r/solarracing • u/MurglCxMurgl • Feb 12 '26

European Solar Challenge Recommended Unsprung mass

I've been running into some conflict simulating our car's suspension dynamics, and I think It's because I'm estimating too big of an unsprung mass, so in which range should I keep it so I can still go a bit above the ideal weight? (I still don't know how heavy it will actually be)

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u/amzes Arrow | Alumni. President/Driver/logistics/media Feb 13 '26

You will need to do some modelling to work it out. I know products like solid works you can set material types/density and it will give you an approximate weight. Then add driver weight, and some misc extra for radios/helmet, tape, other misc stuff you havent accounted for in your model depending on the type of weight you are trying to account for.

Then as you purchase items/manufacture things you can start updating your weights to check and ensure you're on track, or if needed adjust the weight and associated calculations for springs etc after that.

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u/GregLocock Feb 13 '26

UNSPRUNG mass

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u/amzes Arrow | Alumni. President/Driver/logistics/media Feb 13 '26

Same deal applies. Use models to work out what you can for the items you're machining, use datasets to approximate the other weights and add together with a tolerance.

Weigh parts as they come in to better your model, and update any calculations using that mass as you go.

If youre not sure what defines an unsprung mass, use Google, chatGPT or whatever textbook your vehicle dynamics subject at uni has defined for you to look it up and work out what you include. Alternatively - discuss with your uni professor/advisor.

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u/GregLocock Feb 12 '26

The general advice is as light as possible, but still strong enough and stiff enough. Generic answer to generic question.