Cush Drive - Royal Enfield G Workshop Maintenance Manual

ROYAL ENFIELD 350cc and 500cc O.H.V. WORKSHOP MANUAL
8. Fitting Limits for Bearings
The fit of the bearings in the hub barrel is
important. The bearings are locked on the spindle
between shoulders and the distance pieces, which
in turn are held up by the cover plate nuts. In
order to prevent endways pre-loading of the
bearings it is essential that there is a small
clearance between the inner edge of the outer
race of the bearing and the back of the recess in
either end of the hub barrel. To prevent any
possibility of sideways movement of the hub
barrel on the bearings it is, therefore, necessary
for the bearings to be a tight fit in the barrel but
this fit must not be so tight as to close down the
outer race of the bearing and thus overload the
balls. The following are the manufacturing
tolerances which control the fit of the bearings.
The figures for the bearings themselves are for
SKF bearings but other manufacturers' tolerances
are similar.
250 Clipper
S and G
Bearing o/d 1.5622/1.5617 in. 1.8122/1.8117 in.
Housing bore 1.5620/1.5615 in. 1.8115/1.8110 in.
Bearing bore .6252/.6247 in.
Shaft diameter .6252/.6248 in.
9. Refitting Ball Bearings
To refit the bearings in the hub two hollow
drifts are required, as shown in Figs. 3 and 4.
One 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.
DRIFT FOR REFITTING BEARINGS
"250 CLIPPER." MODELS "S" AND "G."
In order to make quite sure that there is
clearance between the inner faces of the outer
bearings and the bottom of the recesses fit the
distance washers against the inner races of the
Page 60
500 Model J2
.6252/.06247 in.
.6252/.6248 in.
Fig. 3
bearings and either fit the assembly of brake
cover plate, speedometer gearbox, etc. or make
up this distance with tubular distance pieces. Fit
and tighten the spindle 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.

10. Cush Drive

The sprocket/brake drum is free to rotate on
the hub barrel. Three radial vanes are formed on
the back of the brake drum and three similar
DRIFT FOR REFITTING BEARINGS
"500 MODEL J2"
vanes are formed on the cush drive shell. Six
rubber blocks are fitted between the vanes on the
brake drum and those on the cush drive shell,
thus permitting only a small amount of angular
movement of the sprocket/brake drum relative to
the hub barrel and transmitting both driving and
braking torques and smoothing out harshness
and irregularity in the former.
If the cush drive rubbers become worn so that
the amount of free movement measured at the
tyre exceeds 1/2 in. to 1 in. the rubbers should
be replaced. To obtain access to them remove
the complete wheel as described above, remove
the brake cover plate complete with the brake
shoe assembly, unscrew the three Simmonds
nuts at the back of the cush drive shell-if
necessary holding the studs by means of the flats
on the heads inside the brake drum. Drive out
the three studs into the brake drum after which
the sprocket/ brake drum can be separated from
the cush drive shell and the six cush drive
rubbers can be lifted out.
Fig. 4