Great Falls tribune. [volume] (Great Falls, Mont.) 1921-current, 1922-12-24
Barney 0ldf9edd says:
TIPS ON FITTING ENGINE
BEARINGS

TIPS ON FITTING ENGINE
BEARINGS
The average car owner would not
know how to refit engine bearings
even if he knew every step in the
work, nevertheless, he should acquaint
himself with such details and what
dangers creep in if this is done by an
incompetent mechanic. Only a short
time ago, a reader of this department
wrote complaining that the engine of
his car was still very noisy after be-
ing o%verhauled. He said the bearings
were tight, as the mechanic did the
work only a week before. This own
err was told that the workman may
have been at fault in not properly
a~ligning the crankshaft bearings, SO
that the crankshaft gear mesh was dls-
turbed: also the connecting rod, piston
alignment and the noises he heard
were the result of this error.
The bearings of every passenger
automobile are made of babbltt, q sort
metal that is something like a solder.
There are many conditions winch IN
time causes this comparatively SOFT
metal to become worn. Lack OF lubr1-
C0IlOu Will lQelL SuIu
short time. insufficient fabrication
will cutthe bearings and the shaft in
time. Dirty oil will cause cutting n
rapid wear. Poor oil or the wrong OIL
ts'body'' will cause rapid wear. When
the engine is new the bearings are
tight and all tight bearings must wear
into a fit. They will not wear IN
properly unless the engine is driven
slowly go miles an hour and under,)
Fast driving may burn a tight bearing;
as such a bearing gets very hot, n
there is not enough oil IN its sur
face to carry off the heat. That is
why new cars and ~overhauled engines
are given an extra quart Of oil SO
that the bearings and other parts Will
be sure to get a good supply.
Absolute Alignment Essential
In fitting either main or connect
ing rod bearings that are badly worn
it is almost impossible to do the Jop
right with the crankshaft in the en-
CINE. A little "take-up'' for slight
wear may be accomplished without do
ing any harm, but when the bearings
are SO badly worn that they pound or
knock, then the work should be done
right or trouble will come later on.
In fitting main bearings, for ex-
ample. the SHIN or spacer between
the bearing halves must be reduced IN
thickness to bring the halves closer.
The bearing is not round when worn,
therefore, when the SHIN is reduced IN
thickness only certain parts OF the
bearing touch the crankshaft Journals.
Those parts that touch are called high
spots. If the bearings were simply
frightened they would run only on the
high spots, which constitute only a
part of the bearing surface.
In the first place, the most essen
tial operation in fitting main bearings
is to get them absolutely In alignment
and this is done in the shop with a
line reamer. which reams the bearings
out and aligns them in one operation.
Other tools are employed to get the
same result. After the roaming the
bearings must be fitted to the shaft.
Some shops employ the method OF mt
ting the bearings tightly and then
running them on that is, operating
The shaft until the bearings have worn
down somewhat and are free. Inns is
a factory production method and IS
satisfactory l. care is taken to get
equal tightness Of bearing and the
right running-in speed.
Finish Center Bearings First =
In some shops after roaming, the
bearings are scraped in by hand, or
thew are simply scraped and no ream-
ing is done. The mechanic must see,
however, that the shaft is not sprung
by having one bearing higher than
another. When the cr~ankshaft is not
perfectly true in the bearings 1T dis
turbs the gear mesh in front and also
upsets clutch action by giving a new
position to the flywheel. Any change
In the position Of the ~crankshaft also
upsets the alignment of the connecting
rods and %pistons, for the rods must be
absolutely at right angles to the shaft,
otherwise there will be rapid rod bear
ing wear, piston wear and cylinder
wear.
In fitting main bearings get the
center one finished first, then the
front bearing and then the rear. After
fitting the front bearing check up the
crankshaft gear mesh or II a chain
sprocket is used be sure he cham Will
ride evenly over the %sprocket.
The connecting rod bearings may
also be reamed, Their scraped to get j
finished fit and then aligned on an
a~ligning jig to be sure the rod IS at
right angles to the shaft. The aligning
Jig may be used before the final
scraping.
Z One Of the most important things is
to be sure that no bearings is fitted
to a journal or crank pin unless it is
perfectly round. Check the %roundness
with a caliper. If as little az OBJ out
of ronnd have the crankshaft re-
surfaced.
The actual scraping Of a bearing
simply consists in cutting off the high
sDots and trying another fit. This is
done until the bearing shows contact
over practically all its surface and the
shaft of rod may be turned by hand,
The use of abrasiyes in fitting bear