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Sudden Impact!
Copy and Photos by Jim Batie

Overview and Background
On April 9, 1971, the National Highway Traffic Safety Administration issued its first regulation on passenger car bumpers. Federal Motor Vehicle Safety Standard 215, "Exterior Protection," was initially effective on September 1, 1972, and imposed requirements which prohibited damage to specified safety-related components such as headlamps and fuel systems in a series of perpendicular barrier impacts, at 5 mph for front and 2.5 mph for rear bumper systems. Subsequent pressure from manufacturers regarding the overkill of this mandate and the limitations it placed on design, forced an amendment to the Bumper Standard more than 10 years later.

The changes to the Bumper Standard effective with the 1983 model year reduced required damage resistance for passenger car bumpers from 5 mph front and rear barrier impacts to 2.5 mph. The amendment proved the initial mandate was not practical. Unfortunately, a decade of "damage" had been done to body styles that were otherwise contiguous and well-integrated.

The '73 Ford Gran Torino Sportsroof is a great example of an appealing body design that was vastly affected by the 5 mph bumper. The combination of the unusually large, extended, and heavy front bumper makes for a very unbalanced look. Weighing well over 100 pounds, the new bumper adds considerable weight to the front of the car as well. Enthusiasts faced with any model incorporating the 5 mph bumper must ask themselves, what can be done to create a more balanced look and reduce weight in the front end?

With careful attention to detail and basic fabrication skills FordMuscle believed the "battering ram" look could easily be restyled and its' weight reduced. We took on the project using a rare 1973 Gran Torino 4-speed sportsroof car. Since the current bumper was in excellent condition, we chose to use a donor vehicle's piece to perform our modification. We weighed the bumper to establish a point of origin and found the assembly totaled almost 120 lbs. Today, Ford enthusiasts who have collected any vehicle with a 5 mph front bumper are left with a less than optimum appeal and design.

Step 1 - Narrowing the Face Bar
A simple square was used to scribe two parallel lines centered exactly in the middle of the face bar. Extreme care was used in cutting precisely on these lines to ensure a consistent and even edge. Next, the ends were to have a similar section removed from them. This area presented two problems as there is a bumper bolt on each end, and it was too difficult to use the square to mark the cuts. To solve this problem it was decided to remove the material on the rear side of the bolt hole and simply use masking tape to mark the lines. A three-inch section was to be removed so a combination of two and one inch tape applied side to side was used. The area was then painted over, leaving a line to cut on, once the tape was removed. This assured that both cuts would be parallel. All cuts on the face bar were done with small hand held grinder fitted with a 4-1/2" cut off wheel.

Step 2 - Narrowing the Support Beam
An identical two-inch section from the center of the support beam was removed. By doing this all bumper bolt holes remained in alignment. No cut was necessary on the ends as a bolt-on support bracket was used to attach to the outside bumper bolt. Remember that the end cuts were past the bolt hole and the relative location remained the same.

Step 3 - Removing Weight from the Support Beam
The support beam offered an excellent opportunity to shave pounds. There is an extremely heavy and bulky reinforcement assembly in the center of the support beam where the center bumper bolts are located. The majority of this was removed leaving only the area surrounding the bumper bolt holes. A piece of flat stock was then welded in at each outside end providing structural support. The center of the remaining reinforcement area would later be welded when the two halves were joined back together. After marking out the areas that would be removed for additional weight savings, on one half, several templates were constructed using 1/4 inch square bar stock. The templates were then used to make matching pattern cuts on both halves of the support beam. All cuts were then cleaned and dressed with an air grinder. Additionally, all areas were chamfered where butt welds would be required.

Step 4 - Finishing and Joining the Support Beam
In preparation for finishing the support beam the two halves were sand
blasted. This was done before joining the two pieces, as it gave better access to some of the internal structure and allowed them to fit in a blast cabinet. With the aid of several lengths of 1/4" X 3" flat stock, as straight edges, the two halves were first clamped and then tack-welded together. The support beam was then welded inside and out. The outside welds were then ground flat while the inside welds received attention only in highly visible areas. After all, the goal in this project was to have the bumper appear as a stock item.


Step 5 - Tack Welding and Test Fitting Face Bar with Support Beam
Reconstruction of the face bar and the task of joining the four pieces into
one unit was the next step in the process. Luckily, the face bar is a very
straight and uniform piece as viewed horizontally from the front. The top edge is very flat and uniform. The center also has a very flat surface where the license plate mounting bracket fits. Both of these areas are a great help in assuring the proper alignment of the two main pieces before, during and after welding. An extremely flat section of floor was also most useful. After clamping the sections together, checking and rechecking for the correct alignment, several tack-welds where made to the outside of the face bar on the top, front, and bottom. With these three sides tacked, the unit could now be test fitted to the support beam. With great care all bolts were installed, checking for proper fitment and alignment with the support. No bolts were tightened and with bit of luck everything fit well and flush in their holes.


(Bumper Modification, continued)
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In This Article:
Customize and correct the arguably unappealing result that Federal Motor Vehicle Safety Standard 215 had on Ford passenger cars. The
5 mph Bumper Standard.
 

The 1973 Ford Gran Torino is a prime example of a model that suffered from compromised engineering and styling resulting from the federal mandate.
 

With careful attention to detail and basic fabrication skills we believed the "battering ram" look could easily be restyled and its' weight reduced.
 

The result of our modification was a bumper design that would make ex-Ford engineers proud. The stringent mandate was eventually considered overkill and amended making our design up to current specs.

 

 





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