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rear diff trouble

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by GMC4by4, May 30, 2000.

  1. GMC4by4

    GMC4by4 Registered Member

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    My 89 Jimmy has had a high pitched whine in the rear for about a year now. The mechanic said they all do it and if I didn't want to buy a new one, to just get used to the noise. Well, now there's some grinding and vibration sounds with it. It's full of oil and all U-joints and tires are new. Is it best to replace the gears and seals or replace the entire rear end? Anyone with similar experience? Anyone have a spare 3.73 posi rear they'd like to sell? Thanks.

    -Rick
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    A whine is usually gears, I would have a rear-end specilist look at it and then see what they say. You probably need new gears or it just may need a readjustment.

    One other thought, ever change your gear lube?? (no offense)

    Mike
    82 GMC Jimmy "Emmett" "Built for function, not for beauty!"
    IN TOO DEEP Off-Road Club
     
  3. Oil Man

    Oil Man Registered Member

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    I can't tell you if your diff is done, but when you get it fixed you might want to put a Mag-hytec diff cover on it. They are not cheep but they are great. They hold a lot more oil they cool about 45 deg F more than the stock cover, they look great, Have a dipstick and two magnets in it. And have a drain plug. Mag-Hytec recommends the Lubrication Engineers #607 gear oil that has shown about 33 times less wear than Amsoil synthetic oil. Cost is about $200.00 for the diff cover and $9.50 per quart of the LE gear oil.

    Sincerely, Kevin
     
  4. GMC4by4

    GMC4by4 Registered Member

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    I have only had the truck for a year, but I doubt the previous owner ever changed the gear oil. I asked the dealer what it would cost to totally rebuild the rear axle. Ready?... $1250-1400.00 worst case!! Looks like I'll be looking for a 12 bolt in the junkyards.

    -Rick
     
  5. Emmettology 101

    Emmettology 101 3/4 ton status

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    Someone just had a 12 bolt with a Detroit posted for sale for around $400! That is a good deal, and I believe they said it was only about a year old since the rebuild and it had about 8K on it.

    Good Luck! and stay away from dealer prices!

    Mike
    82 GMC Jimmy "Emmett" "Built for function, not for beauty!"
    IN TOO DEEP Off-Road Club
     
  6. 6.2Blazer

    6.2Blazer 1/2 ton status

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    The dealer cost for rebuilding an axle is incredibly high due to the costs of factory components. When my Blazer was stolen and the rearend grenaded, the insurance company wanted a certified GM dealer to writed the estimate for repairs. It turned out to just under $2,000, which was replacing everything except for one axle shaft! Needless to say, I talked the insurance adjustor into just cutting me a check for the amount, and then bought all aftermarket parts including 4.10 gears, Detroit TruTrac, alloy axle shafts, and all bearings and setup parts. You can't beat getting much better parts for substantially less money. The same dealer installed the parts and the labor was inline with other rearend shops in the area. There was enough money left over to buy and install a front posi and 4.10 gears.........
     

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