 and it has the button you have to push to turn traction control off. I NEVER would have known to do that! Now if I can just figure out what rear end is in it I'll be good to go. Where can I find that information?


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## buster (Nov 16, 2006)

your local dealer can check codes in glove box and tell you or there should be a tag on the rear end where cover bolts on


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## straps57 (Nov 19, 2008)

Pomatomus salta said:


> looking at 2 GMC sierras -one has a 3.08 rear axle ratio - the other 3.42....which would do better in the sand ? I know the 3.08 would give slightly better mpg's but* I'm more worried about cooking the tranny* or digging in the tires due to excess speed/torque? any help appreciated , thanks


Put the gear shift in 1 and you shouldn't overheat your transmission. It will keep the transmission from searching for the best gear to be in.


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## dena (Jun 20, 2010)

straps57 said:


> Put the gear shift in 1 and you shouldn't overheat your transmission. It will keep the transmission from searching for the best gear to be in.


I agree with this, pull the gear selector down to L or 2.
If you had a manual transmission, you wouldn't get much out of second gear at the slow speeds we are supposed to drive. 
These modern day automatics, in their quest for every inch of gas mileage, will always go up a gear or two, and lug along until the speed picks up. That leads, in the sand, to heat, and slippage in the viscous coupling, killing the box.


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## Pomatomus salta (May 3, 2016)

Guy at the dealership said - just run it in 4 low ...and change the transfer case oil often..."its better than burning out your transmission"......any thoughts ???


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## Hikes run (Aug 9, 2015)

I did some searching and found where I could enter my VIN number and get the build sheet for my truck that shows all standard and optional equipment on it. Very cool for us used Dodge guys. It has a 3.55 rear end with 33's. From what I've read that's pretty much middle of the road kind of gears I guess. My previous truck was an 05 Ram 1500 with the smaller 4.7 liter engine and it did excellent in the sand. It did't get stuck in 5 years and sure pulled its share of folks out. I'm not sure what gears it had though and no way to find out now. Not sure how much difference tires make in sand but I was running on Cooper Discoverer A/T3's and I absolutely loved them, best tire I've run on by far. That's what's going on the new truck as well.

The new truck has a couple of nice options I would have otherwise not known it had without finding the build sheet though. Heavy duty engine cooling, Heavy duty transmission oil cooler and 5 additional gallons of gas on a 26 gallon tank!

Here's the link to get the build sheets if any of you Dodge guys are interested. It spits out a printable PDF in a few seconds but only works on 98 and newer. Enjoy!

- Go to this website ---> 
- Click on the link down the left side of the page that says "Equipment List" 
- Enter your VIN in the smaller search bar and click search


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