Travis R

I'm in the process of redesigning the suspension for my race car. I've already done the front, and am starting on the back. And I was wondering if anyone has put the stock FC3S rear suspension into CAD already to save me a bunch of work, even if it's just the mounting points in space, not a fully rendered assembly. Pretty please?
I have SoldWorks, and should be able to convert from most major CAD programs.
Thanks.

CJarrett

Im sure some people have. If you do get the info, please share! I'd be interested in getting it into Solidworks as well

Shainiac

iTrader: (7)

I would also love to get a copy. I'd be willing to swap my engine models for suspension models

CJarrett

You have 13b CAD?

Shainiac

iTrader: (7)

I do. Shoot me a PM with your email and I can send what I have done so far.

Travis R

Made some good progress on this over the weekend. I have the points mapped in 3d, but it's a little "sloppy" by typical CAD standards... probably +/- 1/16 on some points. But it's the best I can do with a tape measure sliding around under the car. If someone wants to give me a few hundred bucks I'll rent a Faro arm and we can do this thing right!
I'll disassemble the rear end soon to get more accurate numbers, specifically for the dog-bone and the lateral control link.

Travis R

As goofy as it looks, I've decided that the FC rear suspension is actually pure genius.
The roll center and camber gain can be modified independently.
But I really wish I knew the cg axis...

Travis R

This is what I've got so far... a little messy, but I'm testing out a couple different tire sizes.

Audiophile426

Travis R, I'm really interested in this project and would like to know how far you took it? I am on a Formula SAE team and have learned enough about vehicle dynamics to know that I don't want to start messing around with suspension modifications until I understand the system better. I would be very interested in any information you would be willing to share. I just got done with school and need to finish this competition season but starting next fall I hope to start re-engineering my FC. I will likely focus on the powertrain first since that's my area of expertise but the suspension will be next on the list.

Travis R

Sorry, just saw this.
I believe the easiest way to make the biggest changes to the car are by moving the inboard mount of the lateral control link up and down. This will raise/lower the rear roll center.
Camber gain in the rear is pretty good, especially compared to the front. So there is not as much need to modify that aspect (of the rear).
By making the roll axis more flat you can take some of the load off the front tires and that should decrease the understeer.
But I wouldn't lower the front any more than what makes the front lower control arms parallel to the ground. If you lower the front too much the roll center goes too low and I don't think you will be able to modify the rear enough to make up for it.
But as far as the CAD model goes, I don't think I'm going to share it at this time. Like I mentioned above, it's a little "sloppy" and I don't want to trust it too much. The best learning will be done by modifying the car and seeing how it changes the driving characteristics.
Feel free to ask any more questions, and I'll do my best to answer them.
Good luck to your FSAE team.