Discussion in 'General Chevy & GM Tech Questions' started by catmechanic07, May 15, 2012.

  1. catmechanic07

    catmechanic07 Former Member

    I am considering the task of re-gearing. I will be tackling this process on my own. My question: On my 2009, I currently have 3.73 gears. Can I go up to a 4.10 or 4.56 ration in the same OEM housing? OR is the 3.73 the largest ring gear that will fit into that housing. I am asking about the front carrier, I would assume the rear housing should offer plenty of room. Why Im asking, I just replaced the front carrier in mine and have a carrier sitting at work. If I can get the new ring gear in that housing, Ill replace that since its just siting there. Ill also have to repair the housing (reason for removing). FYI.....this carrier is SOOOOO easy to change out a monkey coould do it.

  2. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I don't know about a 2009, but on my 04 the OEM housing was re-used both front and rear.
  3. Boonduff

    Boonduff Rockstar 4 Years 100 Posts

    If you haven't set up a ring and pinion by yourself I really recommend you have a pro do it or at least have an experienced helper. I say this because it's not just a plug and play operation. The contact pattern and backlash need to be with-in spec or you'll eat up your new gears in very little time. Concerning the housings, yes you can reuse your current housings and you also can reuse your current differential cases.
  4. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    I'd agree with Boonduff's comments. I've not done it before and when I looked into it I realized that it's not just pure science ... it's both art and science. What I mean by this is there's no precise measurement (science) to which the shims have to be set for a given vehicle; it' a tolerance range. Thus, the contact pattern has to be looked at and adjusted (art) by someone who has a good grip on what's correct.

    Had it been pure science I'd have done my own work, but it isn't...
  5. steved

    steved Former Member

    The housing will take the change, but the differential carrier (piece the ring gear rides on) may need changed in order to take up the slack for the smaller pinion gear (the carrier moves the ring gear closer to the pinion because the pinon gets smaller with the deeper the gear set).

    It not a hard process if you've done mechanical stuff before...but it will be time consuming the first time around. I can't remember if all the AAMs have side adjuster on the carrier, but if so the only shims needed are on the pinion. There are special setup bearings, special spanner tools, etc...and they definitely help. We made some of our own. My father and I were of the mind at one point that differentials are "special", then we decided they are nothing more than a gear box and we rebuilt a Corp 9.25, the rest came easy after that first one.

    My only bit of advice, pull the entire differential out of the truck and work on it while its sitting on jack makes life much easier when you're not laying on your back trying to guess patterns.
  6. aloxdaddy99

    aloxdaddy99 Epic Member 5+ Years 1000 Posts

    There aren't many things I won't try to fix on my own. The diff's and tranny are 2 I would leave to someone who know's what they are doing.
  7. catmechanic07

    catmechanic07 Former Member

    LOL......Im a diesel mechanic. I rebuild engines, transmissions, and rear ends all the time. I know all about the backlash and shimming process. Then again, Im sure it will be a little different in a pick up compared to a tractor trailer. All of our rears are Eaton, Spicer (which was bought out by Eaton), Rockwell (Meritor). The transmissions are various but mainly Eatons or Rockwells. Engines are Cats, Cummins, Detroits, Navistar, Mack, ......pretty much anything comming or going.

    All I wanted to know was if the ring gear would even fit inside the 3.73 housing. I'll make a call to a few people around here and the dealer to make sure. Im thinking about doing a 3" body lift and running 37's or 38's. May eventually swap out the 6" BDS lift and throw a custom 14" lift under it. WHO KNOWS!!!!

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