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  1. #1

    Default re-gear questions for 08 Silverado

    Im hoping someone can give me some advice on re-gearing. I have an 08 Silverado 4x4 ext. cab with 5.3L V8. I have 7 1/2 inches of suspension lift and Im running 35 inch Toyo MT's on 20 inch rims. I have a catback flowmaster 1 in 2 out and a K&N CAI. I drove it on the highway for about a 6 hr. round trip and the transmission kept having to downshift when going up an incline. I have been considering re-gearing and have read on here to go with 4.56 gears. Does anyone know what this will do to my gas mileage and what kind of rpm's the truck will be running at highway speeds (70 to 80 mph)? Would I be better to go with 4.11's? My real concern is I do drive on the highway on small trips every now and then and do not want my engine having to run at 4000 rpms because the gears. Thanks for any help!

    Bobby - North Carolina
    2008 4x4 5.3L V8
    6" Suspension Lift and 1.5" Body Lift
    20x9 Ballistic Jesters w/35" Toyo Open Country MT's & 1.5" rear wheel spacers
    4:56 Yukon Gears
    Hypertech Speedometer Calibrator
    Baja style bed mount spare tire carrier
    Flowmaster 40 series dual exhaust
    Recon Smoked LED tails/3rd brake lights/black projectors w/switchback LED's in the corners
    N-Fab Nerf Steps
    K&N CAI
    No Fear Pedals
    Tint, Line-X bedliner, Window visors, Rear wheel well liners
    Painted front grill, bow ties and door badges, de-"lettered" tailgate
    Powder coated front and rear bumpers

  2. #2

    Default

    do you have the 4 or 6spd tranny?
    ROTARYENGINEPETE
    '07 GMC SIERRA SLT | Z71 | 4X4 | 5.3L FF

    LIFT:
    ROUGH COUNTRY 3" PREMIUM SUSPENSION LIFT + ADD-A-LEAF
    18" ATX THUG WHEELS
    33" NITTO TRAIL GRAPPLER TIRES
    EBC SPORT ROTORS
    EBC YELLOW STUFF BRAKE PADS
    LIGHTING:
    HELLA/VVME 4300K HID LOW BEAMS

    HELLA BLACK MAGIC OFFROAD LIGHTS
    ANZO USA PROJECTORS HEADLIGHTS
    ANZO USA LED TAIL LIGHTS
    ENGINE:
    K&N 63 SERIES INTAKE
    MAGNAFLOW CATBACK D.O.S.I.F.T. EXHAUST
    BULLYDOG TRIPLE DOG GT TUNER

    PULSTAR IGNITORS
    OPTIMA RED TOP
    DRIVETRAIN:
    YUKON 4.56 GEARS
    MAG-HYTEC DIFF COVER
    CORVETTE SERVO
    TRANSGO SHIFT KIT
    Z-PACK 3-4 CLUTCH
    REBUILT WARN XFER CASE
    BODY:
    RUNCOOL HOOD LOUVERS
    FULL WEATHERTECH VISORS/BUGSHIELDS
    DUPONT BEDLINER

    DEEZEE BLACK DIAMOND PLATE BED CAPS
    BULLDOG LOCKING SPORT FUEL DOOR
    DOOR MOLDINGS REMOVED
    CUSTOM WIRE MESH GRILL
    BUSHWACKER BOSS FENDER FLARES
    CB THRU GLASS RADIO ANTENNA

    5.5sec 0-60mph on pavement (5.2sec running E85), and a little less in 3 feet of muddy water

  3. #3

    Default

    Not sure...I will have to call chevy with my vin.

  4. #4

    Default

    I just checked with the dealer...it is a 4 speed transmission.

  5. #5

    Default

    Did you get any new info and make a decision? If you did what did you go with?

  6. #6

    Default

    i would recommend the 411's the you will be turning around 3k rpms near 80 mph and thats not just hard on the trans its self but also on your fuel mileage ive been doin some homework about getting an 6 speed planted into my older chevy i all ready have the 456's front and rear and a full posi out back and its a gas hog once im over 70 mph

  7. #7

    Default go with 4.11 gears

    i have the same set up 35 inch tires, 4.56 gears. 1st off the 4.56 gears cause the servcie brake system warning to be triggered. 2nd @ 65 mph i turn around 2100 RPMs. 3rd do you pull a trailer? 4th Gas mileage avg. is 14 mpg with Factory tuning & 13.5 with Hyper Tech Tuner installed.

    If i had to do it all over again i would install 4.11 gears.

  8. #8

    Default

    Ditto on the 4.11 gears. Shop around but the best prices I've found are at Randy's Ring and Pinion. They also have a lot of good tech on their website.

    http://www.ringpinion.com/
    Jim

    2004 SILVERADO 2500HD LS
    Pro Comp Leveling Kit
    285-75-16 Cooper ST All Terrains
    Pro Comp Programmer
    Bilstein Shocks
    Linux Bed Liner
    Tinted Windows



    Other rides:

    1967 Landcruiser <350 Chevy>
    1970 Camaro
    1990 Geo Metro Convertible
    2007 FJ Cruiser

  9. #9

    Default

    I say go with 4.56s. I have them and love em!

    Caterpillar, are you still having issues with your Service brake light?
    2005 Chevy Silverado Z71 in Black

    6" BDS Suspension Lift | 3" BDS Body Lift |17" Rock Crawler Stellies | 35" Cooper STTs | 4.56 Yukon Gears | AirAid CAI and TBS | Flowmaster 40s | HyperPAC Programmer


    2001 TJ Sahara in Sienna

    3.5" RE Suspension Lift | 33x12.50 Baja MTZs | D30/44 | ROKMEN Merc Front Bumper | Warn Rockcrawler Rear w/ Carrier | Warn M8000 Winch



  10. #10

    Default

    I went with the 4.56's and love them so far. I have not had them on the highway yet though. My abs light does come on when driving now, but Superlift sells a product to fix that, I have already ordered it and Diablo is making a custom tune for my handheld to adjust for the gears, since their handheld only adjusts for tire sizes on the nnbs trucks.
    MasterFoxscout, what kind of rpm's are you running at 70 mph?

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