![background image](http://html.mh-extra.com/html/otis/s-71/s-71_technical-information_1658597015.webp)
15
Page
REAR AXLE AND DIFFERENTIAL
The rear axle and differential are of the
automotive type. The differential can
provide power to either rear wheel. I
strongly suspect the S-71 uses the
same components as were used for
Otis gasoline-powered products of
higher power and speed.
The differential cover (facing rear) has
an oil plug for inspecting and adding
gear oil (see photo). Standard 90-
weight gear oil is recommended.
Each rear wheel uses a ball-bearing wheel bearing located in the end of the axle. For
access, jack up the rear axle and remove the rear wheel. Remove the cotter pin and castle
nut holding the hub and pull the hub straight off- it is splined to the axle shaft. The
bearing will be visible at the end of the axle. This bearing should be flooded with clean
grease. I have not removed one of these so cannot say further the exact procedure for
bearing removal. The bearing appears to be retained by a plate that bolts to the end of the
axle housing (with a large opening for the axle and through which the bearing may be
viewed). To replace the hub align the splines of the hub and rear axle and push on.
Replace the castle nut and tighten until it is tight, then back off the nut until the cotter pin
can be inserted through the castle nut and axle and locked in place. Then replace the
wheel. The wheel lug nut torque is unknown to me but I use a 3/8 hand-ratchet and ¾-
inch deep well socket for this wit h good results.
SEATS AND BATTERY ACCESS
The two individual seats are bolted to a piece of ½- inch plywood (covered with indoor-
outdoor carpet) that is hinged at the front edge for access to the batteries. A rod and rod-
holder (for propping up this cover during battery maintenance) are located on the battery
side behind the driver’s seat. The passenger seat mounts with four bolts from the rear of
this cover into tapped nuts in the seat. The driver’s seat mounts to adjustable tracks so it
can be moved fore and aft to accommodate the driver. The tracks have threaded studs that
extend through the cover and are attached with washers and nuts. One of these nuts also
secures the rod and another one secures the rod holder.