Rick New Reader
Oct. 31, 2015 11:18 p.m.

So I want to be a suspension expert. Where can I find material about this? I understand the basics. I've read several books. I remember reading old Super Sport magazines that discussed the Ackerman and slip angle etc. I'll have to refresh myself on that. My goal is to be able to spec out roll bars and basic spring and shock rates. I want my car to be Fun with a capital F. i.e. predictable and forgiving handling at the expense of ultimate grip and handling. Similar to a BRZ but with sticker tires. I currently have a 2013 Mustang GT but I want to be able to apply this strategy to any car and suspension setup.

ncjay Dork
Nov. 1, 2015 12:02 a.m.

Carroll Smith has several excellent books that will keep you busy for a while, but there are other excellent books out there as well.

friedgreencorrado UltimaDork
Nov. 1, 2015 2:34 a.m.

Oldie, but a goodie. Covers the basics. http://www.amazon.com/How-Make-Your-Car-Handle/dp/0912656468

NOHOME UberDork
Nov. 1, 2015 5:11 a.m.
Rick wrote: I want my car to be Fun with a capital F. i.e. predictable and forgiving handling at the expense of ultimate grip and handling. Similar to a BRZ but with sticker tires. I currently have a 2013 Mustang GT but I want to be able to apply this strategy to any car and suspension setup.

So...basically the same goals as any car company's engineer with an engineering degree, 15 years experience and a bazillion dollars worth of resources wants.

Should be easy enough.

The first thing you need to know about suspension design is that it is a huge game of paying Peter by stealing from Paul. And then, when you do finally get it all figured out, the project goes mobile and you have to start dealing with transient conditions. And the fact that it is a "subjective science".

I agree with the "Engineer to Win" series of books as being a good place to start. I also know from years in the engineering management field that unless you have a project to start with, you never really learn the theory well enough to apply. There are some reasonably priced suspension calculators out there, buy one.

I at one time had the same goal as you. As I went down the path learning, what I learned is that it is hard to beat the factory engineers at their game. I also found that I never did any baseline testing, so I never had any way to say that I had improved the car. But I continue to have fun trying.

flatlander937 Reader
Nov. 1, 2015 5:19 a.m.

For auto-x specific, this is a great resource:

http://farnorthracing.com/autocross_secrets.html

chaparral HalfDork
Nov. 1, 2015 6:35 a.m.

Race Car Vehicle Dynamics by Milliken and Milliken. If you've got enough travel (no bottoming or topping on the largest bumps on your track - no cheating by use of too-stiff springs and letting wheels fly), enough total spring rate (no bottoming or topping under full acceleration or braking), enough total roll rate (no bottoming or topping on the biggest bump in the fastest corner on the track), and balanced roll and spring rates (to get neutral midcorner balance even over a bump - stiff springs and a small ARB at one end and soft springs and a big ARB at the other is great until you hit a bump), you'll be close if you have good tires.

Bushings are for factories (yours should ditch the compliance), dampers are for transients, and geometry changes usually don't work because your replacement parts are nowhere near as stiff as factory parts.

alfadriver UltimaDork
Nov. 1, 2015 7:48 a.m.

It would also help to study multi link mechanism dynamics (starting with 4 bar links), spring and damper dynamics, or even going backwards- statics and dynamics.

Modelling goes a long way too- a friend of mine made his own suspension model- and his cars were really fast over a long run.

I'm assuming by expert you want to design suspensions and not just tune them.

SVreX MegaDork
Nov. 1, 2015 7:58 a.m.

I generally just stick stuff on the car and jump in, then measure it's "Oh E36 M3" factor!

The engineers have answered (correctly). But for the rest of us, trial and error is a great learning environment.

You said your goal is to be able to spec out roll bars and basic spring and shock rates. I am pretty good at that- I don't think you need to be a "suspension expert".

I think it's a field where the best of the best come to realize that the more they know, the more they understand what they don't understand. It's a moving target (literally and figuratively).

Nov. 1, 2015 8:37 a.m.

Motoiq is a good site to check out too.

kb58
kb58 Dork
Nov. 1, 2015 10:04 a.m.
chaparral wrote: Race Car Vehicle Dynamics by Milliken and Milliken.

+1000, but also agree, good luck out-thinking the mfg engineers. That said, if their solutions are limited by cost - which they are - then you may be able to switch to a different type of suspension. That can end up being a lot of work, and by that time, may as well start from scratch. That's what I did.

erohslc Dork
Nov. 1, 2015 10:33 a.m.

Another thing, the less torsional stiffness your chassis has, the more that chassis becomes a part of the suspension.
(Spitfire drivers, I'm talking to you)

RossD UltimaDork
Nov. 1, 2015 11:10 a.m.

I took a vehicle dynamics and design class in college. This was the major text book: http://www.amazon.com/Chassis-Design-Principles-Analysis-Premiere/dp/0768008263

The dude literally wrote the book on automotive suspension design. Well actually Milliken and Milliken wrote the book based on Maurice Olley's work.

NOHOME UberDork
Nov. 1, 2015 6:37 p.m.

When designing anything, the critical component to get before you commit is the voice of the customer.

Who exactly do you want to design suspensions for? Street racing? Slalom? Oval? Off Road? Road course? Drag racing?

curtis73 PowerDork
Nov. 1, 2015 7:51 p.m.
chaparral wrote: Race Car Vehicle Dynamics by Milliken and Milliken.

/thread.

Seriously worth owning. It is an engineering textbook. There is a fair amount of calculus and geometry maths but it is everything you need to know.

The "how to build suspensions for dummies" books are nice, light, condensed versions and are fine for a start, but Milliken's RCVD takes you from nothing to EVERYTHING in 863 erudite pages.

I bought it back in 2003 and took it with me on a 4-day train trip. I read it like it was a novel. Every page. I couldn't put it down.

Keith Tanner MegaDork
Nov. 1, 2015 8:45 p.m.

Puhns is good. Staniforth is better.

And nothing beats seat time and experimentation when it comes to tuning.

Btw, I've read multiple engineer biographies (Horsman, Donahue, Yunick) that tell stories of chasing their tails on setup and eventually discovering they were out of travel due to incremental changes. The math changes quite a bit on the boundary cases, keep this in mind when you start playing with your pure spreadsheet solutions.

Wall-e MegaDork
Nov. 1, 2015 9:48 p.m.
friedgreencorrado wrote: Oldie, but a goodie. Covers the basics. http://www.amazon.com/How-Make-Your-Car-Handle/dp/0912656468

That is a good one. My father had that and this one when I was a kid.
I tried to use them for book reports in I think the fourth grade but the teacher said no. She also suggested some kind of testing to my parents.

Ransom PowerDork
Nov. 2, 2015 1:43 p.m.

Milliken, Staniforth, and Smith as mentioned above. I also found Neil Roberts' "Think Fast" to be fascinating; he's got some interesting points around the relative unimportance of the inside of the car's contribution to roll center geometry, and about avoiding geometric anti-roll, anti-dive, etc because they complicate tuning due to increased side effects of any given change. Not to get bogged down in details here, just to give an example of the sort of thing different sources can bring.

Of course, I mostly have years of experience reading these books

Seriously, reading different knowledgeable people's takes has been helpful in getting it ingrained (e.g. I'm not sure Roberts' book is the best intro to a lot of concepts, but it fleshes them out nicely and adds new insights), though I really need to do some application to find out whether the understanding I think I have is anywhere near right, and of course as noted above (also), even really, really smart people with a great fundamental understanding don't just spit out a perfect solution...

chaparral HalfDork
Nov. 8, 2015 8:06 p.m.

Of course the "can't beat the factory" stuff has some merit - your own uprights, hubs, arms might not be as stiff - but there's a reason the SP, P, and M classes exist!

Stock cars are rolly (5 + degrees/g rather than the 2 you'd want), soft in heave (1.5-2 hz rather than 2.5-3), and have horrid lateral and longitudinal compliance (measured in WHOLE INCHES some places!).

loosecannon HalfDork
Nov. 8, 2015 9:59 p.m.

I purchased the Performance Trends Suspension Analyzer and used that to design a suspension from scratch. It's also useful for making the right changes to an existing suspension. It doesn't directly tell you if your suspension is good or bad, just what the numbers are. To know what your target is, one of those books already mentioned would be a good place to start.

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