Royal Enfield 500 TWIN 1949 Workshop Maintenance Manual page 84

ROYAL ENFIELD WORKSHOP MANUAL
bearing is first fitted to one end of the spindle by
means of the hollow drift; the spindle and
bearing are then entered into one end of the hub
barrel which is then supported on one of the
hollow drifts. The other bearing is then threaded
over the upper end of the spindle and driven
home by means of the second hollow drift either
under a press or by means of a hammer which
will thus drive both bearings into position
simultaneously. In order to make quite sure that
there is clearance between the inner faces of the
outer bearing races and the bottom of the
recesses, fit the distance washers, 30538, and the
cover plate nuts, 31347, with either the cover
plates themselves or additional packing washers
behind the nuts. 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 onto Cover
Plates
Assemble each pair of 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, 28715, and washer,
17551. Fit the operating lever, 38905 or 38906,
on its splines in a position to suit the extent of
wear on the linings and secure with the nut,
10314, and washer, 14613. Note that the
position of the operating levers may have to be
corrected when adjusting the brake after refitting
the wheel. The range of adjustment can be
extended by moving these levers on to different
splines. 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 Housings
Note that the cam housings, Part No. 26836,
are intended to be left free to float. The bolt
holes in the cam housings are slotted and the
securing pins, Part No. 252, are provided with
double coil spring washers beneath their heads
to enable them to be tightened sufficiently to
prevent the cam housings moving under the
influence of road shocks, while at the same time
they can be, and should be, left free enough to
be capable of being moved by hand in the
direction of the slots. The pins, 252 are secured
by locknuts, 7916, which are centre punched as
an additional precaution.
The leading shoes (i.e. those towards the rear
of the machine) have a servo action which render
them more effective than the trailing shoes. This
servo action causes the linings on the leading
shoes to wear more quickly than those on the
trailing shoes and at the same time tends to lift
the leading shoes off the cams and press the
trailing shoes harder on to the cams. 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 Plates
After assembling the brake shoe pivot pins
and operating cams into the cover plates repack
the hub bearings with grease. The 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 into the
hubs.
Before fitting the distance washers and felt
washers make sure that the inside of the brake
drums are quite clean and free from oil or
grease, damp, etc and replace the brake cover
plate assemblies. Securely tighten the cover
plate nuts, 31347.
12. Wheel Rim
The rim is Type WM2-19 in. plunged and
pierced with forty holes for spoke nipples. The
spoke holes are symmetrical, i.e. the rim can be
assembled to the hub either way round. Rim
diameter after building is 19.062 in., 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.
Section K1 Page 3