MOTOR TRUCK SERVICE MANUAL
INSTRUMENTS
list in the Parts Merchandising Catalog (MT-86),
with nuts and ferrules at both ends and a wire-wound
group 10.
flexible inner coil assembly with squared ends or crimped
on tip.
3. Select proper core size and cut to correct overall
length, using the swaging cutting fixture.
The semirigid type cable assembly consists of an
inner liner of nylon, then a wire braid followed by an outer
4. Select correct tips and position tips on core.
covering of polypropylene or polyethylene(plastic). It is
fabricated so that the three separate processes, Fig. 17,
5. Check overall length to be sure the core was cut to
become a single unit. The core is a wire-wound flexible
the correct length.
inner coil assembly.
NOTE: It is very important that the core is not too
long, since a long core wile produce a thrust on the
head of the speedometer when installed on the
vehicle.
6. Swage ends in place on core.
7. Lubricate core; refer to "LUBRICATION Flexible
Shafts".
Fig. 17. Semi-Rigid Speedometer Cable.
8. Install bushing at upper end of core if required.
In addition, some of the semirigid type cables use a
REPAIRING SPEEDOMETER AND TACHOMETER
"floating tip" at the lower end. This floating tip is
FLEXIBLE AND SEMI-RIGID SHAFTS
detachable from the cable assembly and when attached
allows the core to float, thereby minimizing the thrust on
Disconnect both ends of the shaft and remove from
the head of the speedometer, Fig. 18.
the vehicle. Pull the core out of the casing and check for
kinks by rolling on a flat surface. If a flat surface is not
available, take an end in each hand and roll core
between fingers. In either case, a core kink will show up
as a "hop" at the kinked point, Never reuse a kinked
core, because it will cause fluctuation of the
speedometer or tachometer pointer. Also, check for
frayed spots by running it loosely through your fingers.
Do not use a frayed core. A kinked or frayed core
usually indicates a casing with very sharp bend.
Fig. 18. Semi-Rigid Cable Floating Tip.
NOTE: Under no circumstances should a casing
have less than a six-inch radius bend.
Three popular sizes of speedometer cable cores are
available through regular service parts channels in bulk
LUBRICATION - Flexible Shafts
form. The three sizes of cores are . 130", .150" and
.187". In addition to the three sizes of cores, various tips
Flexible Cable: Every 15, 000 to 25, 000 miles apply
are also available which can be used in making different
a thin coat of graphite impregnated non-hardening
core assemblies.
grease on the core only. Lubricate only 3/4 of the way up
the core (starting at the lower end) and leaving the top
The following procedure has been prepared to assist
1/4 free of grease to eliminate any possibility of grease
in making a new core assembly.
getting into the instrument head. Hold the casing with
one hand and feed the core with lubricant into casing.
Fabricating Flexible Cable Cores
Semi-Rigid Cable: Apply a thin coat of "Lubriplate
1. Determine correct part number of core from the
110" or equivalent at reassembly or overhaul. Clean
Motor Truck Parts Catalog.
core. With about a teaspoon of lubricant in one hand,
feed the core
2. Locate this part number in the numerical
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