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Thread: rearend shot

  1. #16
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    Okey-dokey,

    Got to the blazer and snapped some pix. I said foggy memory, and sure enough,
    it's a 7.5.

    Has those type tabs on the bottom and no swells at the diff.

    Forgot the key of all things and couldn't access the glovebox.

    Thanks to all. Now, off for the 3.42s. Thanks blazin4low!

    Btw, is there a way to tell if I need the "thick" ring or not without opening the rear?
    Again, forgot the key and couldn't get at the box for codes, if it's even there.

    Thanks again to all!
    Last edited by 01sport; 11-04-2010 at 03:44 PM.

  2. #17
    5.7L VORTEC 350 blazin4low's Avatar
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    only way to tell is to find out what sixe gears you have now......3.23 and up you have the 3 series and don't need the thick gear, any thing smaller than 3.23 and you have a 2 series and would need the thick gear to go with a taller gear set
    http://i158.photobucket.com/albums/t114/VortecBlazer/sidredo.jpg
    Tuned by Bland Tuning
    Transmission built by Transbuilderguy on FSC!
    Marine Intake swap by me

  3. #18
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    Quote Originally Posted by blazin4low View Post
    only way to tell is to find out what sixe gears you have now......3.23 and up you have the 3 series and don't need the thick gear, any thing smaller than 3.23 and you have a 2 series and would need the thick gear to go with a taller gear set
    Now I gotta remember the key and get the codes. Or open it.:p:

  4. #19
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    The 8.5 is the way to go. I have an 85 2dr blazers. Stock suspension, 389 cubic inch sbc making 530 hp, 350 trans with 3500 stall and transbrake, plus a bigger driveshaft. The stock 7.5 rear and driveshaft didn't make through the first burnout in the driveway. I found my 8.5 bone stock on eBay. Bolted right in, but I did have to make one hard brake line and weld the new e-brake bracket to the frame. I could have bolted it in but I like to weld. Anyway back to the strength of the rear. My blazer with the still stock 8.5, 3.08 gears( only 2 choices 3.08 or 3.42), bf goodrich t/a radials 255/60/15 not launching off the transbrake will pull the drivers side front tire about a foot off the ground. If I launch off the transbrake I just do a massive burn out. At 65 mph my engine turns about 2700 rpm. The only reason to go with a 9" is if your gonna make Stupid amounts of power and tub out your truck. The strength of an 8.5 is comparable to a 12 bolt. And if for some reason the 8.5 fails theirs tons of parts out their to beef em up to the point where they'll run with a 9". Now 8.5's do require some special treatment. Just like an engine if it runs without oil it ain't pretty. They require gear oil made just for lockers. If that rear wasn't stock in your truck and someone put regular 80w 90 in it, failure isn't far away. Like I said before I dog the heck out of my blazer and the still stock 8.5 is holding up just fine. Hope I could be of help to someone. I'm also the new guy, my first ever post on a forum!

  5. #20
    5.7L VORTEC 350 blazin4low's Avatar
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    all posi differentials require an additive to the gear oil for the clutches

    if you have an open diff or a zexel worm gear style posi you don't need the additive
    http://i158.photobucket.com/albums/t114/VortecBlazer/sidredo.jpg
    Tuned by Bland Tuning
    Transmission built by Transbuilderguy on FSC!
    Marine Intake swap by me

  6. #21
    Zombie Killer 6SpeedBlazer's Avatar
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    Quote Originally Posted by blazin4low View Post
    all posi differentials require an additive to the gear oil for the clutches

    if you have an open diff or a zexel worm gear style posi you don't need the additive
    not true

    the Stock G80 Gov-Lok has clutches and does not require friction modifier.

    additionally GM said to add the friction modifier to the zexel units. this helped to prevent the "rusty nails" sound from the helical gear style differential.

    For those that dont know the friction modifier actually LOWERS the coefiecient of friction in the gear oil so that the clutches can slip more. This process in its self is the complete opposite of what is trying to be accomplished by adding a POSI to a differential.

    My eaton HD posi unit calls for friction modifier and i opted not to run it. That thing is tight and will chirp the tires when im making sharp turns.

  7. #22
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    Got the codes out of it. ID'd the 7.5

    3.42 in it now.

    Still decoding to see what traction device it has.

    Like I said, I haven't opened the diff yet. No time, other truck down, work, etc.

  8. #23
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    Update: Other truck DOA for now. Got the diff opened on the blaze, and carrier bearings detonated.
    Bearings were laying in the bottom and the race is haning under the cap on driver's side.
    Passenger side is loose.

    A few teeth on the ring gear have sharp edges from chewing the bearings. It was only drove 75-100 feet after the bearings went. I know the advice will be to replace them, but I have to get it on the road ASAP.

    I plan to pull the carrier when I get more time available. (Which will be soon.) I plan to pull it, remove any sharp edges from the teeth, have new bearings pressed on.
    I understand this is not the recommended method, but circumstances dictate transportation to work.

    My questions are: How feasable is it to go this route and "get by"?
    What detrimental effects would be expected?
    I know the shims aren't reusable.

    Any thing else I should know?
    Last edited by 01sport; 11-14-2010 at 11:40 AM.

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