What parts/kits are needed to change 3.73 front and rear axle gearing to 4.88 for 2004 silverado 4×4?

I’m trying to change the axle gearing of my truck from 3.73 to 4.88 by myself since i purchased some 35" tires. can somebody tell me the new parts/kits needed to do this? i might search a local junk yard first or buy parts online instead of dealing with an autoshop. help is appreciated.


3 Responses to What parts/kits are needed to change 3.73 front and rear axle gearing to 4.88 for 2004 silverado 4×4?

  1. Christopher May 24, 2010 at 2:29 pm #

    If you have never done this before, I wouldn’t recommend it. There are specific clearance tests that need to be done. You can’t just remove one and put it back together. Lateral run out needs to be measured, inner bearings need to be shimmed, and the ring gear backlash needs to be correct or the rear end will howl and not last very long. There is also the fact that this is a 4×4 and both axles need to be the same gear ratio or one can cause damage to the other when in four wheel drive.
    These are things you need to consider prior to replacement.
    The parts that will be needed are the ring and pinion gear set, the pinion seal, both axle seals, and a crush sleeve that is a one time use sleeve that goes between the inner and outer bearing on the pinion shaft. The inner bearing is pressed on the pinion shaft.
    I wouldn’t recommend salvage yard parts for this, unless you are going to replace the whole axle from brake backing plate to brake backing plate.
    Your best to leave this to a specialist. Hope this helps and good luck. Christopher

  2. asf06 May 24, 2010 at 2:29 pm #

    first, you need to know your axles:
    if its a 1500 idk about the front ifs shit, but the rear is a 10 bolt
    if its a 2500 im pretty sure it’s a dana 44 front with a 9.5" 14 bolt rear
    if its a 3500 idk about the front (maybe a 60) with a 10.5" 14 bolt rear
    double check this (‘im not sure about the chevy fronts) to verify

    for the front axle, you need to check to see if it is a high or low pinion. (HP driveshaft connects at top, LP driveshaft connects at bottom) that will determine what parts you need. if it is a high pinion you will need reverse rotation ring and pinion gears. i don’t know where to order chevy parts (im a jeep man), but you need the ring and pinion gear sets to match your axle in your truck. i would reccomend the Yukon gears. they are the best out there, but the’re pricey though. you will need axle rebuild kits when doing this. the kits come with new bolts, bearings, shims, loctite, mustard, etc. with the gears you purchase it will give you an instruction book with all the specs needed to complete the job.

    as far as tools are concerned, you will need vernier calipers, the dial gauge (can’t remember what it’s called) but it measures backlash. an impact wrench would be helpful. you also need a socket big enough for the pinion nut.

    if you choose to go the junkyard route it will be a pain in the ass finding the right R&P for your application. i think only the duallies with the big 14 were geared down to 4.88s. most of what you need needs to be new anyways.

    i don’t really know that much about chevys or regearing, but i hope this helps. i would check with a mechanic or a local 4×4 club for more advice.

  3. Sten May 24, 2010 at 2:29 pm #

    If you try to use a gearing from a junk yard. Use the same shims as it had and don’t try to re shims it or you wasted your money. An worn gear can’t get the correct contact pattern that it should have and if you try to fix an bad pattern and you get it done with new shims it will wear down the gear very fast when the gear pattern are changing. Anyway a junk yard ain’t the right place to search for a ring and pinion setup. Get new stuff if you want to re gear. And a little tip, don’t try to make it your self if you never done it before. Try to get an pal that have done it before to help you out for the first time and you can see how it’s done and remember the backlash and if you don’t know what I’m talking about. Just forget it and get it done by an Professional mechanic.