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new gears necessary?

Discussion in 'GM Powertrain' started by hutch_pt, May 9, 2008.

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  1. hutch_pt

    hutch_pt New Member 100 Posts

    I have the 3.73 posi rear end in my truck, and want to go from 33" tires to 35" tires at the next time they are due. Do I need to put new gears in the rear end? I have heard 4.10 or 4.56. Which would be better? Also, do I need to change the front differential gears as well, if possible?

    Thanks
  2. 95CTburb19

    95CTburb19 New Member 1000 Posts 100 Posts

    If your upgrading to 35's then you really should do the gears. And you will need to do front and rear otherwise it will just bind and break everything. I would probably do 4.56 because then if you ever want to put on tires bigger than 35's you don't need to worry about buying gears a second time.
  3. Pete95Sierra

    Pete95Sierra New Member 1000 Posts 100 Posts

    i would go with exactly what dan said... go 4.56's and you will need to do the front too
  4. dwill3015

    dwill3015 New Member 1000 Posts 100 Posts

    X2-what he said!
  5. finalday7

    finalday7 New Member 1000 Posts 100 Posts

    If 500-800 bucks isn't in the budget right now then you don't HAVE to change them right away. A change in the near future would be a safe bet.
  6. hutch_pt

    hutch_pt New Member 100 Posts

    $500-800 installed or just for the parts? Dad's a heavy equipment mechanic, and he has helped me with most of the stuff for the truck, but he has only done two rear ends in a pickup in his 30+ years as mechanic. Does it in cranes all the time, but very rarely a truck. How difficult is it to install the gears ourselves, or is it best to have a garage/shop do it for me?

    Thanks
  7. tbplus10

    tbplus10 Super Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    If dads a Heavy Eqpt. Mech. with a gear change or two under his belt he should be able to tackle this job with you. Plan for a whole day of work to do both diffs.
    Remove one gear set at a time, swap the gears, trial fit and shim as required. Probably want to replace the axle seals at the same time (cheap insurance). When purchasing the gears buy a master install kit (axle seals wont be included and will need to be purchased separately), and a gallon of your favorite diff. lube.
    I'd recommend 4.56's for 35" tires.
    $500 to $800 sounds like parts only for both diffs, install with parts is usually closer to $1100-$1200

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