Poor braking can also be caused by oil on the disc.
Oil on the disc must bc cleaned o f f with trichloro-
ethylene or a high flash-point solvent. Do not use one
which will leave an oily residue.
The brake fluid is an extra heavy duty type with
a high boiling point to withstand the heat produced by
friction o f the caliper pads on the disc. Since the boiling
point and thus the performance o f the fluid would be
reduced by contamination with water vapor or dirt from
the air, the reservoir is sealed with a rubber diaphragm
under the cap. This cap seal also prevents fluid evapo-
ration and spillage should the motorcycle fall over. The
fluid i s further protected by rubber seals in the caliper
assembly and at the master cylinder brake line fitting.
When the brake i s applied, heat i s generated by the
friction between the disc and the brake pads. While
much o f this heat is immediately dissipated, some o f
i t i s transmitted to the brake fluid and may raise fluid
temperature to as high as 1 5 0 " ~ (300°F) during brake
operation. This temperature could boil the brake fluid
and cause a vapor lock in the lines unless fluid with a
high boiling point is used and has been kept from being
contaminated with dirt, moisture, or a different type
o f fluid.
Poor quality or contaminated fluid can also
deteriorate from contact with the recommended brake
The graph o f Fig.
shows how brake fluid con-
tamination with moisture lowers the fluid boiling point.
Although not shown in the graph, the boiling point also
lowers as the fluid gets old, i s contaminated with dirt,
or i f two different types o f brake fluid are mixed.
When working with the disc brake, observe the
: Single disc brake model
4.5 mm, @ 6.0 mm
precautions listed below.
1. Never reuse old brake fluid.
Do not use fluid from a container that has been
left unsealed or that has been open a long time.
3. Do not mix two types o f fluid for use in the
brake. This lowers the brake fluid boiling point
and could cause the brake to be ineffective. I f
may also cause the rubber brake parts t o dete-
Recommended fluids are given in the
N O T E : The type of fluid originally used in the
disc brake is not available in most areas, but i t
should be necessary to add very little fluid be-
fore the first brake fluid change. After changing
the fluid, use only the same type thereafter.
Recommended Disc Brake Fluid
Atlas Extra Heavy Duty
Shell Super Heavy Duty
Texaco Super Heavy Duty
Wagner Lockheed Heavy Duty
Castrol GT (LMA)
Castrol Disc Brake Fluid
The correct fluid will come in a can labeled
Do not use fluid that does not have
4. Don't leave the reservoir cap o f f for any length
o f time to avoid moisture contamination o f the
5. Don't change the fluid in the rain or when a
strong wind i s blowing.
6. Except for the disc pads and discs, use only disc
brake fluid, isopropyl alcohol, or ethyl alcohol
for cleaning brake parts. Do not use any other
fluid for cleaning these parts.
oil, or any other petroleum distillate will cause
deterioration o f the rubber parts. Oil spilled on
any part will be difficult to wash o f f complete-
ly and will eventually reach and break down the
rubber used in the disc brake.
7. When handling the disc pads or disc, be careful
that no disc brake fluid or any oil gets on them.
Clean o f f any fluid or oil that inadvertently
gets on the pads or disc with a high flash-point
Do not use one which will leave an oily
Replace the pads with new ones i f they
cannot be cleaned satisfactorily.
8. Brake fluid quickly ruins painted surfaces; any
spilled fluid should be completely wiped up
9. I f any o f the brake line fittings or the bleed
valve is opened at any time, the AIR MUST BE
BLED F R O M T H E BRAKE.
10. When installing or assembling the disc brake,
tighten the disc brake fittings to the values given
in Table G I .
Improper torque may cause the
brake to malfunction.