With leftover parts, how much is too much?

Dear Car Talk:

I have a question that’s been gnawing at me. For many years, I ran a gold mine in remote Alaska. During that time, I had to do a lot of mechanical work on all kinds of equipment and vehicles.

Are there a certain number of nuts and bolts that it’s OK to have left over at the end of a job? Thanks.

— Keith

Is this a mechanical question or a philosophical question, Keith? If it’s philosophical, you may be better off sending it to the Dear Dalai Lama column. Mechanically, it depends on the job, Keith.

If you’re assembling a backyard umbrella and you have a couple of nuts and bolts left over, well, what’s the worst that’s going to happen? The thing will collapse on your potato salad during your mother-in-law’s birthday brunch. Not a big deal, right?

The equivalent on the automotive side would be something like removing the glove box door. If you leave a few bolts out, it may pop open and expose your passengers to your collection of “Besame Mucho” CDs.

Similarly, if you removed your dashboard and ended up with some leftover screws (not an uncommon occurrence, because there are so many screws holding it in place) that’s not going to cause death or injury. It’s going to cause the dashboard to squeak and rattle when you go over bumps. But if it’s something that’s important to life, limb, or expensive property, I think the tolerance for leftover parts goes way down. Really to zero.

For instance, let’s say you’re rebuilding your engine, and you put it all back together, and you find a single nut left over. Well, what if it’s a nut that holds on one of your connecting rod caps? Well, it’s just one nut, but you can kiss your engine goodbye.

The same is true to safety-related stuff like wheels, brakes, seat belts and steering components. So, the goal is always zero, Keith. And for critical parts, it’s a goal you really don’t want to compromise on.