Brake Master Cylinder replacement interval

Discussion in 'E46 M3 (2001-2006)' started by klan8456, Apr 18, 2018.

  1. 18 Apr 2018 at 11:58 AM #1
    klan8456

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    Hi all,

    What are your thoughts / experiences on the replacement interval for the brake master cylinder? The youngest of our cars are 12 years old (some are now 15) and with many being track cars where a brake failure could be fatal, it makes sense to me that these should be replaced as preventative maintenance rather than waiting for a failure.
     
  2. 18 Apr 2018 at 12:10 PM #2
    AC427

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    Does anyone know of any failures and if so at what mileage?
     
  3. 18 Apr 2018 at 12:11 PM #3
    TouringRob

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    IMO, when it needs doing. Remember that your potentially replacing a known good unit with a proven track record with a new item which could just as easily have a manufacturing defect causing it to fail prematurely.

    I think most failures tent to not be catastrophic, in that they end up letting air into the system giving you a soft pedal.
     
  4. 18 Apr 2018 at 12:18 PM #4
    klan8456

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    I had a catastrophic failure on my Peugeot. Pedal straight to the floor.
     
  5. 18 Apr 2018 at 12:35 PM #5
    TouringRob

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    You maybe more sensitive to the situation that me then :)
     
  6. 18 Apr 2018 at 1:07 PM #6
    JamesNL

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    I don't think I've seen any posts of MC failure on here. It will obviously wear out eventually, but when, no idea.

    Bad bleeding procedure is likely 99% of issues with brake pedal feel.
     
  7. 18 Apr 2018 at 1:34 PM #7
    Jimbo25

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    I think the only time I would expect one to fail (barring sudden unexpected failure like a bad casting or similar) would be if you've knocked a brake line off with a stone or ever popped a piston out of a caliper servicing the brakes. You may then find pressing the brake pedal, that the seals will travel far deeper into an area with corrosion etc from years of non use, as usually happens to clutch masters when the slaves go.

    Years ago on my E30 my slave went, fixed no bother, everyone told me the master would follow but no, young 18 year old I knows far better.

    In the end I had to drive from Alton Towers back to Uni Halls in Derby without any clutch, fine on the move but there's some bloody big roundabouts on the way :eek:

    I think it's highly unlikely as James points out, I've never heard of one failing.
     
  8. 18 Apr 2018 at 1:40 PM #8
    TouringRob

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    That made me chuckle, I had a very similar experience with Ford Sierra when I was at uni, although from memory that was a broken clutch cable.

    I got really good at crunching between gears and starting the car in gear by the time I made it home.
     

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