Suspension Testing with Force Transducers
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Why Component-Level Measurement Matters
Total force and moment at the wheel can be captured using Wheel Force Transducers or virtual road estimation. But to understand how loads are distributed through the suspension and into the chassis, component-level measurements are required. That’s where suspension transducers come in.
Michigan Scientific’s Approach
Michigan Scientific has extensive experience in instrumenting suspension components to accurately measure forces in individual suspension components and chassis. Our transducers are engineered to minimize crosstalk and reduce sensitivity to boundary conditions and mounting effects.
The specific component selected for instrumentation depends on both the component’s geometry and the suspension layout. Our experience allows us to identify which components will yield the most accurate and meaningful force measurements for each design. Michigan Scientific offers free consultations and quotes for this type of work.
All complex components will go through FEA to determine the optimal strain gauge type and placement. This promotes high-quality strain gauge output and minimizes crosstalk. Every transducer is temperature compensated and coated with a durable, waterproof coating to ensure long-term reliability in demanding environment
Common Suspension Components
Tie Rod Force Transducer
Tie rods are a commonly instrumented component to measure steering forces. Michigan Scientific can instrument either the inner or outer tie rod. We prefer inner tie rod transducers because they have more strain output and are generally more accurate.
Ball Joint Transducers
Most vehicles have several ball joints. Lower control arm ball joints often experience the highest load and are the most important instrument. Michigan Scientific can instrument ball joints to measure two- or three-dimensional forces. A reference line is machined across the end of the ball joint stud to indicate the measurement axes. Custom calibration fixtures are fabricated to match the specific ball joint geometry. As an additional service, Michigan Scientific can remove ball joints from control arms for instrumentation and reinstall them afterward. If the ball joint cannot be removed due to design constraints, strain gauging can be performed with the joint still installed in the control arm. To maintain transducer integrity, care must be taken during installation to avoid bottoming out the ball joint stud.
Sway Bar Link Force Transducer
The sway bar link is a commonly instrumented component. Michigan Scientific ensures that boundary conditions during calibration match boundary conditions in the vehicle.
Sway Bar Torsion Transducer
Michigan Scientific can strain gauge and calibrate the sway bar to measure torque.
Suspension Link Axial Force Transducer
Michigan Scientific can strain gauge the suspension links to measure axial force. Curved or complex geometry links require FEA to determine the ideal strain gauge location.
Strut Transducers
Measuring force in a strut is challenging due to the coil spring and damper being arranged in parallel and directly mounted to the chassis. There are several effective methods that allow for accurate measurement without altering suspension height or geometry. Each of the approaches captures the total load transmitted into the strut.
Strut Bracket Transducer
A semi-custom transducer that replaces the bottom bracket portion of the Macpherson strut and clamps onto the strut tube. This does not require modification to the knuckle. This four-beam transducer is made from high strength stainless steel and makes a very accurate transducer.
Double Shear Pins Strut Force
An alternative approach that replaces the two bolts connecting the MacPherson strut to the knuckle with custom-engineered shear pins. These transducers are designed to measure load directly through the joint. While this method requires minor modifications to the knuckle and strut bracket, it offers excellent accuracy and preserves suspension geometry.
Shear Pin Strut Force
In cases of a strut with a lower through hole bushing, Michigan Scientific can replace the bolted joint at the bottom of the damper with a one- or two-axis Shear Pin Transducer to measure total force into the damper. Shear pins are semi-custom transducers that replace a bolted joint. This option requires some modification to the damper bushing and lower control arm.
Crossbar Strut Force
In cases of a strut with a lower bolting crossbar, Michigan Scientific press/machine out the lower bolting crossbar at the bottom of the damper. Then replace that crossbar with a one- or two-axis custom transducer to measure total force into the damper. A new crossbar would then be pressed into the bushing, and the strut can be installed as normal. This requires no modification to the lower control arm.
Fork/Clevis Strut Force Transducer
In cases of a strut with a lower fork or clevis, Michigan Scientific can strain gauge the OEM fork/clevis with accurate results. If the geometry allows, this is the quickest and most cost-effective option and requires minimal modification. Michigan Scientific ensures the bolt clamping load is representative of OEM installation to ensure accurate results.
Non-Recommended Method
Attempts have been made to instrument MacPherson struts by installing strain gauges on the strut tube. This method does not yield accurate results due to the piston moving inside the damper and the fluid pressure inside the tube.
Damper Transducers
Damper Fork/Clevis Transducer
In cases of a damper with a lower fork or clevis, Michigan Scientific can strain gauge the OEM fork/clevis with accurate results. If the geometry allows, this is the quickest and most cost-effective option and requires minimal modification. Michigan Scientific ensures the bolt clamping load is representative of OEM installation to ensure accurate results.
Damper Rod Force Transducer
Michigan Scientific can strain gauge damper rods to measure force specifically going through the damper rod. For this transducer, the damper shroud is removed or modified to allow for gauging. Some dampers allow for the wire to simply exit through the remaining shroud. Some dampers require the drilling of the end of the damper rod to allow the wire to exit through the end of the rod.
Damper Top Mount Force Transducer
If the damper top mount geometry allows, we can modify and strain gauge the top of the damper mount or replace it with a custom transducer to measure force. This will measure the total force from the damper to the chassis.
Rear Suspension Components
Shackle Force Transducer
Michigan Scientific can instrument the shackle to measure vertical force from the leaf spring into the chassis at one end of the leaf spring. We will run FEA on the shackle to determine the best strain gauge location. Maintaining representative boundary conditions is critical for this transducer.
Coil Spring Force Transducer
Measuring force in a coil spring provides valuable insight into how vertical loads are transmitted through the suspension system. Michigan Scientific can instrument coil springs to capture this data accurately, even under dynamic conditions. In addition to force, coil springs can be calibrated to measure displacement, which is useful for correlating spring compression with ride height and suspension travel.
Contact us for a free consultation to discuss suspension instrumentation. Michigan Scientific engineers will work with you to identify the most effective instrumentation strategy based on your specific suspension layout and testing goals.