Annoying Brake Screech
Q:I have a 2002 Ford Ranger that's had front-brake problems every 1500-2000 miles since it was brand-new. The problem starts as a rubbing noise, whether or not I'm stepping on the brake pedal. The noise is audible only at speeds of less than 25 mph and increases and decreases in frequency with the speed of the vehicle. When I first start driving, I can hear it, but by the end of my 40-mile commute, it's very noticeable in the cab. The dealer has replaced the brake pads (more than once), the rotors, and something he called the "cradle" for the pads, to eliminate vibration. It appears to make one rubbing noise per rotation of the tire; it rubs for half a rotation and doesn't rub for the other half. Would drilled brake rotors and aftermarket pads be a good move?
A:Cross-drilled brake rotors are a performance modification that provides additional heat dissipation. You get what you pay for when dealing with aftermarket pads, and original-equipment linings are often higher quality. The noise occurring with your foot off the brake pedal makes me think it's not coming from the pads themselves. If there was a frozen caliper producing a brake drag, chances are there would be more severe heat-related symptoms. The first thing to inspect is the protective shield backing the rotor. It may have become bent somewhere down the line and is now touching the rotor. The noise coming and going with rotation could be from contact with an imperfect machined surface or a rough cast portion of the rotor. This type of contact can vary with expansion and contraction of the brakes and therefore produce changes in noise levels while driving. There are other potential causes, possibly even something rubbing against the inside of a wheel. Get it to the repair shop while the noise is pronounced. They may be able to put the vehicle up on a lift, spin the wheel, and see and/or hear exactly where the sound originates.
How Much Power Now
Q:I did a few performance modifications to my 2002 Dodge Ram 1500 pickup with the 5.9-liter Magnum engine. I've added the Gibson split-rear exhaust, K&N AirCharger, Tornado Fuelsaver, and a Superchips Microtuner. What horsepower numbers can I expect with these add-ons? When it was stock, the truck had 245 horses and 335 pound-feet of torque. I think I should be at or near 300 horsepower and am thinking about adding headers. Let me know where I'm at and where I need to go to compete with the Fords, Chevrolets, and the new Nissan.
A:The majority of aftermarket performance-parts manufacturers advertise an approximation of power gain with the installation of their products on your car or truck. However, accuracy can only go so far, with numerous variables between the test vehicles and your own, unknown quality and integrity of the test equipment, and the folks behind the switch. There also may be discrepancies when adding on multiple components from different companies. In other words, one company saying its component adds 10 horsepower and another boasting 15 may not add up to 25. The best way to calculate peak horsepower and torque ratings is with a dynamometer, with a qualified technician running the test. However, this brings up a communication barrier. Most automotive manufacturers publicize their power numbers in an SAE Net Rating. This is done with an engine dynamometer, taking measurements at the crankshaft with the engine out of the vehicle on a test stand. I don't know how many amateur drivers are willing to pull an engine to satisfy their curiosity. The more convenient and common method, using a chassis dynamometer, provides ratings at the driven wheels. These numbers are always lower, due to the power lost to friction between the crankshaft and tires (torque converter, transmission, driveshaft, and so on). Find a performance-oriented shop with a good reputation and realistic records of vehicles tested before and after the installation of hi-po components. This can give you a good idea as to where you stand within the Big Three--or Four.