How to: K2500 front rotor / disc replacement - 8 lug, 4x4

Discussion in '6.2 and 6.5 Technical Reference Library' started by WarWagon, Jan 6, 2010.

  1. WarWagon

    WarWagon Well it hits on 7 of 8...

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    The Haynes book misses this. After doing it and assuming the 2500 rotors just come off after caliper removal BS the book says - well another reason to burn that worthless book on the Bar-B-Q...

    You need more information when a decision needs to be made to do it yourself or sub it out.

    Took 3 days including 1 day to get extra parts. 1993 vintage brake lines were cracked by the calipers and the driver's side dust boot was filled with brake fluid.

    I usually do the passenger side first as it will have the most wear and bad parts that you have to replace on both sides. So if the passenger side needs it you get it for the driver's side. I was not happy when I discovered the brake fluid in the driver's side after putting new slider o rings on the passenger side... :mad2:

    The heavy 3/4 ton, 8700 LBS, 8 lug has different brake hoses than the lighter 6 lug version. They also appear to require hub removal and pounding out of rusty studs to replace the rotors (Brake Disc).

    Parts used:
    calipers
    brake hoses
    slider bolts for calipers
    antiseize
    rotors
    pads
    grease
    2 big containers of brake fluid
    15 MM 6 point socket - busted...
    Others have suggested that you make sure you can obtain new hub bolts...

    Lets get started.
    Raise the vehicle and support on jack stands.
    Use the trusty impact to remove the wheels.
    Use penetrating oil on the center axle bolt and knock it off with the impact.
    Hit the splines with penetrating oil.

    Remove the brake caliper.
    Seriously get it out of the way: remove the brake hose from it. Might as well flush the system while you are at it and this makes putting new slider o rings and seals in cake. ​

    Hit the 4 hub bolts with penetrating oil both by the bolt head and what you can get to with the caliper out of the way. The front bottom bolt requires you to spray it through the rotor vents. (You are tossing the rotors so what if you get some oil on them now? ):h ) You need to get to the rust end of the bolt and that is the hidden by the rotor side!

    Let the oil soak...

    A couple whacks on the axle should free it from the hub. Yes, with the hub bolts in.

    I suggest a deep well impact grade 15 MM socket to knock the hub bolts out. The light duty ones break even with a lifetime warranty and a big enough ratchet... Or hit them with an impact. Mine came out with a torque wrench length tool.

    If that wasn't fun...

    Now you get to remove the studs!
     

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    Last edited: Jan 6, 2010
  2. WarWagon

    WarWagon Well it hits on 7 of 8...

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    Stud Removal

    Get a bigger hammer!!! :hammer:

    Support the assembly by the brake rotor. Who cares if you screw up the old one. You don't want to screw up the hub bearings!

    I used a punch to knock out some studs and then just hit the studs directly. They came out faster with a direct hit. I would have felt better with a lug nut on it, but, there is plenty of room for a hit without messing up the threads.

    With the studs out change your supports to a higher height and carefully flip the rotor/hub assembly over. Being careful they don't just fall apart.

    Use a punch and the 4 hub notches to evenly pound the hub from the rotor.

    Line up the hub with the notches to remove the hub when it is loose.

    Clean up the studs with a wire brush.

    Install new rotor.

    I suggest use of lock tight on the stud heads as mine were slightly loose after pounding them in. Note: The splines on the studs do line up with splines in the flange. You may need to rotate the studs to align them as rust can prevent this. They will not go in if misaligned. Unless you have a really big press... (Wheel install knocked a stud loose until the lug nut tightened it up.) There may be a better way...


    I used wood blocks on the hub flange to support everything while pounding the studs back in with a punch.

    I cleaned and greased the axle seals both on the back of the hub and by pushing the axle out of the spindle seal.

    I then used antiseize on the hub bolts and reinstalled the assembly.

    Be careful installing the wheel as to not knock studs loose. Drive around the block and re-torque the studs in case they broke through some rust and loosened up. Then re-torque again after 100 miles or a week for the same reason.

    Notice the rust on the rotor deeper than the firepath can clean up? This truck has sat several times for a long time allowing the rotors to rust deeply. Then normal use cleans it up except where the rust pitted them. Aka: Lot Rot.
     

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    Last edited: Jan 6, 2010
  3. WarWagon

    WarWagon Well it hits on 7 of 8...

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    Other

    It is easy to remove the caliper rather than hang it out of the way. Brake fluid absorbs moisture. This lowers it's boiling point and can lead to brake fade. The water that condenses out will rust holes/pits in the calipers and wheel cylinders. This can cut and ruin a seal when new pads are installed. So flushing this old fluid and pouring the fluid, black cr@p, and water out of the caliper never hurt.

    Shown is beading the air from the dust boot by using a small screwdriver to pry the seal away from the piston. I wondered why the boot was full and didn't go down on it's own. Answer was being full of brake fluid. See how the dust boot is completely full looking? So the simple screwdriver air release caught a bad caliper seal. Around $22.00 wholesale at Auto Zone rebuilt and back on the road.

    This is also a good time to check brake hose condition on the older and/or higher mile stuff.

    Notice how easy it is to put in the AC Delco pad included hardware of 4 O rings and 4 dust seals while it is firmly held in a vise and easy access? This is worth the extra time required to bled the system! Esp. as I had to replace them anyway. Being out of the way for the hub removal helped a lot!
     

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    Last edited: Jan 6, 2010
  4. treegump

    treegump Romans 3:22-24

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    If I may add - make sure before you leave the store, that the hub they give you is GOOD. When this was done to my truck, the one I picked up from autozone was worse than the one we removed - it'll save time and money.

    Also, a question. If the truck has ABS, but I don't use the ABS (no fuse) - if its cheaper, could I just buy a hub w/o ABS?
     
  5. hereismylife

    hereismylife formerly j k auto

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    Also don't forget to repack your hub assembly. This way your bearings will last longer. This goes for the ones with abs.:thumbsup:
     
  6. whatnot

    whatnot Member

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    When putting the studs back in, use an old rotor and lay it on a solid surface. I never tried lining up the splines. That may be why you had the problem with them being loose.
    Pound them in as far as they will go, put nuts on them and tighten with an impact wrench. You may need to stop and pound them a couple times if they are going in hard. Don't over tighten them, if the nut stops turning, pound the stud so it doesn't spin.
    This way you can make certain they are in all the way. If they are not quite all the way in then you might end up with loose lugnuts after a while.
     
  7. ronale

    ronale New Member

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    Disc replacement

    warwagon
    GM's shopmanual doesn't show how disc/hub is assembled so I appreciate your photos. Always good to know how to do the job before you start.
    I am going to replace both discs on my Suburban 1996 K1500. Probably a HD edition (UV-joints are larger than standard K1500). Label in the glove box specify JD7 - disc 12.5"x1.26".
    Searching the web for part numbers makes me a little bit confused.
    If this is the same size of disc as in the photos, what is AC Delco part.no.?

    ronale
     
  8. WarWagon

    WarWagon Well it hits on 7 of 8...

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    Your dealer can match your VIN to the proper part numbers. Call some dealers and ask for a quote and part number. Sometimes their price is close enough to the local parts house or more important – IN STOCK! The JD7 is the heavy duty 1 ton or 4x4 brake system. Used on whatever GM wanted to though. For example brake lines and the hydrobooster is different from the JD6 system. JDx is located in the glove box with all your option codes for the curious.
     
  9. mgray

    mgray New Member

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    Are those splines I see on the base of the studs? Are they supposed to line up with grooves in the rotor or the hub? What is holding the studs in the rotor or hub? Do we just hammer them and wedge them in?

    Also I thought I heard/read that the bearings are sealed and don't need repacking? I might have read that in the GM shop manual as well, but it was pretty vague with the rotor/hub mating description so I don't know what's right.
     
  10. rdobirdman

    rdobirdman New Member

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    Forgive my ignorance but I'm trying to replace my rotors for the first time. So you remove the hub and rotor together, then remove the hub bolts? the hub bolts are what is holding the rotor on, yes?
     
  11. ak diesel driver

    ak diesel driver Active Member

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  12. WarWagon

    WarWagon Well it hits on 7 of 8...

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    Yes line splines up and hammer in as said in the 1st post. Bearings are sealed but you can add grease from what I have read. Not sure how.

    The 4 bolts holding the hub/rotor on are the worst part of the job for some.
     
  13. rdobirdman

    rdobirdman New Member

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    So, whack the axle with the hub bolts still tight? then undo the hub bolts and pull off the hub/rotor assembly?
     
  14. jrsavoie

    jrsavoie Recruit

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    Check my thread on this subject. Pounding on the axel will get you nothing but a messed up axel or worse. You do have the bolts out, correct?
    I don't know how to remove the bearing housing other than to whack the bolt heads or slidehammer the whole assembly from the rotors.
    The bad is I ended up pulling my bearing housing apart. If you can get at the 4 bolts and not have to beat them so bad that you ruin the bearing assembly, that is the best way. Do not forget the antiseez around the bearing assembly when re-assembling.
     
  15. rdobirdman

    rdobirdman New Member

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    Well being a beginner on this procedure I took the previous posts at face value as in "couple whacks on the axle should free it from the hub. Yes, with the hub bolts in. " I then asked if you remove the hub, then the bolts and got the answer "yes" Now that I understand how this assembly goes together I see that I have to loosen the hub bolts FIRST. I hope I didn't mess up my axle. Seems dumb now, but I really had no idea.
     
  16. rdobirdman

    rdobirdman New Member

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    Anybody know what the hub bolts need to be torqued to when I put it back together?
     
  17. jrsavoie

    jrsavoie Recruit

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    I have not had to free the axel from the hub. The axel has to move in the hub as the wheel travels over bumps. It seems to me that if the axel is stuck in the spline you have additional problems.
     
  18. whatnot

    whatnot Member

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    The axle splines do not move in the hub. If they do you have major problems. The movement is in the CV joints.
     
  19. rdobirdman

    rdobirdman New Member

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    Got it all done, thanks guys. Changing rotors on a GMC 2500 turned out to be a much bigger job than I expected. This was the only place that I found the right way to do it.
     
  20. Steve93mustanglx

    Steve93mustanglx Diesel fanatic!

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    This is a great write up! Saved me lots of frustration, thanks War Wagon!
     

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