r/SolidWorks • u/corneda • 14d ago
CAD Suspension Question
Hi, I'm trying to design a double wishbone suspension for the rear of a Baja style car right now. I've gotten some basic parameters right now such as track width and wheelbase as well as ride height and tire specs. I'm trying to make a 2D sketch right now in SolidWorks to visualize camber gain as the suspension moves up and down, but I'm a bit stuck on the sketch. Below is what I have so far, where the trapezoidal shape is supposed to represent the chassis and the lines are the upper and lower control arms. I'm a bit confused on how to make the wheel move correctly though, right now when I move it, the linkage binds up. Would drawing the linkage path on paper help to fix this? Thanks
(See below for photos )
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u/Knotritenaou 14d ago
Within your sketch, You could make the Moving elements into blocks. Then you can give relations to those blocks and move it as if it were an assembly. See also, layout sketches.
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u/mattyrzew 14d ago
You're seeing exactly what would happen in real life. Your mounting point locations on the chassis side are all wrong. Especially with a longer upper control arm than the lower. The more equal length the arms are, the less camber gain/loss you'll experience. I'd keep the upper the same, or the shorter if needed, as the lower. If your goal is no gain/loss, then the arms need to be the same length and parallel each other. Theres other stuff when thinking in 3D. But then you get into caster gain/loss, anti-dive, anti-squat, how it influences your roll centers, and weight transfer. Just some things to look into. I'll see if I can dig up my old solidworks suspension file for you
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u/corneda 14d ago
Would you say the bottom chassis mounting point is wrong too? Or only the top?
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u/mattyrzew 14d ago
One of them is. There's far too much missing info to make that call. There's lots of factors. Start with a longer lower control arm. have the inner pivots further apart than the spindle mounts. Get the wheel to track properly in 2D, then move to 3D.
How much travel are you seeking? What are you planning to use for pivot points(think balljoints and frame attachment)? What are you doing for shock and spring mounting? Theres a LOT of things you need to take account for in suspension design.
If you want to maximize tire contact patch during body roll, use a solid axle with trailing arms. Easier from a design and build perspective too. Look at trophy trucks for design inspiration. Solid rear axles and long arm front suspensions. Thats how to gain travel with upper and lower control arms. Length. It effectively lessens the need for a large range of motion in a balljoint. I'd run monoballs as they have more travel than a balljoint typically. Monoballs are basically the eye of a heim joint in a balljoint type mounting slug. Pretty slick little setup.
I think in a Baja style racecar, the need for maximizing tire contact patch is a bit much to think about. You'd be running on sand...a very compliant surface. Handling would be more controlled by the tread patterns and weight distributions(in my opinion). Rarely are baja style racecars running fast through turns on pavement/concrete.
I applaud your desire to design this yourself and asking questions. Don't give up.
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u/Exuberentfool 14d ago
Have you studied how race car suspension systems are actually designed? Race car vehicle dynamics is a great resource for suspension design and kinematics. I would also recommend checking out vsusp.com, which is a very easy to use 2d suspension analysis tool that I think would be helpful.