Rick's Free Auto Repair Advice

How long struts last — A guide to when they require replacement

How long struts last — It depends

The simple answer to how long struts last is this; 80,000 to 120,000 miles. But it depends on the road conditions in your area. If your roads are in rough shape with potholes, you can wear them out in as little as 50,000 miles. On normal roads, they’re seriously compromised by the time they rack up 100,000 miles. However, since they wear slowly, drivers rarely notice.

Bad Strut symptoms

• Excessive nose dive in normal stops
• Scalloping wear on your tires
• Oil leaks down the side of the strut or shock
• Car doesn’t want to stay in its lane on curves

Their job dampen spring oscillations after hitting a bump. When they wear, they lose their dampening ability, so the tire spends more time bouncing and less time in contact with the road. So you have less control, especially in curves.

Worn units increase stopping distance and decrease stability

When you stop hard, the vehicle weight transfers to the front tires and loads the front suspension, causing the springs to compress. But bumps in the road cause the tire to bounce and if the strut can’t stop the bouncing, the tire will spend more time in the air, increasing your stopping distance.

Meanwhile, as the weight shifts towards the front, the rear lifts, taking more weight off the rear tires, again giving you less traction on the rear tires and forcing a more pronounced nose dive on the front tires. All of which increases stopping distance and decreases stability.

The combination of weight transfer and the smaller contact patch causes oversteer or understeer which compromises vehicle stability.

A leak is different than a weep

Many shops unscrupulously recommend replacement any time they see evidence of even a drop of oil on the outside of the shock/strut. But there’s a huge difference between a weep that happens on all shocks and struts and is NOT a reason for replacement and a leak, which is a reason for replacement.

All shocks/struts can weep oil to the exterior. That’s because as the shaft travels past the seal, some oil sticks to the shaft and weeps down the shaft and appears on the body of the shock/strut. That small amount of oil weep is normal and doesn’t require replacement.

However, if the exterior of the shock/strut is coated in oil, then the seal has failed and it is time to replace the unit.

How much is strut replacement? See this post

Shocks/struts increase traction and control by dampening spring oscillations

As you can see in the image shown here, the bottom portion odiagram of front suspensionf the strut is attached to the steering knuckle, and the top portion is attached to the body of the vehicle. When you hit a bump, the bottom portion quickly compresses against the coil spring and into a fluid-filled chamber.  When it reaches the peak of upward travel, the strut restricts the decompression by slowing down fluid flow inside the strut.

Here’s how to tell if you have worn shocks/struts

Your car nose dives at stops.

• On bumpy roads, you’ll have to fight the steering wheel to keep the car in its own lane.
• Your tires begin to show a “cupping” pattern as if someone was “scooping” little pockets of rubber from your tire.cupped tire from worn shock or strut
• You’ll notice a less comfortable ride. Dips in the road seem more noticeable. Bumps seem to “rattle” your car more.

Here are the physical signs of a bad shock unit

  1. Visible signs of oil leakage between the leaking strutchrome piston and the body.

2) Cracked or disintegrated rubber bushings where it attach to the vehicle.

3) Advanced rusting on the shock/strut cylinder, or pitting on the chrome piston.

Most people think you can bounce on a strut and determine it’s condition by counting how many times it rebounds. That’s NOT a legitimate test. Many worn struts will pass that test. See this post to learn how to test a strut.

How to Buy Shocks/Struts

There are three main manufacturers of shocks/struts—Monroe, Gabriel, and KYB. In the past, you could only buy units from Monroe, KYB, or Gabriel. But now, many companies are importing sub-par units from China and selling them for low prices. They’re really low-quality units and you won’t be happy with the ride quality.

Other shock absorber Tips

• Front shocks wear faster than rear struts/shocks.
• Always replace them in pairs on either the front or rear.
• The old bounce test for shocks (get the car rocking and make sure it doesn’t rebound more than 1 time) doesn’t apply to struts. If an auto shop tries to sell you struts based solely on this test, find another shop.
• New struts/shocks cannot compensate for worn springs. If your car “bottoms out” on large bumps, ask the shop to check your vehicle’s “ride height” before doing a strut replacement. If your car needs new springs, have it done at the same time as strut replacement. The labor is already paid for at that point.
• If your vehicle is equipped with air shocks, you do NOT have to buy replacements from the dealer. Try these vendors: www.suncoreindustries.com, www.strutmasters.com, www.shockwarehouse.com, or www.rockauto.com.

© 2012 Rick Muscoplat

Save

Save

Save

Posted on by Rick Muscoplat



Custom Wordpress Website created by Wizzy Wig Web Design, Minneapolis MN