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How To Replace A Strut On Most Vehicles

a pair of worn out struts

Does your car ride more like a bouncy house than an automobile? Does your front end sound like 14 pennies in a tin cup every time you hit a bump? If so, then chances are you need to replace your front struts. Most vehicles today use a specialized suspension system where the coil springs and shocks are an integrated unit called a strut. Most modern cars use what is called the Macpherson strut. So what does it take to replace a strut?

What is a suspension strut?

The Macpherson strut was designed by Earle Macpherson in the 1940s. Commonly used at the front, Macpherson struts are also sometimes used in the rear of the vehicle as well. The strut supports the weight of the vehicle and manages the shock duties as well. When the shock component of a strut goes out, the entire assembly must be removed, you can purchase the main body of the strut with or without the spring. The upper mount is also a consumable item, typically made of hard rubber and plastic. When the upper mount wears out or breaks, you end up with a rattling suspension and in severe cases, an extremely dangerous situation. Struts should also be replaced in pairs, because if one side has gone bad it is highly likely the other side is worn out as well.

Getting ready

Replacing a strut can be done in your garage; however the spring is under a great deal of tension. Removing the spring is incredibly dangerous and requires a great deal of attention and care. You need a special tool to compress the spring so that the spring cap can be removed. This is called a Macpherson strut compressor, and they can be purchased  from any NAPA Auto Parts Store. If you aren’t comfortable compressing the spring, you can always purchase a complete strut assembly that has the hard work done already. Known also as a “quick strut”, a strut assembly is also a great time saver.

Beyond the spring issue, replacing a strut is a fairly straight-forward process. Typically, removing the strut involves removing the strut from the steering spindle, though some vehicles have the steering spindle built into the strut. Most vehicles do not require breaking down the ball joints, but some do. This is usually so that the lower suspension can be dropped enough to take the pressure off of the spring so that the strut can be removed.

We’re covering a generic overview of what it would take to replace a strut on most vehicles. For detailed instructions, we recommend you get a repair manual for your exact year/make/model vehicle. Either a traditional paper manual or a digital version will work just fine.

Swapping the strut

As with any time you are working under a car, always support the vehicle on stable ground (never on dirty or gravel) with a set of jack stands. NEVER work under a car supported by only a jack. With the vehicle properly supported, you can begin by removing the wheel.

Never support a vehicle with just a jack, always just jackstands. Once safe, remove the wheel.
Never support a vehicle with just a jack, always just jack stands. Once safe, remove the wheel.

With the wheel off, the next step is to remove the lower strut bolts. Leave the bolt in place, just break it loose or remove the nut.

There may be several bolts holding your strut in place, including the stabilizer bar.
There may be several bolts holding your strut in place, including the stabilizer bar.

Some vehicles, such as this 2009 Challenger, have an upper control arm which requires breaking down the ball joint. The cotter pin and nut are removed first.

If there is an upper control arm, the ball joint will have to come out. Remove the cotter pin and unbolt the joint.
If there is an upper control arm, the ball joint will have to come out. Remove the cotter pin and unbolt the joint.

Then a tie-rod separator is used to pop the joint out of the spindle. Once the separator is tight, a few taps with a hammer should pop it loose.

New ball joints usually pop loose fairly easily. We used a ball-joint separator tool.
New ball joints usually pop loose fairly easily. We used a ball-joint separator tool.

Now the upper strut bolts are removed. This should allow the strut assembly to drop out of the chassis.

Some cars use bolts to hold upper mount in place like this Challenger.
Some cars use bolts to hold the upper mount in place like this Challenger.

 

Other vehicles use a rubber isolator mount like this Mercury Cougar. These usually need to be replaced at the same time as the strut.
Other vehicles use a rubber isolator mount like this Mercury Cougar. These usually need to be replaced at the same time as the strut.

This is a bad upper mount from a 2001 Mercury Cougar. This vehicle was in really bad shape, the struts were just rattling around in the inner fender.

You can see how worn out the mounting hole is. Time for a new one.
You can see how worn out the mounting hole is. Time for a new one.

Removing the spring from the strut is the most challenging part. While most mechanic shops have a wall-mounted spring compressor, the DIY garage can get the job done safely and quickly with a bolt-on compressor. These are two-piece tools that use bolt-on loops which are attached to threaded rods. The two rods are slowly tightened which collapses the spring. Once the spring is compressed enough, the center nut on the top of the strut can be removed, allowing the top cap to come off and the spring removed from the strut body. Carefully release the pressure on the spring by slowly unthreading the rods a little at a time in equal amounts between the two.

These threaded rods and clamps are the DIY tool for compressing the spring. Be very careful and make sure the tool is assembled correctly.
These threaded rods and clamps are the DIY tool for compressing the spring. Be very careful and make sure the tool is assembled correctly.

 

Once compressed, the upper mount can be disassembled safely. The top of the shock piston is threaded. It usually requires two wrenches to hold the shaft and remove the nut.
Once compressed, the upper mount can be disassembled safely. The top of the shock piston is threaded. It usually requires two wrenches to hold the shaft and remove the nut.

Installation is the reverse of the removal; each spring must be compressed, installed and then slowly decompressed in the assembly.

The strut from the Cougar was is such bad shape, the piston rod came out of the shock body. We had to replace all of the mounts too.
The strut from the Cougar was in such bad shape, the piston rod came out of the shock body. We had to replace all of the mounts too.

With the new strut assembled, it is slid into the chassis and bolted down.

The Cougar strut slides into the spindle upper mount and is secured with a large nut and bolt, compressing the spindle.
The Cougar strut slides into the spindle upper mount and is secured with a large nut and bolt, compressing the spindle.

Any time you replace suspension/steering components, the vehicle must be aligned. While it may not seem like a big deal, a misalignment of even a half degree can wreck your tires in just a few hundred miles, not to mention poor handling characteristics. As with any mechanic work, if at any point you do not feel comfortable, please take it to any NAPA Auto Care service center for assistance.

Check out all the steering and suspension parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how to replace a strut, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Jefferson Bryant View All

A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a shop manager, eventually working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin’, Mopar Muscle, and many more. Jefferson has also written 4 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced.

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