To Strut or Not to Strut



A question that comes up occasionally is “What does a strut do for a Car?” The really simple answer to that question is that it is part of the suspension, but it does not tell you a thing about what a “Macpherson strut” is or what it does. Most vehicles on the road today use the Macpherson strut in one form or another, for both front and rear suspensions.

Earlier vehicles typically used a double “control arm” or “A-Arm suspension” design in the front and, with rear wheel drive, used a leaf or coil spring with a separate “shock absorber” in the rear suspension.


A-Arm suspension

Rear Axle Leaf Spring Suspension with Shock absorber

Macpherson Strut Front Suspension


The Macpherson Strut design incorporates several pieces of a conventional suspension into one component. It eliminates the upper “ball joint”, connects directly to the spindle and uses the strut body to hold the suspension spring and shock absorber together as a single unit. This creates a lighter less complicated design that reduces the total number of parts while making the entire suspension lighter and more compact.

I hope this answers another question that I hear as well, Are struts important?” Again the simple answer, YES! On top of supporting the vehicle, they smooth out the ride, help control body roll and keep the car stable. Think of your tire as a basketball with every bump it hits causing the tire to dribble. In this scenario the tire is only in contact with the road about 50% of the time. A shock absorber, whether in the form of a single shock or as part of a strut controls the bounce and keeps the tire on the road.

This picture illustrates the individual components of a Macpherson strut. One portion of the strut unit often overlooked is the “upper strut mount” and bearing. This bearing allows the strut and steering knuckle to rotate as the vehicle turns. It also supports the weight of the vehicle. This is the point where the strut assembly attaches to the vehicle.

Over time the mount, bearing, bumper, spring and strut all wear and will reduce the quality of quality of ride and more importantly reduces vehicle control. Increases tire wear and can increase stopping distance.

Now that you know the basics of what a strut is, the next question is “How long do shocks and struts last?” Many manufactures suggest replacing shocks and struts at 50k miles. I feel that may be a little early in many cases. A more realistic interval in my opinion is in the 80 – 100k mile range.

Remember that all this wear is occurring while your backside is in the seat, so it is not always obvious as the ride quality deteriorates. Usually, if anything the old car just doesn’t “feel” like it did when it was new. Most people are really surprised once the shocks and struts are replaced, it almost feels like a new car again!

Remember that most of today’s vehicles will provide reliable service and comfort up to about 300,000 miles! All they need is a little TLC from time to time. Regular service and maintenance will maximize your investment.
To Learn more about shocks and struts click here

Visit or call us here at London’s Automotive for an inspection and analysis of your car or trucks suspension.

Written by London's Automotive