Diagnosis And Testing; Clutch Contamination; Clutch Runout; General Information - Jeep Cherokee 1999 Electronic Service Manual

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DESCRI PT I ON AN D OPERAT I ON (Cont inue d)
lin e. In t u r n , t h e sla ve cylin der oper a t es t h e clu t ch
r elea se lever.
Th e clu t ch r elea se bea r in g is m ou n t ed on t h e
t r a n sm ission fr on t bea r in g r et a in er. Th e bea r in g is
a t t a ch ed t o t h e r elea se lever, wh ich m oves t h e bea r-
in g in t o con t a ct wit h t h e clu t ch cover dia ph r a gm
spr in g.
Sla ve cylin der for ce ca u ses t h e r elea se lever t o
m ove t h e r elea se bea r in g in t o con t a ct wit h t h e dia -
ph r a gm spr in g. As a ddit ion a l for ce is a pplied, t h e
bea r in g pr esses t h e dia ph r a gm spr in g fin ger s in wa r d
on t h e fu lcr u m s. Th is a ct ion m oves t h e pr essu r e
pla t e r ea r wa r d r elievin g cla m p for ce on t h e disc. Th e
clu t ch disc is disen ga ged a n d fr eewh eelin g a t t h is
poin t .
Th e pr ocess of clu t ch r e-en ga gem en t is sim ply t h e
r ever se of wh a t occu r s du r in g disen ga gem en t . Relea s-
in g peda l pr essu r e r em oves clu t ch lin ka ge pr essu r e.
Th e r elea se bea r in g m oves a wa y fr om t h e dia ph r a gm
spr in g wh ich a llows t h e pr essu r e pla t e t o exer t
cla m pin g for ce on t h e clu t ch disc.
DI AGN OSI S AN D T EST I N G
GENERAL INFORMA TION
P r oblem dia gn osis will gen er a lly r equ ir e a r oa d
t est t o det er m in e t h e t ype of fa u lt . Com pon en t
in spect ion will t h en det er m in e t h e pr oblem ca u se
a ft er r oa d t est in g.
Dr ive t h e veh icle a t n or m a l speeds du r in g t h e r oa d
t est . Sh ift t h e t r a n sm ission t h r ou gh a ll gea r r a n ges
a n d obser ve clu t ch a ct ion .
If ch a t t er, gr a b, slip, or im pr oper r elea se is exper i-
en ced, r em ove a n d in spect t h e clu t ch com pon en t s.
H owever, if t h e pr oblem is n oise or h a r d sh ift in g, fu r-
t h er dia gn osis m a y be n eeded. Th e t r a n sm ission or
a n ot h er dr ivelin e com pon en t m a y a ct u a lly be a t
fa u lt . Ca r efu l obser va t ion du r in g t h e t est will h elp
n a r r ow t h e pr oblem a r ea .
CLUTCH CONTAMINA TION
F lu id con t a m in a t ion is a fr equ en t ca u se of clu t ch
m a lfu n ct ion s. Oil, gr ea se, wa t er, or ot h er flu ids on
t h e clu t ch con t a ct su r fa ces will ca u se fa u lt y oper a -
t ion . Th e u su a l r esu lt is ch a t t er, slip a n d gr a b.
Du r in g in spect ion , n ot e if a n y com pon en t s a r e con -
t a m in a t ed. Look for eviden ce of oil, gr ea se, clu t ch
h ydr a u lic flu id, or wa t er /r oa d spla sh on clu t ch com -
pon en t s.
Oil con t a m in a t ion in dica t es a lea k a t eit h er t h e
r ea r m a in sea l or t r a n sm ission in pu t sh a ft . Oil lea ks
pr odu ce a r esidu e of oil on t h e h ou sin g in t er ior a n d
on t h e clu t ch cover a n d flywh eel. H ea t bu ildu p
ca u sed by slippa ge bet ween t h e clu t ch cover, disc,
a n d flywh eel ca n som et im es ba ke t h e oil r esidu e on t o
t h e com pon en t s. Th e gla ze-like r esidu e r a n ges in
color fr om a m ber t o bla ck.
Roa d spla sh con t a m in a t ion m ea n s dir t /wa t er is
en t er in g t h e clu t ch h ou sin g. Th is m a y be du e t o loose
bolt s, h ou sin g cr a cks, or t h r ou gh t h e sla ve cylin der
open in g. Dr ivin g t h r ou gh deep wa t er pu ddles ca n
for ce wa t er /r oa d spla sh in t o t h e h ou sin g t h r ou gh
su ch open in gs.
Clu t ch flu id lea ks a r e fr om loose or da m a ged
clu t ch lin ka ge flu id lin es or con n ect ion s. H owever,
m ost clu t ch flu id lea ks will u su a lly be n ot ed a n d cor-
r ect ed befor e sever e con t a m in a t ion occu r s.
Gr ea se con t a m in a t ion is u su a lly a pr odu ct of exces-
sive lu br ica t ion du r in g clu t ch ser vice. Apply on ly a
sm a ll a m ou n t of gr ea se t o t h e in pu t sh a ft splin es,
bea r in g r et a in er, pilot bea r in g, r elea se for k a n d pivot
st u d. E xcess gr ea se ca n be t h r own off du r in g oper a -
t ion a n d con t a m in a t e t h e disc.
IMPROPER CLUTCH RELEASE OR
ENGAGEMENT
Clu t ch r elea se or en ga gem en t pr oblem s a r e ca u sed
by wea r, or da m a ge t o on e or m or e clu t ch com po-
n en t s. A visu a l in spect ion of t h e r elea se com pon en t s
will u su a lly r evea l t h e pr oblem pa r t .
Relea se pr oblem s ca n r esu lt in h a r d sh ift in g a n d
n oise. It em s t o look for a r e: lea ks a t t h e clu t ch cylin -
der s a n d in t er con n ect in g lin e; loose sla ve cylin der
bolt s; wor n /loose r elea se for k a n d pivot st u d; da m -
a ged r elea se bea r in g; a n d a wor n clu t ch disc, or pr es-
su r e pla t e.
Nor m a l con den sa t ion in veh icles t h a t a r e st or ed or
ou t of ser vice for lon g per iods of t im e ca n gen er a t e
en ou gh cor r osion t o m a ke t h e disc st ick t o t h e fly-
wh eel, or pr essu r e pla t e. If t h is con dit ion is exper i-
en ced, cor r ect ion on ly r equ ir es t h a t t h e disc be
loosen ed m a n u a lly t h r ou gh t h e in spect ion pla t e open -
in g.
E n ga gem en t pr oblem s u su a lly r esu lt in slip, ch a t -
t er /sh u dder, a n d n oisy oper a t ion . Th e pr im a r y ca u ses
a r e clu t ch disc con t a m in a t ion ; clu t ch disc wea r ; m is-
a lign m en t , or dist or t ion ; flywh eel da m a ge; or a com -
bin a t ion of t h e for egoin g. A visu a l in spect ion is
r equ ir ed t o det er m in e t h e pa r t a ct u a lly ca u sin g t h e
pr oblem .

CLUTCH RUNOUT

CLUTCH DISC
Ch eck t h e clu t ch disc befor e in st a lla t ion . Axia l
(fa ce) r u n ou t of a n ew disc sh ou ld n ot exceed 0.5 m m
(0.020 in .). Mea su r e r u n ou t a bou t 6 m m (1/4 in .) fr om
t h e ou t er edge of t h e disc fa cin g. Obt a in a n ot h er disc
if r u n ou t is excessive.
CLUTCH 6 - 3