Royal Enfield SPRING FRAME O.H.V. 250cc CLIPPER 1954 Workshop Maintenance Manual page 66

ROYAL ENFIELD WORKSHOP MANUAL
the nuts on the spindle. Tightening the nuts
should not have any effect on the ease with
which the spindle can be turned. If tightening
the nuts makes the spindle hard to turn this
may be taken as proof that the bearings are
bottoming in the recesses in the hub barrel
before they are solid against the shoulders on
the spindle. In this case the bearing should be
removed and a thin packing shim fitted
between the inner race and the shoulder on the
spindle.
9. Reassembly of Brake Shoes to Cover
Plate
Assemble the shoes with their return
springs on to the pivot pin and operating cam,
putting a smear of grease in the grooves of the
pivot pin and on the operating faces of the
cam. Now fit the assembly into the cover
plate, putting a smear of grease on to the
cylindrical bearing surface of the operating
cam and secure with the pivot pin locknut and
washer. Fit the operating lever on its spline in
a position to suit the extent of wear on the
linings and secure with the nut and washer.
Note that the position of the operating lever
may have to be corrected when adjusting the
brake after refitting the wheel. The range of
adjustment can be extended by moving this
lever on to a different spline. Limit of wear is
reached when the cam is turned through nearly
90° with the brake hard on so that there is a
danger that the operating springs cannot return
the brake to the off position.
10. Floating Cam Housing
Note that the cam housing is intended to be
left free to float. The bolt holes in the cam
housing are slotted and the securing pins are
provided with double coil spring washers
beneath their heads to enable them to be
tightened sufficiently to prevent the cam
housing moving under the influence of road
shocks, while at the same time it can be, and
should be, left free enough to be capable of
being moved by hand in the direction of the
slots. The pins are secured by locknuts which
are centre punched as an additional precaution.
The leading shoe (i.e. the one towards the
rear of the machine) has a servo action which
renders it more effective than the trailing shoe.
This servo action causes the lining on the
leading shoe to wear more quickly than that on
the trailing shoe and at the same time tends to
lift the leading shoe off the cam and press the
trailing shoe harder on to the cam. With a fixed
cam housing the result is that the majority of
the cam pressure is applied to the less efficient
trailing shoe. By leaving the housing free to
float the cam can follow up the leading shoe
thus maintaining equal pressure between the
cam and the two shoes and so making full use
of the more efficient leading shoe. Owing to the
servo action the wear on the leading shoe with
a floating cam housing is greater than that of
the trailing shoe and in time the limit of float of
the cam housing will be reached, after which
the brake will continue to function as a fixed
cam brake with some loss of efficiency. This
can be restored by removing the shoes and
fitting them in the opposite positions. Floating
cam brakes are self-centering and there is no
need to take any special precautions to see that
the two linings are of equal thickness, or that
the brake shoe assembly is centered in the
drum.
11. Refitting Brake Cover Plate
After assembling the brake shoe pivot pin
and operating cam into the cover plate repack
the hub bearings
recommended greases are Castrolease (Heavy),
Mobilgrease (No. 4), Esso Grease, Energrease
C3 or Shell Retinax A. These are all medium
heavy lime soap or aluminium soap greases.
The use of H.M.P. greases which have a soda
soap base is not recommended as these tend to
be slightly corrosive if any damp finds its way
in to the hubs.
Before fitting the distance washer and felt
washer make sure that the inside of the brake
drum is quite clean and free from oil or grease,
damp, etc. and replace the brake cover plate
assembly. Securely tighten the cover plate nut.
12. Wheel Rims
The rim used on the 250 Clipper and Model
"S" is type WM1-19 in., internal width 1.60 in.
The rim used on the other models is type
WM2-19 in., internal width 1.580in.
The rim diameter after building is the same
in each case, i.e. 19.062 in., the tolerances on
the circumference of the rim shoulders where
the tyre fits being 59.930/59.870 in. The
standard steel measuring tape for checking rims
is 5/16 in. wide, .011 in. thick and its length is
59.964/59.904 in. All rims are pierced with
forty holes for spoke nipples.
Note that two makes of rim are used
"Dunlop" and "Palmer Jointless." These differ
in the positions of the pierced spoke holes. The
Dunlop rims have a group of three holes on one
side of the centre line, then a single hole on the
other side, a further group of three and a single
hole and so on. Palmer rims have the holes
alternately spaced either side of the centre line.
Both rims are interchangeable and both use the
same length spokes but the method of lacing
the wheel is different (see Subsection 14).
Neither types of the wheel rim are symmetrical
and care must be taken they are built the right
way round into the wheel.
with grease. The
Section K2 Page 3