1994 JAGUAR XJ6 Workshop Manual

Body Systems & Body Repair
A4.2.3 ZINC COATED PANELS
A4.2.3.1
Description
Approximately 65% of the 'body in white' (BIW) mass is made up of zinc coated panels.
All exterior skin panels, with the exception of the roof, are double side zinc plated and this coating (nominally
7,5 mi- crons) provides corrosion protection in two ways.
1. Should the outer layer of paint become chipped but the zinc coating remain intact, the zinc will oxidize on contact
with air. This coat of oxidation is impermeable and will prevent corrosion damage to the base metal.
2. If both the outer layer of paint and the zinc coating become damaged, the zinc will react with the air and 'sacrifice'
itself to corrosion, rather than the base metal. In this process the zinc is known as a 'sacrificial anode'.
Iynpp: To maintain the protective qualities of the zinc treatment, repairs to any damaged coated area MUST be made as soon as possible after the damage has occurred.
A4.2.3.2 Wdding Preparation
Where 'resistance spot welding' is employed, the zinc coating should be lightly abraded away on the mating surfaces
and those in contact with the electrode tips. Do not remove more of the zinc coating than is absolutely necessary.
Before welding,
a weld-through primer or inter-weld sealer should be applied, as detailed in the Body Sealing and
Preservation man ua I.
Contamination of the weld will occur ifthe plating is not removed, thus making the joint less strong; another side effect
of this will be a greater need for electrode tip dressing and increased tool down time.
In exceptional cases where the plating must remain intact, increase the tip pressure and welding current by 10 to
20%.
Where MIG welding is used as an alternative to resistance spot welding for plug, butt welds, or limited access, the prob- lems caused by the presence of zinc coating are much the same as those previously mentioned. There may also be
the added problems of increased weld spatter and nozzle contamination.
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A4.2.3.3 Body Fillers
Conventional polyester fillers do not adhere satisfactorily to zinc plated panels. Therefore, it is important to use only
those products specifically designed for this application and follow the manufacturers recommendations.
A4.2.3.4 Refinishing
Use only those products approved by Jaguar Cars Ltd and take special care with zinc coated panels.
Replacement panels are supplied ready primed
so there should be no need for bare metal to be exposed, other than
those areas prepared for welding etc (see 'Welding Preparation' sub section 4.2.3.2).
Where any part of a panel is dressed backto a bare surface, it should be treated with a zinc rich primer compatible with
the chosen paint application system, please refer to section A4.4.1.1.
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Body Systems & Body Repair
A4.2.4 PANELS - ASSOCIATED, RENEW
SRO 77.10.02
w: Where other components must be removed to gain access, please referto the relevant manual section for guid- ance. This is critically important with regard to steering, braking, suspension, electrical and safety systems.
. Expose the resistance spot welds, for those spot welds which are not obviously visible, use a rotary wire brush fitted to an air drill or a hand held wire brush (A Fig. 1).
WARM: DO NOT BURN UNDERSEAL OFF. USE A 'HOT KNIFE' OR SUITABLE SOLVENT.
. Cut out the spot welds using a Zipcutter or Roto-Bor (B Fig. 1).
Jhh: On some panels, before removing the bulk of panel with the pneumatic saw, brazed areas and MIG welded
seams should be removed.
= Separate the spot welded joints and remove the panel remnants.
At
this point
it may be necessary to cut out the bulk of the panel using a pneumatic saw (C Fig. 1).
A
C
Fia. 1
B
II I
II I
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Body Systems & Body Repair
A4.2.5 SURFACES (OLD), PREPARE
SRO
77.10.03
Observe all appropriate safety procedures.
WARNINO: DO NOT BURN UNDERSEAL OFF. USE A 'HOT KNIFE' OR SUITABLE SOLVENT
Remove the weld nuggets with a sander and 36 grit disc.
Clean all flanges to a bright smooth finish. (A Fig. 1).
Straighten existing panel joint edges as required.
A4.2.5.1 SURFACES (NEW), PREPARE
SRO 77.10.04
Observe all appropriate safety procedures.
Mark off the area of new panel and cut to size leaving approximately two inches overlap on the existing panel.
Offer up new panel or section, and align with associated parts, i.e. new rear fender aligned with door / luggage com- partment lid / backlight aperture.
Clamp the panel into position.
Where necessary, cut the new and original panels to form a butt joint.
Remove all clamps and the new panel.
rn If required, apply inner panel protection and or sound insulation.
Prepare the new panel joint edges for welding by cleaning to bright metal (A Fig. 1); this includes all interior and
Apply weld-through primer or interweld sealer (6 Fig. 1) to all surfaces to be resistance spot welded.
Where appropriate, apply metal-to-metal adhesive or sealer (C Fig 1) in accordance with the manufacturer's instruc
exterior edges.
tions.
6
C
,,,A'
Fig. 1
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A4.2.5.2 PANELS, ALIGN AND WELD
. Observe all appropriate safety procedures.
. Apply appropriate sealer or joint preparation.
. Align the replacement panel with associated panels and clamp in position; with certain panels it may be necessary
. Recheck alignment and panel contours and readjust as necessary.
= Select the correct 'arms' for resistance spot welding and ensure that tips are correctly trimmed.
w:
0 SRO 77.10.05 di77.10.06
to MIG tack weld (A Fig. 1) or use 'PK screws.
It is recommended that 'arms' of not more than 300 mm (12 in.) long are used and test the equipment for satis-
factory operation by producing test coupons (B Fig. 1). In the absence of test equipment, a satisfactory weld
can be verified by pulling the test coupons apart and viewing the welded condition.
Resistance spot weld where required (C Fig. 1).
. Note the presence of zinc coated panels and treat as detailed in the previous sections.
. Dress back all MIG tack welds.
. MIG seam weld the butt joints (D Fig. 1).
. As required, dress all welds.
. Final braze and fill as necessary prior to paint preparation.
//
C
Fig. 1
B
D
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Body Systems & Body Repair
A4.2.6 CU77/NG AND WELDlNG SYMBOLS
1. SawCut
2. Chisel Cut AkAAAkAAkAA
666666@6646
4. Resistance Spot Weld 00000000000
3. Cut Out Spot Weld
5. MIG Tack Weld DmmDmm=m=
6. MIG Seam / Butt Weld BBBBBBBBBBB
7. Braze
8. Gas Weld
9. MIG Plug Weld WIIBIIBBIII
Fig. 1 Key to symbols
CAUTION: Reference should always be made to the welding tables and illustrations in the relevant procedures. Obsenfo all safety precautions with respect to yourself, other peopIe, your equipment and the workplace.
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~ Body Systems & Body Repair
Language
Dutch
English
Italian
French
German
Japanese Spanish
A4.3.1 ADHESIVES, SEALERS AND BODY PROTECTION - APPROVED SYSTEMS
0 Specifications and recommendations may be found in the 'Body Sealing and Preservation Manual' which is available in the following languages:
RdercHlco
AKM 9165
AKM 9137
AKM 9164
AKM 9162
AKM 9163
AKM 9178
AKM 9166
Section Relevance
.Cavity wax injection points I Not applicable, see A4.3.2 for specific injection points
Underbody
& underhood wax
Approved paint
refinish pro-
cesses
Health and Safety
A4.3.2 CAVITY WAX INJECTION
Protective wax should be applied in the locations as specified in the following illustrations. Please refer to the 'Body
Sealing and Preservation Manual' for processes, materials and equipment. ~ ~~ ~~
Not
applicable
Not applicable, see section
A4.4.1.1
Legislation applicable U.K. only; general precautions and advice applicable to all
blnfn: Cavity wax processes should only be applied after ALL other refinishing and protection procedures are com-
plete.
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Body Systems & Body kpdir I
A4.3.2.2 Cavity wax injection points - Rear
J 76-1045
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