I need a crash course in basic racecar suspension design. Possible? Where to start?

Considering going 11/10ths on adding suspension to f-dat (a challenge car currently sitting on an only f440 frame complete with rubber pucks). Adding a spring and a damper and allowing a joint to move is one thing. Actually have it work well as a system seems an entirely different - and much more important - problem. 

So, I need to learn some basic stuff. Right now I've got dual a-arms up front front, and a solid rear axle that probably works mostly like undamped super stiff leaf springs and a spool. 

I'm not even really sure where I need to start. I just know everything affects everything else. I also know I don't want to make changes for the sake of changes, I want to minimize the changes needed for maximum improvement. Which means (I assume), measuring, documenting, engineering, etc. 

Any books or sources I should be starting with? I'm trying to keep the suspension system of the car as a whole in mind, rather than starting with the minutia of the effects of each specific adjustment, if that makes sense. 

What if I told you I was already in the middle of making a giant story all about this with the 350Z as the test subject and Andy Hollis as the expert, and you'd be able to read it online in a few weeks? I have about 40 hours into the process so far, and the car hasn't turned a wheel on track yet. That's just time measuring/mathing/repeating those two steps.

All my research is from 15 years ago.  Since then due to improvements in computer simulation some additional theories and ideas on more complicated suspension design have developed particularly WRT roll center calculations and movements .  That said suspensions designed using these theories still work.

Tune to Win by Carroll Smith is the best "all around" I think.  It does a good job of distilling things down to what matters in a suspension. ($25 worth it)

I got value out of Competition Car Suspension by Allan Staniforth also (But I don't think I would spend $75 on it).

Race Car Vehicle Dynamics by Milliken is great if you want to get DEEP into the weeds (Pricy at $110 but potentially worth it if you are excited by texbook level books,  I don't own this one).

Suspension design is all a big compromise and you have to decide where you want to compromise.  Reading a book like Tune to Win will help you understand what will happen when you make your chosen compromise but as he points out there is no perfect suspension.  

I'll gladly help you setup things and review stuff as you go.  I did suspension design on 2-3 FSAE cars, the MG, and now the LMP360.  So far 4/5 have worked ok.

"Tune to win" by Carroll Smith would be the book I would normally go to, but for something with such a weird suspension system like a F440, I'm going to suggest Competition car suspension. It has more weird formula type info.

Well! that is good news. I have "tune to win" sitting on the shelf and I did read it long ago. Might be worth another pass. 

I'll see if I can get competition car suspension from the library...

There's also Herb Adam's "Chassis Engineering", it has a good explanation of design.

Here's another vote for "Chassis Engineering" its a good read

Tune to win has always been my go to.

I do have questions on why you want to change the suspension.

What year and which F440 chassis do you have?

Have you added a significant amount of weight to the car?

F440 / F500s are quite capable as is, they turn very close to shifter kart times on an autocross course. 0-60 times are also under 4 seconds with autocross gearing.  The are crude but they work.

I'm using "Chassis Engineering" because it takes it from the theoretical to the practical- gives you good numbers/guidance to start with, which is one of the hardest things. Also, I cannot recommend the website VSusp enough- no more string calculators. You can make a million changes instantly and get the perfect setup for you.

In reply to Tom Suddard :

I can't wait to read it!

Tom1200 said:

Tune to win has always been my go to.

I do have questions on why you want to change the suspension.

What year and which F440 chassis do you have?

Have you added a significant amount of weight to the car?

F440 / F500s are quite capable as is, they turn very close to shifter kart times on an autocross course. 0-60 times are also under 4 seconds with autocross gearing.  The are crude but they work.

82/83/84 red devil chassis. The car currently has a significant problem of going 'mostly airborne' after bumps. When turning as well as hitting a bump, this causes a violent 'shimmying' on landing that is undamped and you cannot drive out of it, you basically just have to wait till it stops. 

I'm pretty sure the body is too heavy and that exacerbates the problem - I will be working on that. But I think the root cause is that the rear swingarm has been poorly extended (by the guy prior to me, of course). That makes it so the pucks actually do less of the suspension movement and control than they should, and 2 1 inch horizontal square tubes loaded in bending are essentially the rear leaf springs. Another issue is that the puck 'pickup points' have been screwed with and I think there is a problem with having essentially zero resistance to rebound action until steel hits steel and the rate goes up FAST. The puck compresses on rear bound, but in the other direction there is nothing until metal interference. One thing I was going to try first was to replace all my pucks with fresh rubber (they are old), and to add extra rubber on the rear rebound side. But I still don't think that solves issue number 1, which is the rear subframe acting as the main 'suspension'. 

I know that the weight of the body is not the root cause because I have autoxed the car with and without body. Without the body the issue was much harder to induce and the effect wasn't as bad, but it still was there. Unfortunately, when I think about trying to suspend the rear axle, that's when pandora's box is opened, and everything affects everything else, and round and round we go. 

another vote for herb adams chassis engineering and carroll smith tune to win

In reply to Robbie (Forum Supporter) :

OK you have the generation of car that the whole backend went up and down or it was converted from a solid rear car. Those cars are not so great.  My 87 Novakar doesn't behave that way at all but I am familiar with the earlier cars.

Another vote for Chassis Engineering. It's a great book, mine is dogeared and referred to often. 

There's also Fred Puhn's How to Make Your Car Handle. I found it a good one if you're looking for practical and accessible.

I view Adams as the "so you're starting from scratch" book and Puhns as the "so you have a race car and it won't go around corners" book. 

More suggestions....

New Directions in Suspension Designby Colin Campbell

Race Car Design and Development by Len Terry and Alan Baker

Race Car Engineering & Mechanics by Paul Van Valkenburgh

Racing and Sports Car Chassis Design by Michael Costin and David Phipps

I snagged a copy of Milliken's RCVD many moons ago to keep around as a reference.  I ended up reading it cover to cover in 5 days.  I couldn't put it down.

It is NOT a fun read.  It's an engineering textbook. But if it's something that interests you and you enjoy that kind of learning, I think you'll find the Millikensese's writing style to be very concise.  They have a way of using the least amount of words to accurately describe a concept that it just jived with my brainwaves.

There is plenty of maths if you're into that sort of thing.  I am, so I enjoyed the Calculus and Trig (although much of it was over my head since it had been 15 years since I had any education on it.)  It really helped me a good bit when I was working in custom shops.  Someone would come in with a lead sled wanting an air suspension, and I could sit down with them to identify what they wanted and came up with a solution and was able to fab it for them.  Most of my stuff didn't suck, and none of it killed anyone, so thanks, Millikens.

Maybe not the one to start with, but a solid addition to the library will be Maurice Olley's Chassis Design: Principles and Analysis (Milliken was also involved in the writing of it, but it was mostly taken from Olley's works.)

https://smile.amazon.com/gp/product/0768008263

Tom1200 said:

In reply to Robbie (Forum Supporter) :

OK you have the generation of car that the whole backend went up and down or it was converted from a solid rear car. Those cars are not so great.  My 87 Novakar doesn't behave that way at all but I am familiar with the earlier cars.

Can you send me a pic of your rear end? Hur hur hur.

But seriously?

I am curious as to what your thoughts are with the suspension considering how tight the budget was last time I heard.

Don't know if I sent you this before, but here's pics of my kbs MK7. I think it's updated from original design to a much later one than it's 1994 manufacture, but was done by quadrini (he sold similar cars as invaders later)

Some of the pics are from before I did the chain conversion (to prevent confusion).

4 links with same lengths, a panhard bar, and well, the load path to the canisters containing the pucks is interesting and easier to just explain by saying look at photos.  One of the keys is location of the jackshaft relative to the motion of the axle.

Most of the traditional solid axle geometry stuff only applies to braking and turning. The anti-squat I think will be dependant more on the chain geometry, but I haven't really sat down to work out the details for sure. Torque reaction acting through chain rather than a ring gear making the reaction through suspension links on a normal car.

As far as learning material, I generally suggest everything written by Carroll Smith. There's good stuff in each of them and it's the best practical crash course in motorsports engineering you will find. Distills theory and application without making you understand too much of the nitty gritty math to get there.

I have Milliken, it's well worth it, but strap on your math boots. 

If you want to compute exact best type of design, Milliken. If you are a hold the thumb up and say good enough, Smith will get you there. 

I have a copy of Race Car Vehicle Dynamics by Milliken (10/10 condition) and How to Make Your Car Handle by Puhn (8/10 condition). Would ship both to you (or anyone else if interested) via USPS Media Mail for $60 including shipping. 

Mr_Asa said:

I am curious as to what your thoughts are with the suspension considering how tight the budget was last time I heard.

This is absolutely an issue. I was at $1845 in as raced condition last challenge. If I make my own wing and build my own wing support, I can remove 214 from the budget (add back materials to make the replacements of course, but I know I can do it pretty cheap), and I did some parts trading recently that allowed me to get a fuel pump and a throttle body unit and a few other little things that I had to budget for last year (they added up to about 120), so now after some part swapping I can also remove the 120 from budget as well - maybe a bit more, depends on if I can make some of the small stuff work. In the same trade, I also netted a second cbr600 rear shock, so now I've got two matching motorcycle shocks in budget and I can be about 300-350 less than last year. Which puts me at about 1500. That's plenty of room to build suspension AND throw in some epoxy for fiberglass. 

Oh, and I also bought a 3rd cbr600 rear shock on ebay for $19.80. They're all day at $30, but I'm keeping my eye out for deals. So if I decide to suspend all 4 wheels and need a 4th, they are cheap. Also I still have some cbr600 stuff and I've maxed out recoup, so I might be able to work a trade for another shock or two.