Eliot Silverman

Eliot Silverman

Wednesday, December 21, 2011

Steering Systems Part 2

Cars use a manual steering system or a power steering system.  Manual steering systems do not have a power steering pump.  When you turn the steering wheel, you directly turn the wheels. 
With a power steering system, the power steering pump assists in turning the wheels.  If the power steering pump system fails, you can turn the wheels, but it is hard to do so.
A belt turns the power steering pump.  The power steering pump sends power steering fluid to the rack and pinion, or the gear box. If the belt breaks, or the pump does not work, it becomes hard to turn the steering wheel.

In most cases, the belt which turns the power steering pump also turns other devices such as the alternator, water pump, a/c compressor etc. A belt fails for two reasons.  One, it can break.  Two it can fall off the pulleys.  If either of these two things happen, the power steering system stops working.  As I said, you can still steer your car, but it becomes hard to turn the steering wheel.

 If there is a leak in the power steering system, once you run out of power steering fluid, the power steering system stops working.  You can still steer your car, but as I said, it becomes hard to turn the steering wheel.

Tuesday, December 13, 2011

Steering Systems - Part One

Vehicle manufacturers use two types of steering systems.  A parallelogram system, and ‘rack and pinion’ system.  Rack and Pinion (R&P) systems have fewer parts than a parallelogram system.  R R&P has two outer tie rods, two inner tie rods, and center section, which is called the “Rack and Pinion.”

A Parallelogram system has two outer tie rods, two inner tie rods, two connecting sleeves, one or two idler arms, one center link, one pitman arm, and a gear box. 

Since a R&P system has fewer parts, there are less parts to wear out, and it takes up less space under the car.  This has become important as manufacturers make  cars smaller and there is less space for steering components.  Similarly, as car have been made smaller, manufacturers have done away with “springs and shocks” in favor of struts.  Struts have fewer parts, and takes up less space than a ‘shock absorber/spring suspension system.
Above is a picture of a Rack and Pinion system.  The ends are the outer tie rods.  The Center section is the Rack and pinion, and the straight metal rods coming out of the black bellows are the inner tie rods.
This drawing shows all the parts but the gear box.

When you go for an oil change and hear the words “Lube job, “ this refers to lubing the steering components.  Years ago, with a parallelogram steering, we’d lube about seven places- outer tie rods, inner tie rods, center links, and the idler arm.   With a R&P system there were only two places to lube – the outer tie rods. Most cars made in the last ten years come with ‘Sealed’ outer tie rods.  This means the outer tie rods never need to be lubed.  With R&P steering, the inner tie rods cannot be greased, and the outer tie rods are only greased if they are not sealed. 

I don’t think the parts in the parallelogram steering system were made to last the life of the car, then again, very few cars made in the 70’s or older, ever lasted over 100,000 miles.  Today, that has changed.  Cars made in the 90’s and later will easily run over 100,000 miles.  Most cars made since the 90’s will last over 200,000 if they are properly maintained.

I have a 1993 Buick Park Avenue with over 260,000 miles and it runs without any problems.  I have never replaced the engine or transmission, or any other major component.  I do normal maintenance and the car keeps on running.  Rack and Pinion systems last a very long time. 

The outer tie rods, at some point need to be replaced, but the inner tie rods and the rack and pinion rarely go bad.  When they go bad, they usually leak power steering fluid.  If your rack and pinion as a very small leak, I normally suggest that you just add more fluid.  If the leak is a continuous dripping or greater, then you will need to replace the rack and pinion. 

After replacing any steering component, you’ll need to do an alignment inspection.  Our alignment system is accurate to 1/100 of a degree.  The only way to know if the alignment is good, after a steering component is installed, is to do an alignment inspection 

Friday, March 4, 2011


Watching old movies, and mean really old movies, I’d see a man take a crank from the inside of the car, insert it into the front of the car, and turn the crank.  The driver was turning a “watch spring.”  Once the watch spring was wound up, he’d get inside the car and release the watch spring.  As the watch spring unwound it would turn the engine. 

Around 1913 Henry Leland and Charles Kettering developed the electric starter.  An obvious improvement over the hand cranking method to start a car. 

Electric starters have three parts.  An electric motor, a starter gear, and an item referred to as a “Bendix.”  Also a flywheel is bolted to the back of your engine.  The flywheel has teeth similar to the teeth you see on the back of a bicycle wheel. 

Bicycles use a chain to turn the rear wheels.  Cars use starter gear which meshes with a flywheel similarly to the way a bicycle chain meshes with the teeth on the rear bicycle wheel. 

When you turn your key to the “start” position, 12 volts are sent from the ignition switch to the bendix.  This causes the bendix to extend the starter gear so it meshes with the flywheel. At the same time, the bendix starts the flow of electricity from the battery to starter motor.   When this happens your engine cranks. 

A starter does not cause a car to start; it just causes the engine to “Turn over.”

When you release the key, it bendix causes the starter gear to retract back inside the starter, and stops the flow of electricity from the battery to the starter motor. 

A starter needs replacing if the bendix is bad, the starter gear is bad, or the starter motor does not work. 

If electricity does not flow from the ignition switch to the bendix, the starter will not turn.  This can happened if the ignition switch is bad, or the alarm system on your car has not been ‘turned off.’  Also, a small amount of corrosion at either end of the wire from the battery to the starter motor can prevent the starter motor from turning by reducing the amount of power which flows through this wire.

A discharged battery or a bad battery cannot provide enough power to “turn-over” an engine.

Understanding all this, if your car’s starter does not crank your engine, it does not mean your starter is bad.  It means you need to bring your car to a qualified mechanic to have it properly diagnosed. 

Friday, January 28, 2011

There’s MORE to know about TIRES than you might think….

Tire Basics:
Underinflated tires reduce gas mileage and causes tires to prematurely wear out.  Many years ago tires were inflated to approximately 32 psi, today most tires are inflated to 40 psi.   A simple, inexpensive tire gauge is used to measure tire pressure.  If you don’t know how to use a tire pressure gauge, most repair shops or an automotive parts store will show you how to use one.

Tire Sizes:
The size of your tire is printed on the tire and it starts with a “P.” After the “P” are two numbers an “R” then two more numbers.  For example a common tire we replace is a P215/65R15.   The “P” means passenger tires, the 215 is the width of the tire in millimeters, 65 is the ratio of the height to the width of the tire (basically the distance from the edge of the rim to the face of the tire), and 15 is the radius of the rim in inches.

Load Index & Speed Rating:
After the size is a group of two to three numbers and a letter.  The numbers are a “Load Index” and indicate how much weight the tires can support.  A load index of 94 supports up to 1477 pounds.  The letter after the load index is the speed rating- the maximum safe speed for the tires.  A “T” speed rating is safe up to 118 miles per hour.  A “W” speed rating is safe up to 168 miles per hour.  Between T and W there are many other speed ratings.  The higher the speed rating the better the tire ‘grips’ the road.  However, since it grips the road better than a lower speed rated tire, the higher speed rated tire wears out quicker. 

You may use a higher speed rated tire than the manufacturer recommends, but you should never use a lower speed rated tire.

Winter- Summer Tires
I remember as a kid helping my father change his tires in the fall from summer tires to winter tires, and in the spring we’d change them back.  I don’t know how the tire manufactures did it, but we no longer have to change tires for the winter and the summer.  There are winter tires, but you probably don’t need them.  If you look at your tires and see “M + S” printed after the speed rating then your tires are good for winter and summer. 

Tire Manufacturing Date Stamps:
Starting in 2000 tires have a manufactured date stamped on the side of the tires.  Sometimes the date is on the inside of the tire, and sometimes it is on the outside of the tire.  It is a four digit code.  The firs two digits indicate the week the tire was made and the last two digits indicate the year it was made.  So a ‘4010’ would mean the tire was made in the 40th week of 2010.

TPMS (Something new):
A few years ago a rash of roll-overs was attributed to old and underinflated tires.  After investigating why these vehicles rolled-over Ford recommended that tires be replaced every five years regardless of wear.  The NTSB mandated the use of a “Tire Pressure Monitoring System.” This system is referred to as “TPMS.”  All cars and trucks manufactured since 2010 have this system. 

TPMS use a wireless pressure sensor in the tire to communicate with an onboard computer.  If a tire is underinflated by 20% or more a light on the dash illuminates indicating an underinflated tire.  The sensor in the tire is battery operated and the valve stem is part of this system.  When the battery goes bad, or the valve stem breaks the sensor must be replaced, and they are not cheap.  While it’s too early to tell, I have been told the battery will last for seven years.

On some cars, after the tires are rotated, the TPMS computer must be reset or the dash light will come on falsely indicating an underinflated tire.

While TPMS have added a measure of safety, they come with a cost.