Replacing front brake discs

As well as their legendary handling (hang on, that was meant in jest!), Sierra's are also known for their appetite for warping front brake discs. While some cars may go for hundreds of thousands of miles, others may warp even new discs after only a few hundred - it really depends on how well the discs were manufactured and fitted, style of driving and, to some extent, luck.


Warped front brake discs can be caused by overheating, dirt or corrosion on the mounting hub or uneven stresses in the disc itself caused by poor manufacture. They can usually be detected by either or all the following symptoms under braking:

  • a pulsing sensation transmitted back through the brake pedal (not to be confused with the ABS activating if fitted);
  • excessive vibration through the steering wheel or dashboard;
  • an odd humming sound (particularly under heavy braking, but grooved discs can also naturally produce this noise).

Whatever your symptoms, warped discs are a danger as they will almost certainly affect the performance of your brakes. At best this is inconvenient as it may mean an MOT failure, or long term excessive steering and front suspension wear. At worst it may mean a failure to stop in time, or in a controlled manner, and having an accident.

Here I will cover replacing the Sierra's front brake discs. Although this 'How to' guide was originally written with replacing warped discs in mind, it is equally applicable for anyone wanting to replace worn discs.


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