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