So, I have some new found free time on my hands and I'm going to try use it practically. One of the things I've been messing with lately is chassis/suspension/geometry simulation for my Magna.

Initially this all started for "sh!ts and giggles" but it kinda got serious. This has lead me to the idea that the best way to get an idea of what's happening under certain conditions, or changes to geometry, specific to my car is to model it in 3D. My plan is to create a model of all four corners, suspension, brakes and wheels as accurately as possibly without pulling too much of the car apart. From here I can calculate roll centers and so on, as well as get some visual feed back on what happens to X when I do Y.

Now, when I say "free time" I mean a few of hours on the weekend and maybe a couple of hours on the odd night during the week. I'm a dad, have a missus and I work (mechanical design draftsman) so it'll be relatively slow going. I'll update this post/thread as the work progresses with the ultimate aim to produce drawings/models that may be of use to us all.

This week I've just modelled the fgront right brakes and a wheel. I can reuse these parts as I go, so essentially I model a single side of the car and my work is nearly done.

Brakes so far (http://imgur.com/HgVgX) for comparison to the original (large photo (http://imgur.com/4ihgD))

If I do get stuck for a critical measurement though I might call on you guys to spot me on it. Cool?

Anyway, I'm off to measure the front control arms. Keep you posted.

Better than what I can do with a modelling program lol

What program are you using? I used Catia in Uni and it was terrible.

Better than what I can do with a modelling program lol

What program are you using? I used Catia in Uni and it was terrible.

Currently using AutoDesk Inventor. Shifted from Solidworks. Never used Catia though... Things happen faster in Inventor, and the learning curve isnt as steep as other programs. The end drawing templates in Inventor need tweaking though, I did a trade as a graphic artist so I tend to fuss over my drawings... and, in all the places I've worked as a draftsman the emphasis has been on producing clear drawings.

Update #1 (http://i.imgur.com/COvP0.png) Steering knuckle.

Note that I'm omitting detail that wont be required for the intended task. There's no brake line inlet or bleeder valve, no ABS connector and the drive shafts wont be detailed. The crucial thing is correct measurements of bolt hole locations in relation to each other. The assembly we're looking at this stage is purely for part development. Once I have the parts drawn correctly I'll reassemble it all into another so I can apply motion etc.

Let me know if you run into any problems with inventor I have just updated to autodesk inventor pro 2013. Will post a pic of my RC rock crawler.

That actually looks like a real one! lol
Did it take long to get to this stage?

That actually looks like a real one! lol
Did it take long to get to this stage?

Not that long actually. It took longer to get started on the job. I'd say it about six hours work so far for what we see. I'm currently modelling a front strut... kinda avoiding the control arm as I dont have my measure tools from work with me. That control arm doesnt look like its going to be simple to model.

Another update, strut body and wheel added. (http://imgur.com/HYiF1) The wheel was always there, just suppressed for visibility. The strut I'm drawing in two parts to allow it to move.

Front suspension complete enough to start assembling. UPDATE (http://imgur.com/uByvA)

Will start the rear suspension this weekend.

Front suspension is now complete. To factory standards, or as close as I can get them without spending weeks pulling the car apart and measuring each component. Updated from last night with new steering knuckles.

http://imgur.com/KSGJY

In a word . . . . brilliant!:happy: Wish I could do that. :woot: Lacking somewhat in the patience department though.

Rear Suspension started (http://imgur.com/EvDvn)

Having trouble making it work. I mean, it "works" but my front trailing arm limits movement when I constrain it by bolt centers.

Any idea what I'm missing here? Is there that much movement in the bushes during normal operation?

Thinking I might have divided by zero in one of my measurements...

Another 3D project update. I'm still trying to nut out the rear suspension. Had brought some measuring tools back from work... but, didnt get near it during my holidays.

Its pretty damn difficult to measure/model the rear suspension with everything assembled. Still working at it though, so watch for updates.

I've also added the correct caster angle to the front suspension - was incorrect (2 degrees) on my previous model.

Very nice work

Very impressive stuff.
Can you have it animated to see dynamic camber etc?

Very nice work
Thanks chief, appreciate it.


Very impressive stuff.
Can you have it animated to see dynamic camber etc?
Hell yes I can! I'd like to wait until I have the rear suspension done, so I can see all four wheels react. Rubber, or the affects on the sidewalls of the tyres might be out of the reach of the software.

Another slow project is to model as much of the engine bay components as possible, without pulling too much apart. If I had a spare car, or engine, laying around I'd strip it and measure everything. EVERYTHING! Next year maybe. Here's the start of the airbox arrangement. I did this because I'm looking to find the total volume of the intact tract. Currently, the volume of the parts you see modeled in the link/image is 8.4 liters.... maybe a shade less as I didnt include all of the ribbing inside the airbox and my air filter is pretty "rudimentary". Over the next few days I'll complete the intake track from the snorkel back to the intake plenum. Then the plenum and intake manifold as best I can from measuring what I can.

I'm looking to have a model of the engine ultimately. Not a working one, just the external shape. I want to put it in an engine bay for my headers project I'm working on, and, to kick around different intake manifold concept. Nothing serious though, this is all just practice and fooling around. There will be useful data though from time to time.

http://imgur.com/aRC6d Link if no image - HERE (http://imgur.com/aRC6d)

In a word . . . . brilliant!:happy: Wish I could do that. :woot: Lacking somewhat in the patience department though.

Ah, you'd be amazed how easy this is. If you can visualise an object you can draw it. The catch is knowing the capabilities/shortcuts of the software. Having a good grip on mechanical concepts is extremely handy also. For things like this, measuring/modeling parts fr my car its pretty relaxed. If I were at work I'd take more care, mostly because things can change quickly and regularly.

The modelling part is honestly a snap, the drawings or communicating to others what you've modeled is where the time is at.

To be honest I think the most important dynamic camber change is the front. The rear being double wishbone will be fine, but with the strut suspension at the front having the car too low may start causing positive camber change, so maybe your animations can tell people the ideal amount to lower their cars by

To be honest I think the most important dynamic camber change is the front. The rear being double wishbone will be fine, but with the strut suspension at the front having the car too low may start causing positive camber change, so maybe your animations can tell people the ideal amount to lower their cars by

I'm not sure an animation by itself will enlighten us to a magic number for suspension geometry... I'd have done it by now if that was the case :P

The best that could come of this is roll centers, center of gravity and all those other terms that elude me right now. To see how those elements are affected by changes in suspension.

I've been running the figures I've measured in a (super basic) program that simulates the car and its suspension etc in a closed circuit environment. it doesn't do AWD which really bums me out, but I'm fumbling my way through it. Not in an effort to reinvent the wheel - make my own control arms etc. More so I'm looking to find which combination works best; lowered springs + stiff shocks + 17" wheels and so on. Then from there maybe trying to find out what changes compensate for each combinations failings. I doubt you could ever pluck an ideal setup from simulated results, let me just make that clear. The best you could get is a starting point. Add to that some real world experience and you "could" find an ideal setup.... for a specific track/environment. No one ideal setup will be a one size fits all.

Back to animations. If I could get the 3D software to simulate the true nature of the tyres it would be more beneficial. At this stage, if I animate my model turning a corner and taking a bump you won't "see" a useful result. The tyres in my model a pneumatic but the simulation doesn't allow sidewall flex etc. it just won't rubber brother. :(

I'm still going to do it though... mostly because my brain is shouting at me "challenge - accepted!". Just not until I have my rear suspension done sorry.

You should do my front suspension setup and animate it, that would be cool

You should do my front suspension setup and animate it, that would be cool

er... is yours that crazy JDM multilink front suspension?

Must... resist.... urge.... to accept... challenge.

I'm finding that measuring/modeling the multilink rear suspension is requiring a whole lot of accuracy and patience. That's measuring it still on the car.... if I could pull it all apart, that would make things easier.

So.... can I pull your car apart? It's for science remember :P

er... is yours that crazy JDM multilink front suspension?

Must... resist.... urge.... to accept... challenge.

I'm finding that measuring/modeling the multilink rear suspension is requiring a whole lot of accuracy and patience. That's measuring it still on the car.... if I could pull it all apart, that would make things easier.

So.... can I pull your car apart? It's for science remember :P

No its got a thing called perfohub. I took my front wheel off once and was wondering what the F was going on in there. The steering is not really connected to the hub - no torque steer

http://www.evo.co.uk/front_website/gallery.php?o=1&id=338011

No its got a thing called perfohub. I took my front wheel off once and was wondering what the F was going on in there. The steering is not really connected to the hub - no torque steer

http://www.evo.co.uk/front_website/gallery.php?o=1&id=338011

That does look interesting. What's it handle like really? I love seeing stuff like this, ideas in motion.

That does look interesting. What's it handle like really? I love seeing stuff like this, ideas in motion.

Its good, does what it says on the tin - no torque steer :)

Its more suited to the bigger megane where the turbo makes a lot more torque than my little NA beast