4790692 93ZJ Secc 13 Frame and Bumpers

8/14/2019 4790692 93ZJ Secc 13 Frame and Bumpers

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FRAME AND BUMPERS

CONTENTS

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BUMPERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 FRAME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

FRAME

GENERAL INFORMATIONJ e e p Grand Cherokee vehicles do not have a con-

v en t i on a l fr a m e (F i g. 1 ). T h e y a r e con s t r u ct e d a s a

u n i t iz ed b od y a n d fr a m e . J e e p unibodies are con-

structed from special h igh-strength steel an d coated

m e t a ls . T h is p r oce s s r e d u ce s w ei gh t a n d p r ov id e ss t r en g th t o w it h s t a n d t h e for ce s a p plie d a ga in s t

structural members. The structural members provide

a unibody that has great structural strength.

A v e h icl e i s d e si gn e d w it h i n a t h r e e d im e n s ion a l

g r id p a r t i t ion e d i n t o 1 0 0 m m (3 .9 2 i n .) cu b es . T h e

l i n e s t h a t m a k e t h e g r i d r u n i n t h r e e p l a n e s d e f i n e d

as X, Y and Z (Fig 1.). The X-plane extends from the

front to t he rear of th e vehicle. The Y-plane extends

from 50 mm (2.00 in.) below the frame rails upward

(D a t u m ). T h e Z-p la n e e xt e n d s fr om t h e ce n t e r l in e

(C/L) of the vehicle outward. The Zero point of th e

grid is located 50 mm (2.00 in.) below the front Prin-

ciple Location Points (PLPs) at the center l ine of th evehicle. Most Z-plane dimensions are symmetrical to

the center line.

COLLISION DAMAGE

DAMAGE DIAGNOSIS

A u n i b od y r e a ct s d iffe r en t l y t o i m p a ct t h a n a v e-

hicle with a conventional frame. While damage at the

point of impact is noticed, the extent of hidden dam-

age must be diagnosed to expose it.

With unibody constru ction, there are five logical

areas to examine to expose dama ge.

(1) Damage at immediate point of impactprimarydamage.

(2) Other body damagesecondary damage.

(3 ) D a m a ge t o e xt e r ior t r im a n d ot h e r a t t a ch e d

components.

(4) Damage to mechanical components.

(5) Interior trim and accessory damage.

DAMAGE REPAIR

A logical approach to damage repair must be used.

Usually, the repairs are done in the reverse order of

consequence.

Also, when there is damage to a unibody, the crit i-

c a l a l i g n m e n t p o i n t s m u s t b e r e t u r n e d t o t h e m a n u -

factur ers specificat ions (Figs. 2 and 3). This en ta ils:

Accura te measurement

Repetitive measurement

Re-check of measurem ents.

Collision damage repair can be done right the first

time:

I f t h e fu n d a m en t a l s t ep s for d a m a ge r e pa ir a r e

correctly followed

If the basic structural details of unibody construc-

tion a re correctly considered.

Fig. 1 Grand Cherokee

Z FRAME AND BUMPERS 13 - 1


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Fig. 2 Frame Dimension LocationsFront

13 - 2 FRAME AND BUMPERS Z


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Fig. 3 Frame Dimension LocationsRear



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BUMPERS

INDEX

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Front Bumper/Fascia . . . . . . . . . . . . . . . . . . . . . . . 4Front Tow Hooks . . . . . . . . . . . . . . . . . . . . . . . . . . 4Rear Bumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Rear Bumper Fascia . . . . . . . . . . . . . . . . . . . . . . . 5Rear Tow Hook . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

FRONT BUMPER/FASCIA

GENERAL IN FORMATI ON

T h e G r a n d C h er ok e e fr on t b u m pe r is a ct u a lly a

b u m p er fa s ci a i n cor p or a t e d w it h a l ow er w el de d

cr os s m em b er . T h e l ow er cr os s m em b er i s a fi xe d

welded structure. To replace the crossmember a frame

machine should be used to correctly align

the crossmember to the unibody.

REMOVAL

(1) Remove 3 gril le screws at gril le opening r ein-

forcemen t (GOR) (Fig. 1).

(2) Unsn ap lower clips a t grille. Remove grille from

(GOR).

(3 ) R e m ov e t u r n s ig n a ls , s i d e m a r k e r s a n d h e a d -

lamps. Refer to Group 8L, Lamps for service informa-

tion.

(4) Remove the 6 retainers at the front fascia (Fig.

2).

(5) Remove the 3 plastic rivets at each front wheel

well (Fig. 3).

(6) Slide the fascia off of the retainer pegs at the

s id e of t h e fe n de r a t t a ch b r a ck et s . U s in g a s m a ll

s cr e wd r i ve r, p u ll u p on l oca t i n g t a n g s u n d e r t u r n

signal m oun ting location.

(7) Remove the fascia from t he veh icle (Fig. 2).

Reverse removal procedure for insta llat ion.

FRONT TOW HOOKS

REMOVAL

( 1 ) R e m o v e t h e n u t s a n d b o l t s t h a t a t t a c h t h e t o w

hooks to t he lower crossmember (Fig. 4).

(2 ) R e m ov e t h e t ow h ook s fr om t h e l ow er cr os s -

member (Fig. 4).

INSTALLATION

(1) Position the tow hooks at the lower crossmem-

b er . I n s t a ll t h e b ol t s a n d n u t s t h a t a t t a c h t ow h ook s

( F i g . 4 ) . T i g h t e n t h e r e t a i n i n g n u t s t o 1 0 0 Nm (74

ft-lbs) torque.Fig. 1 Grille Removal

Fig. 2 Lower Fascia Removal

Fig. 3 Wheel Well Retainers



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REAR BUMPER

REMOVAL

(1) For vehicles equipped with a trailer h itch, re-

move the hitch before removing the bumper. If neces-

s a r y, r e fe r t o t h e r e m ov a l p r oce d u r e w it h i n G r ou p

23Body Components.

(2) Raise and su pport the rear of the vehicle.

(3) Support the bumper.

(4 ) R e m ov e 2 p u s h -i n r e t a i n er s a t e a ch s id e r e a r

wheel well.

( 5 ) R e m o v e t h e b o l t s t h a t a t t a c h t h e b u m p e r s u p -

port brackets to the rear rails (Fig. 5).

(6) Slide the bumper beam/fascia off of the retainer

pegs on t he side of the lower quar ter panel.

(7) Remove th e beam /fascia from th e vehicle.

(8) Remove the bumper support brackets from the

bumper (Fig. 6).

(9 ) R e m ov e t h e u p p er s cu ff p a d fr om t h e b u m p er

fa s ci a b y s q u ee zi n g fa s t e n er s a n d p u s h in g t h r o u gh

slots.(Fig. 6).

(10) Remove the 4 lower retainers from the bumper

fascia (Fig. 6).

(11) Remove the bumper fascia from the bumper.

INSTALLATION

(1) Install brackets onto bumper beam.

(2) Install beam/brackets onto vehicle rails finger-

tight (Fig. 6).

(3) Install fascia onto bumper assembly (Fig. 6).

(4) Check gaps a nd fit. Adjust a s n ecessary. Tighten

bolts to 56 Nm (41 ft-lbs).

(5) Inst all scuff pad (Fig. 6).

(6 ) I f r e m ov ed , i n st a l l t h e t r a i le r h i t ch . I f n e ce s-

sary, refer to the installation procedure within Group23Body Components.

REAR BUMPER FASCIA

REMOVAL

(1) For vehicles equipped with a trailer h itch, re-

move the hitch before removing the bumper fascia. If

n e ce s sa r y, r e fe r t o t h e r e m ov a l p r oce d u r e w it h i n

Group 23Body Components.

Fig. 4 Tow Hook Removal

Fig. 5 Bumper Support Bracket

Fig. 6 Bumper Removal



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(2) Raise and su pport the rear of the vehicle.

(3) Remove th e u pper scuff pad from fascia (Fig. 6).

(4) Remove t he 4 lower retainers from fascia (Fig.

6).

(5 ) R e m ov e t h e 2 p u s h -i n r e t a in e r s l oca t e d a t t h e

rear wheel well on each side.

(6) Remove the fascia from the bumper.

For installation, reverse removal procedure.

REAR TOW HOOK

REMOVAL

( 1 ) R e m o v e t h e n u t s a n d b o l t s t h a t a t t a c h t h e t o w

hook to th e lower crossmember (Fig. 7).

(2) Remove th e tow hook from th e lower crossmem-

ber (Fig. 7).

INSTALLATION

(1) Position t he t ow hook at th e lower crossmember.

I n s t a ll t h e b ol t s a n d n u t s t h a t a t t a c h t ow h ook (F i g.7). Tighten the retaining nuts to 100 Nm (74 ft-lbs)

torque.Fig. 7 Tow Hook Removal


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4790692 93ZJ Secc 13 Frame and Bumpers