Bearing Installation; Shrink Fit - Polaris 1999 Sportsman 400 Service Manual

28 CHAPTER ONE
Hou s ing
®
•
Bearing Installation
1. W hen installing a bearing in a housing, pressure
must be applied to the outer hearing race (F igure 39) .
When installing a bea ring on a sha ft. pressure must be
appl ied to the inner bearing race (F igure 40).
2. Wh en install ing a bearing as descr ibed in Step I,
some type of driver
will
be requ ired. Never strike
the bearing d irect ly with a hammer or the bearing
will
be damaged, Whe n ins talling a bearing, a piece
of pipe or a socket with a diameter that matc hes the
bearing race is required. Figure 41 shows the cor-
rect wa y to use a soc ket and ham mer when install-
ing a bea ri ng .
3. Step I describes how to insta ll a bearing in a case
hal f or over a sha ft. However, w hen insta lling a
bea rin g over a sha ft and into a hou sing at the same
time, a snug
fit will
be required for both outer and
inne r bearing races.
[11
this situation, a spac er must
be installed underneath the dr iver tool so that pre s-
sure is applied even ly ac ross bot h races. See Figure
42 . If the outer rac e is not supported as sho wn in
Figure 42 , the ba lls w ill push against the o uter bear-
ing track an
d damage
it.
Shaft
Shrink F it
I . Insta lling a bearing over a shaft: When a tight fit
is required , the bea ring inside d iame ter w ill be
s maller tha n the shaft. In this case, d riving the bear-
ing
on
the shaft using normal methods may cause
bearing da mage . Instead , the bear ing sho uld be
hea ted before installation, Note the fn lJowing:
a.
Secure the shaft so that it is ready for bearing
instal lat ion.
b. C lea n a ll residue from the bearing surface of
the shaft. Remove burrs w ith a file o r sandpa-
per.
c .
FiB
a suitable po t or beaker w ith clean min -
era i oil. Place a thermome ter (rated high er
tha n 120° C [24 8° F]) in the oil. Support the
thermometer so that it d oes not rest on the
bottom or side of the pot.
d . Remove the beari ng from its wrapper and se-
cure it with a piece of heavy w ire bent to ho ld
it in the po t. Han g the bearing in the pot so
that it docs not touch the bottom or sides of
the pot.
e. Turn the hea t on and monitor the thermome-
ter. When the oi l tempera ture rises to approxi-
mately 120° C (248 ° F), remove the bearing
from the pot and quickly install it. If neces-
sary, place a socket on the inner bea ring rac e
and tap the bea ring into pla ce. As the bearing
chills, it will tighten on the shaft so work mu st
be done quick ly when install ing it. Ma ke sure
the bearing is install ed all the way.
2. Installing a bearing in a housing: Bea ring s are
ge nerally insta lled in a housing w ith a slight inter-
feren ce
fi t.
Driving the bearing into the ho using us-
ing norma l methods may damage the hou sing or
cause
bearing damage. Instead. the hous ing sho uld
be heated before the bearing is ins talled. Note the
follo wing:
CAUTION
Before heating the crankcases in this
procedure to remove the bearings.
wash the cases thoroughly with
deter-
gent
and water:
Rinse
and
rewash the