Struts: Suspension Evolution

MacPherson Loaded StrutLoaded suspension struts are a very popular repair option for both professional mechanics and do-it-yourselfers due to their ease of installation and cost effectiveness.  Loaded struts were originally created for DIY applications so that customers wouldn’t have to go out and buy or rent a spring compressing machine for a one time fix.  The first loaded struts were introduced to the market in 2003 and were aimed at the DIY market.  Shortly after their release, many professionals started to use them in their shops to help save time and money.  Today, there are many different suppliers with their own line of loaded struts available. There are also many poor quality off brand struts being sold on the internet that aren’t meeting the standards put forth by the vehicle manufacturers.

Why Struts?

MacPherson struts were first used on import cars in the 1970s and have grown to be used widespread in everything from passenger cars to full-size trucks and SUVs as an alternative to short long arm suspension. The struts were invented by Earl MacPherson and replaced the complex suspension with a simple spring and strut. It’s the perfect packaging solution for front-wheel drive and unibody construction. A strut is a structural component that also serves as the steering pivot for the front wheels. The spring holds the weight of the vehicle while the shock elements inside of the strut act like an over-sized shock absorber. Another benefit of using a strut is that alignment is easier depending on the application. Struts are also used in rear suspensions for many of the same reasons, and because they allow for more trunk space.

Why a Loaded Strut?

Other than time savings and convenience, a loaded strut allows all of the strut components to be replaced with one part meaning that nothing can be forgotten or overlooked. Also, if the customer wants a loaded strut and you don’t have any, you may lose the sale.

When to Replace?

High mileage struts may be replaced for a variety of reasons such as poor ride control, fluid leakage, sagging or broken spring, poor handling, collision damage, or suspension noise. The upper bearing plate that connects the strut to the chassis is an often overlooked part. If the plate is reused, the wear and corrosion can cause problems down the road. Symptoms of a bad upper strut bearing plate include increased steering stiffness, poor steering return after turning a corner and suspension noise. Most struts today are gas-charged to reduce aeration and fluid foaming for better ride control. As the miles add up, the seals can become worn and break, causing the gases and fluids to leak out, rendering the strut useless. Worn struts and shocks can cause uneven, cupped tire wear, increase the wear on other steering and suspension components and cause noise, steering and handling problems. They can also increase the distance it takes to stop a vehicle on a rough road. Another benefit to using a loaded strut is that it includes a new spring. The spring could be replaced separately, but that takes much more time, and other interior parts could be worn out, and would have to be replaced at a later date. Loaded struts also include new spring isolators and bumpers. On many struts, a thin rubber isolator is placed between the spring and the upper and/or lower spring seat to dampen suspension noise. A larger rubber jounce bumper may also be located around the upper strut rod to cushion the strut in case it bottoms out. Another benefit of a loaded strut is that it is much safer than a regular strut change. To change a normal strut, the spring must be compressed, while a loaded strut only needs to be installed with a couple of bolts. *IMPORTANT* Never remove the large nut on the top of the strut without compressing the spring first.

Installation Tips

It is recommended to replace all struts as a pair, unless it is being replaced for collision damage. No special tools, other than hand tools, are required to change a pair of loaded struts. However, on applications where there is no separate upper wishbone control arm to maintain wheel alignment, replacing a strut or pair of struts always requires checking and adjusting wheel alignment after the new struts have been installed.