3-Link Suspension
March 2024 - April 2024
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To design and build a custom 3-link front suspension for a 1987 Toyota 4Runner. The suspension must provide a comfortable daily driving experience while providing enough articulation to tackle off road terrain.
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Designed in SolidWorks
3 Link suspension design
Geometry balances road manners and off-road capabilities
Laser cut and press brake formed
Relief cuts placed in multi-corner bends and interfacing parts
Suspension travel: ~4” up / ~8” down
3 Position upper link mount adjusts anti-dive characteristics
Brackets are 1/4” HRPO Steel
1.5” OD x 1/4” Wall DOM tubing
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Lessons:
Spending a little extra time in the design phase can save you a headache in the assembly phase.
Outcome:
This was my first exposure and attempt at a 3-link suspension. I spent around 2 weeks researching suspension geometry before kicking off the CAD. I also spent some time using online tools such as the "3-link calculator" to get ideal specifications. I used those specifications as guiding perimeters while working around the dimensions of the truck and packaging the brackets to fit. In the end, all brackets and assemblies fit together very well.
Overview
A custom designed 3-link front suspension with a pan-hard bar for 1987 Toyota 4Runner.
↓↓ Photos ↓↓
Suspension Geometry
An online tool called the 3 Link Calculator was used to generate an “ideal” model. This model was cross referenced to the frame of the truck and adjusted accordingly. With a moderate anti-dive and roll center height, this design in theory should produce comfortable and predictable on road manners.
Mechanical Design
This design allows for 4” of up travel and 8” of down travel. To prevent bump steer, the pan-hard bar is equal in length and in plane to the steering drag-link and sits flat at ride height. The lower links are slightly triangulated to reduce stress on the upper link which is also slightly shorter than the lowers to allow better steering characteristics at full droop. In addition, the coil overs are mounted with zero angle to allow full vertical travel.
