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How to Replace Early Mustang Framerails
Framerail R&R: How to repair and replace an early Mustang’s framerail
A few decades ago, when a car suffered severe frame damage it was usually easier and cheaper to total the car than try to fix the extensive damage. But with Mustangs increasing in value every year, it is now common practice to repair or replace any damage that occurs. That is also true about framerails.
Jason White had a 1966 fastback come into his shop that had been in a wreck severe enough to shove the driver-side front wheel into the framerail. For a lesser car the junkyard might have been called, but an early fastback—any early Mustang really—deserves quality time in the metal hospital to get back on its feet. That is the job Jason decided to tackle.
We asked him how daunting the task was going to be, and he replied, “It’s not that extensive.” We didn’t believe him, so we stood by with our camera and documented what it took. You be the judge.
01. The 1966 fastback’s driver-side outer framerail was bent and needed to be replaced for both good alignment and looks.
02. From National Parts Depot, Jason White bought a driver-side outer front framerail, which is made of 14-gauge steel, the same thickness as factory.
03. With a 1/8-inch drill bit, drill pilot holes in each 3/8-inch circular spot-weld visible along the length of the bent outer framerail. There is no need to drill completely through the 14-gauge steel. The purpose of the pilot holes is to provide indentations to hold the end of a spot-weld cutter, which will bore out the entire spot weld to help free the outer framerail.
04. There are many tools on the market to cut out spot welds. White used a rotary cutter that, in his words, “has a lot of life to it.” Make sure to wear a face shield or a pair of safety glasses to protect yourself from flying debris.
05. Insert the tip of the rotary spot-weld cutter into each pilot hole, and drill out each spot weld.
06. Drill each spot weld as deep as the thickness of the steel.
07. After drilling out each spot weld, you can finish pulling off the outer framerail one of two ways. One is to hammer a chisel between the outer and inner framerails. The second is to pound and pry off the outer framerail with the chisel.
08. A faster method to remove the outer framerail is with an air hammer and chisel.
09. Continue chiseling the framerail along the bottom.
10. The framerail will drop off to expose dirt inside.
11. Scrape and vacuum the accumulated dirt of a half-century inside the framerail. Then, using an assortment of body shaping tools, such as a hammer and dolly, straighten the framerail.
12. White used a large crescent wrench to straighten the edges of the framerails.
13. Using an angle grinder mounted with 60-grit sandpaper, grind flush the old spot welds to create a clean surface for the new panel.
14. Drill holes in the top of the new panel with a 3/8-inch drill bit. These holes do not have to align with the original factory spot welds—White placed the holes about an inch apart.
15. Flip the panel on its backside and grind off the burrs for a flush mounting surface, then test the new panel for fit.
16. Inside the front of the framerail is the factory’s mounting flange for the front bumpers.
17. You can retain, cut off, or knock back out of the way this front bumper-mounting flange. The new outer framerail comes with machined mounting holes for the front bumper brackets. White prefers to use the new-machined bolt holes. He cut off the flange because he says bumper bolts “tend to spin” in the old flange.
18. Clamp the panel in place and then measure the distance from the first bumper bolt hole to the end of the panel. Then compare this measurement with the framerail’s placement on the other side, which is stock.
19. To move our panel back half an inch, we cut a notch in the back of the panel and bent the flange for fit.
20. We clamped our panel back in place and checked alignment again. Use punches (or bolts) to line up the holes in the outer framerail panel with the factory holes. The three holes in the center part of this photo are for the steering gearbox. The small hole to the right is for a power steering bracket. The two small holes on the left are for a brake hose bracket. (Note: A mistake here will require slotting the holes later, which will not look good.)
21. White did a liberal amount of pounding to make the panel fit.
22. Once all the bolt holes line up, clamp the panel in place for welding.
23. White used a Miller 140 MIG wire-feed welder set at 8-9. He started at the front of the panel and moved the clamps for a tight fit as he plug-welded each 3/8-inch hole.
24. Hammering here and there helped the new panel to fit flush.
25. With the welding finished, the panel is firmly in place. Notice on this end of the panel the two machined holes for the bumper brackets.
26. Grind the spot welds flush with 60-grit paper.
27. The new framerail panel is installed and looks factory.