3.42 & 35"

[DwelveAT]

Hey guys hopefully someone can assist me on the matter, I finally called a local GMC dealership and recieved some information on what type of gearing I have on my Sierra. I do have the 6 speed automatic with the 3.42 gearing in it, well recently I lifted the truck and I would like to know, would I need to re-gear my gears from the 3.42 to 4.56 seeing its lifted 6" and running 35"? The reason I picked 4.56 was based off a chart someone posted from 4wheelparts which show better gas mileage. I tried searching on the site, but couldnt find anything cut n' dry. Everything I could find was leaning more towards towing concerns, I on the other hand am leaning towards longevity concerns and trying to avoid causing any possible damage to the drive system, so I figure if it needs it, knock it out right away. Does anybody know if its required for my type of situation and the truck is just a daily driver in which I use it to commute back n' forth to work. Never do I tow, so towing is out of the question, but I am just wondering do I seriously need to re-gear? She still pulls pretty good with the exception of the 3rd gear which lags sometimes, but not all the time.

[jro909]

i would say no...the 6 speed trans coupled with the 3.42s is the equivelent of a speed speed with 4.10s...does the truck struggle at all with the load out?

[DwelveAT]

i would say no...the 6 speed trans coupled with the 3.42s is the equivelent of a speed speed with 4.10s...does the truck struggle at all with the load out?

 

Nah.... the truck pulls pretty strong, even from a launch. Just my concern is based off what i've read on the site from other people's discussion is damage to the driveline system. I don't know much about the internals on these vehicles so as I read and get confused, I feel the need to ask to get better understanding.

[Matt_]

first: disregard those gear charts... they're useless! too many different engine/tranny combos to summarize every vehicle in one chart

 

second: the 6spd with 3.42s is not equivalent to the 4spd with 4.10s... theres absolutely no basis for that statement unless you're referring to one specific gear for each trans... not the entire gear spectrum. FYI, 3.42s in 6th gear of the 6spd is like having 3.23s in 4th gear of the 4spd. Try driving a truck with 3.23s and 35s on the highway and see if it ever gets into OD...

 

third: yes you'll want to regear. 5th and 6th gears will be near useless with 3.42s and 35s. 4.10s would be ideal for decent performance and gas mileage. 4.30s will give you more performance and decent towing. OR if you live in mountainous area id err towards the 4.30s as well

[DwelveAT]

I appreciate the information Matt, so I guess I will be ordering 4.30 gears for my rig then, just incase for some oddball reason I ever do have to tow.

[Matt_]

either 4.10 or 4.30 should suit you well. if you do a lot of highway, the 4.30s will definitely help. if you're mostly city driving you may want to go with the 4.10s since the 6spd has really low 1-2 gears.

 

dont jump into purchasing anything... research as much as you can: gears are expensive! all im paying is my $.02 =)

[DwelveAT]

From what i've found online so far, the average is $250+ something. My second ? is do I need to buy a set for the front also seeing its 4wd?

[Silverado4x4]

From what i've found online so far, the average is $250+ something. My second ? is do I need to buy a set for the front also seeing its 4wd?

 

Yes.

[Nytemare]

From what i've found online so far, the average is $250+ something. My second ? is do I need to buy a set for the front also seeing its 4wd?

 

Yes.

 

Well...not really...if you disconnect the front shaft and never use 4wd again you don't.

[Silverado4x4]

From what i've found online so far, the average is $250+ something. My second ? is do I need to buy a set for the front also seeing its 4wd?

 

Yes.

 

Well...not really...if you disconnect the front shaft and never use 4wd again you don't.

 

 

Well maybe he can PUT THE GEARS IN THE FRONT and disconnect the rear driveshaft.

[DwelveAT]

Well either way I will be ordering some new gearing for the truck in the next couple of months. Thanks for the info guys.

[Nytemare]

From what i've found online so far, the average is $250+ something. My second ? is do I need to buy a set for the front also seeing its 4wd?

 

Yes.

 

Well...not really...if you disconnect the front shaft and never use 4wd again you don't.

 

 

Well maybe he can PUT THE GEARS IN THE FRONT and disconnect the rear driveshaft.