How to Read Shock Dyno Sheets (and What They Tell You About Real-World Grip)
Shock dyno sheets are the fastest way to turn damper tuning from “it feels different” into measurable, repeatable data. Whether you’re selecting dampers, verifying a build, or comparing click settings, a dyno plot shows exactly what force the damper generates at specific shaft speeds in both compression and rebound.
This post explains how to interpret a typical shock dyno printout, how to compare runs, and what to look for when adjusting rebound—specifically: rebound adjustment primarily changes low-speed rebound, with minimal effect on high-speed rebound and compression.
These examples are from a Thunder Lane TL-ONE setup utilizing a check valve. If you want the design background, read this first:
https://thunderlane.us/blogs/tech-tips/tech-tip-what-a-check-valve-does-in-a-performance-damper-and-why-it-matters
What a Shock Dyno Measures
A shock dyno cycles the damper through a controlled stroke at controlled shaft velocities and records force output. The result is a standardized way to evaluate:
- Damping force vs shaft velocity
- Compression vs rebound balance
- Repeatability and consistency
- The effect of adjustment clicks
- General behavior across low-speed and high-speed regimes
Important clarification: “Low-speed” and “high-speed” refer to shaft speed, not vehicle speed. A car can be traveling 120 mph and still be operating the damper in the “low-speed” region during steady-state cornering.
Reading the Dyno Sheet: The Two Primary Plots
1) Force vs Velocity (Left Plot)
The left plot is the most direct representation of damper behavior.
- X-axis: Shaft velocity (typically m/s)
- Y-axis: Force (typically N)
- The curve shows how force increases as shaft speed increases, in both directions.
What this plot is used for:
- Comparing damping force at specific velocities (e.g., 0.05 m/s vs 0.49 m/s)
- Identifying how an adjuster changes the damper (where the curve moves and by how much)
- Comparing two different shock builds or valve stacks
General interpretation framework:
- Low-speed region (~0.00–0.10 m/s): platform control (pitch/roll/heave, transient response)
- High-speed region (~0.20–0.50+ m/s): bump/curb/impact response and tire compliance over rough surfaces
2) Force vs Displacement (Right Plot)
The right plot shows force as the shock moves through its stroke.
- X-axis: Displacement (mm)
- Y-axis: Force (N)
- You’ll usually see multiple “loops” stacked together.
On the TL-ONE dyno sheets used here:
- There are 10 traces on the right plot
- Each trace corresponds to a specific test velocity
- The exact velocities and associated force data are listed in the table at the bottom of the sheet
What this plot is used for:
- Checking cycle-to-cycle consistency
- Visualizing hysteresis and how force builds through the stroke
- Verifying that the damper behavior is stable across repeated runs
How to Decode the Run Filename (Front/Rear + Click Setting)
The dyno run filename is printed near the center of the sheet. The suffix provides two key pieces of information:
- F = Front (rear would be marked with R)
- The number after the dash indicates the rebound adjuster click position
- Example: F-1 = front shock, rebound at 1 click (full soft)
This matters when you’re comparing sheets. If you compare different click settings, ensure you’re comparing the same corner (F vs R) and that the only intended variable is the click position.
The Key Tuning Concept: Low-Speed vs High-Speed Damping
A dyno plot is most useful when you relate the curves to vehicle behavior.
Low-speed damping (platform / attitude control)
Low-speed damping heavily influences:
- Roll support in transitions
- Brake dive and acceleration squat control
- Steering response and “platform” stability
- How quickly the chassis takes a set
High-speed damping (bump / compliance control)
High-speed damping heavily influences:
- Curb behavior
- Harshness over sharp edges
- Stability over rough surfaces
- Tire contact consistency through high-frequency inputs
A well-tuned damper provides sufficient low-speed control without forcing excessive high-speed force that can reduce compliance and mechanical grip.
Rebound Adjustment: What Changes on the Dyno (and What Usually Doesn’t)
On these TL-ONE examples, the rebound adjuster is doing what a properly-designed rebound adjuster should do:
- Large effect on low-speed rebound
- Much smaller effect on high-speed rebound
- Minimal effect on compression
Why the rebound knob primarily changes low-speed rebound
Most rebound adjusters control a low-speed metering path (often described as a bleed/needle or controlled restriction). At low shaft speeds, that path represents a significant portion of total flow control, so changing the adjuster creates a noticeable force change.
As shaft speed increases, flow demand increases rapidly. The damper transitions to regimes dominated more by main valving behavior (and in designs like TL-ONE, features such as check-valve behavior depending on direction and flow demand). In that region, the adjuster contributes less to the overall pressure/flow balance, so curves tend to move less at high speeds.
Practical interpretation
If you add rebound clicks and see:
- A large force increase at 0.01–0.10 m/s on rebound
- A smaller change by 0.20–0.49 m/s
- Compression curves staying near the original values
…that is a strong indicator the adjuster is targeted to chassis platform control rather than fundamentally changing bump compliance.
F-10 rebound setting: low-speed rebound increases relative to F-1, while high-speed regions change less.
How to Compare Click Settings Using the Data Table
The most objective way to compare runs is to use the bottom table. Since each of the 10 traces corresponds to a specific velocity, you can compare force output at the same velocities between different click settings.
Recommended comparison method:
- Confirm you’re comparing the same position (e.g., F-1 vs F-10 vs F-20).
- Pick specific velocities that map to the behavior you’re tuning:
- 0.01–0.05 m/s: very low-speed control (platform, response)
- 0.10–0.20 m/s: transition region
- 0.30–0.49 m/s: higher-speed events (bumps/curbs)
- Compare the rebound force values at those velocities across click settings.
- Verify compression values remain relatively stable if only rebound is being adjusted.
This approach avoids subjective “curve reading” and gives you numbers that can be logged, shared, and used for tuning decisions.
F-20 rebound setting: further low-speed rebound increase with comparatively small change to high-speed rebound and compression.
What a Check Valve Can Change (TL-ONE Context)
Because these runs are from a TL-ONE setup using a check valve, it’s worth stating what the customer should look for in the plots:
- Improved separation of behavior between regimes (controlled low-speed tuning without forcing a matching increase everywhere)
- More controlled direction-dependent flow behavior
- A tuning window where platform can be adjusted via rebound clicks without an equal penalty in high-speed harshness
For the detailed functional explanation of the check valve and why it matters in a performance damper, refer to the linked tech tip above.
Practical Trackside Takeaways
- If the car feels lazy in transitions, lacks support, or takes too long to settle, increasing rebound clicks can add low-speed rebound control and sharpen response.
- If the car feels harsh over curbs or sharp bumps, don’t assume the rebound knob will solve it. On many dampers (including the behavior shown here), rebound adjustment does not dramatically change high-speed force. High-speed issues often require changes in compression strategy, valving configuration, or overall damper specification.
- Dyno sheets allow you to confirm whether an adjustment is affecting the part of the curve you’re trying to tune—before you chase setup changes blindly.
Summary
A shock dyno sheet is a force map of what the damper actually does. Read the left plot (force vs velocity) to understand behavior across shaft speed, and use the right plot and the data table to compare specific velocities and verify consistency.
On the TL-ONE examples shown here:
- The rebound adjustment knob produces significant changes in low-speed rebound
- It produces smaller changes in high-speed rebound
- It produces minimal changes in compression
That’s exactly the behavior you want when tuning chassis platform and response without unintentionally turning the damper into a harsh, high-speed force generator.
If you want help interpreting your specific runs (or building a recommended baseline for your car and tire), contact Thunder Lane US with your dyno sheets, vehicle details, and current click settings.
