Send questions to Franz Kafkas Garage, 1585 Eisenhower Place, Ann Arbor, MI 48108 or e-mail FKG@CARandDRIVER.com.
I have a question no one seems to be able to answer. What does fob, as in key fob, mean?
Albuquerque, New Mexico
The term fob goes back to the days of pocket watches. It was the short chain or ribbon attached to a pocket watch and worn hanging in front of the vest or waist. Today, its a remote control used to lock and unlock a car, among other functions.
STEEL YOUR FACE
Why does Car and Driver (and every other magazine) insist on saying that a car has gotten stiffer due to increased usage of high-tensile or high-strength steel? Those terms only refer to the strength of the steel, which doesnt impact the stiffness. All carbon steel has pretty much the identical stiffness, or Youngs modulus, of 30 million psi. The only way to make a steel structure stiffer is through design geometry or increasing its thickness. The strength of the steel improves crashworthiness. Please help spread the word.
Youre right, but Kafka thinks you must be confusing C/D with some other magazine, as weve been spreading the word for years. Think of a steel rod clamped to a table and extending over the edge, with a weight hanging on its end. Stiffness is a measure of how far the rod will bend relative to the weight hanging on it. Of course, if you hang enough weight on the bar, it will eventually either break or bend so far that it wont return to its original straight shape. The point where the bar bends permanently, or breaks, defines the strength of the steel. As you mentioned, the cheapest steel water pipe and the finest tool steel have basically the same stiffness (or Youngs modulus), so changing the grade of steel alone wont change the stiffness of any part or structure. High-strength steel does improve crash performance, though, because the steel is able to absorb more energy before and during its deformation.
|Tourist attraction in Greeceor was it Turkey? John Gintoli was so stunned he cant remember now.|
HOT AND COLD
For 50 years, I have read that cold starts are very hard on a car and warm starts are relatively benign. Now a Toyota engineer [quoted in C/D] says a warm start is among the more stressful things for an engine [Mileage Myths and Misconceptions, December 2008]. I organize my driving to minimize cold starts. Are the previous 50 years of information wrong?
San Luis Obispo, California
Cold starts are still tough on engines, one reason being that cold oil provides less lubrication. As for warm starts, Kafka thinks Toyotas Paul Williamsen was referring to the fact that repeated warm starts are more abusive than continuous idling. Hybrids, on the other hand, are optimized for repeated stops and starts and dont use a conventional starter motor. Basically, any start is tough on an enginewhile the starter is cranking, the oil pump isnt up to speed, which reduces lubricationbut cold starts are still tougher than warm ones.
A QUIET CAR POOL
When using the car-pool/HOV lane, does your passenger have to be alive? A few of my colleagues and I were wondering. Thank you.
Licensed Funeral Director
As far as Kafka can tell, youre out of luck. HOV lanes were created to reduce traffic by encouraging carpooling, and its not like the recently deceased are going to be clogging highways by driving themselves. The California Highway Patrol denies HOV rights to pregnant womenpassengers must be separate individuals. Kafka would guess that other states with high-occupancy-vehicle lanes dont count cadavers as passengers, either.
Ive asked a dozen people this question and got back either a confounded look or one of annoyance but never an answer. Could you tell me if there is a measurable difference in psi in checking a tires pressure if the tire is in operational status (affixed to the vehicle and on the road) or simply lying out (in a spare-tire well)?
The air pressure wont vary in the examples you cite because the amount of air within the tire doesnt change (at least not in the short term), nor does the tires volume. Temperature changes will cause tire pressures to vary. So if, like Kafka, you enjoy keeping your spare tires in a walk-in freezerwhat fun!then the pressure will increase if the outside temperature is higher. More realistically, a tire warmed from driving or from direct sunlight will be a few psi higher than a tire that sits in a trunk.