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1. Steps to performing a Perfect!!!
Front Disc Brake job
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2. This is a good example of worn front
disc brakes.
Rotor is dished in the center and high
on the edges.
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3. The lower edge of the inner pad is worn
to about 2mm (.080”) in thickness.
Minimum spec is typically 1mm.
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4. Check the rotor thickness and record.
Micrometer reads .924”. This is an
import and the specs will be metric.
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5. Rotors are always stuck to the hub.
A little penetrating oil helps here..
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6. This is the minimum thickness spec.
It is 22mm.
This needs to be changed to SAE form.
The magic conversion
number is…
.03937”
The rotor minimum
thickness is .866”
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7. In order to produce an accurate finish,
things will need to be cleaned up a bit
on the mounting surface of the rotor.
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8. The outside surface where the wheel
mounts will need some attention too…
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9. A good carbide scraper will clean the
rust and scale up nicely without
damaging the part.
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10. The inside mounting surface is ready.
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11. Follow up with sandpaper on a file on
the outside surface…
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12. …and this rotor is ready for machining.
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13. Let’s not forget the hub. It is just as
dirty and if not cleaned, all the work we
are about to do will be wasted!
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14. The brake lathe adaptor mounted in
place on hub and rotor.
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15. The on-car brake lathe mounted and
ready to surface both sides at once!
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16. If you look closely, you can see the
dark low spots on the rotor surface
compared to the light high spots.
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17. Locked and loaded,
ready to rock and roll.
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18. Machine work done…
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19. Finish with a little sanding to blend the
machine tool marks, measure finished
thickness. At .905”, we are well over
the .866” service limit.
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20. Now that this is a machined assembly,
we need to make sure it stays that way
with the addition of “witness marks”.
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21. As the brake pads wear, the caliper
pistons move out to self adjust. The
pistons must be retracted to allow for
the new pad thickness.
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22. Place the old pads into the caliper and
using a spreader, push the pistons
back into the caliper body.
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23. Done!
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24. Assemble the brake pad shims to the
backside of the pads with silencing
compound to dampen vibrations and
noise.
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25. Install and lube the pad retaining
shims. This will help contain the pads
while allowing the pads to move in and
out when braking.
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26. Brake pads, hardware and caliper
holder assembled and ready to
reinstall.
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27. All back together and ready for years of
trouble-free use.
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28. Icing on the cake! A power brake fluid
flush will make this job even better!
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29. Remove old fluid from brake master
cylinder, attach flush machine to
system…
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30. …and remove old fluid at caliper while
flush machine replaces fluid at master
cylinder. With new fluid, temperature
performance will be assured.
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31. Let’s hope your brake job turns out better than this
EPIC FAIL!
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