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  1. #1

    Default 2006 4x4 burb - 4.10 gears to 3.73

    I think I posted in the wrong area the first time so here it goes!

    Have a 2006 burb with 4 speed tranny, Z71, off road package with 4.10 gears and would like to know if I can put the 3.73 gearing in it. A few notes:

    • Estimated cost?
    • What will it do for gas mileage
    • What will the RPM's look like
    Any help would be great

    Tom

    ---------- Post added at 03:55 PM ---------- Previous post was at 03:53 PM ----------

    Sorry, has 5.3 engine.

  2. #2

    Default

    I would be surprised if it has 4.10 gears. It is a half ton (1500 series), correct? Pretty sure 3.73 was the lowest from the factory. Of course it's possible someone changed them.

    Anyhow, assuming it does have 4.10s, swapping to 3.73 would probably cost $1000 for two axles give or take a couple hundred depending on your local labor rate and what else you change - bearings, seals, etc.

    Dropping from 4.10 to 3.73 would reduce your RPMS by about 8% in cruise/TC locked conditions. Actual MPG improvement will depend on many things. Driving conditions (city/highway), driving style, tire size, etc. The more time you spend at high cruising speed, the better the benefit. Long and short, you will need to drive many many highway miles to pay for it. Money would probably be spent on a custom tune. More power, better MPG for a couple hundred bucks or so.

    What size tires do you have, and do you plan to change them?
    When you hear hoofbeats, look for horses not zebras.

  3. #3
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    stephan's Avatar
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    Default

    Hey Tom, welcome to the GM truck club.
    I do not know your tire diameter so I can only give an example for what I think they might be.
    At 70mph with 4:10 gears & 32" tire diameter, your engine rpms should be approximately 3100rpms.
    3:73 gears @ the same 3,100 rpms would give you 77 mph with the 32" tires.
    There are rpm/gear ratio calculators online. The one I have is for 1/4 mile only, so your info is at the very low end of my slide rule.
    You will definitely gain better mpg with the higher gears, & especially if you keep it under 65 70mph.

    Labor for installing gears varies from shop to shop & there is also a wide disparity from one part of the country to another so you will have to call shops in your area to find out the prices.

    edit** Go to this link & plug your vin# & rpo codes & it will tell you what gear ratio was put in it originally, but like 2cor said someone could have changed gear ratio if you didn't buy it new.

    http://www.compnine.com/vid.php

    Last edited by stephan; 11-27-2010 at 06:31 PM. Reason: more info
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  4. #4

    Default

    I dont think its gonaa make a huge differents and remember to change the front ones too if u do the swap or u will be breaking gear cases as soon as u hit 4X4 !!!!!!

    1996 Suburban K3500 SLT DUALLY
    1988 Camaro RS 383 stroker LT1
    1992 32' Aero-tek Race Boat, 600 CI BBC
    WE CAN STICK A DIESEL IN ANYTHING
    SPECIALIZED IN CUSTOM CONVERSIONS OF ANY KIND
    Scott:glasses:

  5. #5

    Default

    Welcome to the club. I believe 4.10's were a optional gear in your Burb. Look in your glove box for the code GT5, thats a 4.10 gear. GU6 is a 3.42 and GT4 is 3.73's. I agree with the above that its not really worth the cost to go from 4.10's to 3.73's. Maybe if you drop down to 3.42's, but you will loose that low end power for trailering, but if you spend ALOT on time on the highway than it may pay for itself.

  6. #6

    Default

    If saving money is the final goal I think you'll have to drive a lot of miles and burn a lot of fuel to recoup the cost of the swap and start saving.

  7. #7

    Default

    I looked at the code before I posted and yes it does have the 4.10 gears. It was a special order vehicle. Thanks for the info and could you provide some feedback on custom tune-ups that would work for the Burb with the 5.3 engine. It does have P265/70 17 tires and they have a lot of tread left so not planning on changing for a while.

    Tom

  8. #8
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    mfleetwood's Avatar
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    Default

    This link will help you see the differences in gear size and should help you visualize what has been said. I am sure someone will answer your custom tune questions shortly...there are plenty of experts here but I am not one of them.

    Good luck!

    http://www.4lo.com/calc/geartable.htm


    Mike (Denver, CO) - 2008 Sierra 1500 Z71 SLE 5.3L 4WD

    SUSPENSION: Rancho 4" Suspension Lift; Rancho RS9000XL Shocks; Rancho Skid Plates; Rancho MyRide Wireless Shock Controller;
    TIRES:
    BFG All Terrain KO 315/70/17
    DRIVE TRAIN: 4.56 Gears; Detroit TrueTrac Differential; True Cool 40k Transmission Cooler
    PERFORMANCE: DiableSport Predator Tuner; Custom Tuned by Diablew; Magnaflow Exhaust; AFE Cold Air Intake
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  9. #9

    Default

    What kind of driving do you do. The 5.3 loves to rev, the 4.10 gears are ideal if you do mostly around town.

  10. #10
    Jr. Apprentice
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    Default

    There is more to consider when deciding on the viability of the swap. What does a guy want? Some people spend that much money on wheels and a body lift.
    I've seen a lot of people want to make this change and there's always people shooting them down as not being economically viable.
    There's also the fact that running your engine at lower RPM's for the rest of it's years just might save you a buck or 2 in the long run.
    One of the best things I ever did was switch from a granny 4 speed to a 5 speed in my 1989 GMC 6.2 diesel C2500. It paid for itself more than once in the next 600,000 miles.

    By the way I am wanting to swap the 3.73 differentials in my 1998 K2500 Suburban & 1995 Tahoe 6.5 TD's to 3.42's.
    And the 4.10 in my 1994 6.5 TD K3500 with 5 speed to a 3.73.
    Quote Originally Posted by 2COR517 View Post
    I would be surprised if it has 4.10 gears. It is a half ton (1500 series), correct? Pretty sure 3.73 was the lowest from the factory. Of course it's possible someone changed them.

    Anyhow, assuming it does have 4.10s, swapping to 3.73 would probably cost $1000 for two axles give or take a couple hundred depending on your local labor rate and what else you change - bearings, seals, etc.

    Dropping from 4.10 to 3.73 would reduce your RPMS by about 8% in cruise/TC locked conditions. Actual MPG improvement will depend on many things. Driving conditions (city/highway), driving style, tire size, etc. The more time you spend at high cruising speed, the better the benefit. Long and short, you will need to drive many many highway miles to pay for it. Money would probably be spent on a custom tune. More power, better MPG for a couple hundred bucks or so.

    What size tires do you have, and do you plan to change them?
    1994 Chevy 6.5 turbo diesel K3500 4x4 long bed, crew cab, 5 speed 235,000 miles

    1995 Chevy Tahoe 6.5 turbo diesel 4x4

    1995 Chevy 6.5 turbo diesel C2500 2 wheel drive, long bed, extended cab

    1996 Chevy K1500 Suburban 6.5 turbo diesel 4x4 245,000 miles

    1998 Chevy K2500 Suburban 6.5 turbo diesel 4x4 235,000 miles

    !991 International box truck, 4700 low pro, Spicer 6 speed, DTA 360, 18' box with side door. 500,000 miles, for sale $3000

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