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NCT - Brake Ovality Failure

  • 10-05-2013 01:10PM
    #1
    wandererz
    Registered Users, Registered Users 2 Posts: 2,868 ✭✭✭


    NCT failure on ovality.

    Would this be the shoes or drums?

    Also, been quoted some crazy (and widely differing) prices for replacement of rear drums and shoes on a Focus.

    Any idea what this should cost from your experience?


Comments

  • #2
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,196 ✭✭✭✭jimgoose


    Wear/scoring of the drums, most likely. What year/mileage? You should be able to get a pair of drums for it for under €100, and a couple of hours at most to replace.


  • #3
    CiniO
    Registered Users, Registered Users 2 Posts: 16,069 ✭✭✭✭CiniO


    Could anyone tell me what "ovality" means in relation to brakes?
    I never could understand this term...


  • #4
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,196 ✭✭✭✭jimgoose


    CiniO wrote: »
    Could anyone tell me what "ovality" means in relation to brakes?
    I never could understand this term...

    Ovality is the difference in braking force measured during one rotation of the wheel. It is indicative of worn drums and damagaed or "warped" rotors.


  • #5
    biko
    Registered Users, Registered Users 2 Posts: 81,219 ✭✭✭✭biko


    Afaik it simply means "not perfectly round/is warped" depending on if it's drum or disc.
    Both can become disfigured by overheating/cooling down too fast/other.


  • #6
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,196 ✭✭✭✭jimgoose


    biko wrote: »
    Afaik it simply means "not perfectly round/is warped" depending on if it's drum or disc.
    Both can become disfigured by overheating/cooling down too fast/other.

    Actual disc "warping" is rare, especially with ductile iron rotors. What does happen though, is when you get the brakes nicely hot, as in braking down nice and lively from some speed, then leaving the brakes on hard after coming to a stop. This permanently deposits a thin layer of pad material onto the rotor, and eventually the resulting slight variation in thickness accelerates the process. Eventually, the internal ferrite structure of the disc is altered.


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