Question - I've heard that you both graduated from MIT in Mechanical Engineering. If this is true, then we have that in common. But I hope we don't have my car problem in common. My car builds up a static charge. And as soon as I get out of the car and touch the frame, I get zapped. It's quite painful. I've tried wearing shoes with different soles, kicking the door shut, and now I just close the door by pushing on the window. However, the static charge remains in me, and the next thing I touch which is grounded zaps me.
Some of my friends have suggested that my hair is too long, or that I have some sort of extra-chargeable seats. The most common comment I get is that I have an "electrifying personality." Short of shaving my head, what suggestions would you have to keep me from building up such a large static charge? - ChristineTOM: We happened to solve a similar mystery about static electricity on our radio show a few years ago, Christine. A toll-taker called us and told us that whenever a then-brand-new Honda Accord came by and the driver handed him a quarter, he'd get zapped! POW! So much so that he began ducking down in his booth whenever he saw a new Accord coming along.
RAY: It turned out that the new Accords were using a relatively new "low rolling resistance" tire, which reduced rolling friction to improve gas mileage. And, you guessed it; static electricity leaves a car primarily through the tires. In changing the rubber compound to increase mileage, the tiremaker had made the tire a poorer "grounder." So those new Accords were not dissipating static electricity as well as most of the other cars on the road.
TOM: And while the tiremaker claims to have improved the grounding ability of that particular tire, the truth is that many tires are now "low rolling resistance" tires and probably don't dissipate static electricity as well as tires of old. It's one of the prices we're paying for better fuel economy. And my guess is that your tires are the crucial element in this equation, Christine.
RAY: Assuming that you're otherwise perfectly happy with your tires and your mileage, there are a couple of other things we can suggest. The simplest is to "discharge" yourself through something else. If you hold your metal car key, for instance, and touch IT against the grounded car, the charge will jump from the end of the key to the car, leaving your finger "unzapped."
TOM: But if you don't want to bother with it at all, most auto parts stores now sell "grounding strips" that hang from the frame of the car and touch along the ground. I've tried those, and they work pretty well - although since they scrape along the ground, they do wear out after several months and need to be replaced.
RAY: Of course, it's possible that the friction of the grounding strips will reduce your mileage by as much as the "low rolling resistance" tires increase it. But you'll have to figure that out, Christine. After all, you're the mechanical engineer. My brother graduated from MIT in chemical engineering.
TOM: And my brother graduated with a degree in animal husbandry, and even practiced for a few years . . . until they caught him at it!
Question - My 1988 Nissan 200SX gave me quite a scare. I turned the ignition key and it sounded like the motor was already running. I sat there for a minute thinking I had left my car running. No, I had the keys with me. I turned the key again and it started immediately. This happened again about a week later to a mechanic when I had my car in the muffler shop. This was three weeks ago and it hasn't happened since. What could it be? Will this get worse, quit happening or should I get to a repair shop? - Lea
TOM: Well, I have good news and bad news, Lea. The good news is that you're not losing your mind; you had not left your car running when you turned the key.
RAY: The bad news is that after you hear our diagnosis, you're going to WISH you had just left the car running.
TOM: You've got a bad ring gear on your flywheel, Lea. When you turn the key to start the car, a little gear on the starter meshes with a big gear (the ring gear) on the flywheel. And turning that flywheel is what starts the engine. The problem is that the gear on your flywheel has some broken teeth.
RAY: Has it been eating at my mother's house lately?
TOM: When you turn off the engine, and the flywheel happens to stop in just the wrong place (where the broken teeth are perfectly lined up with the starter gear), you get that horrible gnashing noise next time you turn the key. And if you're lucky, that gnashing is enough to move the flywheel a couple of degrees; just enough so on the next try, the starter hits some good teeth and the car starts right up.
RAY: But it's going to get slowly worse, Lea. If you don't mind the inconvenience, you can drive it like this for a while, but as time goes by, it's going to happen more and more often. And someday it won't start at all.
TOM: So if you've got $500 or $600 lying around with nothing to do, you might as well grit your teeth (ha, ha) and get a new flywheel. If not, you might see if your local bank has a "flywheel club" to help you start saving. Good luck.
Question - On my 1991 Camry, there's a button called "overdrive." Can you please explain to me its functions and usage? - Mike
TOM: Yes, Mike. That's the mother-in-law ejection seat. But it only works once, Mike, so make sure you wait until she's in the middle of a good, loud rant before you hit the button.
RAY: Actually, overdrive is just another name for fourth gear on your car. Overdrive is a gear designed for high-speed driving. It provides little power to accelerate, but allows the engine to run relatively slowly so you get excellent gas mileage.
TOM: And that button is there to turn overdrive OFF. Now, at this point, you may be asking yourself, "If I have an automatic transmission which chooses my gears for me automatically, why would I ever want to turn overdrive off?" That's a very good question, Mike! And in most cases, you don't want to turn it off.
RAY: There's only one exception, really. There may be certain road or traffic conditions that force you to maintain a speed that keeps the transmission right on the hairy edge between third gear and overdrive. That speed is generally about 35 mph. And at that speed, the transmission tends to "hunt." That means it goes back and forth between third and overdrive trying to find the right gear to be in.
RAY: Is that bad for the car? Not particularly. But it can be annoying to the driver and passengers. And that's why that overdrive button is there. So when the transmission is "hunting," you can turn off overdrive and force the transmission to stay in third gear until your driving conditions change.
TOM: Other than that situation, I would suggest you just ignore the overdrive button, as you've obviously done quite successfully since 1991, Mike.
The Magliozzi brothers' radio show "Car Talk" can be heard each Saturday at 10 a.m. on KUER FM 90.1 If you have a question about cars, write to Click and Clack Talk Cars c/o King Features Syndicate, 235 E. 45th St., New York, NY 10017. You can e-mail them at (http://cartalk.com).