Service Manual

Page 22
be less than that shown in Table 1. Replace the
entire disc pack if one disc needs replacing.
Table 1.
2. The splines on the friction disc should be reviewed
for wear or cracks evident on the spline teeth. The
backing plate and stationary disc should be
inspected for scratches on the mating surface to
the friction disc. Scratches may be removed with
emery cloth, India stone, or crocus cloth. The tangs
on the stationary disc(s) should be inspected for
wear.
3. Inspect the backing plate for scratches on mating
surfaces to the friction plate. Scratches may be
removed with emery cloth, India stone, or crocus
cloth. The tangs should be inspected for wear.
4. Inspect the wet brake piston for any signs of wear
or light scratches. The piston's 2 seal grooves
need to be inspected for any wear or burrs. Burrs
and light scratches may be removed with emery
cloth, India stone, or crocus cloth. Inspect the
housing’s piston bores for wear or rough spots.
Polish out rough spots with fine crocus cloth.
5. Inspect the D-Ring seals for nicks, cuts, torn
material, swelling, or evidence that the seal is
damaged or worn. If any damage is noted, these
D-Ring seals should be replaced with new
components.
6. Inspect the wet brake piston return springs and
dowels for damage or wear. Scratches on the
dowels, may be removed with emery cloth, India
stone, or crocus cloth.
7. Inspect any wet brake hydraulic tubing assemblies
and the fittings for any signs of damage to the
tubes, hydraulic nut faces, or fitting threads.
Replacement with new components is required
if any damaged is noted.
8. Inspect TRS Toric Ring face seals as follows:
CAUTION
Install face seal halves in the same positions
where they were located prior to disassembly.
Mixing up f
ace seal halv
es can cause component
damage.
• Look for obvious signs of damage. Replace any
damaged face seal or O-ring. Replace any
O-ring that is stuck to the seal or brake housing or
any that has taken a “set” or cannot be pulled and
“snapped” into position on the seal ring retaining lip.
!
• Toric Ring formed face seals are more flexible than
cast ring seals and, as a result, produce a wear
pattern different than cast ring designs. Typically,
formed seals wear in an axial rather than radial
direction, as depicted below, due to their increased
flexibility. Figure 3.7.
• The total thickness of the flange is the usable wear
material on the formed seal rings, and good seal
performance can generally be expected until the
flange is completely worn away. Estimate the
remaining service life of the seal ring by measuring
the ring flange thickness and comparing that meas-
urement to those listed in Table 2. The minimum
flange thickness required for seal ring usability is
1.27 mm (0.050 in.).
• With formed seal rings, the measured parameter
used to check the remaining seal ring life is the
flange thickness at the outer edge. Measure care-
fully, since the shoulder is only 1.52 mm (0.060 in.)
from the edge of the flange.
*Seal ring not usable. Replace seal ring.
Section 3
Prepare Parts for Assembly
Minimum Brake Disc Thickness
Disc Type Part Number Minimum Thickness
Friction A3281L1260 0.192 Inch (4.87 mm)
Stationary 3281M1261 0.167 Inch (4.24 mm)
Flange Thickness Seal Wear
mm (inch) % Worn
1.91 (0.075)
0
1.59 (0.062) 25
1.27 (0.050)
50
0.95 (0.038)* 75
0.64 (0.025)* 100
0.32 (0.012)*
125
0.00 (0.000)* 150
Table 2. Formed Seal Wear Chart
Figure 3.7
LOCATION OF WEAR LIP WHICH
MUST BE REMOVED
DEVELOPMENT OF A WEAR LIP IN
THIS AREA MAKES IT NECESSARY
TO INSTALL A NEW SEAL