Jim’s Blog: One Size Fits None

Back when I was wrenching for a living, we used to have a sign in our office that read, “Mechanics are like doctors, except doctors only work on two models.”


Part of what I love about working on old cars is the requirement to think on your toes, and to solve problems that the original engineers never considered.


I’m dealing with this right now, as I’ve been working on building a driveshaft loop for my ’66 Caprice, which of course never had anything like it installed from the factory.


A loop is an important safety device for any car that will ever see dragstrip duty, as it completely surrounds the driveshaft with a thick steel bar to keep it located where it’s supposed to be in the event of a U-joint failure. If that front joint breaks — and they do — that shaft can drop down and hit the ground, upsetting the car and causing a wreck. Or, even worse, it can come inside the car and beat up the driver. Best to have the loop there to save the car and yourself. I’ve lived without one forever and finally decided to fix it.


But here’s the problem: my car has headers and custom 3-inch exhaust that crosses into an x-pipe right below the transmission, and right in the way of where the one-size-fits-all loop I bought was supposed to sit. It was too tall, too wide, and it hit the exhaust and the parking brake cable. Solving all this meant I had to get creative.


The original loop is a four-piece design: two steel U-bends and two angle brackets that all bolt together using grade-eight hardware. I ended up cutting about two inches off each side of one of the U-bends, used a vice to match up each U-bend, and then had my friend — a professional welder — TIG the thing up so I could trust it. Then, I slid the completed hoop over the driveline and positioned it where I wanted it, marked the angle brackets, cut them to fit, and had them welded solid to the hoop. All that’s left is the hard part — pulling up the carpet, drilling a few holes in the floor to mount the thing, and hoping that it clears the driveline, floor, and exhaust system.


Will it fit? Don’t know yet. But it’s looking good, and even if I have to break out the tools again and start over, it’s not a huge deal. To me, outsmarting problems is part of the fun of working on old cars.


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