Category Archives: Steering

Blogs concerning steering

Common Steering and Suspension Problems

Of all the components in your car, the steering and suspension take some of the heaviest wear. Being alert to the symptoms of steering and suspension problems and practicing proper maintenance are, as always, the way to catch small problems before they turn into catastrophic and costly ones. Before reading this entry, you may want to take a quick look at my discussions of how steering works and how a suspension system works, since these provide background that will make it much easier to understand the discussion below.

If you don’t already, you should know what kind of steering and suspension your car has. Does your car use rack and pinion steering or another system? Do you have power steering? Is your car front wheel drive or rear wheel drive? The answers to these questions can be found in your owner’s manual. In addition to helping you to diagnose steering problems, this knowledge will alter the way you respond to certain driving emergencies, such as entering a skid.

Now let’s take a look at some of the most common symptoms of steering and suspension problems. In a few cases, these problems can be easily corrected. Most problems, however, will require the assistance of a skilled mechanic, so make sure that you’ve found a mechanic you can trust before any serious problems occur.

The car “jumps” when you hit bumpy terrain

It will feel like someone has pulled the steering wheel in your hands. You may also notice clunks or bumping noises. This most likely means that the ball joints connecting the suspension to the tires are starting to wear out. Continuing to drive with worn ball joins can result in serious damage so don’t wait to have your suspension checked!

The car is unusually difficult to steer

If your car has power steering, a stiff steering wheel is likely the result of a problem with the power steering system. First, there may not be enough fluid. Check the fluid reservoir. This is located under the hood and is normally labeled (See figure 1).

 

Figure 1: steering fluid reservoir

If you have trouble locating it, consult your owner’s manual. The fluid reservoir may be transparent and have “high” and “low” markers; if not, it will have a dipstick, similar to your oil reservoir’s, that will allow you to check the fluid level (see figure 2).

 

Figure 2: power steering fluid

 

Use the same procedure that you would for checking oil levels. [Link to entry on checking oil.] Your car may have markings for “hot” and “cold” levels, depending on whether the car has been running recently or not, similar to the automatic transmission fluid. If the fluid is low, add more fluid, using a funnel to prevent spilling. If fluid levels drop again soon after adding fluid, there’s a strong possibility of a leak, and you should have the system checked more thoroughly.

If the fluid level is fine, try listening to your steering as you drive. If you notice an odd noise or feel stronger resistance when turning, then there’s likely a problem with the power steering pump or belt. A lack of lubrication in the steering system or an improper alignment of the front suspension could also be making steering difficult.

The car is difficult to keep on a straight path and/or tends to drift

Since most power steering systems are very easy to control, you may not notice the car “pulling” in one direction or another. You can diagnose this kind of problem by taking your hands off the steering wheel and seeing if the car continues in a straight line or drifts one way or the other. If the latter is the case, there’s likely a problem with the alignment of your wheels. Drifting could also be caused by worn tires or tires that are inflated unevenly. Check your tire pressure and tread depth. If your tires are fine, this could be a symptom of a dragging brake on one of your wheels.

The steering wheel shakes or vibrates

If your steering wheel vibrates when you accelerate, then it’s likely that there’s a problem in the suspension or the tires. This could mean that the wheel bolts are loose or the tires are worn unevenly. You should test to make sure none of the wheels are loose by shaking each wheel while the car is parked. This should cause some movement in the car (unless it is very heavy.) However, the wheel shouldn’t move independently from the car. If it does, you should first try to tighten the lug nuts, as you would when replacing a flat tire. If the lug nuts appear damaged or won’t tighten, then it’s time to replace them. Should tightening the lug nuts not correct the problem, then there’s probably damage to the wheel bearing or tie rod. However, if the whole car shakes at high speeds, you probably have a tire or axle that’s not rotating probably, as this kind of problem tends to be amplified at particular speeds.

There is a clunking of banging noise when you go over a bump

This is probably the result of damage to the suspension. Damaged strut bearings, a broken strut, or worn shock absorbers could be the culprits. Increased swaying or bouncing on uneven roads may also be a symptom of this kind of suspension problem. You can check for a bad strut by pushing down on each corner of the car. If it takes several bounces for the car to settle, then there’s likely a problem somewhere in the strut assembly; this could be caused by a broken coil spring (which will probably produce a rattling sound), oil leaking from the shock absorber, or another structural problem. 

There is a screeching noise when you steer

This is probably being caused by the power steering belt, which connects the power steering pump to the engine. The belt could be worn or too loose. While this may be an easy part to replace in older cars, many newer models use a “serpentine belt” to connect all accessories to the engine; this will be more difficult to replace. A screeching sound could also be the result of low fluid levels, so make sure to also check your power steering fluid.

As always, an ounce of prevention is worth a pound of cure. Check the condition of your power steering belt and fluid levels whenever you check your oil and tires. Additionally, make sure to drive carefully. Hitting potholes or grazing a curb can bend suspension components and put wheels out of alignment, which can result in further damage to tires, steering, and suspension.

To read more on a broad range of subjects from “How To Change A Tire” to “How To Jumpstart Your Car”, visit DefensiveDriving.com’s Safe Driver Resources website!

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Stop, Go, Swerve: What to do if there is an animal in the roadway

While my grandmother has been known to make road kill stew, this isn’t a delicacy that most enjoy. Being prepared to encounter animals and knowing what to do when these encounters occur is a better way to use the road efficiently. Reacting quickly and correctly will help to protect the lives of all humans and animals involved in an incident.

With roadways becoming more crowded and suburban developments encroaching on wild habitats, animal-related accidents have been on the rise in recent years. According to State Farm, 1.2 million animal-related accident claims were made in 2008, representing an increase of 15 percent since 2003. Failure on the part of human drivers to respond correctly to these situations makes many of these accidents worse than they need to be.

When we see an animal—or other obstacle—in the road, our typical instinctive response is to swerve to avoid the obstacle. This would only make sense in a situation where one was driving slowly on an empty road. Under any other conditions, swerving can create more problems than it solves: if traveling quickly, you could enter a skid or flip your car; you could send your car hurtling off the road and into another obstacle; or you could put your car in the way of oncoming traffic.

According to experts, the best response is to remain in your lane while attempting to slow down as quickly as possible. If you have room to do so, move toward the right side, or outer edge, of the road. When you accidentally step too close to a hazard, your first instinct is likely to jump back; an animal, however, will instinctively move faster along its chosen path, i.e. forward across the road. Moving slightly in the direction that the animal was coming from and slowing down will, ideally, give the animal time and space to escape safely.

Next, be aware of your surroundings. If you’re driving through a rural area or have noticed a number of deer or moose crossing signs, be particularly alert; scan the edges of the road to see if you can spot any animals lurking on the shoulders. If you have passengers, ask them to scan the roadsides for animals. At night, animals’ eyes will glow (the exception being moose, whose eyes do not reflect light.)

If you do, slow down and be particularly vigilant. Never speed, especially at night; remember that you should always be able to stop within the area illuminated by your headlights. Experts recommend traveling no more than 55mph in high-density wildlife areas. This speed should be reduced in inclement weather. Many animals, including deer and moose, are most active at dusk and dawn, when our visibility is often limited. Be particularly alert during these hours. You should use your high beams when not surrounded by other drivers and, if possible, move the car as close to the center of the road as possible.

If you do end up in a collision with a moose or deer, duck down into your car; large animals like these can come through the windshield or crush the car roof. Should you end up in a collision with an animal, first check to make sure that your passengers are okay. If the injured animal is still alive, do not approach it, as, scared and in pain, it could still be dangerous. Only attempt to move the animal out of the road if you are certain that it is dead. Use flares or emergency lights to alert others on the road to your predicament and call the police.

To read more on a broad range of subjects from “How To Change A Tire” to “How To Jumpstart Your Car”, visit DefensiveDriving.com’s Safe Driver Resources website!

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What To Do If Your Steering Fails

While total steering failure is very rare, it can still happen. Recently, a friend recounted to me what is perhaps the most dramatic steering failure story I’ve ever heard. Visiting South Africa during the World Cup, she took one of the country’s notorious “minibus taxis,” essentially a large van that picks up and drops of passengers along predetermined routes. These taxis are known for their powerful sound systems, aggressive marketing strategies, and lack of regularly scheduled maintenance (aside from upgrades of said sound system.)

One day, she chanced to flag down a very old and rickety taxi with a particularly aggressive driver. After a harrowing five minutes hurtling down a busy road, the taxi driver turned sharply into a side street to drop off a passenger and, as he did so, the steering wheel came off in his hands. Luckily, the side street was empty and he was able to bring the vehicle to a safe, albeit abrupt, stop. My friend quickly decided to walk to her destination.

Hopefully, you will never let your car’s condition deteriorate to this point! However, steering failure can occur for other reasons and, in the spirit of being prepared, it’s good to know what to do in such a situation.

First off, there are two kinds of steering failure: total failure and a loss of power steering. I’ll begin with the latter, as this is more likely. In cars that have power steering, failure can occur for a number of reasons. The most likely is a leak in the hydraulics, which enable the system to function. If it’s a slow leak, you’ll start to notice a whining sound in your steering column and/or a gradual stiffening of the steering. If this is the case, you’ll hopefully have time to get your car checked out by a mechanic before steering functions are seriously compromised.

In the case of a fast leak, however, you could lose function fairly quickly. If this happens, the first thing that you, as the driver, will notice is that the steering becomes stiffer or “heavier,” i.e. the wheel is more difficult to turn. Hang on tight to maintain control of the car! You will still have steering control over the car, but it will be more difficult. Avoid the impulse to brake suddenly and bring your car to a very slow speed or stop, as manual steering will be more difficult at lower speeds. Instead, slow down gradually and, if possible, turn on your emergency flashers (or have a passenger do so.) Then, carefully make your way to a location where you can bring your car safely to a stop and call for assistance. Note that a failure in the hydraulic system may also compromise your brake system, so be prepared for brakes that feel stiffer or don’t function properly. You may need to respond to brake failure as well as steering failure.

Mechanical failures (like your steering wheel falling off) can also occur, although these are even more rare. In this case, you will lose all steering capability. In such a situation, you don’t have too many options. As with all emergencies, the key thing is to make sure that you remain calm. Think clearly, respond appropriately, and avoid panic.

If your steering fails, you will need to stop as soon as it is safe to do so. If you are in an area without much traffic and conditions are dry, brake as quickly as possible. If it is wet or icy, try to pump your brakes and downshift to avoid skidding, since you won’t be able to steer to correct a skid.

If you are in a heavily trafficked area, such as on a highway, first try to alert other drivers by flashing your lights, honking, and gesturing with your hands. At night time, flick your high beams on and off. Once you’ve done this, begin to slow down gradually (if possible) so that other drivers have time to respond. Try to use a combination of downshifting and braking to gradually bring your car to rest on a shoulder or near a divider—anywhere you can stop in relative safety. Then, move away from your car and call for help.

To read more on a broad range of subjects from “How To Change A Tire” to “How To Jumpstart Your Car”, visit DefensiveDriving.com’s Safe Driver Resources website!

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How A Car’s Steering Works – PART TWO

Power Steering

When a car is said to have power steering, it means that the steering system contains a hydraulic component that amplifies the force exerted by the driver. This makes it much easier to steer the car. While it’s possible to drive cars without power steering, it can be very difficult to turn the wheels when the car is stationary or moving slowly; this can make maneuvers like parallel parking extremely difficult. Patents for power steering systems date back to the 1930s, but the first vehicle with power steering, the Chrysler Imperial, didn’t appear until 1951.

A power steering system requires a modified design for the rack and pinion gear. In this system, the rack contains a cylinder with a piston inside of it. Hoses pass from the pinion gear to both sides of the piston. When the driver turns the wheel, fluid moves to one side of the piston or the other, forcing the track rod right or left.

There are two other key components to this system: the rotary-vane pump, which provides the hydraulic pressure, and the rotary valve, which senses how much pressure to exert on the rack and in which direction.

Let’s start by talking about the pump, which is the simpler of the two components. The pump is connected to the engine by a pulley. As the engine spins, the pump turns and forces low pressure fluid from a reservoir into the power steering system at high pressure (See figure six).

 

Figure 6: Rotary-vane pump

 

As the engine turns the rotor, the vanes, which can slide in and out, pull the fluid from the return (input) hose and force it into the pressure (output) hose at a higher pressure. Since it’s important that the pump be able to provide force even when the engine is idling, the pressure is magnified a great deal by the pump. For this reason, the pump has a built in release valve, which can siphon off some of the pressure should it become too much. This valve is connected to the pressure hose on one side; when open, it allows fluid from the output hose back to the return hose.

All the pump does, however, is supply the brute force needed to amplify the driver’s input. The amount of power provided and the direction in which force is exerted is determined by the rotary valve. The rotary valve has two components: the torsion bar and the spool-valve assembly.

The torsion bar is a thin metal bar that twists when torque (rotational force) is applied to it. The top end of the torsion bar is connected to the input shaft from the steering wheel while the bottom end is connected to the pinion gear. Thus, the more force the driver exerts in turning, the greater the twist in the torsion bar.

The torsion bar is also connected to the spool valve assembly (see figure 7).

 

Figure 7: spool valve assembly

As you can see, the inner valve is connected to the input shaft (and the top end of the torsion bar), while the outer valve is connected to the bottom end of the torsion bar. As you turn the wheel, the inner valve and outer valve rotate in relation to one another. The amount of rotation (and direction) depends on the force exerted on the steering wheel and the direction in which the steering wheel is turned. As the valves rotate, the channels (orange, yellow, and green components) are brought into alignment with one another, so that pressurized fluid flows from the rotary vane pump to the cylinder inside the rack. Notice that the yellow channels send force to the right side of the rack, while the green channels send force to the left side of the rack. Depending on which way the valves rotate, force is thus directed to one side or the other of the rack.

Looking to the future: electric steering systems

Unfortunately, this power steering system isn’t very efficient, and a lot of energy is lost in the transfer of hydraulic power. Many carmakers are now investigating alternatives, such as the steer-by-wire system. This is an entirely electronic system in which the steering wheel functions more like a Wii controller, sensing motion and force and transmitting power to the wheels accordingly. This kind of system would reduce vibrations within the car, improve efficiency, and allow individual drivers to tailor the responsiveness of the car’s steering to their individual preferences. It would also provide a roughly 1 MPG advantage in fuel efficiency over traditional hydraulic systems.

Another system under development is the electro-hydraulic system, which is a compromise between a fully electric and fully hydraulic system. In this system, turning power is still supplied by a hydraulic system, but this is powered by a fully independent electric pump, rather than the engine itself. In this system, the power supplied by the hydraulics is no longer linked to engine RPM, so that the power steering can provide greater assist at lower speeds and become more efficient at higher speeds.

Read Part One of this two-part series.

To read more on a broad range of subjects from “How To Change A Tire” to “How To Jumpstart Your Car”, visit DefensiveDriving.com’s Safe Driver Resources website!

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How a Car’s Steering Works – PART ONE

The steering mechanism in a car seems like a fairly simple mechanism: you turn the steering wheel, the car’s wheel turns, and the car goes in a different direction. Right? Actually, a car’s steering mechanism, while simpler than, say, the transmission, is still a fairly complex piece of machinery. Today, I’ll discuss how basic steering systems function.

Steering basics

When you round a corner, not all of your car’s wheels turn at the same angle. Think about it. Say you are turning right. The right front wheel, or inside wheel, will need to turn around a smaller circle than the outer wheel, which means it will need to be positioned at a different angle (see figure one).

 

Figure 1: turning angles

 

The image above provides an illustration of this phenomenon. Before the car enters the turn, both front wheels are straight. As the car goes into the turn, however, the two front wheels must both be placed at an angle; the angle is much steeper for the inside wheel. Notice that if you draw lines perpendicular to the center-line of each wheel, these lines will intersect at the center of the turn.

The way in which the wheels and steering wheel are linked together allows this to happen smoothly when you turn the wheel (See figure two).

 

Figure 2: Steering linkage

 

The steering wheel itself is attached to the track rod, which shifts from left to right when you turn the wheel. Ball bearings connect the track rod to two tie rods, which are then connected, also by ball bearings, to the steering arms. These are connected to the wheels. Taken together, these parts form a sort of parallelogram. As a result, when you turn the wheel, the inside wheel is turned at a steeper angle than the outside wheel (See figures three and four).

 

Figure 3: Before turning

 

Figure 4: After turning

 

The Rack and Pinion Gearset

In most modern cars, the connection between steering wheel and track rod is made by a rack-and-pinion gearset, a fairly simple arrangement. A notched rod, called the rack, extends out of the track rod. The steering shaft itself ends in a round gear called a pinion. As you turn the wheel, the pinion rolls through the notches on the rack, pushing the track rod to the left or right (see figure five).

 

Figure 5: Rack and pinion gear

 

This system does two things. First, it turns the rotational motion of the steering wheel into the linear motion needed to turn the wheels. Second, it makes it easier for you to turn the wheels by providing a gear reduction. As in the transmission, the locking together of gears of different diameters means that you don’t have to turn the wheel as far (or as hard) in order to get a response.

A car’s steering ratio indicates how many degrees you have to turn the steering wheel in order to turn the wheels by a certain amount. For example, if a car has a 20:1 steering ratio, then you need to turn the wheel 20 degrees for every 1 degree that the wheels turn. The steering ratio is determined by the spacing of the teeth on the rack and the size of the pinion gear.

If a car has a low steering ratio, it means that the car will respond quickly to input from the steering wheel but will be difficult to steer. Cars with higher steering ratios are easier to steer but less responsive, i.e. you will have to turn the wheel further in order to produce a response. Most cars have steering ratios between 12:1 and 20:1. However, the steering ratio in a racing car will be closer to 1:1, so that the car is more responsive; since these cars are generally very light, difficulty in turning isn’t an issue.

Some cars have something called variable ratio steering. In this system, the teeth at the center of the rack are placed close together, so that the car responds quickly when you enter a turn. However, as you get closer to the edges of the rack, the teeth are spaced further apart, so that the wheels don’t become difficult to move as you approach the limits of the turn.

Rack-and-pinion is the most common design in use on the road today. However, there are a number of other steering mechanisms in use. Re-circulating ball steering is used on many heavier vehicles, such as trucks and SUVs. In this system, the rack and pinion gear is replaced by a worm gear, which is filled with re-circulating ball bearings that help to keep the teeth in this gear in contact with one another. Since this system isn’t as common, I won’t go into its workings detail. Basically, this system gives a greater mechanical advantage, i.e., like the brake system, it converts the input force into a greater output. This is why it is often used on heavier vehicles. However, since power steering is now common on most vehicles, this type of steering arrangement is no longer used as frequently. I’ll discuss power steering in my next entry.

To read more on a broad range of subjects from “How To Change A Tire” to “How To Jumpstart Your Car”, visit DefensiveDriving.com’s Safe Driver Resources website!

Check out these sites for more information about defensive driving and business driver safety.