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Rearend noise help!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by RAY, Feb 12, 2001.

  1. RAY

    RAY 1/2 ton status Premium Member

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    I just swapped my 10 bolt for a 12 bolt mainly for the gear ratio 3.73 from a 2.73. The problem is now I'm getting a humming noise whenever I am on the gas. If I let off the gas the noise goes away, but once you step back on the gas it comes back. also the pitch of the noise gets higher as the speed increases. Does anybody know what my problem could be? Any ideas would be greatly appreciated.
    Thanks,
    Ray
     
  2. reddog64

    reddog64 1/2 ton status

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    Does it do it at a certain speed??? Does it have a vibration... I think your driveline might be the culprit... Check for a worn u joint... or possibly a bad bearing on the axle... I'd say the driveline is the humming you hear...

    Um... yes officer I know it's too big...
     
  3. Wheels

    Wheels 1/2 ton status

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    Could be several things. But from the sounds of it, noise during load but gone in coast, ring and pinion wear, carrier bearing wear, or pinion bearing wear. Did someone change the gears out to make it a 3.73, or are they stock gears? If they changed gears, probably didn't get them set up right or didn't break them in properly. Not much you can do to eliminate the noise now except tear it down and rebuild it. You can pull the cover and check the wear on the ring teeth, this would give you an idea. The rest would require a complete tear down to gain access to the components. Just out of curosity, did you put in new u-joints? Try re-indexing the u-joint at the diff yoke (disconnect it from the yoke and rotate the shaft 180 degrees and reconnect it to the yoke). Sometimes this helps depending on how bad the humm is. Anyone else got ideas???
     
  4. lowlevell

    lowlevell 1/2 ton status

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    Did you rebuild the axle when you swaped it?If so, it might just need "broke in", or something inside is too tight/loose.Can't really help ya,sorry.

    One From None
     
  5. TX Mudder

    TX Mudder 1/2 ton status

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    My 12-bolt started making a noise a few days before the pinion bearings grenaded and the ring walked all over the carrier.
    Forward momentum ceased, obviously.
    Glad it's 4wd, I just put the tcase in 4hi and drove on the front axle till I swapped in a 14bolt.
    -- Mike
     
  6. RAY

    RAY 1/2 ton status Premium Member

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    Yes, I put in new a u - joint, but I didn't rebuild the rearend. the noise is noticeable from about 30 mph on up.
    thanks
    Ray
     
  7. Panther

    Panther 1/2 ton status

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    I gotta go with Wheels. Take off the cover and have a look.

    I have a similar (if not exactly the same) problem. I (with help!!) popped the cover and it seems to be the carrier bearings cause the ring and pinion look good but there was a little movement in the carrier..


    <font color=blue>"It's just a differentialator....Totally unnecessary" [​IMG]</font color=blue>
     

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