Have you ever tried to actually read your owner’s manual, especially the part about maintenance and service? As if this kind of stuff isn’t confusing enough, there are always two schedules listed, one for a vehicle driven under “normal” conditions and another for “severe.” But what exactly does this mean? I have yet to see an automaker that actually explains, in plain English, what these terms mean.

This article is the third in a series of four that addresses the differences between severe and normal service recommendations. We’ve already covered engine oil and other fluids, so now we’re moving on to the brakes and suspension components.

Service Schedules For Brakes And Suspension

Let’s start by trying to understand the differences between normal and severe. The severe schedule, as it is commonly described in your owner’s manual, applies if any of the following are true:

You make frequent short trips, say to the store and back, or to work and back, with a total distance under 10 miles.

You drive your vehicle heavily loaded or use it to tow.

You often drive in dusty, dirty environments like construction sites or off road.

You drive mostly in stop-and-go situations like in city traffic or on a delivery route.

Sometimes the effects of severe duty are obvious, such as how much more rapidly your brakes will wear when hauling heavy loads or constantly slowing and stopping when driving in heavy traffic. However, when you’re dealing with brakes and suspension, there are other severe driving conditions that may not be as apparent, and aren’t necessarily covered in the above list.

For example, let’s say that you live in the Snowbelt. Winter can be hard enough on the undercarriage of your vehicle, but when springtime hits, potholes the size of the Sea of Tranquility can open up. The stress is so great that control arm bushings, steering linkages, and the likes can actually be ripped from the undercarriage of a vehicle -- I have this firsthand on more than one occasion. Also, sidewalls of tires can blow out when going through the sharp edges of a pothole. Add into the mix the effects of salts (used in most areas to de-ice roadways) on the suspension parts and its easy to see that plenty of people should consider themselves candidates for the severe schedule.

When you consider the effect poorly maintained roadways have on a car’s suspension, I would say that most drivers should follow the severe maintenance schedule for their vehicle. The problem is, that with respect to brakes, tires, and steering and suspension, the maintenance schedules just suggest inspecting these parts and rotating the tires at every oil change -- there is no actual maintenance suggested for these items aside from tire rotations. Is this enough? Probably not.

Brakes

Brakes should be inspected at every oil change and the friction materials -- either brake shoe linings for drum brakes or pads for disc brakes -- should be replaced when there is 20 percent of the material remaining. This is a proactive approach to brake service to avoid having to replace the disc brake rotors or brake drums prematurely, which is far more expensive.

Yet many people continue to drive their vehicles until they experience a brake squeal or worse. If you can hear a grinding noise when applying the brakes, you have likely quadrupled the cost of your repair by waiting so long.

A correctly performed brake job will also include the resurfacing of the drums and/or rotors -- provided they haven’t been worn out -- so that the new friction materials break-in properly.

If you drive in dusty and dirty environments, for safety’s sake you should have the brakes cleaned and adjusted semi-annually to guarantee their correct operation, even if they don’t need replacing. Dirt and grime tends to impede the self-adjusters and caliper operation, causing premature wear and failure.

Tires

Most tire manufacturers suggest rotating the tires every six months or six thousand miles, whichever comes first. I subscribe to the tire manufacturer’s schedule because it covers all service applications, taking into consideration both the time interval and the mileage interval.

However, I add one additional step: Have the tires rebalanced every time you rotate them. This extra step ensures that the tire spins “true” as it rolls down the road. Tires are balanced based on the mass of rubber that is present at the time of their installation or rebalance. As the tire rolls down the road, rubber wears off, and the tire is no longer “balanced.” Therefore, it is imperative that you have the tires rebalanced when they are rotated in order to maintain a smooth action when rolling. An imbalanced tire bounces and “tramps” its way down the road, resulting in a chopped or cupped tread wear pattern.

Finally, keep a close eye on tire condition. When impact breaks are evident in a sidewall, replace the tire. Other factors that render a tire unsafe are dry rot (caused by road oils that dry out rubber), shifted belts, a gash in the tread area, or cracked bead areas.

Steering and Suspension Systems

Worn tires can also result from worn steering and suspension parts. Steering and suspension systems suffer when subject to heavy hauling and towing or operation on rough roads or in other bad conditions. Steering and suspension systems are built with ball-and-socket joints and bushings made of rubber, neoprene, or some other synthetic product. Thus, they are subject to environmental elements, road jostle, and other forms of stress. When these bushings and joints become sloppy from wear, the alignment goes out. If you are driving on rough roads, or working the vehicle hard in some other way, the wheel alignment angles will migrate out quite quickly.

Because wheels are knocked out of alignment when steering and suspension parts wear out, I strongly recommend that you check the wheel alignment once per year. There are two benefits from this practice. The first is just to correct alignment issues, which will keep your tires from wearing prematurely. But the second is that the tech will conduct a through inspection of the steering and suspension before aligning the vehicle, because worn parts make it impossible to properly align a vehicle to factory specs. Thus, by having an alignment check every year you kill two birds with one stone.

While few people are willing to spend the money to replace worn suspension components like shocks and struts, let alone bushings, these parts can compromise the ability of the car to maintain traction on the road, which can impact braking and other accident avoidance measures. Keeping your car’s suspension in a reasonable state of repair is necessity if you care at all about safety.