Considering Rear End Gears
10-02-2011, 12:25 PM
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Considering Rear End Gears
Hey guys. I am currently considering changing the rear gears on my 08 sierra denali. I currently have 3.42's and I am thinking of going to 3.73's. I want to get a little more off the line grunt since I just added the supercharger however I do not want to sacrafice too much more fuel economy. The majority of my driving is in the city with a little highway here and there. I also tow a pair of sea doo durring the summer. I will be doing a custom 2 piece steel drive shaft as well when I get the gears done. Do you think the 3.73's are the best choice? Also will I have to have to computer reprogramed for the new gears? Thanks for your advice.
10-02-2011, 12:51 PM
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You will have to re-program the computer for the new gears.
I would probably go with 4.10s just to make it worth the hassle and cost of changing gears.
A cheaper option may be to get some lighter wheels. Your fuel economy would most likely go up with lighter wheels as well.
I would probably go with 4.10s just to make it worth the hassle and cost of changing gears.
A cheaper option may be to get some lighter wheels. Your fuel economy would most likely go up with lighter wheels as well.
10-02-2011, 01:37 PM
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I am considering the smaller pulley as well. I was just thinking while it would be in the shop for the drivershaft why not look at gears too. If I go with 4.10's how is that going to impact the mid range. Right now I love the pull it has in mid range. The truck is a beast right now when you step on it from say 30 or 40mph.
Last edited by mjdxtreme; 10-02-2011 at 01:42 PM.
10-02-2011, 02:32 PM
#5
I have 3.42s in mine and I do have a set of 3.73s for it which I may use after I put my converter in. From my observation with my truck, 4.10s will put you in overdrive at the top of the quarter mile. I say dont go higher than 3.73. Its not about how much you'll notice, its about what is going to be the most effective.
10-02-2011, 08:08 PM
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I run 4:10s on a 275/55/20 and it turns 2050rpm @ 70mph. On a 28" DR i cross the traps about 5700rpm in 4th gear and i pull my truck to 6500rpm. Just an idea that honestly 4:10s arent that bad, i have a big cam and stock stall and i get 16mpg average and i do not drive like a pawpaw. My trips usually involve a few 120mph runs from time to time 
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10-02-2011, 10:00 PM
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Has anybody have times before and after gear swaps? I am considering 3.73s for my truck. I know the mileage difference isnt much, just want to know what I would see at the track.
10-03-2011, 09:41 AM
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As mentioned before, you'd be less than impressed with going from 3:42's to 3:73's, atleast step it up to 4.10's, Go to a tire calculator and put the rear end size and the Tire size (OD). You will be impressed with how little amount of rpm the truck actually turns.
