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Warped rotors?

Discussion in 'Brakes' started by Niori, Nov 24, 2020.

  1. Niori

    Niori Junior Member

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    I have an 86 C20 pickup. About a week or two after I got it, I put new tires on it all the way around. My next day off after that, I put new brake pads on. When I am driving, I still get a fairly violent shaking when braking, and am wondering if it could be warped rotors.

    Also, in front rotor replacement, could anyone recommend some rotors to go with?
     
  2. Bextreme04

    Bextreme04 Full Access Member

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    If it vibrates when driving, you have tires out of balance. If it vibrates only when brakes are applied, you have warped rotors. I usually get my rotors turned when I change pads, since I usually use long life pads that don't get changed often. It's also a good opportunity to check wheel bearings and repack them. Getting the rotors turned is only about $10-15 per side for me locally, so it is well worth doing the whole thing all at once.
     
  3. Ricko1966

    Ricko1966 Full Access Member

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    I disagree on the rotor turning, so does GM as of about 2005. IMHO if you warped them before they are now more prone to warp again.Thinner now, metal memory, and hotspots.I put a dial indicator on them if there in spec I put a nondirectional swirl on them with my die grinder and a scotch Brite pad.If they are damaged rotors I replace them with brand name rotors and am sure they get a final wash with hot water and soap.

    I have several dial indicators with different style mounts, not everyone does.Poormans method rig a piece of angle strap whatever to a solid point close to the rotor.Drill a hole in your jig for a fine thread bolt and 2 nuts spin your rotor gradually running the bolt closer and closer until just touches on the high spots measure clearance at low spots with feeler gauges.I used to do it this way all the time, checking crank end play rotors differentials etc.
     
    Last edited: Nov 24, 2020
  4. Bextreme04

    Bextreme04 Full Access Member

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    Yeah, I'm sure it's way easier and "safer" for GM to recommend people just replace their brake rotors to the tune of $120/ea. or more rather than just having them turned.... I've always just had them turned, on every car I've ever had, down to the minimum thickness before I replace them(if they don't get damaged in another way). It generally takes a whole lot of wrong things in order for you to warp your rotors and there is always a chance that you wont be able to correct it by getting them turned. The most common ones I've seen are getting the brakes really hot with some spirited driving and then hitting a big water puddle that cools the rotor unevenly.

    I have never had a front end vibration that was caused by a warped rotor that wasn't able to be corrected by turning it. I've never had that warp come back either. I have had a warped rotor that also had some surface rust pitting that couldn't be machined out, those rotors got replaced with new OEM rotors.

    You can get AC Delco rotors from rockauto for $143/ea... which is a little bit pricier than what you would pay for whatever knockoff brand you would get from the local parts store. I'm sure the same thing from the local chevy dealer would be $200 or more.

    I would recommend you pull the front rotors and take them down to Napa or Oreillys and have them see how bad they are out. Its cheap and easy and can be done same day. They will check the specs and condition and try to true them up. If they can't get them flat while still being over the minimum thickness, or they are damaged in some way, you'll have to replace them anyways.

    While you have the rotors off... clean, inspect, and repack the bearings. Then when you put it back together you can make sure the rotor are properly installed and torqued to spec, since that can also cause some vibrations.
     
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  5. Snoots

    Snoots Supporting Member Supporting Member

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    Been there, done that.
    It's called Lateral Runout.
    No long term fix. You must replace them.
    There is a 'break-in' on brakes.
    If you didn't go easy on stopping after you installed the new pads or, like @Bextreme04 said, hit water after they were VERY heated, that's what caused your problem.

    Raybestos used to offer rotors that were high in quality.

    Another thing @Bextreme04 mentioned was bearings and seals. I'd put on new ones, and use a good, high-temp BEARING grease. No cheep stuff.
     
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  6. fast68chevy

    fast68chevy I am the original fast68chevy

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    buy new ones and dont buy cheapo chinese crap ones.. buy good decent one and dont hold pedal down/brakes on when brakes are hot this is quickest way to warp them.

    no turning rotors the days any more.. just replace them. turning rotors/drums days are basically over, athing of the past, in th olden days really now.. for the most part.
     
  7. Niori

    Niori Junior Member

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    Just wanted to give you guys a quick update. Ended up replacing the rotors, the brake hoses,the pads, and the driver's side caliper. After all that, my truck now stops like a dream! No more vibrating the truck apart while coming to a stop!
     
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  8. RoryH19

    RoryH19 Full Access Member

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    Good to hear. Starting to have this problem on my R10. I thought it was warped rotors and this seems to confirm.
    No vibration while driving, no matter the speed only braking.
    What brand did you use?
     
  9. Turbo4whl

    Turbo4whl Supporting Member Supporting Member

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    @Ricko1966

    Square trucks were designed when fuel was 30 cents a gallon. The rotors can be turned. 2005 trucks have much thinner rotors.
     
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  10. Ricko1966

    Ricko1966 Full Access Member

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    What I was more trying to get across is I don't just turn them, to turn them. If they aren't warped I put a nondirectional swirl on with my die grinder and run them. And if they are warped I prefer new ones.
     
    Last edited: Dec 20, 2020
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  11. Niori

    Niori Junior Member

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    All the brake parts I got (with the exception of the Caliper) were Raybestos, and I got them from Rock Auto. After using them myself, I found that their prices are a lot better if you are able to wait a few days for the shipping, as opposed to the local parts stores. But be sure you know the size of your rear brake drums when ordering. I thought I knew mine, but the hoses I ordered initially were for the 11" rears, and didn't work, so I had to wait a couple extra days to get the correct hoses in for my 13" drums. Not sure why the size of the rears make a difference when replacing the front brakes, but they do. Apparently, heavier duty for the 13" drums.

    But as for the vibration, it turned out that I had a cracked rotor on the driver's side, and the brake hose on the driver's side was collapsed, causing the brakes to drag, due to the caliper not being able to retract.
     
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