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Cheryl Hughes: Screwed on Backwards

On Saturday afternoon, I was on the front porch hanging Christmas lights when Garey came outside to vent.  

“I can’t even watch it anymore!” he said. (The “it” referred to the Alabama-Georgia SEC playoff game.  Alabama was down by two touchdowns.  Garey was not happy.)

“Here, hold this,” I said, handing him one end of a two strand string of lights,” it’ll take your mind off of it.  I’m trying to figure out where the middle is, so I can begin in the middle of the arch.”

“I would say the middle is where the two strands are plugged together,” Garey said, with that look he has when something simple has escaped my understanding.  I get confused about a lot of concepts that seem easily understood by others.  Earlier that day, we had been discussing things that are reverse-threaded, like acetylene tanks and commode handles.  

While I was up on the ladder, I returned to the earlier conversation about things that are screwed on backwards.  

“I get why tanks with highly flammable gases you’re welding with are reverse threaded, but I still don’t get why commode handles are reverse threaded,” I said, “It’s not like we’re going to blow ourselves up when we flush the toilet.”

“The reason they are reverse threaded,” Garey said, “is because the flush lever is on the left and when you flush, the bolt turns counter clockwise.  A counter clockwise motion would loosen a nut and bolt put on clockwise, so they reverse the threads in order to cause the nut and bolt to tighten when you flush.  Back in the sixties, there were some automobiles that had lug nuts on the left-hand side of the car that were reverse-threaded for the same reason, so the lug nuts would tighten as the tires rolled down the road.”

I really didn’t get that, but I didn’t say anything.  I did ask about the propane tank hooked up to our grill.  “With a propane tank, it can only hook up to one thing on a grill and I don’t understand why the threads are reversed on it,” I said.

“They do that so somebody doesn’t hook something else up to it,” Garey said.

“Why would somebody hook something else up to it?” I asked.

“Because people are idiots!” Garey shouted, as he headed back into the house to check the score.  (Note to Self: Do not ask Garey stupid questions while Alabama is down by two touchdowns.)

While I finished hanging the lights, I became curious about cars in the sixties that had reverse threaded lug nuts, so when I finished, I looked up some information online.

According to, there were some pre-1975 Mopar muscle cars with those lug nuts, as well as a few pre-1965 Buick, Pontiac and Oldsmobile models.  On the Car Talk website, it was explained like this: “The idea was if the motion of the wheel happened to make the lug nuts turn, Chrysler wanted them to turn in a tightening direction rather than a loosening direction.  And to do that, they reversed the threads on the left side of the car.  They abandoned the practice after so many lugs were torn off by knucklehead 17-year-old tire jockeys.”

It took me a while to process that information, but after I saw the picture in my mind of the guys at work tightening and loosening lug nuts during tire rotations, I finally understood.  Now, what I don’t understand is why didn’t the guy who invented the commode just put the handle on the right side of the tank instead of the left?

Alabama won the football game, so I guess it’s safe to ask Garey.


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