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Determining Alcon caliper seal diameters

Determining Alcon caliper seal diameters

Do you need help with what size brake seals to order?  There are a few ways:

  1. Measure your pistons.  Measure the outside diameter (OD) of your pistons in mm.  This will reference to piston and seal sizes.
  2. Caliper part number: Calipers come with a sticker that has the part number.  The letters in the part number indicate seal size configuration.  See below.

Alcon caliper part numbers look like this: CAR9750ZG22SRL.   ZG is the piston diameter designation.  It can also be a single letter.  Here are the sizes that correspond to those letters:


W: 33.3/38.1/44.5
Y : 27/31.8/38.1
Z : 30.2/34.9/41.3
AF: 26/31.8/36
AG: 28.6/33.3/36
AM: 31.8/34.9/41.3
AN: 28.6/31.8/41.3
AD: 30.2(x6)


A: 28.6/28.6
B: 31.8/31.8
C: 31.8/34.9
B: 25.4(x6)
D: 34.9/34.9
E: 34.9/38.1
F: 34.9/41.3
G: 38.1/38.1
H: 38.1/41.3
J: 38.1/44.5
L: 41.3/44.5
K: 41.3/41.3
M: 41.3/46.8
N: 41.3/47.6
P : 44.5/44.5
R : 44.5/46.8
S: 44.5/47.6
T : 22/25. 4/30.2
U : 36/38
V : 22.2/25.4
AH: 40.0(x4)
AJ: 30.2/34.9
AK: 27.0/30.2
AP: 28.6/31.8
AR: 28.6/34.9
AT: 27/28.6
AU: 33.3/38.1
AV: 48.0/48.0
AW: 30.2/33.3


AA: 25.4(x12)
AC: 25.4(x4)/22.2(x2)
AE: 28.6(x2)/34.9(x2)
AL: 28.6(x8)
AS: 30.2(x8)


C - Caliper

A - (A)luminum or (I)ron

R - (R)adial or (L) lug mount

1111 - Caliper Series

B(B) - Piston Sizes (See chart below)

22 - Serial Number

CC - Piston Spec  (A)luminum, (T)itanium, (V)entilated titanium, (S)tainless, (D) Clip in insert, (X) clip in insert ventilated, (E) Low friction coating, (A) Low Friction coating type 2.

D - Abutment Matrial (A)luminum, (S)teel, (T)itanium, or (Z) no abutments

E - Side - (L)eft or (R)ight

F - Location (L)eading or (T)trailing


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