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By Jim Wilk, Licensed Auto Body
Technician
Start:
Note: This is
Part 2 of a two-part article.
To read the Part 1,
click here.
Two mechanics, who repair wrecked
Jeeps as a hobby, bought
a 2005 Jeep that had been "totalled" in a
rollover accident on a trail.
They had a local "frame shop"
straighten the frame, and then the owners brought the Jeep
to us for the remaining body repair work.
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In
Part 1,
I removed the damaged sheet metal and repaired
the frame where the back bumper attached. |
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Replacing Body Panels:
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The new grille radiator
support and left front fender has been assembled.
This step involved a lot of bolts and wires,
but it was easy
work. |
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After the hood was repaired
the front sheet metal fit properly. |
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Next I returned to the rear of the vehicle. I
removed the rear quarter-panel and applied weld-thru
primer to the areas that will be welded. |
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Body Shop Welding Technique:
Before assembling
the body panels, I drilled several holes in the panels
(red arrows) to
coincide with the metal support underneath.
I like to weld in the center of the hole and
fill it in until it creates a button on
the outside (which can be seen next to the
holes with arrows). These buttons can
be ground down flush later.
I'll explain more later in this article. |
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I drilled holes in the end of the side panel
then clamped the end cap to the side panel.
These two panels need to be welded together
before mounting on the vehicle. |
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| After welding
the panels together along the flange (red arrow)
I cleaned and primed the area. As the photo shows, it would be a hard area to
clamp and weld these pieces on the vehicle.
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Then I started the final fitting of the panel
and door. After taking some measurements, I
discovered that the left door was situated
too far in at the top and too far out at
the bottom. That meant that the body had been
damaged around the driver's side hinge area.
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| After taking
measurements from another Jeep, I pulled out
the top hinge area using the frame straightening
equipment. |
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I also found the upper area of the rear side
panel was pushed in from the rollover. Also, a section of
the driver's side roll bar had to be replaced. |
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| Finally, I
was starting to develop nice gaps... |
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...and the door and tail gate opened and
closed properly. |
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When
repairing a vehicle where panels have to be
replaced and welded, we "jig the area".
That means we support, screw down and clamp all the metal
panels.Then
we weld it solid.
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left side has its outer skin loosely attached
with some clamps and sheet metal screws, (and
the right side is still original), the left side
can be moved inward or outward. I used two
cable winches (red arrows) to hold the left
side in the proper position relative to the
right side. |
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The alignment of all the inner (structural)
panels and the outer (skin) panels is
double-checked. All of the panel gaps are checked again before welding. |
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| Also, the rest of
the hinge bolts are tightened down. |
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I checked the door gaps again. |
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Welding The Body Panels:
| Using a MIG
welder, I welded in
small strips of about one inch and then let the
metal cool before welding more. I often use a
wet rag to cool the metal, but some body
technicians prefer to use compressed air. This
"stitch welding" is done to prevent the metal
from warping.
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Then I removed the temporary hold-down screws... |
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...And I filled in the
screw holes with weld bead. |
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| Remember how
I mentioned earlier that I drilled small holes
in the outer panels? I welded
through those holes into the inner structural
panel to bind the two panels together.
During welding the area is clamped as tight
as possible using special Vise-Grips.
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I like to weld in the center of the hole and
spiral outward to fill in the hole until it creates a button
of weld bead, which can be ground down flush
later. |
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Caution When Welding Around The Gas Filler:
Whenever I
weld around a gas filler I take some special
precautions to prevent any gas fumes from
igniting.
I apply masking tape
around the cap (in case the cap doesn't seal
perfectly) and then wrap it with a wet rag.
Then I cross
my fingers and weld. |
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Once the welding was completed, I removed all the supports, screws and clamps.
Then I checked the gaps again. If any gaps were
too big or too small, I would rework the area. |
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| Then I ground down
all the welds until they were flush and smooth. |
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| I
sanded the panel down to bare metal. Then the joint was filled
with fiberglass filler and finished smooth. |
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The bare areas were primed by the painter. |
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A Problem Arises:
I don't normally second-guess the
work done by another auto-body professional, but on this job
the person who straightened the frame missed some important
measurements.
Any vehicle with a body-on-frame
construction (which includes most trucks and many SUV's) has
a chance of frame damage in a collision. A common type of
frame damage is what we call a "diamond" in the body
trade. Most frames are built like a ladder, with side rails
and "rungs" or cross-members that connect the two sides.
When a frame becomes diamond-shaped, it's like one side rail
of the ladder has been pushed forwards or backwards compared
to the other side rail. Consequently, the cross-members no
longer make a perfect 90-degree angle with the side rails.
If you measured the diagonals (from front-right to the
back-left corners, and vise-versa), they would be different
lengths... but they should be the same.
Have you ever seen a vehicle driving
down the road where it looks like the rear of the vehicle is
too far to one side? This is called dog-tracking, and it's
often caused by the frame being diamond-shaped.
Dog-tracking causes all sorts of
problems, such as improper steering function and excessive
tire wear.
| While the
Jeep looked like it was ready to be painted, it
wasn't. It needed to be returned to the frame
shop for more repair work. |
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The left rear frame doesn't stick out as far
as the right
side.
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| At the right
rear, the frame was sticking out one-half
inch farther than the left side. I
suspected that this frame might be
diamond-shaped. |
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At The Front:
The anti-sway bar (stabilizer bar) left
mounting bolt (which I marked in red) is
farther away from the radiator support than the
other side. |
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| Note how the
corresponding bolt on the right side was almost
touching the radiator support. This confirmed
my suspicion that the frame was diamond-shaped. |
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I explained this fact to the owners
of the Jeep, and they sent it back to the frame shop to fix
the problem.
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After the frame shop fixed the diamond-shaped
frame, the rear frame looked perfectly parallel
to the body. |
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| The painter
applied Matrix Systems color coat followed by a
clear coat. |
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After painting I couldn't see any dents or
waviness even when bright light was reflecting
off the repaired side. |
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| At the
request of the owner, we applied a special
abrasion-resistant paint on the inside of the
bed. |
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After these body repairs, the owners
took the Jeep back to their shop and replaced all the
miscellaneous parts, such as tail lights, bumper, wheel
flares, etc.
More Info:
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Tools Used:
- Basic Mechanics
Tools
- Cable Winches
- Body Puller and
Clamps
- Porta-Power
Hydraulic Jacks
- MIG Welder
- Surge Protector
- Oxy-Acetylene
Torch
- Spray Finishing
Equipment
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Materials Used:
- Replacement Body
Panels, Aftermarket
- Professional Auto
Body Supplies
- Matrix Systems
Paint and Clear Coat
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