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Nct fail on worn brake discs....

  • 15-11-2021 6:36pm
    Registered Users Posts: 361 ✭✭ Hyperbollix

    Got a fail on this today, only info on the sheet is that the discs are worn on "axle 1" - Had a look around online but don't see any specific reference to this. Is "axle 1" the front axle?


  • Axle 1 is the front axle, if it failed the NCT you should be able to visually see the worn brake discs, run your finger from the surface of the disc to the edge, you should feel a lip on the edge, there will also probably be grooves on the discs if they're severely worn.

    It's a good idea to change brake pads along with discs

  • Now take a measurement. I do not believe they made there real thickness check, typically they only visually check the things. If the real thickness is over minimum thickness, your car is not failed. Sure, there can be other visual things too to see not only the lip. Example cracks, deep grooves, discolor. If the discs is not under minimum thickness, they made the wrong call and you should pass.

    On other hand service your car brakes every year. It does not need new parts every year, it need to check how caliper works. The slide pins can cause the problem. Need to check, clean and lube if necessary. Id slide pins does not work properly your car brakes remain on constantly and it wears fast the pads and disc. Also it can be very dangerous because these days car brakes is not only for stopping the car, the car stability control use too the brakes. So brakes are very important. Unfortunately nobody does not care. They drive until wheels falls off.

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  • Thanks lads. Only bought the car in April and previous owner had nearly new pads in it but never thought to check the discs. I'll replace everything anyway.

  • Measure first. If thickness is over allowed minimum thickness, ask from NCT wtf. If they made wrong call you should pass by free. Anyway replace and service properly

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  • Had a look before ordering. Minimum thickness was printed on the hub......... 28.4mm. Calipers showed the disk was at 29mm but of course when you account for the lip, that's around another mil off so the disk would be 28mm.

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  • Measure exactly. If lip is too big, use something as spacer. I do not have a special tool for that purpose, I use typically 2x 1/2" sockets, set zero and measure the value. Please do not understand me wrong, I do not justify to keep using unsafe car. Safety first but before proof they made a wrong call or not.

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  • Yeah with the needle on the vernier caliper I measure 0.5 of a mil between the mating surface of the disk and the top of the lip. Assuming similar wear on inside of the disk, that's 1 full milimetre of additional wear above what you can measure from inside lip to outside lip. So that would mean the disk is at 28.0 mm and is below minimum thickness.

    I'm not going to argue with the NCT over brake disks. It's the classic cut off nose to spite face situation. Someone has changed the pads once or twice before but possibly never changed the disks so at 140k miles, it's time.

  • 140k is replaced once 100% sure. Disc can last very long time if you do not use the brakes. It is possible to reduce the brake usage if you do not drive as mad. Motorway, use engine as brake. Still on normal use 140k is too much

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  • If the previous owner was thinking of selling it, they probably just done the pads rather than spending more money on discs. Throw a set of front discs and pads in it and it will be fine