Do Not Overtorque Lug Nuts!!!
A few months ago, I took my car to Monro for an oil change, tire rotation, and flat tire fix. It was simple enough, or so I thought.
On Friday, Mac and I were out and about, stopping at Costco, September Farm Cheese, and Dream Dinners. At Costco, Mac ventured out to the car while I completed a comment card about their switch to Pepsi at their snack bar. As I walked out of the store, he was backing the Jeep out of our parking spot. While he was doing that, I heard a pop, and figured it was simply the suspension, so I didn't mention it to him. He heard the same thing at September Farm Cheese while backing out, but he too thought it was the suspension, and didn't mention it to me.
On Saturday, we dashed out to run a few errands, including picking up beer and dog food. We were headed out to the sportsmen's club for their annual corn roast, and then Mac was going to camp there, while I continued home with the dogs to visit with my parents. As we were headed back home after our last stop, we made a right turn, and suddenly, it sounded like there was something in one of the tires. We both commented on it, and noticed that when Mac applied the brakes, the noise stopped, but returned when he accelerated. We were close to home, so we opted to nurse the Jeep home, and deal with it there.
When we parked the Jeep at home, I noticed that the front passenger side tire was missing four of the five lug nuts. I commented on this to Mac, and figured that the reason for the noise was that the tire was wobbling. I figured Monro failed to tighten the lug nuts properly. He took a closer look at it, and noticed that four of the five wheel studs were sheared off instead!
How do wheel studs shear off, you ask? If lug nuts are overtorqued, the wheel studs twist and stretch, which weakens the metal. When additional force is applied, such as when one turns, the metal can shear off or break. If all of the wheel studs shear off, the tire falls off of the vehicle, causing that portion of the vehicle to fall, and potentially causing an accident and additional vehicle damage.
We were extremely lucky that we noticed it before that happened, especially as we were going to travel on the interstate and turnpike later in the day. Had the last one sheared off while we were on one of those roads, I question if I'd be around to write about it.
Mac tasked me with sourcing the wheel studs and lug nuts while he started the process to remove the tire, brake caliper, and all of the other pieces that it involved. I found them at our local Napa Auto Parts store, and once he disassembled everything, we drove to Napa and purchased all of the parts. He then installed everything while I packed and showered, and then I worked on loading the car while he packed and showered.
Even with the delay, we were on the road only two hours late. Today, I will call Monro's corporate number, and will talk to them about reimbursing us for the cost of 20 wheel studs and five lug nuts, as I do not trust the other wheel studs, nor do I trust them to replace the rest of them. At this point, I do not trust Monro to do anything for my vehicles, and I'll be looking for a new mechanic. The lesson to learn from this is that while one should make sure that the lug nuts are properly tightened, one should not overtorque them.