Announcement

Collapse
No announcement yet.

Brake discs

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • mascher
    replied
    When you remove the discs check that the holes don't have a burr raised on the inside and that the drive flanges don't have a burr on the outer portion of the threaded holes. I'm assuming these are 8.4" brakes and I'm assuming that I remember how they go together. You can use a large drill bid to deburr the holes if you don't have a large countersink.


    Kelley

    Leave a comment:


  • Rowls Mini
    replied
    Yes the max and min points are 180 degrees opposite each other. With the dial gauge I have I couldn't accurately get near the hub to check there. I had Tru-Line do a wheel alignment less than 1,500 miles ago. If there were issues with the hubs would't these have shown up then? (they noted "Light brake warpage" at the time) Next step disassemble and try again?
    Thanks for your help.

    Leave a comment:


  • mascher
    replied
    The max run-out in my manuals is 0.15mm which is about 0.006". You are seeing a little less than double that or about 0.011" (0.28mm). 0.05mm would be about 0.002" which seems really small for brakes. Volvos and Chevy pickups are 0.004" (0.10mm) for comparison.



    As you probably know I don't generally believe in discs warping. Even if it's true it's so rare it is the least likely result.


    I think your measure set up is good. It isolates you from movement in the ball joints but not the wheel bearings (and I'm not sure there's a way to do that). Try finding the highest and the lowest points and mark them. If they're opposite each other on the disc it's likely the problem is in the mounting on the drive flange or the drive flange itself. Do this several times to make sure the high and low points don't move around. Shake the disc really hard between measurements (nothing wrong with hitting it with a rubber hammer).


    Please report the results. Thank you.


    Kelley

    Leave a comment:


  • James T
    replied
    As long as everything is still torqued down. That should work. Move the dial indicator inboard, close to the nut. Check run out there to make sure the wheel bearing and axle shaft are running true. If theses were new disc on an old drive flange. Them may have not seated fully when put together. They may need to come back apart to verify correct assembly.
    Wish I had my shop up and running! Hard to diagnose through the wed site.

    Leave a comment:


  • Rowls Mini
    replied
    I mounted a dial gauge on the caliper and with the point near the outer edge of the rotor noted the maximum change in the gauge as I rotated the rotor 360-degrees.

    Leave a comment:


  • James T
    replied
    Is the disc new? It may not have been fully seated when assembled. Theses need further inspection in my opinion.

    Leave a comment:


  • James T
    replied
    How did you check the run out???.

    Leave a comment:


  • Rowls Mini
    replied
    how do you know if the disc is warped or not sitting true on the hub flange? I didn't check the run-out when I installed them.

    Leave a comment:


  • Dixminion
    replied
    The question is, why did they warp so soon?

    Don

    Leave a comment:


  • James T
    replied
    Yes that is a lot of runout. They need to be cut down on a lath to straighten.

    Leave a comment:


  • Rowls Mini
    started a topic Brake discs

    Brake discs

    I checked the disc run-out on my '89 Mini (12-inch wheels) and got a maximum variation on the dial indicator of 0.28 mm. Haynes says the maximum should be 0.15 mm and the Rover manual says 0.05 mm. Am I interpreting run-out correctly? What is the fix? The rotors only have 2,000 miles on them. I sanded the rotors and pads as suggested in the October meeting, but am still getting some shuddering with heavy braking.
Working...
X