changing rear end gears 3.73 to 4.10? [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: changing rear end gears 3.73 to 4.10?


TrialBlazerSST
04-30-2009, 12:45 PM
Ok guys and gals have a few questions. Im going to take the 3.73 out and go to 4.10 gears. Now with you all knowing this what all on these tb's do i have to change do i have to change the case or spider gears? or do i just have to change out the ring and pinion gears?

also r gear is 8" correct so i wont need to change out the differential cover plate

so if you guys could help me id appreciate it just gotta know what all I have to change

BUC NASTY
04-30-2009, 12:59 PM
first fill out your truck information on your edit page so we know what truck, year, and engine you have.

if you have a 4x4 your would have to change both gear ratios (front and back) including the "master installation" kit.

you would also need a tune up to change the gear ratio calibration.

TrialBlazerSST
04-30-2009, 01:08 PM
ok well engine size doesnt matter year is 07 doesnt matter same rear end still and no i do not have a 4x4 i have filled that **** out 5times and it isnt saving starting to piss me off ill fix that today thank you for letting me know

TrialBlazerSST
04-30-2009, 01:58 PM
hey i just Checked my profile and everything u asked about is on my profile so it did save did you even try to check my profile

MajesticLT03
04-30-2009, 03:53 PM
just the ring and pinion is required to change to a 4.10..

everything else can stay

TrialBlazerSST
04-30-2009, 04:00 PM
just the ring and pinion is required to change to a 4.10..

everything else can stay

awesome thanks for the info and do you really have to get a tune if you change your gears in the TB's if so you have to get a tune for every ****in thing you do

MajesticLT03
04-30-2009, 04:26 PM
no you dont have to get a tune... it helps but its not necessary

WOOLUF1952
04-30-2009, 04:38 PM
hey i just Checked my profile and everything u asked about is on my profile so it did save did you even try to check my profile
Part of the problem is, you have this posted in the 4x4 section.
no you dont have to get a tune... it helps but its not necessary

You don't need a tune, but you will need to get the PCM changed for the new ratio.

BUC NASTY
04-30-2009, 05:08 PM
no you dont have to get a tune... it helps but its not necessary

yes you have to get a tune. it will effect your transmission shifts and can cause the engine light to light up

LMMJ
04-30-2009, 05:49 PM
yes you have to get a tune. it will effect your transmission shifts and can cause the engine light to light up

i went from 3.42 to 3.73 and beat the crap out if it for a few days and nothing has happened yet. It's the same thing as if you changed tire sizes. Not a big difference.

our computers are calibrated to run 29.5" tall tires and people use all sorts of different sizes. Bigger tires is like going down in gear ratio.

265/40/22 = 30.3"
245/75/16 = 30.5"
265/65/17 = 30.6"
255/50/20 = 30"
265/50/20" = 30.4"

the gear change isn't a huge deal unless it throws a CEL which mine hasn't

TrialBlazerSST
04-30-2009, 06:15 PM
well everyone i appreciate the advice and i am already throwing a code for not having now cat. But besides that what do all of you think i will gain in my 1/4 mile time with having CAI, dual exhaust can mufflers only, no cat and 4.10 gears and how much of a lower time could i expect with all this done plus a Torque Converter + a tune

LMMJ
04-30-2009, 06:22 PM
nothing breathtakingly spectacular. It's really hard to say.

ylab
04-30-2009, 06:23 PM
If you're bottom line is faster 1/4s and 0-60, get a tune, it makes a 3.42 geared truck feel and run like one with 4.10 gears, add the two together and she'll be loads quicker. I've driven an identical truck with 4.10 gears and it was night and day, but with a tune my 3.42 felt pretty much like my friend's 4.10, only quicker to respond to throttle inputs with faster shifts.

Back in '02, trucks with 4.10 gears ran around 8.0 seconds 0-60 compared to 9.0-9.2 for those with 3.42 gears.....the 3.73 should fall in the middle of the two. (Those numbers are in 4x4 trim, so a little quicker with 2WD).

ScarabEpic22
04-30-2009, 06:28 PM
ok well engine size doesnt matter year is 07 doesnt matter same rear end still and no i do not have a 4x4 i have filled that **** out 5times and it isnt saving starting to piss me off ill fix that today thank you for letting me know

Yea it does man, SWB I6s get 8" rears, LWB I6s and all 5.3s get 8.6" rears, and the SS gets a 9.5" 14 bolt.

Now if you mean what you need to change, that doesnt change depending on diff size but thats about it.

As for a tune/reprogramming, you should do it eventually as your speedometer, odo, and trans shift points will be off. Besides, it'd be an excuse to get a tune.

BUC NASTY
04-30-2009, 08:59 PM
As for a tune/reprogramming, you should do it eventually as your speedometer, odo, and trans shift points will be off. Besides, it'd be an excuse to get a tune.

:iagree: the CEL may light up like it did on mine giving me a hesistation shift problem. At first the truck seemed fine without the tune until the CEL came on. So for safety measures get a tune.

TrialBlazerSST
04-30-2009, 11:05 PM
besides PCM for less where can i get a tune i dont have money for HP Tuners but id like to have a Tune from HP Tuners

repaxx
12-14-2009, 04:48 PM
just the ring and pinion is required to change to a 4.10..

everything else can stay

Does this one apply on changing from 4.10 to 3.42 ratio?
By the way I have a 4x4. How big is the job if I do this?:confused:

the roadie
12-14-2009, 06:03 PM
By the way I have a 4x4. How big is the job if I do this?:confused:I wouldn't even try. You have a rare and very useful ratio for towing or offroading. But changing the FRONT differential is a true bear of a job. Have you looked where it's bolted to? Consensus is that you'd never get a payback on fuel economy in a reasonable time.

repaxx
12-15-2009, 12:10 AM
Thanks for the info. I didn't know it is rare to have 4.10 to 1 rear axle ratio. But coming from a person with almost 15,000 post, I wouldn't have any doubt at all. It is settled then I will keep it and just put up with 400Km/tank fuel economy. Thanks again!!! :thx

ScarabEpic22
12-15-2009, 12:20 AM
Thanks for the info. I didn't know it is rare to have 4.10 to 1 rear axle ratio. But coming from a person with almost 15,000 post, I wouldn't have any doubt at all. It is settled then I will keep it and just put up with 400Km/tank fuel economy. Thanks again!!! :thx

Come to the mini-Vancouver meet on Jan 3rd and drive a tuned I6, get better mileage and more power. Im not sure if Ill have my 02 I6 w/3.73s or my SS, kinda depends if I get a hitch mounted ski carrier for my SS but you're welcome to come take a ride with me. Most likely Ill have the 02 as Ill throw the ski box up there.

Plus for better mileage you'd want to go with 3.42s not 4.10s