https://www.hotrod.com/how-to/disc-brake-pad-friction-codes-explained/
Disc Brake Pad Friction Codes Explained
Understanding Brake Pad Codes
·
All U.S. street-legal and many racing pads have a two-letter
friction designator stamped on the pad edge or the backing plate.
·
The first letter
designates low-temperature friction performance (200 to 400 degrees F).
·
The second letter
designates high-temperature performance (300 to 650 degrees F).
·
The higher the letter in the alphabet, the better the friction
performance.
·
Normal pad code letters range from C through H.
·
If the first letter is
lower than the second letter, the pad works better at high temperatures and
needs a warm-up.
·
If the second letter
is lower than the first letter, the pad may fade at high temperature.
·
The best all-round street pads have
good friction at both high and low temperatures (as in code "FF").
|
SAE J866 Friction Designators |
|
|
FRICTION COEFFICIENT |
CODE |
|
Up to 0.15 |
C |
|
Over 0.15 up to 0.25 |
D |
|
Over 0.25 up to 0.35 |
E |
|
Over 0.35 up to 0.45 |
F |
|
Over 0.45 up to 0.55 |
G |
|
Over 0.55 |
H |
|
Unclassified |
Z |
