Shock Absorbers and Stopping Distance

Springs and shocks control the motion of each wheel of a car. Springs enable the suspension to move up and down over bumps and imperfections in the road. Shocks absorb and dissipate the energy from that motion. Without shocks the car would continue to bounce on the springs after hitting a bump. Having worn shocks is somewhat like that.

Good shocks are important not just for passenger comfort, but also for safety. We have often heard that shocks keep tires in contact with the road, which is only partially correct. How often have you seen tires not in contact with the road? Even worn shocks won't cause your tires to dribble off the ground.

The full reason is that, for a given set of conditions, it's the amount of downward force which varies a tire's traction. Good shocks keep the tire in optimal contact with the road, enabling consistent maximum traction and shorter stopping distance.

See Wikipedia for more.

Tests carried out by Monroe Shocks (a leading manufacturer) indicate worn shocks can increase stopping distance from 60 mph on the order of about 10 feet, which is about 7% to 9% (most cars stop from 60 mph in about 110 to 130 ft).

Here's a good animated site by Gabriel (shock manufacturer) that explains the effect of shock and strut wear (http://www.checkyourshocks.com/).

How to Price Auto Parts Fast

My pickup truck failed its safety inspection last weekend. One of the front shock absorbers needed replacement.

So I looked up the phone numbers for 3 nearby auto parts stores and let my fingers do the walking. Using the following script I've used for years, I called for pricing and availability:

Parts Guy/Girl: [Store name] Auto Parts. How can I help you?

Me: Hi, I need to get a quote for front shocks for my '91 Toyota Pickup

Parts Guy/Girl: Is that four wheel drive or two wheel drive?

Me: Two wheel drive.

Parts Guy/Girl: Which engine does it have?

Me: 2.4 liter.

Parts Guy/Girl: Ok, we have [Brand X] for $x and [Brand Y] for $y each.

Me: Do you have it in-stock?

Parts Guy/Girl: Yes, both types are in-stock.

Me: What's the part number on that?

Parts Guy/Girl: [part # X] and [part # Y]

Me: And how late are you open?

Parts Guy/Girl: Until 9 pm each night.

Me: And what's your name?

Parts Guy/Girl: [first name]

Me: Great, thanks very much.

In a couple of minutes I had called and found prices ranging from $20 to $62 each. So replacing the pair would run from $40 to $124 for parts. I wrote everything down so I knew which store had what for how much, and who I spoke to. That always comes in handy if you show up on site and the rules have changed. You can hold someone accountable.

Then I price shopped online using Google and Amazon. The prices were in between, not including shipping and waiting.

Next I called up the manager of the service station where I had the inspection done (he was out when I was there) to get a labor quote. Ninety dollars. Ok, fair enough.

So I just went to one of the local shops and picked up a pair of shocks for $40. Total bill will be about $130 plus $16 to get the truck reinspected.

The moral of this post is that when you know what needs to be done and it's pretty routine, use a script to get it done quickly.