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Thread: pinion gear

  1. #1
    Join Date
    Mar 2008
    Location
    Fremont, Ohio
    Posts
    126

    Default pinion gear

    I have developed a whine in the rear of the truck that raises and lowers with with the speed of the truck. Is it as easy to change as it looks? Take the drive shaft out, unbolt the front yoke and bring the pinion gear and bearing with it? i have plenty of fluid in the differential. Any info would be greatly appreciated.
    1997 GMC 1-ton Dually 4x4 crew cab, 4.10 gears, homemade mechanical boost controller, 2.5" crossover pipe, 3" downpipe, 4" exhaust, 19 mpg thanks to the propane injection kit, Remote PMD, marine injectors, instant heat glow plugs and just turned 141,000 miles

  2. #2
    Join Date
    Feb 2007
    Location
    Baja California Sur Mexico
    Posts
    2,807

    Default

    Remove back cover, axels, carrier with crown wheel gear, drive shaft, pinion yoke, then it gomes out from the rear. If the noise is a fuzzy whine, and begins at around 30 mph, it is pinion bearing or bearing in the center of the 2 piece drive shaft if you have that setup. If the whine is clean and starts at around 50 mph and only with thottle, it is worn gears. This can sometimes be cured by moving the crown wheel away from the pinion a fraction.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban "F" VIN #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  3. #3
    Join Date
    Mar 2008
    Location
    Fremont, Ohio
    Posts
    126

    Default

    This noise is there at all speeds, hard to hear really when accelerating but it is there and definitely can hear it when coasting and stopping.
    1997 GMC 1-ton Dually 4x4 crew cab, 4.10 gears, homemade mechanical boost controller, 2.5" crossover pipe, 3" downpipe, 4" exhaust, 19 mpg thanks to the propane injection kit, Remote PMD, marine injectors, instant heat glow plugs and just turned 141,000 miles

  4. #4
    Join Date
    Feb 2007
    Location
    Baja California Sur Mexico
    Posts
    2,807

    Default

    Most likely the center carrier bearing for the drive shafts, lift both back wheels off the ground, run the engine in gear and listen under the truck.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban "F" VIN #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  5. #5
    Join Date
    Mar 2008
    Location
    Fremont, Ohio
    Posts
    126

    Default

    i just replaced that center carrier bearing last year but i guess that doesn't mean it isn't bad. i will check it out
    1997 GMC 1-ton Dually 4x4 crew cab, 4.10 gears, homemade mechanical boost controller, 2.5" crossover pipe, 3" downpipe, 4" exhaust, 19 mpg thanks to the propane injection kit, Remote PMD, marine injectors, instant heat glow plugs and just turned 141,000 miles

  6. #6
    Join Date
    Oct 2010
    Location
    Scugog Island Ontario Canada
    Posts
    203

    Default

    Pinion bearings are most often a rythmic noise.

  7. #7
    Join Date
    Mar 2008
    Location
    Fremont, Ohio
    Posts
    126

    Default

    i hear the noise as soon as i start moving and it gets worse as i get up to speed. there is no vibration of grinding, just a hum fro m the rear of the truck. Doesn't go away when braking or turning. hopefully next Saturday will be the day to tear into it and see if its really the pinion bearing.
    1997 GMC 1-ton Dually 4x4 crew cab, 4.10 gears, homemade mechanical boost controller, 2.5" crossover pipe, 3" downpipe, 4" exhaust, 19 mpg thanks to the propane injection kit, Remote PMD, marine injectors, instant heat glow plugs and just turned 141,000 miles

  8. #8
    Join Date
    Nov 2010
    Location
    Nashville
    Posts
    54

    Default

    Not to doubt the proper procedure was done, but the torque down of the crush sleeve and setting the proper bearing pre-load is critical to longevity and service of the pinion bearings. Need to make sure this is done correctly per specs to get the life out of the bearings.
    95 K2500 Suburban, orig owner, 101000 miles,F vin, Banks Stinger system in 2000 (EGT & Boost gages,air intake,K&N,chip), CAT reqd here, 3.73 posi, 4L80E w/mercon V semisynthetic, Flight Systems remote PMD (#9 res), new IP @78,000 under warranty,SSD cooling sys w/ Dmax fan upgrade @95600 and all new hoses. New main pulley & Fluidamper @99200. PMDCable extension to bumper @ 101000. Walbro FR pump w/prefilter. FloPro Crossover. Diamond Eye 4" exhaust and high flow CAT

  9. #9
    Join Date
    Mar 2008
    Location
    Fremont, Ohio
    Posts
    126

    Default

    Ok actually took the diff cover off staurday morning and pulled out what used to be a bearing. How i am still driving this thing is beyoud me and trust me i dont want to be driving it but i dont have a choice. My quetions is this, one of the places i called asked me what design differential i had. Evidently there is a 1st design and a 2nd design for that that year. Would there happen to be a code in the glove box that indicates what design i have? Is there any other way to know besides taking the VIN to the dealer? I really dont want to get the wrong parts especially since every parts store in town has to order what i need. Any help would be greatly appreciated. Thank you.
    1997 GMC 1-ton Dually 4x4 crew cab, 4.10 gears, homemade mechanical boost controller, 2.5" crossover pipe, 3" downpipe, 4" exhaust, 19 mpg thanks to the propane injection kit, Remote PMD, marine injectors, instant heat glow plugs and just turned 141,000 miles

  10. #10
    Join Date
    Oct 2010
    Location
    Scugog Island Ontario Canada
    Posts
    203

    Default

    Going to the dealer to verify by the vin is the best bet.
    The difference is the size of the rear pinion bearing-there were 2 different diameters available and bearing retainers and both retainers will fit the center housing.

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