Q 1: If my brakes are not worn out, then why do they squeak?
Here at KO Automotive in Lake Forest, we get this question asked every day. Well, here is the thorough answer to it:
Ever think about what the brakes in your vehicle have to do? To put it simply, they have to stop 3,000 pounds (some SUV’s double that) moving as fast as 70 miles per hour and do it in an efficient manner. On a compact car, the size of the front brake pads at one wheel would be about the same as a piece of toast. On a large SUV, two pieces of toast. Now if we take a 4,000 pound car, you would assume that the front brakes would handle 2,000 pounds and the rear brakes the other half. In reality because of weight “shifting” forward during the braking process, the front brakes are handling well over half of the vehicle’s weight. That’s asking a lot out of something about the size of a piece of toast. The reason I’m telling you all this is because of the heavy demand imposed on the front brakes, front brakes are the ones that usually squeak.
Brake pad quality plays a big role not only in not producing squeaks but also in how well your vehicle stops. Brake pad material is formulated differently for different vehicles. Unfortunately, some brake pad manufacturers use a “one composition fits all” approach in formulating their brake pad compound. While this approach makes manufacturing the brake pads much easier and enables the manufacturer to sell them at a lower price, these type of brake pads will cause problems. The material in the pads may work well in a heavy vehicle but not so well in a lighter vehicle or vice versa. As a general rule, the more expensive the brake pads the better they are and the less prone they are to squeaking.
The finish on a brake rotor (disc) can also cause brake squeak. The rotors are part of the wheel assembly and spins every time the vehicle is moving. The brake pads squeeze against the spinning rotor in order to stop the vehicle. If the brake rotors on your vehicle are serviceable, they are machined whenever the brake pads are replaced. Machining the rotor creates a nice flat area for the new brake pads to squeeze against. Not only does the rotor have to be flat, the finish has to be somewhat smooth and uniform. A rotor that is worn out or not machined properly will not allow the brake pad to have full contact against it and will create excessive heat in the parts that do make contact. This excessive heat will lead to overheated areas on the pads and rotors which can lead to squeaks.
Your vehicle can have the correct pads installed and properly refinished rotors, or even new ones installed, but will squeak if the brakes are overheated. When new brakes are installed, it is the responsibility of the installer to properly “seat” the new brakes. Not seating the new brakes properly can overheat them and lead to squeaks. Even if the brakes are seated properly, they can be overheated afterwards. Driving down a hill can cause brakes to overheat. Most don’t realize that even the slightest pressure on the brake pedal will lightly apply the brakes so, even driving with one foot on the brake and the other on the gas, will overheat the brakes. If you’re driving down a hill and are just “resting” your foot against the brake pedal, the brakes could be applying a very slight pressure against the rotor. It only takes a few seconds for the brakes to get hot. On some vehicles, applying the brakes continuously (while moving) for over 20 seconds will overheat them. Now imagine going downhill for several minutes like this. The brakes will get very hot. You may even smell the brakes overheating. You may have even seen vehicles on the side of the road with their brakes smoking or even on fire. This is a result of keeping the brake applied (even lightly) for too long. As we discussed earlier, overheated brakes can lead to squeaking. Now you’re probably asking yourself “how am I supposed to keep my car from going too fast down a hill?” There are two things you can do. First of all, as your downhill speed increases, apply the brakes and slow the vehicle down. Once you have slowed sufficiently, release the brake pedal completely. This will give the brakes a chance to cool until you have to slow the vehicle down again. Secondly, you can shift the transmission down to the next lower gear and let the engine and transmission do some of the work.
Believe it or not, even worn out shocks can cause the front brakes to overheat. Remember how weight shifting during braking causes the front brakes to do the majority of the work? Well, if the shocks are worn out the weight shift is even more severe since the front of the car is allowed to dip much further than it should which increases the load on the front brakes.
Worn out or missing brake pad hardware will cause brakes to squeak. Pad hardware is what holds and positions the brake pads properly in their mountings. Most brake pads will also have thin metal shims on the backing. If the brake pad hardware is worn out, or if the pad shims are missing, this will allow the pads to shift within their mounting which may produce brake squeak.
As you can see, there are many things that have to be right and go right in order for your brakes to not squeak and work properly. With all the possibilities for brake squeak, one of the best things you can do to prevent brake squeak is to have top quality brake pads installed by a professional. Remember, not all brake pads are created equal and not all installers are professionals.
Q 2: What can I do to get the best fuel economy from my vehicle?
Servicing your car on a regular basis is one of the most important things you can do to maximize the fuel efficiency of your vehicle. Driving a vehicle with worn out spark plugs can reduce fuel mileage by as much as 4 percent. Replacing a clogged air filter can improve your car’s mileage by as much as 10 percent. Fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve mileage by as much as 40 percent.
Keeping your tires inflated to the proper pressure will improve fuel mileage. If each tire were underinflated by 5 psi (pounds per square inch), your fuel mileage could drop by as much as 2 percent.
Do not keep unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your mileage by up to 2 percent. The mileage reduction is based on the percentage of extra weight relative to the vehicle weight and affects lighter vehicles more than heavier ones.
Aggressive driving, such as speeding and rapid acceleration, can lower your gas mileage by 33 percent at highway speeds and by 5 percent around town. Drive sensibly.
For more information go to http://www.fueleconomy.gov/
Q 3: Why should I change my engine oil every 3,000 miles when the manufacturer recommends changing it every 5,000 miles?
You should change your oil on a regular basis to protect your investment and extend the life of your vehicle. How often you change your engine oil depends on what you expect out of your vehicle. If you buy a new vehicle every 3 to 5 years you don’t have to change the oil every 3,000 miles. Why? Because you won’t own it long enough to see the problems associated with long intervals between oil changes. If you plan on keeping your vehicle longer than 5 years and want to keep the engine in the best condition possible, you should change the oil every 3,000 miles.
Two things happen to the oil in your engine. First of all, it is subjected to high temperatures, which over a period of time causes the oil to lose its ability to lubricate. Secondly, the oil gets contaminated with by-products of combustion and microscopic pieces of metal wearing off the engine. Even though your engine has an oil filter, it can’t catch everything, and over a period of time, these microscopic metal particles suspended in the oil reach a point where they act like sandpaper and accelerate the rate of wear on your engine. Synthetic oils will not break down as quickly as regular oil but particles will become suspended in it.
The longer the oil stays in your engine the more damage is caused to your engine. Why do dealers ask you to go longer between oil changes? They’re in the business of selling cars. They don’t want you to keep that car too long. They want you to buy another one.
Ask Your Own Question