GMC 1982 Light Duty Truck Service Manual page 426

4 B -1 2 REAR A X L E
DIFFERENTIAL A N D REAR A XLE BEA R IN G D IA G N O SIS
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C R A C K E D I N N E R R A C E
R AC E C R A C K E D D U E TO IM P R O P E R F IT ,
C O C K IN G . O R POOR B E A R IN G S EAT S.
R E P L A C E B E A R IN G A N D C O R R E C T B E A R IN G
S EATS.
F R E T T A G E
C O R R O S IO N SET UP BY S M A L L R E L A T IV E
M O V E M E N T O F P A R T S W IT H N O L U B R IC A T IO N .
R E P LA C E B E A R IN G . C L E A N R E L A T E D PA R T S .
C H EC K S E A LS A N D C H E C K FOR PRO PER L U B R IC A T IO N .
SMEARS
S M E A R IN G OF M E T A L D U E TO S LIP P A G E .
S LIP P AG E C A N BE C A U S E D BY POOR F IT S .
L U B R IC A T IO N , O V E R H E A T IN G , O V E R L O A D S
OR H A N D L IN G D A M A G E .
R E P LA C E B E A R IN G S , C L E A N R E L A T E D P A R T S
A N D C H E C K FO R PROPER F IT S A N D
L U B R IC A T IO N
(CO NT'D)
F A T I G U E S P A L L I
F L A K IN G OF S U R F A C E M E T A L R E S U L T IN G FROM
F A T IG U E .
R E P L A C E B E A R IN G C L E A N A L L R E L A T E D PARTS.
STAIN D I S C O L OR A T I O N
D IS C O L O R A T IO N C A N R A N G E FR O M L IG H T BROW N
TO B L A C K C A U S E D BY IN C O R R E C T L U B R IC A N T OR
M O IS T U R E .
RE USE B E A R IN G S IF S T A IN S C A N BE R E M O V E D BY
L IG H T P O L IS H IN G OR IF NO E V ID E N C E OF O V E R
H E A T IN G IS O B S E R V E D .
C H E C K S E A L S A N D R E L A T E D P A R T S FOR D A M A G E .
Keyliner-Differential and Axle Bearing Diagnosis Chart B
G
B R I N E L L I N G
S U R F A C E IN D E N T A T IO N S IN R A C E W A Y C A U S E D BY
R O L L E R S E IT H E R U N D E R IM P A C T L O A D IN G OR
V IB R A T IO N W H IL E TH E B E A R IN G IS N O T R O T A T IN G .
R E PLAC E B E A R IN G IF R O U G H O R N O IS Y .
HEAT D I S COL ORA T I ON
H E A T D IS C O L O R A T IO N C A N R A N G E FR O M F A IN T
Y E L L O W TO D A R K B L U E R E S U L T IN G FR O M O V E R
L O A D (W A G O N 'S ) OR IN C O R R E C T L U B R IC A N T .
E X C E S S IV E H E A T C A N C A U S E S O F T E N IN G O F R AC ES
OR R O L L E R S .
TO C H E C K FO R LOSS O F T E M P E R ON RA C ES OR
R O L L E R S A S IM P LE F IL E T E S T M A Y BE M A D E . A
F IL E D R A W N O V E R A T E M P E R E D P A R T W IL L G R A B
A N D C U T M E T A L , W H E R E A S , A F IL E D R A W N O V E R A
H A R D P A R T W IL L G L ID E R E A D IL Y W IT H N O M E T A L
C U T T IN G .
R E P LA C E B E A R IN G S IF O V E R H E A T IN G D A M A G E IS
IN D IC A T E D . C H E C K S E A LS A N D O T H E R P A R TS .