wanting to do gear swap on AWD sierra denali need HELP
07-10-2008, 07:51 PM
#1
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wanting to do gear swap on AWD sierra denali need HELP
truck is a AWD crew 6.2 with 20s it has the original 3.42's i need a better off the line take off and just to be quicker in general from any speed would 3.73's do this? would any bigger be overdoing it and im guessing i would have to do front and back
im trying to get opinons if this is even something i should mess with or leave alone i dont even now what kind of effect this will have with this 6spd auto
im trying to get opinons if this is even something i should mess with or leave alone i dont even now what kind of effect this will have with this 6spd auto
07-10-2008, 09:50 PM
#2
Grrr...trying this for the 3rd time and getting angry. I had a whole 5 paragraph essay type of response for you on how to choose the gear set but each time I click submit my browser freezes.
Anyways, to keep it short because I'm tired of typing this, 3.73's would be my choice. You will have to do both front and rear, otherwise you'll burn up the transfer case in a short time. With that double OD 6th gear, you could get away with 4.10's too at the cost of a little gas mileage on the highway. With a tune you'll be back to what you're getting now, MPG-wise. Whatever you choose, you'll have to get the PCM tuned to recognize the gears otherwise your shift points and speedometer will be off.
What size tires on those 20's btw?
Anyways, to keep it short because I'm tired of typing this, 3.73's would be my choice. You will have to do both front and rear, otherwise you'll burn up the transfer case in a short time. With that double OD 6th gear, you could get away with 4.10's too at the cost of a little gas mileage on the highway. With a tune you'll be back to what you're getting now, MPG-wise. Whatever you choose, you'll have to get the PCM tuned to recognize the gears otherwise your shift points and speedometer will be off.
What size tires on those 20's btw?
07-11-2008, 01:29 PM
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that is going to cost you a lot of money for both gear swaps, I would go with a programmer or a tune to get some more power and your spedometer and everything else working correctly. doing gear swaps is quite pricey if you dont do it yourself
07-11-2008, 05:05 PM
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^^^^^^ also depends on how much highway driving he does, because that gear change with out too much if any of a tire diameter change will just hurt his mileage, costing him more for the gear swap, plus fuel day by day. Unless (OP) you are thinking about putting a small lift on it and/or bigger tires to offset the rpms on the highway with 4:10's
07-11-2008, 07:11 PM
#7
You guys have got to look at the system as a whole, all working together. Remember you're all running the 4 speed auto. He has the 6 speed auto. Even with 4.10's he'll cruise around 2070 rpms @ 70mph. 3.73's would sit him at 1900. Since when is 2070 rpms @ 70mph not acceptable? A stock Silverado, Suburban, Tahoe, Sierra, Yukon... they all cruise at 1950 rpms going 70mph. He has heavy 20's...the extra 100 rpms would actually help so the torque converter could remain locked instead of unlocking and locking all the time, shifting from 6th to 5th to keep the truck moving.
I totally agree though about the expense. Please take no offense when I say if you can't select your own gear set, you don't belong doing a gear swap. That is perfectly ok by me and hopefully everyone else on this site...just count on having to pay a driveline shop to do the swap. Expect no less than $600 in parts and about 3 hours of labor per axle.
I totally agree though about the expense. Please take no offense when I say if you can't select your own gear set, you don't belong doing a gear swap. That is perfectly ok by me and hopefully everyone else on this site...just count on having to pay a driveline shop to do the swap. Expect no less than $600 in parts and about 3 hours of labor per axle.
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07-11-2008, 08:14 PM
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not to step on anyones toes in this thread, but 3 hours labor, to swap gears is insane. Maybe this was just a guess, but I turn wrenches for a living and get no less than 6 hours to rebuild a rear diff...hope this helps
07-11-2008, 08:26 PM
#10
It was a guess based on how long a gear swap usually takes me, with the axles still in the vehicle. My first swap took 8 hours and I did it when I was 17, and they've been getting easier and easier the more I do throughout the years, especially the 14 bolt I just did. God I love adjustable pinion supports.
The front diff will probably take the longest of the 2 axles.
The front diff will probably take the longest of the 2 axles.