Brake disc thickness

Technical Area Wheels, Tyres & Brakes
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  1. My model of MX-5 is: _ ND 1.5Sel
  2. I’m based near: NI__
  3. I’m looking for technical help or recommendations on: _Minimum brake Disc Thickeness

Any one know what the minimum brake disc thickness for front and back discs? (1.5 ND)

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20 and 7.5mm respectively

3

The 20mm for the front discs seems to be the measurement between the outside of the two rotor flanges.
I would have thought the minimum thickness would be the thickness of one or the other flange separately. Although I stand to be corrected.

4

I believe even a vented disc just uses overall thickness from inner to outer friction face. It should be noted that minimum thickness measurement is increased slightly when discs have been re-faced ie when the whole face area has had material removed rather than just the groove wear of the pad contact area.

5

This gives chapter and verse:
Manual pages - MX5 Manual | Mazda MX5 (Mk4) 2015+
Manual pages - MX5 Manual | Mazda MX5 (Mk4) 2015+
:heart:

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6

Articles explain clearly and in detail.

Answers my simplistic question about rotor thickness.

Article mainly deals with effect of brake disc lateral run out on brake judder with lateral run out tolerance of 0.002".

Makes me concerned that after removing old corroded parts, cleaning, lubricating parts, replacing brake disc and pads can in itself result in lateral run out exceeding 0.002"

7

It was only at its most recent disc change that I actually measured runout on my Mk.1 with a dial gauge and I was surprised at just how scrupulously the hubs had to be cleaned to meet the spec. It took more than one attempt at scrubbing each of the front hubs.

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