Does your car pull to one side when you are braking? Someone may have told you that the brake pads on one side are overly worn down, but this may not be the issue at all. The pads may be in perfectly good condition, but a much smaller but nevertheless important part may be to blame. What do you need to know about "guide pins" and how they can cause a problem if they are not correctly cared for?
Small Parts, Big Job
Few people outside of the automotive trade have heard of these parts or know exactly what they do. However, they have an important job.
You will find a pair of these pins at each corner of the car fitted within the caliper housing. Their job is to guide the brake pads as they move from one position to another when called upon to decelerate the vehicle.
Brakes in Action
As you may know, when you press your foot on the pedal, hydraulic fluid is pushed along pipes to the caliper. This fluid will activate pistons which will then push the brake pads from their resting position against the rotary disc. As the pads rub against the disc, they will slow it down and, consequently, slow the vehicle down as well.
Gliding Back and Forth
Clearly, those pads have to move back and forth often during a typical car journey and they will usually do so smoothly along a pair of guide pins. Still, these pins have to be in good condition to allow this to happen, and from time to time, problems can arise.
Typically, the guide pins are contained within a protective rubber boot so that they do not become contaminated by dirt and debris. They should also sport a thin layer of high-temperature grease, a synthetic lubricant designed to deal with high temperatures and harsh conditions.
Sticking in Position
If the protective boot is damaged or you have an insufficient amount of grease, the brake pads could stick in one place rather than moving back and forth. Should the pads on one side of the vehicle stick in the "on" position, they may apply more force to that side of the vehicle than the opposing pads can supply. This is why the vehicle would tend to pull to one side under heavy braking.
Now that you are more familiar with these humble guide pins, you know how important it is to keep up with regular, scheduled service. Should you do this, your mechanic will always check the condition of the guide pins and clean and lubricate as necessary.
Contact an auto mechanic for more information about brakes.