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Stock Gears in rear...which ones?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89k5blazr, Jul 28, 2002.

  1. 89k5blazr

    89k5blazr Registered Member

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    I have a 1989 K5 Chevy Blazer 5.7 V8 with Auto Trans... does anyone know the gears in my rear or know a really easy way to find out (like is it written somewhere or something)???????
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    It will likely have 3.42's or 3.73's. Those were both prety common ratio's in 89. There are 'ratio' codes listed on the glovebox door, but the best way to be certain is to pull the cover and read the ratio right off the edge of the ring gear. The diff could probably use a service anyways...

    Rene
     
  3. 89k5blazr

    89k5blazr Registered Member

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    actually, the reason i ask this question is because i took off from a stop tonite and the truck moved about 3 inches and a loud thunk and the truck wouldnt move, i put it in 4wd and moved to a safer location and repared the U-joint that had broken and i put it in drive and i moved and then there was a loud grind then i would move then a loud grind and so on.... my ignorant guess is that some teeth got chipped off and when the gear gets to that location it spins free and "grinds" until it catches the rest of the good gear... Does this sounds right? Can i fix this my self? I was just thinking about buying a junk yard rear and swapping it in, but i thought i would ask you guys if there is a cheaper alternative? If it needs to be professionally serviced what kind of $ are we talking??? -thanks!-
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Junkyard rear is the cheapest.

    If it was me...it's 3/4 ton time! I replace my 1/2 ton axles, broke them, and thank god I already had the 3/4 ton stuff waiting in the garage.
     
  5. steve85fla

    steve85fla Registered Member

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    Pull the diff cover and assess the damage. If you get a junkyard rear you might have to rebuild it anyway, so I would fix the one you have. Labor around here is about $250. to install a ring and pinion, plus parts. I have bought from West Coast Differentials and had good service, alot of people use Randy's Ring and Pinion and like them. This is a good time to put in a locker or some kind of traction device if you want. One word of caution, I would not do this by myself for the first time, the gear set-up has to be precise. Best if you have a friend who has the dial indicator and experience and work with him, otherwise find a good local shop and let them do it. You might ask the board if anyone has a good reference in your area.

    Good Luck!
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    A buddy of kne bought an 89 blazer a couple of months ago and after having the truck for 3 days the 10 bolt rear was making some wierd noises...
    He pulled the cover and all looked good until he pried gently under the ring gear and the whole carrier moved up and down about 1/4" or more. The carrier bearings were gone...
    His truck is currently geting 3/4 ton axles and a 4" lift.

    His ratio was 3.42, 350 TBI, 700R-4, and 31's.

    I'd swap in 3/4 ton axles with better gears...sinking money into a 10 bolt isn't too smart. For what it would cost to rebuild and add some stronger parts you could buy a 14 bolt and front D44 or 10bolt and swap em under the truck. At least with the 14 bolt you will likely never have any problems.

    Rene
     
  7. testosterone

    testosterone Registered Member

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  8. 89k5blazr

    89k5blazr Registered Member

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    cool... the glove box shows a GU4 which means its a 3.08. I yanked the rear out and opened up the cover and OMG the ring gears is so messed up its not even funny, i was picking about 20 small chunks of metal out of the fluid. The pinion is messed up too. Tomorrow i am going to call some junk yards for a rear.. i would do an upgrade but $ is tight and its got 174k miles on it and by making one part stonger, it makes the weaker parts break...so i am going to stick with a stock rear.... THANKS!!!!
     
  9. BJarvis354

    BJarvis354 Registered Member

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    So I have been researching this since I read this thread to figure out what I have and I have been worried that my rear had the "stock" 3.08 gears...Lo and Behold the codes say I got 2.73! /forums/images/icons/blush.gif Damn no wonder my tranny is working so hard on the highway with my 32s. I been missing out on that lowend torque too. So I need some advice on getting this fixed. Anyone know of a good shop in NYC area? I don't think I will attempt this myself...or could I?

    Brady
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    The easiest way to do it is to find someone parting a K5 out, and get both the front and rear axles. Somewhere along the lines of $400 isn't bad, but I've picked up 10 bolt pairs for $200.

    It's not a real hard swap, slightly time consuming.
     

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