RECONDITIONING BRAKE DRUMS AND SHOES
Check brake lining for possible out-of-square condition
which would indicate a distorted shoe and/or bent
backing plate, Figure 11. Rusted shoe support pads
suggest possible distortion. A loose or bent backing plate
may cause unbalanced braking and/or noise. Check
backing plate for distortion by placing a straightedge
across its flat. Check for galled or loose anchor pins.
When removing worn lining from shoes, drill out old
rivets if possible to prevent distorting shoe table. After
the old linings are removed from the shoes, the shoes
should be cleaned and buffed to remove all dirt and
grease. Grease is one of the greatest deteriorating
agents of lining.
Discard used lock washers after removing lining bolts.
Use new washers when installing new lining. Replace
bolts and nuts if signs of distortion or wear are present.
Do not handle new brake linings or relined shoes with
greasy hands or allow linings to come in contact with
mineral oil or grease.
Care should be used in selecting the correct thickness of
lining for each brake shoe and drum. Usually the
standard thickness will be used. If the drum has been
turned or has become worn, increasing the diameter,
oversize lining may be required.
Figure 11 - Checking for Out-of-Square Lining
If it is not known how much material has been removed
from the drum during the turning operation, the following
simple test may be used to help select the proper lining.
Hold standard size lining snugly to the shoe, position it
against the inner surface of the drum, forcing it into
contact with the drum surface. The lining is now in the
’same position as during a brake application. If space is
noted at the ends of the shoe (shoe can be rocked), an
oversize lining is required (Figure 12). If lining selected is
too thick, only the ends of the lining will contact the drum.
Refer to Figure 13.
Figure 12 - Space at End of Shoe Lining Selected Too
Thin
Figure 13 - Space at Center of Shoe And Lining
Contacting Ends, Lining Selected Too Thick
The lining must be installed on the shoe so that it fits
smoothly and evenly, contacting the shoe throughout the
entire radius. If gaps occur between the rivets, difficulty
will be met in adjusting the brakes in that "spongy" or
rubbery pedal may occur which makes satisfactory brake
application impossible.
CTS-4082B - Page 6
