What is Low-speed Compression, and Why Might You Need to Adjust it?

Imagine purchasing expensive shocks and not squeezing every ounce of performance out of them. You run that risk if you don’t optimize your setup by first understanding high and low-speed damping and applying that knowledge to your setup. 

A suspension setup that compliments your driving style and preferences should be highly-adjustable. To prepare for the many variables you’ll encounter when you drive or ride, you can tweak your shocks for a better driving experience and reap performance gains.

This article will explore low-speed compression, why you might need to adjust it, and how to adjust for maximum performance.

What is Low-Speed Compression?

You can’t leave any stone unturned when it comes to optimizing performance. Low-speed compression is a popular part of a suspension to tune, but it has to be done properly to make the most of it.

You can’t turn it a few clicks and expect miracles, and you need to test and retest and notice the subtle differences in feel. Before we get into how compression works, let’s look at shocks as a part and then delve into low-speed compression for a comprehensive overview.

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In this free download, we provide both our Standard Shock Build Sheet, which is a great way to keep all your shock builds organized, and a Setup/Lap Time Sheet, a great tool to help improve your communication and record keeping of your chassis setup.

How do Shocks Work?

A shock is a hydraulic device, and spring-based shocks use coil or leaf springs. By stopping the springs compressing and rebounding too quickly, shock absorbers control the speed of your wheels as they move up and down.

Shocks control the way oil flows inside the shock. Oil is controlled by a base valve and piston, and the resistance the oil experiences while moving through the base valve and piston is called damping force. The kinetic energy produced as the oil moves is converted to thermal energy that dissipates into the atmosphere.

Compression Damping 101

Compression damping is how quickly or slowly your springs are allowed to compress.

Shocks have a primary job: to control the speed at which your wheels move up and down. They perform this job by stopping your springs from compressing and rebounding too quickly. Controlling these variables is essential and allows for a better driving experience.

Shocks keep your tires in contact with the ground over rough and undulating terrain.

Stiffer shock rates slow the movement of springs.

TIP: You want your suspension stiff enough that it doesn’t bottom out, but if your shocks are too stiff, it can cause the tire contact patch to bounce off the road surface over bumps, making your car feel less predictable.

A softer shock rate allows the spring to move faster for compliance and traction. However, too soft shocks will make the body of your car or bike bounce after hitting a bump or rut.

How quickly the suspension compresses or rebounds will determine the level of damping required.

Want to learn more about damping? Check out: Spring Rate or Damping? How to Stiffen Rear Suspension Properly

Low-speed Compression

Low-speed doesn’t refer to the speed of your car or bike but how slow your shock shaft is moving. Low-speed compression comes into play when you apply smooth loads to your suspension.

Generally from driver input, it’s primarily concerned with managing chassis movements, for example, when you apply your brakes.

As you enter a corner and brake, your rear might feel light and want to spin out as the weight shifts to the front of the car (oversteer). You can adjust the resistance to these movements and loads. If you increase low-speed front compression, you’ll limit forward weight transference and find a balance essential for stability.

With stiffer low-speed compression, you can have a softer spring rate offering more mechanical grip.

Why Would You Adjust Low-speed Compression?

When you apply steering, the car will roll to one side or the other compressing the outside suspension. Braking compresses the front suspension, and acceleration compresses the rear suspension.

All of these situations can be optimized with low-speed compression adjustments. Since they are all driver input responses, these settings significantly impact mechanical grip and handling characteristics.

A car that’s too stiff might lose traction in loose or slippery conditions. You can decrease low-speed compression if your car or bike feels too stiff and you prefer a looser feel. Likewise, if your car or bike feels too high, you could decrease low-speed compression to lower the center of gravity.

You might increase low-speed compression if your car or bike feels too soft. You might also increase low-speed compression if your car’s rear squats excessively during acceleration or nose dives during braking.

An excellent indication of whether your suspension is too stiff or too soft is tire temperature. Softer setups take a long time to increase tire temperatures, increasing the tire’s life cycle, whereas stiffer setups increase tire temperature quicker.

As you can see, many of the adjustments you might make depend on driver feel and preferences.

How Do You Adjust Low-speed Compression?

Now that you know why you would adjust low-speed compression, you can learn how to adjust it.

Get out on the track and test incrementally. Make sure you record baseline settings and work from there. Remember that making adjustments to low-speed compression may affect high-speed damper settings. Find a balance between the two.

You don’t need to feel overwhelmed by all of this information.

We can provide everything you need to set up your shocks confidently.  A personalized, custom-built solution from Penske Racing Shocks that addresses your specific requirements ensures you get more out of your shock setup and translates to better handling and speed on the track.

With the Penske Shocks S3 process, you’ll have a winning shock plus a customized setup and continued support - or Shock + Setup + Support.