Rotor Runout: Cause and Correction
The vehicle owner may say that under light braking the vehicle pulses to a stop or under heavy braking the vehicle shudders. Technical service bulletins (TSBs) often describe these symptoms as a “judder.” There are only two causes for judder — lateral runout and disc thickness variation on the rotor’s friction surface. What could have
Drum Brake Self Adjusters: Understanding These Ancient Devices
d bridge bolts. Opposing piston calipers are bolted to the knuckle and have pins to position the pads. Drum brakes have return springs to return the shoes to a rest position and hardware to hold the shoes to the backing plate. The shoes return to a fully retracted or rest position when the master cylinder
A Brief History of the Steering Wheel & Power Steering
It’s 1956 and the 20-inch-diameter steering wheel on a Chevrolet Bel Air or Ford Fairlane provided the leverage to steer the wheels. But, it was especially difficult to turn the steering wheel when the vehicle was stopped. Turning the wheel required a certain amount of upper body strength that was given by God to truck
Wheel, Rotor and Drum Removal
The traffic whizzed by at seventy plus. The good news: The flat is on the rear passenger side and the lug nuts came off with little strain. The bad news: The alloy wheel is seized on the hub and it isn’t going anywhere. Twist of fate: I forgot to chock the front wheel and the
Tie Rod Geometry
Keeping the angles in line with Ackermann Most people consider the common tire rod to be low tech. But, when you consider how front suspensions have evolved from straight axles to independent designs, the tie rod has had to adapt to new angles and geometry. Keeping it on the road was simple with the straight
Steering Stabilizers: Suspension Geometry
Big rims or tires can look good and give a vehicle a unique look. But what is invisible becomes real ugly is the alignment and suspension angles that become altered. Also, that extra weight in stylist alloy rims or thick off-road tires can create a gyroscopic problem. Lifting Why do people lift trucks? The primary
Inspection by the Numbers
As the saying goes: “The devil is in the details”. Another saying is: “The truth is in the numbers.” When performing a brake inspection, both are true. Replacing the calipers and rotors with every brake job may not be the cure all for ending all for fundamental brake repair problems. An inspection of every component,
Under Pressure and Pounding: What Happens to Wheel Bearings and Suspensions When Wheels Get Big?…Stop Using Percentages if You Cannot Show Your Work!
Custom wheels and tires have been an automotive fashion statement since the 1970’s and today custom wheels have become automotive jewelry with 26-inch spinners on a Hummer as one of the ultimate statements. But, the hidden costs come at the price of wheel bearing life and other wheel end components. As an undercar shop, you
Chassis Dynamics
A Firestone sales jingle gave us a good definition of chassis dynamics: “Where the rubber meets the road.” There are four tire tread contact patches that support the weight and control the motion of a vehicle. There are a lot of terms used to describe the motion of an automotive chassis and how it affects
Power Steering Repair
A long time ago in a garage far away a young technician was seeking a repair of a steering system. He found there are a lot of things that can go wrong with a rack and pinion steering gear. The steering wheel vibrates at speeds above 45 miles per hour; the steering wheel doesn’t return
This is a Great Time for the Brake Industry
As the editor of BRAKE & FRONT END, I make it a point to try out as many friction materials as possible. I have tried $20 pads, and expensive performance pads that can cost as much as $180 a set. I fint it amazing what a great set of brake pads or shoes can do
Cracking the Code: Understanding Friction Material Edge Codes
Just about every brake pad or shoe you install has a cryptic code printed on the side of the friction material. As a technician, being able to read this code is just as important as the Dewey Decimal system is to a librarian. The “Edge Code” can tell you information about the product you are