Suspension System Project + technical drawings FF

[polruiz12]

Good morning guys,

I am Pol and I am a 4th year mechanical enginieering student from Spain, I am new to this forum as I've seen it is the best place to keep informed about Formula Ford cars.

Right now I am starting my final degree project which consists on the Design and Optimization of a Formula Ford suspension system.

I have a problem which is that as I am designing a suspension system withhout a reference chassis, I don't really know which dimensiones or chassis values take.

I have two options:

• Designing a suspension system which can be fitted in a big group of cars (imagining I am an independent supplier of suspension system).
• Designing a suspension system designed for a specifical car with a poor performance (I have been told that 84 Van Diemen and 85 Reynard are pretty bad cars) and improved the suspension they have.

I would like to get some advice from you, if possible, on chosing one of the 2 options and telling me models of car with bad performance based on your experience and if it's interesting or hypothetically feasible buying a new set of suspensions which improves their car.

The other main problem derived from that debate is obtaining technical drawing of some Formula Ford cars (if you can tell me some poor performances cars I would like to have those drawings) in order to design the suspension system within the dimensions. I would like to get some information to where or how to find them and if someone can provide me them.

From what I have seen, this is an incredible forum and I would love to receive first-hand help from you, any help will be welcomed and recognized in my final project report.

Thank you.

[10rmotor]

This is a somewhat difficult question to answer. At least looking at potential under performing cars to use as your example to refine. The reason any particular car is an under performer isn't always because the suspension design is poor. As I'm sure you're aware, there are many factors which affect a cars performance, the suspension being only one of them. Chassis rigidity, aerodynamics, CG location being just a few of the factors. As I like to say on a race car, everything is connected to everything else, and one bad component or connection can ruin the whole package.

I'd probably suggest going with your first option of designing a new suspension for a hypothetical car your best bet.

Good luck with your project!

[Roux]

Pol,

this sounds like an interesting and fun final year project! What about starting with a typical 12 inch wide front frame and then design A Arms and uprights to get you to the maximum allowed width (See the SCCA GCR for instance.) I can also share some of my measurements via email. Then ask the following questions. 1) What is the impact of longer lower A Arms (going inside the frame, instead of attaching to the outside.) That should impact camber curves and the scrubbing behavior of the tire during bump. 2) What is the impact of making the A _Arms very narrow at the attachment to the chassis, or wide? Stresses under hard braking certainly are impacted. Is there a sweet spot for lowest mass, for a given peak stress in the steel? 3) Study pushrod angle and buckling stress as you position the bellcranks in the vertical direction. At what angle are we in danger of buckling the pushrod assuming a variety of imperfections in the way the pushrods are welded (you can find discussion of this buckling phenomena on the Forum. R.Pare posted on the topic years ago)

While studying question 1, maybe work on how to attach those long lower A Arms in essenstially the same space as the drivers feet? Not easy to fit everything in there.

If you do such a design study I think you can end up with a nice piece of work and achieve your learning goals

cheers

Steve

[Jim Edmonds]

In your design considerations, think about designs that won't allow an a-arm to penetrate the chassis and into the driver's legs during an accident. Many current designs have that, but in lower-level racing do not have retention tethers to keep the wheel and suspension attached to the car. Have fun with your design. Jim

[polruiz12]

Hello everyone,

thank you a lot for the suggestion you all have made until now, it is something incredible and a unique opportunity for me that you have shared the knowledge of FF owners and enthusiasts.

I've been recollecting all the feedback to keep in mind some questions you proposed me while designing the suspension system in the future.

I have decided to design the suspension system as it was designing a new FF car, as the suspension system definition is the first step in the whole car process. In order to do that, I will research about the correct steps to design it (as far as I am concerned I should start knowing the tire behaviour and then see how can be managed).

I am afraid about chassis I should take as a reference, so I decided I will do a schematic packaging of the components of a usual FFord car and see how the distribution is and where the center of gravity is located. I think that this process is how usually takes place in reality (chassis department works within some constraints but its geometry will depend in its major part on the suspension hardpoints).

I will keep you informed,
Pol.

[Larry H]

What is the reason for making the track as wide as possible?

[S Lathrop]

What is the reason for making the track as wide as possible?

The wider the track, the less weight is transferred from the inside tires to the outside tires as the car corners. Even though you increase the load carrying capability of the outside tires from the weight transfer you loose more from the inside tires than you gain on the outside tires.

[DaveW]

My handling presentation from 2015:

https://www.apexspeed.com/forums/att...3&d=1539115694

[polruiz12]

Hello guys, thank you all for sharing your knowledge un this thread.
While I am studying the tire behaviour (I asume Avon Tyres are the best tyres to analyse) I would like to ask you some help on locating the Center of Gravity of a standard car. I have found some drawing without dimensions nor an actual complete list of all the previsible components of a FF car that I should take into account in this early stage.
It could be really helpful to have a guideline of the components to take in count, so i can know their weight and position.

Thank you as always, Pol

[polruiz12]

Sorry for the mistakes in the last text. Seems that my spanish keyboard corrector took the power.

[Larry H]

The wider the track, the less weight is transferred from the inside tires to the outside tires as the car corners. Even though you increase the load carrying capability of the outside tires from the weight transfer you loose more from the inside tires than you gain on the outside tires.

It seems that track width is used to or can be used to control tire temperature and there would be an optimum track width based on tire hardness and track temperature. Would a formula car with hard tires be better off with a narrower track to get the tires up to temperature?

[DaveW]

It seems that track width is used to or can be used to control tire temperature and there would be an optimum track width based on tire hardness and track temperature. Would a formula car with hard tires be better off with a narrower track to get the tires up to temperature?

I've seen evidence in the past that seems to validate your theory. For example, there was a race (2006 Topeka Runoffs ?) where a competitor, IIRC, in an original narrow-track FC VD (many VD's converted to wider track) ran a noticeably higher than normal ride height to do that exact thing. While he qualified well and did it early in the session, he faded in the race as the tires got hot. At that point I theorize his overall grip capability diminished and he slowed significantly.

So my take on this is that anything (excessive friction, too high roll center, too much damping, too high roll/spring rate, too narrow track, etc.) that causes higher instantaneous tire loading "could' heat tires more quickly, but in the long run corner speed would suffer.

And, there is no disputing the fact that rubber coefficient of friction diminishes as contact pressure/load increases. That's the basis of Steve's comments on weight transfer.

[DaveW]

Delete: dbl post...don't know how I did that...

[Rick Kirchner]

I recall a few years back how one F1 team was noticeably faster at the start of a session than everyone else, and it had to do with the vertical motion of their chassis producing considerable more scrub than everyone else, and getting the tires up to temp faster.

Like your runoffs example, they tended to be harder on tires so it took a different strategy for them vs everyone else.

[Jonathan Lee]

Good morning guys,

I am Pol and I am a 4th year mechanical enginieering student from Spain, I am new to this forum as I've seen it is the best place to keep informed about Formula Ford cars.

Right now I am starting my final degree project which consists on the Design and Optimization of a Formula Ford suspension system.


Thank you.

Hi Pol,

I graduated last year and I also had to do a senior design project.


At my University, the projects seemed to be split up into three main groups.

1. Projects that you could show improvement on.

For example: Re-designing the wing of a racecar & showing the results after wind tunnel testing or CFD analysis.

2. Projects that were based on "fairly new" technology

For example: Building a robotic lawnmower

3. Projects that were theoretical (these were the least popular)

For example: I remember one team came up with a way to 3d print on the moon.



I had a very black and white project, make XYZ better. It was easy for us to prove our advancements through numerical results in our presentation and visits with our professors that our team was on to something...

Suspension design however is a complete different ball park, there is no one answer to a fix all. A bad suspension can be caused by many things. You can't even take a good suspension off of "B" car and put it on "A" car. It doesn't work that way, a suspension is bespoke to each chassis that it is made around.

Without real life testing- you cannot prove that you made a suspension better. I'm not sure about the guidelines that your University has set for your project, but I recommend that you ask yourself "how am I going to show my professor that I made the suspension on a RF85 better?" Since this was your original goal...

By the way, many have said that the RF85/86 was one of the best handling cars that Van Diemen built....

You might want to change your project to

1) Reworking the aero on a RF85.
- You can use CFD to compare the before and after, maybe even show all the iterations in between. If you don't have access to software or don't know how to use the program, I would recommend staying away from this (I know because this was me).

2) Designing a Formula Ford Car or a part of the car...
- Get a copy of the rule book & start designing. This would be a good project, jump on CAD and start drawing, there is no wrong or bad results!


The main problem I see with your project is that your trying to prove that your making something better, when you really can't. Talk to your professor and run through your options. Worst case is that your stuck with your project under the guidelines that you've stated, you'll have to be clever and come up with a well executed presentation.

Most of the time if the University is impressed with your project, work and research - they will give you a good mark even if the project doesn't meet it's original goal. However, this route is often way more stress and requires you to keep your professors in the loop during the multiple stages of your project.

Best of luck

- Jonathan

[polruiz12]

Hi Pol,

I graduated last year and I also had to do a senior design project.


At my University, the projects seemed to be split up into three main groups.

1. Projects that you could show improvement on.

For example: Re-designing the wing of a racecar & showing the results after wind tunnel testing or CFD analysis.

2. Projects that were based on "fairly new" technology

For example: Building a robotic lawnmower

3. Projects that were theoretical (these were the least popular)

For example: I remember one team came up with a way to 3d print on the moon.



I had a very black and white project, make XYZ better. It was easy for us to prove our advancements through numerical results in our presentation and visits with our professors that our team was on to something...

Suspension design however is a complete different ball park, there is no one answer to a fix all. A bad suspension can be caused by many things. You can't even take a good suspension off of "B" car and put it on "A" car. It doesn't work that way, a suspension is bespoke to each chassis that it is made around.

Without real life testing- you cannot prove that you made a suspension better. I'm not sure about the guidelines that your University has set for your project, but I recommend that you ask yourself "how am I going to show my professor that I made the suspension on a RF85 better?" Since this was your original goal...

By the way, many have said that the RF85/86 was one of the best handling cars that Van Diemen built....

You might want to change your project to

1) Reworking the aero on a RF85.
- You can use CFD to compare the before and after, maybe even show all the iterations in between. If you don't have access to software or don't know how to use the program, I would recommend staying away from this (I know because this was me).

2) Designing a Formula Ford Car or a part of the car...
- Get a copy of the rule book & start designing. This would be a good project, jump on CAD and start drawing, there is no wrong or bad results!


The main problem I see with your project is that your trying to prove that your making something better, when you really can't. Talk to your professor and run through your options. Worst case is that your stuck with your project under the guidelines that you've stated, you'll have to be clever and come up with a well executed presentation.

Most of the time if the University is impressed with your project, work and research - they will give you a good mark even if the project doesn't meet it's original goal. However, this route is often way more stress and requires you to keep your professors in the loop during the multiple stages of your project.

Best of luck

- Jonathan

Hi Jonathan, thank you so much for letting me know your opinion about my dilemma.
I think exactly the same when you talked about the main goal of the project, as soon as I realized demonstrating that a new suspension is better than the previous one is something very very hard, I decided to work on a suspension system from scratch and try to make it the best I can.
I am grateful to see your answer because it proves I've chosen the right path (design a component of a FFord Car from scratch without comparing the performance to another old component), so I feel more relaxed now.


Right now I am learning and understanding the Rulebook and calculating the center of gravity and studying tire behavior (Avon Tires) for then designing kinematics, 3D model and also stress and fatigue study. And also manufacturing process.


Thank you a lot.

[Jonathan Lee]

Hi Jonathan, thank you so much for letting me know your opinion about my dilemma.
I think exactly the same when you talked about the main goal of the project, as soon as I realized demonstrating that a new suspension is better than the previous one is something very very hard, I decided to work on a suspension system from scratch and try to make it the best I can.
I am grateful to see your answer because it proves I've chosen the right path (design a component of a FFord Car from scratch without comparing the performance to another old component), so I fell more relaxed now.




Right now I am learning and understanding the Rulebook and calculating the center of gravity and studying tire behavior (Avon Tires) for then designing kinematics, 3D model and also stress and fatigue study. And also manufacturing process.


Thank you a lot.

Hi Pol,

I'm glad that you've found my insight helpful.

Your project is still complicated & too much work in my opinion with the usual 2 semester timeframe that the University allots. Your biting off a lot, especially when this is all new to you, work - life balance, 4 other classes (assuming).

Tire behavior is one of the most complicated studies in motorsports, there isn't good data provided from the manufacture. Kinematics and Forces generated during cornering are complicated and require extensive sensors and data gathering to even begin basic calculations.


Think simple!
Design a component on a FF car around the rules.
Ok - think about something like designing a FF frame that is safe upon impact with a wall.
That is a project with meaning and is feasible too!

• You can create a few versions of a chassis, pop it into FEA (which is a lot easier to setup/learn than CFD) & then simulate a crash test into a concrete wall (block) at X kilometers..
• Get the results, view the stress and fatigue points, record the deformation under impact.
• Voila!!! Iteration/design 1
• Make some changes based on the gathered info or completely re-design and do it again!

At this point, you've shown that the project is: technical, the design was thought out and improved on, the project has positive implications, you and your team have worked together to learned how to use FEA & CAD....

This a great project, there is no crazy weeks with all-nighters, and you can make it more complicated at any step in the process. The senior design project purpose is to simulate teamwork, design and thought-process.






By jumping into the deep end with a project that contains way too many variables to begin, your setting yourself up for 1 year of headaches.

My group did kinematics and calculations on our project, it was embarrassing when the professor questioned where we got the input numbers from, the other guys had to BS them. There was very little/no information online with our project, even when we contacted researchers in our field they couldn't give us answers. It was better for us to just leave the kinematics part out, which we ended up doing in the end...

You also have to think about your other team members, diving into something complicated - that you can't really get concrete answers on, will put stress on everyone. There will be late nights and a lot of internal disputes...


Highly recommend doing CFD on different FF bodywork (noses, engine covers) or doing FEA on the frame for crash test purposes.

If you stick to simple variables like car is going "X" kilometers and weighs "Z" kilos, you can do a lot without having to make ridiculous assumptions and calculations.

Avoid dynamic variables such as roll center and tire behavior. The type of things that you originally wanted to do...

[polruiz12]

Hi Jonathan, thank you again for the answer.

I really appreciate your interest and help showing me different topics to focus on the project but I need to tell that this project is done alone (as any other project in my degree) and I told the University that my topic for suspension design.

I know it can be very very complicated and hard, depends on the level of precision and realism I want to put. I've seen suspension design projects of FSAE cars and there are simple designs that only calculate gravity center, simple kinematics design to accomplish a selected (with no justified reason) value and stress analysis. On the other part are also projects which consists on analysis ttire behaviour, kinematics and their optimization, 3D model and stress analysis... As any other project, I think it depends on the effort and precision you want to put.

For now my plan is to understand some simple values of the tire, constraint some kinematic values as camber, roll centre... (if I have time optimize a bit the kinematics) and finally 3D model and stress analysis. I have 4 months with no classes or external job so I think I can do something quite good.

For me, my personal goal is to gain the biggest amount of knowledge I can for my Motorsport future.

As I've said before, thank you a lot.

[Rick Kirchner]

By the way, many have said that the RF85/86 was one of the best handling cars that Van Diemen built....

Hey Jonathan - he was talking about the 84VD and the 85 Reynard.

[S Lathrop]

One approach to you design study would be to find some one who has a data logging system on their car. A system that had accurate suspension position sensors. With that data, the data for the tires they were using and a good model of the suspension system, you would be in good shape to do the study you are thinking about. There are a lot of racers who will have all the data you are going to need.

Good luck.

[polruiz12]

One approach to you design study would be to find some one who has a data logging system on their car. A system that had accurate suspension position sensors. With that data, the data for the tires they were using and a good model of the suspension system, you would be in good shape to do the study you are thinking about. There are a lot of racers who will have all the data you are going to need.

Good luck.

Hi Lathrop,
Thank you for your proposal.
I see your point and maybe It IS a good start to have some usual data parameters.

It would be awesome if someone is open to share his recorded data in order to help me finding some parameters, like usual camber, roll centre, trail... Values to have as a benchmark.

I have no problem keeping this information to myself and not making it public. I can sign any confidentiality paper if you want.

Any help will be appreciated.

I don't know if I should ask here or in another thread, or if I can look for that in another place.

I leave my e-mail here: polgarcia26@gmail.com

As always, Thank you a lot for your collaboration.

[Larry H]

Pol,

What about comparing the suspension design of a 84 VD vs 85 VD and theorize why the 85 is better than the other or maybe not? The problem I see is obtaining the suspension geometry and there are a ton of variables. The other is just to analyze the 84 VD and using the data theorize why it didn't handle well. Then you might be able to make changes that would make the 84 VD handle better. You might also need some driver feedback on the 84 VD handling deficiencies.

If you want to do a CFD study, there are 3 articles by a Simon McBeth (UK) that performed wind tunnel testing of a Swift SC92 and a more modern Spectrum. He made small modifications to the SC92 car and meticulously measured the results. You could compare your data with his.

Larry

[polruiz12]

Hello everyone, it's Pol.

Thank you for sharing all your thoughts on the project and helping me with the development.
I have done some progress and at the moment I am optimizing the kinematics (I am asking some drivers for feedback) and my next step is to choice a pair of shock absorbers for front and rear suspensions.

I would like to know more about what brands are normally used for these cars and which of them offer more information, specifically dyno plots, for free, as I haven't seen much info of that. I've seen shocks of Ohlins, Penske...

Any help will be appreciated, thank you.

[Hawke]

Hello everyone, it's Pol.

Thank you for sharing all your thoughts on the project and helping me with the development.
I have done some progress and at the moment I am optimizing the kinematics (I am asking some drivers for feedback) and my next step is to choice a pair of shock absorbers for front and rear suspensions.

I would like to know more about what brands are normally used for these cars and which of them offer more information, specifically dyno plots, for free, as I haven't seen much info of that. I've seen shocks of Ohlins, Penske...

Any help will be appreciated, thank you.

Pol, any quality shock supplier will build you a shock to your specifications. And keep in mind the “dyno” plots you see - PVP graphs- are just a computer generated image of the peak forces of the shock at sometimes as little as 3 different piston speeds. What you really need to look at, is the underlying data, and the rate of increase of force, particularly at low speed. Have a good look at “The Damper Handbook “ produced by Chassis Sim.