While compressing the front brake caliper piston on my 93 miata fluid seemed to be getting out of the piston. It only did it on the driver's side. I test drove the car several times and braked hard a couple of times and the fluid didn't drop at all. I would really rather not replace the caliper if I don't have too. Is it safe to drive the car around or does this leak mean its death? Could it be possible that I have used the c-clamp incorrectly on the seal which made it leak a little but other wise fine?

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    That would kinda scare me. Given how inexpensive this fix is... I'd probably replace it. And I would do the other side too, since calipers should be done in pairs.
    – cory
    Mar 22, 2017 at 20:05
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    @cory - While I agree with replacement of the leaking caliper, unless there is an issue with the other caliper, there's no reason to change both ... Meaning, there is no reason to change them out in pairs. As I've stated before, as long as it isn't leaking, binding, or sticking, a good caliper is still good. Mar 23, 2017 at 2:04
  • A 24 year old (presumably) caliper has gone bad. Since you have to bleed the brakes now anyways, and calipers for a miata are cheap, I stand by my recommendation to do both.
    – cory
    Mar 23, 2017 at 13:12

1 Answer 1


Any sort of brake fluid leak is a serious issue which needs to be fixed for several reasons.

  • Any fluid leak means that air is also getting into the system which will accumulate and degrade braking performance.
  • A small leak could turn into a sudden complete failure suddenly and without warning. As well as the obvious safety issue a sudden failure will be much more inconvenient to fix.
  • Brake fluid is quite nasty stuff and you don't really want to be spreading it around
  • Getting brake fluid on the pads will not make them work better.

In some cases you can get a kit to refurbish calipers, usually consisting of pistons and seals which is generally a lot cheaper than a whole new caliper.

It is not uncommon to get this sort of problem after changing pads as the exposed part of the piston can become dirty and corroded as the old pads wear and it has to extend further which can then stick or damage the seals when it is re-compressed to accommodate the new pads.

Obviously check that the bores are clean and free from damage before fitting new pistons/seals.

This is also a good time to check pipes and fittings etc as well.

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