Posted by: rachael ® 07/05/2004, 10:57:52 Author Profile eMail author Edit

This is more of a general question to get some views as i thought it would be interesting to see how many conflicting opinions we will have! Next year for a college project i am helping to build a racing car, i will be involved in the chassis and suspension design. the car is to do a straight line speed race, and an endurance race around a go kart track (lots of corners). My rough ideas are to make the chassis as rigid as possible, i also want to make the suspension adjustable to take into account both stages of the race as good very little resistance and good handling are hard to achieve on just one suspension setup with out coming to some comprmise. does anyone have any thoughts, suggestions, ideas or comments? Thanks

Replies to this message

Re: Racing car design
Re: Racing car design -- rachael	Post Reply	Top of thread	Forum

Posted by: rachael ® 07/15/2004, 07:35:41 Author Profile eMail author Edit

Thanks for the repl(even if it was a novel) full of some very informative stuff. The specs for the car are that the engine can be no bigger than 600cc, there is an air intake restriction (although of the top of my head i don't know what it is). no restriction to size of car just a requirement to have a lap and head roll hoop. We have a year to design, make and analyse the car and a budget of whatever we can scrounge in sponsorship! (sounds like an easy task now doesn't it) probably going for a 400 or 500cc engine due to the air intake size restriction so that we can let the engine breathe properly. suggestions of corner weights is a good idea i reckon 4 sets of bathroom scales would make a good budget choice!   Thanks Rachael

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

Re: Racing car design
Re: Re: Racing car design -- rachael	Post Reply	Top of thread	Forum

Posted by: PAracer ® 07/15/2004, 11:26:40 Author Profile eMail author Edit

It sounds like your going to have a motorcycle power the car.  You could use a two stroke engine from a motocross racer along with its gearbox.  I imagine seeing a low slung car, almost go-kartish with the driver placed next to the engine.  I think you could have a car with 70 horsepower weighing ~500lbs. with a driver Depending on the speeds at which the car will be operating, body panels, wings, and spoilers may be helpful in decreasing drag and increasing downforce.  Even in they're not, they make a great place to stick sponsor decals. Bathroom scales would make perfect budget corner scales.  My father used them to weigh my quarter midget when I was racing some ten years ago.  These links may be helpful to you. (Admin) Removed Links per TOC   Modified by Administrator at Thu, Jul 15, 2004, 12:58:51

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

Re: Racing car design
Re: Racing car design -- rachael	Post Reply	Top of thread	Forum

Posted by: PAracer ® 07/07/2004, 08:11:31 Author Profile eMail author Edit

That's my kind of project!! Sorry for the novel of a reply.  If you have time, let me know some of your constraints that you are working with(engine size, car dimensions, budget, time).  I'd love to help out as much as possible. Key elements of chassis design include weight, shape, and rigidity.  Obviously, you want to be as light as possible.  A lightweight car will outhandle, outbrake, and outaccelarate a similarly powered but heavier machine.  Shape is important as well.  A low center of gravity will enable a car to turn faster.  Also, consider the placement of the engine, driver, and other heavy systems.  Keeping these items as close to the center of the vehicle as possible decreases rotational inertia allowing quicker transitions between turns.  When constructing the car, have on hand a set of scales so that you can keep track of how much weight is on each corner of the car.  Even distribution is perfect.  It may seem that a rigid car will handle better than a flexible one.  This is true for professionals who have years of experience in setting a suspension perfectly(geometry, spring rates, shock valving)  For amateurs like you and I, a slightly flexible chassis can make up for suspension errors. When designing your suspension, be sure to understand the style of drivetrain that you are using.  If you have a solid rear axle with posi-traction, a triple coilover setup is functional and lightweight.  One coilover would take care of chassis loads such as acceleration or bumps that are hit squarly on each rear tire, and the remaining two are located perpendicular to the first.  These allow the chassis to react to cornering forces.  Depending on the size of you car, you may no even need to use a front suspension.  Typically, go-karts have no suspension at all.  They use air pressure to effect handling.  If you have a front suspension, consider how canber and toe will change as the suspension compresses. It is a great idea to make your suspension adjustable.  Coilover shocks are easy to adjust by changing springrates, or revalving.  Anothe way to change the suspension is to alter the geometry.  This is done by altering mounting points and lengths of your tie-rods.  Still, being able to adjust chassis flex is a great tool.  Weight distribution can also be used.  If you have a minimum weight set in your rules, you should still attempt to make the car as light as possible and make up the difference with strategicly placed ballast.  You should not need to change a whole lot to set a car for drag racing.  Your alignment should be straight so as not to have any drag from the tires not being pointed straight ahead(zero toe, zero camber, zero caster).  Your suspension should be stiff on the front, yet soft in the rear to allow for maximum weight shift to the drive wheels(almost to the point of running out of travel).  You want to have as much weight shift to the rear of the car as you can for the best traction at launch(picture a true drag racer doing a wheelie).  A go-kart track setup would require a lot of tweaking to get perfect.  Get as much practice as possible before you start making competition runs.  Start with equal weight distribution with conservative alignment settings.  Have your suspension set about 50% stiff to allow for extreme tuning if needed.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

Re: Racing car design
Re: Re: Racing car design -- PAracer	Post Reply	Top of thread	Forum

Posted by: nexusbhai ® 07/12/2004, 05:21:45 Author Profile eMail author Edit

hey man, i am desparately in need of a project idea and i thought this is a good project. design of a racing car. well...what i need is all the info abt how to design the parts...main parts that is...i have no constraints at present. ny help?

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

Re: Racing car design
Re: Re: Racing car design -- nexusbhai	Post Reply	Top of thread	Forum

Posted by: rachael ® 07/15/2004, 07:52:13 Author Profile eMail author Edit

The best suggestion would be to come up with some constraints and then you can design with those in mind. Engine size, weight, track conditions etc (even if these are imaginary targets it will help). Its a big project though you have been warned!

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

Re: Racing car design
Re: Re: Racing car design -- rachael	Post Reply	Top of thread	Forum

Posted by: charles_a99 ® 07/07/2005, 17:21:30 Author Profile eMail author Edit

Well.. sounds like and FSAE Race Car. I have 2 vehicles under my belt. Just to warn you, this project is extremely demanding. Make sure you have a dedicated team at your side. Make sure you read through the FSAE Rule Book thoroughly. Trust me , you will reference these pages many times throughout the design process. Pick up some race car design books by the late Carrol Smith. Practical books on engineering, design, setup, etc, etc. Try fsae dot com. This is the unofficial Formula SAE site (SAE Int. will not sanction an official site). Everything you need to know will be on this site. Cheers! Modified by Administrator at Thu, Jul 07, 2005, 21:52:50

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

Re: Racing car design
Re: Re: Racing car design -- charles_a99	Post Reply	Top of thread	Forum

Posted by: rusty105 ® 07/11/2005, 07:21:12 Author Profile eMail author Edit

rachael, check out racecars dot jr4net dot net :8080 "Racefab - Racecar Engineering and Construction Forum and Website" . It was a pretty healthy mailing list back in the late 90's, and now been revived into a forum. It is still growing, but there are a few very knowledgeable builders, and racers there. John

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

FSAE
Re: Re: Racing car design -- rusty105	Post Reply	Top of thread	Forum

Posted by: nsit ® 09/09/2006, 08:02:21 Author Profile eMail author Edit

I am about to start work on designing and fabricating a racing car for formula sae with my college team. This is our first attempt at making a racing car and we would be very grateful if you could give us a few tips. Specifically, we need to make a formula style open cockpit car with an engine no bigger than 600cc. Before beginning fabrication, we need to have a design ready. Could you offer some suggestions as to which design software would be best suited for our purpose? Is there a software available that has the component models already provided with it that i can edit and assemble? We wish to use a double wishbone suspension with a spaceframe chassis.

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread

| |

Re: FSAE
Re: FSAE -- nsit	Post Reply	Top of thread	Forum

Posted by: rusty105 ® 09/10/2006, 09:58:46 Author Profile eMail author Edit

You can try the link in the message. The forum is a litle slow right now, but I am sure it would only take a spark to get things going. Rusty

Post Reply Tell a Friend (must be logged in) Alert Admin About Post

Where am I? Original Top of thread