How to Read a Shock Dyno Graph to Gain a Setup Advantage

Aaron Lambert
Post by Aaron Lambert
September 27, 2021
How to Read a Shock Dyno Graph to Gain a Setup Advantage

Struggling to understand what your shock dyno graph is telling you? Leveling up your performance means capitalizing on the data produced by your shock testing, and without being able to read that data, it’s useless.

The multiple graphs from testing tell you how your shocks are working, how durable they are, and how to set them up efficiently. Knowing all of this information means you're leaving no stone unturned when it comes to your suspension performance.

If you’re staring at a screen or printouts, trying to decipher what you’re seeing, we can explain exactly how to read the graphs helping you make informed decisions on your suspension.

Understanding Your Shock Dyno Graph

Many shock suppliers are hesitant to share their work and what a shock dyno graph tells you, but once you know how to read one, you and your team will have the edge over your competitors.

Having industry-standard hardware and software in the form of a shock dyno puts you in a great position. Still, professional drivers and their teams need to validate their suspension’s performance with data, and a dyno graph does just that.

Quality Assurance

First and foremost, a shock dyno graph is your assurance of quality. If shock manufacturers are using a high-quality shock dyno to test their shocks, and providing graphs, your shocks will perform to the specifications you expect. Graphs also provide a baseline for comparison when making changes to shocks over the season.

Since your shocks can wear down over time, it’s essential to test them with a shock dyno and ensure they’re performing within tolerance.

Reading Your Graph

Most graphs read force vs. velocity. There are also force vs. displacement graphs, this is known as the pie or football graph, not typically used for performance tuning.

Put simply, the left axis of the graph measures compression force and rebound.

Positive numbers: Compression
Negative numbers: Rebound

The bottom axis measures velocity in inches per second.

You can split the graph into four quadrants. We’ve already discussed top and bottom.

The left quadrant represents low shaft speed; the right represents high shaft speed.

It’s important to note that many people think the velocity axis is measuring the car’s speed. It’s not.

Low shaft speed represents roll, pitch, squat, and dive.

High shaft speed represents bumps, potholes, curb strikes, etc.

Understanding the Results

Now that we’ve cleared up how to read the graph - we can look at how to read the results.

There are four plot lines on the graph above. The blue line is compression open, or accelerating. The red line is compression closing or decelerating. The green line is rebound open, and accelerating to peak rebound velocity. The black line is rebound closing or decelerating.

From this, we learn that at the bottom of the compression stroke we have zero velocity and zero force. As the damper accelerates and the velocity increases, so does the force that the damper produces.

At full compression, the damper stops again back to zero velocity and force, and the damper begins accelerating in the opposite direction (rebound - plot lines going down).

Compression’s job is to help control the unsprung weight of the car. Rebound is responsible for controlling the energy created by the spring compressing. Knowing this will help you decide which adjustments you need to make to improve handling.

Interpreting the results

For tuning dampers and noticing any damping windows that would affect suspension performance, there are three main speed groups to bear in mind. Speeds between zero and two inches are low-speed movements and are based on body movement such as low to mid-speed cornering. Speeds between two and six inches are experienced during heavy braking and fast direction changes. Speeds above six inches are high speed and experienced when hitting curbs, potholes, or in extreme cases, jumping.

You can identify issues out on circuit within these categories, and use your graph to see how the damping can be adjusted in these windows. This method allows you to fine-tune your suspension.

Shaft Speed: What Does it Mean?

In most forms of racing, motorcycle or car, shaft velocities between 0 in/sec to 2in/sec (50mm/sec) s. Velocities in this range contribute to the vehicle's body movement.

In the2in/sec to 6 in/sec, your shaft velocities will affect your car when braking and making quick changes of direction. This is considered the mid-range of shaft velocities.

For anything over 6 in/sec, in the high-speed shaft velocities, your suspension will better absorb bumps and control the vehicle’s unsprung mass.

All of these details help ensure your shocks are operating correctly so you can make adjustments as necessary.

Different Styles of Shocks

There are a few different types of shock performance characteristics, but for racing, we want to focus on digressive and linear characteristics.

A digressive shock has a much steeper curve on a graph because it has higher damping forces at lower speeds and then begins to level out at higher speeds. Higher damping forces at lower shaft speeds offer more control for the driver, as outlined above. Having lower force at high shaft speeds allows for more compliance when hitting curbs or larger bumps..

Linear shocks typically allow for better mechanical grip and compliance, while giving up a little on platform and body control.

Things to Consider

It’s important to test shocks at a common temperature. Generally, shocks are tested at ninety degrees Fahrenheit. This makes all the tests consistent for comparison as even a few degrees can lead to dramatically different results.

If you receive a graph with multiple plot lines, each line represents different adjustment settings, but they will more than likely all be tested at ninety degrees, unless stated otherwise.

Race conditions can make a shock very hot, so it’s also important to test at higher temperatures to understand how much “fade” your shock will see.

Why Knowing How To Read a Shock Dyno Graph Gives you a Competitive Edge

Setting up your shocks gives you a competitive edge because your car or motorcycle will feel fine-tuned to your driving or riding style and feel. A shock dyno graph acts as a guide. It shows you your entire adjustment range so you know what settings produce a certain force..

Ultimately, setting up your shocks using the graph as a guide will help you make adjustments, but the best way to set up your shocks is to test on the track in ideal conditions and fine-tune your settings throughout the day.

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Aaron Lambert
Post by Aaron Lambert
September 27, 2021
After completing high school, Aaron joined Penske Racing Shocks in 2000 as a damper technician. Since then, Aaron served in multiple management and technical rolls in the company and oversaw all major sales markets including Short Track, NASCAR, Sports Car, and IndyCar. He spearheaded the company’s successful return to the Late Model market as well as the new S-link shock dyno product line. In addition, Aaron handles all dealer relationships and has been a driving force behind Penske Racing Shocks’ long term in-house manufacturing strategy . Aaron was promoted to General Manager in 2019, a position he currently holds.
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