If you drive for long enough, eventually you will experience some sort of shimmy or vibration with your car. Anytime any one of your wheels goes out of round or out of balance, it will introduce a vibration as speed increases. Usually, the vibration will be imperceptible below 40 mph, and it will get progressively worse as you reach highway speeds and beyond. The reason for this is that the faster the wheel spins, the more times the imbalance oscillates per second, and the harder the force of the oscillation due to the increased rotational speed.

Additionally, there will often be a specific speed at which the vibration becomes much more severe. This severity stems from the resonance frequency of the wheel/vibration. There are all sorts of fancy physics and calculations behind resonances, but suffice it to say that at a certain speed, you will notice a greater vibration than at other speeds.

What Causes Shimmies?
A shimmy is caused by any imbalance in the rotation of the wheel/tire combination. An imbalance can come from a non-uniform wheel or tire, a bent wheel, or a flat spot. Read the rest of this entry »

Now that you know the basic terminology of alignments, its time to figure out what settings will work best for your car setup.

Prioritize Your Settings
Toe is more important than camber is more important than caster. In that order, always. The reason is that toe has the greatest impact on how well your car steers, tracks, and generally whether it will tend to behave or try to kill you. Camber simply affects ultimate cornering grip and tire wear. Both are important aspects, but not as important as keeping the car in control NOW. Caster only affects the feel of the steering (for all intents and purposes). Hence, you dial in the caster you want/can WITHOUT impacting your toe or camber settings.

SETTINGS

Toe
Setup for Normal Driving and Road Courses
Yes, odd as it may sound at first, I would recommend the same toe settings for a car that is daily driven normally and a car set up for a road course. The reason is simply stability. Toe in in the front keeps the front end from being too “skittish”, and toe in in the rear keeps the rear from having a mind of its own and getting out of control. Both items are just as important driving on the highway to work as they are pushing the limits around a high speed sweeper on the track.

Toe can be measured in degrees or inches. The computer at the alignment shop I go to uses inches, so that is what I’m familiar with. Anything between 1/32 and 1/8 inches in front and rear would be a good setting. The more toe in, the more stability you get, albeit at the expense of slightly more tire wear. I usually get 1/8 inch in at all four corners, as I’d rather be more stable, and I haven’t noticed any excessive wear from too much toe in.

Be aware that depending on suspension setup, toe can change dramatically as your car’s payload increases. Miatas are known for introducing toe out in the rear with heavier payloads. That means that if you get a perfect toe in of 1/32 inch in the rear with no one sitting in the car, that could easily turn into a LOT of toe out when you are actually sitting in the driver’s seat. Since you are always in the driver’s seat when you drive, that means you will always have toe out. Yet another reason to ALWAYS ballast when getting an alignment (see below).

Setup for Autocross
Rear toe setting should be the same as recommended for a daily driver or road course car. Again, you want the rear to be stable and not have a mind of its own.

For front toe, settings depend on the taste of the driver. Toe in gives stability, as mentioned before, but this isn’t really necessary with autocross. Speeds rarely get above 70 mph, and even then it is only for a brief stint if at all. Most speeds are much slower, typically in the 1st and 2nd gear range. As such, the extra response and “snappiness” of toe out can be quite helpful at an autocross. It just may keep you a bit busier on the drive there and back. Read the rest of this entry »

Yes, you read that right. Yesterday on my way home from the supermarket I saw a fellow motorist pulled over by an unmarked Ford pickup truck. And it definitely was a Policeman, and not an imposter. I could tell because it had a police license plate, there was a uniformed officer inside who got out to talk to the driver, it had a whole slew of fancy blue light racks hidden behind every window (all of which went off when the officer made the stop), and, perhaps most telling, it was painted in “unmarked police car gray/blue” (you know that color that NO ONE ever gets except undercover cop cars?).

So there you have it: your last bastion of relief is gone. Now literally any vehicle on the road could be primed to pull you over at any minute. Be advised.

As with nearly every other jurisdiction in the world, Massachusetts is suffering from a budget crisis. Governor Deval Patrick has proposed a whole slew of ideas to generate money, the latest of which is a 27.5 cents/gallon gas tax. As there is already a 23 cents/gallon gas tax, that would bring the total tax per gallon of gasoline to over 50 cents - the highest in the nation.

Even more troubling, however, is proposal to log how many miles motorist drive and tax accordingly. This would be accomplished via a mandatory ID chip installed on every inspection sticker as early as 2014.

What reports don’t address is HOW and WHERE the chip will monitor miles driven. If it is just on Route 90 (within the 128 belt, as the other tolls are “supposed” to be removed), then it is essentially just a state-mandated fast lane system. There are some pros to this, notably less congestion at the tolls. But, then the state has an easy way of tracking where, when, and how fast you are going.

If it is not just on Route 90, but EVERYWHERE, that raises a whole host of other extremely troubling issues. It is one thing for the state to charge you per miles driven on a toll road. Indeed, that is really all that has been going on for decades when you picked up your ticket at the toll booth. It is another thing entirely for every trip to the supermarket, or every Sunday drive for that matter, to be specifically logged and tracked by the state. That would mean that you could not go ANYWHERE in your car without the state knowing about it, and that is system not likely to go over well with the general public.

Cars nowadays are becoming more and more computerized. This can be beneficial in some cases, as the ECU can control various things very quickly and precisely. And the ECU can also tell your mechanic exactly what is wrong if your car has problems.

But the recent trend is to make EVERYTHING electronic. Things that use to be simple and straightforward to do mechanically have now become absurdly complex. A prime example is the oil monitoring system on the new BWM M3. On every car made in the last 100 odd years, you could read the oil level by looking at the dipstick. While a decidely crude and rudimentary design, the dipstick is nonetheless straightforward to use and has served its intended purpose admirably.

The engineers at BMW decided that with the new M3, reading the oil level could be better performed electronically by the ECU. As you shall see, they are wrong. Read the rest of this entry »

The alignment of your wheels plays a much larger role in car performance and handling than most people give it credit for. In short, while the basic positioning of each wheel is dictated by the various arms, driveshafts, and other parts of the suspension, the attitude of the wheel is adjustable by a few degrees. While a change of only 1 or 2 degrees may seem petty, at high speeds and/or at the limit, those couple of degrees can be the difference between solid handling and a terrifying car.

There are 3 possible adjustments that can be made to align a wheel: toe, camber, and caster (for the front wheels only). Whether any of these three are actually adjustable on any given model of car depends on whether the manufacturer designed the car to have those adjustments. Virtually every car has toe adjustments, most have camber adjustments, and only some have caster adjustments, as a general rule. Your alignment shop should know what is adjustable on your car, as they usually will consult some mechanics’ manual that will explain what is adjustable on your car and how to do it. But, that doesn’t mean they will get it right, necessarily. Read the rest of this entry »