New Rotors?

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by Camaromurph, Nov 30, 2019.

  1. Camaromurph

    Camaromurph Member

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    So it looks like it's time for new rotors. I was getting ready to refinish them as part of my project and I thought I better check the thickness before I put the effort in. I never really drove the car after I bought it except a couple of low speed (<30mph) runs down the street. Didn't notice an problems but far from a real brake test.

    So, one rotor measures 0.958" and the other measures 0.955" Both below the discard value of 0.965". New rotors it is.

    Any recommendations on new rotor/hub assemblies. I have read a lot of bad things about rotors warped right out of the box new. I was going to look at AC Delco at Rock Auto. Any other thoughts?

    Murph
     
  2. COPO

    COPO Veteran Member Lifetime Gold Member

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    I went with Raybestos on my 70 Z28. I told the guy at the counter
    that I didn't want crap that'll warp in a year. I used new GM bearings
    from the 70's or 80's for a 70 Z28. The new bearings back then came
    with races but I left the ones in the rotors which s/b good.
    These work great. Don't forget to break-in new pads. Prior
    to this I still had my orig rotors with the indicator groove
    but they pulsated after breaking at the first stop due to turn
    downs.

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    IMG_2096.JPG IMG_2097.JPG IMG_2104.JPG IMG_5893.jpg IMG_5894.jpg 4FC36B95-CB33-4C8B-B844-3C10B4F2BA8B.jpeg 4C379B59-93F2-4FDB-BD81-80001C7ABCB6.jpeg B2EC6128-90CA-4D9C-9500-D398E9677553.jpeg
     
    Last edited: Nov 30, 2019
  3. jthomas

    jthomas Veteran Member Lifetime Gold Member

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    Unfortunately I have found no good rotors from any brand in the last few years. Unless you are buying high end aftermarket like Wildwood or other such names, all the stock replacement stuff is out of round and out of balance. Right Stuff, Powerstop, Raybestos, Wagner, ACDelco....all the same issues. I finally got a set of Raybestos. They had the lowest amount of runout (.003) of all brands. Right stuff was the worst at .005 and .006. That’s not even useable.

    Anyhow, I put the Raybestos on and had a bad vibration. Took them off and took them to a machine shop and he told me the same thing...most rotors today are junk. If you can find a Canadian made rotor they are the best according to him.

    He re-machined and rebalanced them and now they have less than .001 runout. Needle barely moves. He spun them for me before and after and it was impressive how bad they were out of the box. Now they are smooth as silk. I had him do the same with all four corners. Got rid of all my vibration after years of balancing tires, chasing driveshaft angles, etc. turns out it was the rotors all along.

    In the future when I buy new rotors they go right from the box to the machine shop. It’s a shame, but it’s the way quality is today.
     
  4. COPO

    COPO Veteran Member Lifetime Gold Member

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    I have no issues or vibrations with mine.
     
  5. roeville

    roeville Veteran Member

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    I recall, back in the day, on complete brake jobs that required front rotors, we would cut new rotors out of the box (final cut @.002) routinely.
     
  6. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    please explain? never seen anyone rebalance rotors???
     
  7. jthomas

    jthomas Veteran Member Lifetime Gold Member

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    Here’s the procedure he used:
    1. Checked races to be sure they were seated properly, then mounted rotor on machine.
    2. Checked radial and lateral runout and balance out of the box as baseline.
    3. Refaced disc to get runout less than .001
    4. Machined the hub to eliminate the hub’s casting runout and get balance close.
    5. Drilled hub in several spots on one side to finish the balancing.

    All the rotors were off out of the box. Balance was off by as much as 4.5 ounces on the one and 10.4 ounces on another. Although balance on a rotor isn’t as critical as a rim or tire due to the fact that it is closer to the center of the hub, it still makes a difference. You could see the difference between spinning the rotor before and after. Big difference. And you could definitely feel the difference mounted on the car.

    Since Camaro wheels are lug centric and not hub centric you get a certain amount of imperfection in the assembly as it spins. Truing and balancing the rotors to tighter specs cleans up some of that effect. I do this to all my rotors these days.
     
    Last edited: Dec 3, 2019
    berg2695 likes this.
  8. 1981gMachine

    1981gMachine Veteran Member Lifetime Gold Member

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    Awesome, What's the name of the shop that does yours? My dad lives in Stroudsburg, so North Central, PA isn't far. Add it to my back of the head index for a future time.
     
  9. jthomas

    jthomas Veteran Member Lifetime Gold Member

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    Simpson Machine in Muncy, Pa
     
    1981gMachine likes this.
  10. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    That is how you "tune" a car to ride well!!!!
    probably only a dozen mechanics that would even consider doing that ....

    Thats first class stuff. ;)
     

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