Differential, what model

Discussion in 'General Chevy & GM Tech Questions' started by mrsideways, Apr 6, 2010.

  1. mrsideways

    mrsideways New Member

    2007 Silverado WT 5.3 (new body) with the towing package and a 3.73 (LSD option). Stock LSD became real hit or miss just a few thousand miles into owning it and now it's stopped working all together I've tried and tried to get the dealer to replace this thing but I either get the "could not duplicate" or "it works fine". Short of taking a service advisor for a drive in the rain and roasting one tire till the cows come home I think I've gotta purchase aftermarket. So I'm trying to dig up aftermarket and trying to figure out a way of identifying what is there in order to purchase something. Can anyone help point me in a direction. The Eaton Application guide gives me what appears to be 2 options.
    Page 1
    7.5/7.6 or 8.5 10 bolt C-clip.
  2. Loggerhead Mike

    Loggerhead Mike Rockstar 100 Posts

    call the dealers parts counter with your vin. they will be able to tell you what side diff you have. most likely a 8.5

    My advice as a mechanic at a gm dealer, you need to tell the service writer to take a ride with you and do exactly what you said...
  3. mrsideways

    mrsideways New Member

    Thank you very much. Think they'll claim user abuse and void the warranty? LOL
    It was very frustrating when it was failing as it would remain open and spin a tire for a moment then rapidly lock and kick the back end around. I'd say boardline dangerious in the rain. Now it just spins one for as long as you'd like.
  4. doug_scott

    doug_scott Rockstar

    I don't think that was it failing, that is how the locking diff works. If you have a G80 diff, it is a locker type, one wheel will start to spin, and at a set mhp difference it will lock up, if you spin it up too fast, it will not lock up at all. There is a an operating range the lockup will work in, something like 8 mph to 24 mph difference (do not recall the exact numbers), any higher and no lockup.
  5. mrsideways

    mrsideways New Member

    Well it doesn't do that anymore. But back when it would lock, it would lock and stay locked shuttering the inside tire in parking lots untill I took it out and drove it above 20 mph or so. Something I did notice is a rattle from what appears to be in the axle case. It's very hard to duplicate. I've put it on my lift and gone around with a mallet trying to duplicate it along with tightening everything I can access with no result. Sounds exactly like a loose trailer hitch, but I removed the hitch and the noise stayed. Happens and is very pronouced on brick roads and dirt roads. Again I get the same responce from the dealer as they couldn't duplicate it. I'm now convinced it's coming from the axle housing as the diff never locks I think it's something broken. I also noted a pronouced fuel mileage decrease about the same time as the diff stopped locking. I used to get 18-19mpg towing on the interstate, it's fallen to 15-16mpg. I'm wondering if this is all related and I've got something broken/binding in there.
  6. doug_scott

    doug_scott Rockstar

    I would think that if you have a hoist (and the dealer surely does) you should be able to put the truck on the hoist, raise all wheels off the ground, pull the parking brake cable by hand for one wheel, and then start the truck, and let it idle in gear. That should be enough to enable the locking diff. I doubt anything the rear end could reduce mileage by that amount though. Any tightness in the rear end that could be enough to reduce mileage would not be long before it became catastrophic.

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