Ninehigh
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| posted on 21/4/09 at 09:30 PM |
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Own designs
Going way out here but how could I go about making my own chassis? I mean is there software out there that would enable me to decide what type of
chassis I'd be after and how strong it'll be? What happens about SVA or does that not really matter (with regards to the locost being an
established and recogniseable design)
Is there anything else I'd need to take into consideration before I go into design stages with a (theoretical) view into putting said vehicle
into some sort of production?
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tegwin
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| posted on 21/4/09 at 10:08 PM |
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There are several good books out there... I sugest you buy and read "kimini".....
As for designing a chassis.... once you work out what engine you want, what form to take, what weight distribution you want.... you could make a
moclup chassis in balsawood and see how easily it breaks....
Look at LOTS of photos of other peoples chassis..... especially production cars/racing cars.... if they have common features and bracing... its for a
reason... copy it!
Good luck
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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Ninehigh
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| posted on 21/4/09 at 11:50 PM |
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Cool, shall definately have to buy that book 
What about making a small plasticene model and then fixing say matchsticks to the outside so I can get the frame proportions?
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Badger_McLetcher
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| posted on 22/4/09 at 12:02 AM |
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I'm designing my own chassis for my project, and I have to say it's a long road (for me at any rate!).
The first thing to do really is decide what sizes the major components will be- it's no use designing a chassis then finding out your engine of
choice is too wide...
Apart from that triangulate everything you can (I'm assuming you're doing a space frame), never feed loads into an unsupported member (ie
the middle of a beam) and try to keep it as simple as possible. When designing try to visualise where the loads will be transferred along the chassis.
Building a balsa wood scale model is also a good idea, it allows you to see where problem areas are and to test the chassis' torsional
rigidity.
I'll try to dig out the names of some of the books tomorrow.
Edit: The plasticene model idea isn't bad as long as you can remove the plasticene and leave the match stick chassis. I would actually recommend
making scale models of your components (ie a box roughly the correct size) and then make a mock chassis using balsa strip and a hot glue gun.
[Edited on 22/4/09 by Badger_McLetcher]
If disfunction is a function, then I must be some kind of genius.
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TheGecko
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| posted on 22/4/09 at 01:44 AM |
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To add to all that's already been said. Colin Chapman apparently described the chassis as "just a big bracket that held every thing
together" If you think about it in that context, it means establishing what all of that "everything" is before you do too much
chassis design. Particularly, work out where your major "hard points" are - suspension pickups, engine/transmission mounts, seats etc and
then layout the chassis to fit them not vice-versa. Sounds obvious but a cursory inspection of many cars will show you compromised wishbone brackets
etc that are clear evidence of doing it the other way around.
I, for instance, am now paying the price for changing engines half way through a build (for very good reasons) and finding that the new engine's
oil filter wants to share space with a chassis tube  The solution will probably be to remote mount the filter but life would be easier if I'd
designed the chassis for that engine.
So, as much as possible, collect all of your major components and establish your layout, then (and only then) start on chassis design.
Best of luck,
Dominic
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Ninehigh
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| posted on 22/4/09 at 01:50 AM |
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You make it sound like I was about to make it the wrong way round!
So using this plasticene model idea still, I should make the engine, seats, wheels ect then hold it all together with matchsticks? Not planning on
buying an engine and suspension just to see what kind of car I could make out of it!
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tegwin
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| posted on 22/4/09 at 08:08 AM |
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quote:
Not planning on buying an engine and suspension just to see what kind of car I could make out of it!
Why not? That would be the most logical way of building a car!
Get the engine, gearbox, seats.... lay them out on a build table and design your chassis around them!
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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iank
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| posted on 22/4/09 at 08:13 AM |
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Once you've decided where everything goes build a scale model from balsa and hot glue.
Grab it by the suspension pick-up points and twist to see if it's stiff - if it flops around add/move/remove sticks until it's stiff.
Then weld it up from steel full size.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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hughpinder
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| posted on 22/4/09 at 08:26 AM |
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I have been (slowly) designing a middy chassis. I found it impossible to fix various bits of the chassis without actually having the
engine/gearbox/driveshafts and front uprights to hand. I bought a mondeo 2.0 for £100 and stripped out everything vaguely useful, mounted the
engine/box on a stand made from scrap, then measured up. It means you can check for clearance issues. Built a 'cabin' for the drivers
side from 1 sheet of 12mm ply and a few roofing battens and screws to check cabin size, then built an initial balsa model. Its all helped. Also,
having all the donor bits sat around means I am tending to design to fit the bits I've got (header tanks, brake resevoirs,steering column,
wiring and connectors, possibly radiator ..... so its keeping the overall cost down pretty well.
I am lucky in having the space to keep all the bits though!( engine/box and 2 tea chests of bits + the 'cabin' (about 4 ft by 2 ft when on
the floor). The bits I dont have (like shock absorbers, brake master cylinders etc I obviously have to look up sizes, but it is much harder to
visualise them in the chassis.
Regards
Hugh
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Fred W B
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| posted on 22/4/09 at 10:17 AM |
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See some discussion in
this thread
Cheers
Fred W B
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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Badger_McLetcher
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| posted on 22/4/09 at 09:43 PM |
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quote:
Originally posted by Ninehigh
You make it sound like I was about to make it the wrong way round!
So using this plasticene model idea still, I should make the engine, seats, wheels ect then hold it all together with matchsticks? Not planning on
buying an engine and suspension just to see what kind of car I could make out of it!
You saying I'm doing this all wrong? 
Kind of. You need to make the frame so it's self supporting - just use plasticene lumps as a guide to size, not anything structurul. Unless of
course you are using engine or gearbox as structural members 
If disfunction is a function, then I must be some kind of genius.
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TheGecko
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| posted on 22/4/09 at 11:09 PM |
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quote:
Originally posted by Ninehigh
You make it sound like I was about to make it the wrong way round!
So using this plasticene model idea still, I should make the engine, seats, wheels ect then hold it all together with matchsticks? Not planning on
buying an engine and suspension just to see what kind of car I could make out of it!
Is this a purely intellectual exercise or do you actually intend to build one (or more)? If it's just for "shits and giggles" then
draw/model/design whatever you want. If you're genuinely planning to build one then you're going to need to have some idea of the size
and shape of the major components.
If I said to an architect - "Design me a house" and when he asked "How many rooms, how many floors, etc?" if I said "I
don't know. I don't want to make decisions like that yet. I just want the house designed" I would expect to get shown the door
You can't design a car chassis without knowing what's going in to it (at least not a workable one). What engine is intended, located
where - front, mid, or rear? What track and wheelbase (roughly)? Two seat, four seat, open body, coupe? What suspension style - live axle, de dion,
wishbone, trailing arm, leading arm, swing axle, strut? Each decision will dictate differences in the chassis design.
At the end of the day, what are you actually hoping to do?
Dominic
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Ninehigh
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| posted on 22/4/09 at 11:13 PM |
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At the moment I'm working out the process, then one day I might well have a crack at making my own one. Hopefully other people will like it and
pay me to make some
I suppose it's for shits and giggles with a view to being able to make it for real one day
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cheapracer
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| posted on 24/4/09 at 01:34 PM |
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quote:
Originally posted by Ninehigh
At the moment I'm working out the process, then one day I might well have a crack at making my own one. Hopefully other people will like it and
pay me to make some
I suppose it's for shits and giggles with a view to being able to make it for real one day
Your making the same mistake that 99 out of 100 people make when they make their own designed car, you want to start with the chassis.
It's coming....
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kb58
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| posted on 24/4/09 at 01:51 PM |
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As others have said, you have to start with the non-negotiable components first: you, the seats, steering wheel placement, pedal placement, tire
selection, wheel selection, engine size and shape, THEN you start on the suspension, THEN the chassis.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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cloudy
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| posted on 24/4/09 at 02:26 PM |
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nail. head. 
My first saved CAD design of R4 just had the wheels, seats, engine and wishbones, in their respective coordinates. Certainly no chassis!
www.warnercars.com
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Ninehigh
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| posted on 24/4/09 at 03:50 PM |
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Any good CAD programs about? I've heard about solidworks but it looks really complicated to me
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JoelP
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| posted on 24/4/09 at 04:24 PM |
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nowt wrong with a pad of graph paper if you want to keep it simple. And id agree, it definately helps if you buy the components in advance - but it
does make failure expensive, if you give up before its done.
This has been my major problem; i go through whims and rarely finish a project. I managed a bec conversion because it only took 4 weeks, but other
projects have been chopped up when i got bored. Just about finished a boat now, nice and simple! Unless i run into a stack of cash, the 4x4 and
submarine will have to wait.
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cheapracer
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| posted on 24/4/09 at 04:35 PM |
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Unless you want to actually learn a computer program I suggest go to your local school supplies and buy pencils, paper, rulers and all those plastic
shapes such as squares and degree wheels and start drawing on paper.
Very fast, very accurate, easy to translate into the real thing and much easier to take with you to an engineer/machinist if you want something made
up.
It's coming....
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Staple balls
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| posted on 24/4/09 at 04:57 PM |
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quote:
Originally posted by cheapracer
Unless you want to actually learn a computer program I suggest go to your local school supplies and buy pencils, paper, rulers and all those plastic
shapes such as squares and degree wheels and start drawing on paper.
Very fast, very accurate, easy to translate into the real thing and much easier to take with you to an engineer/machinist if you want something made
up.
This, so bloody hard.
Also brass split-pin things are handy for getting suspension geometry about right.
Course, CAD stuff can be handy, but I always found it easier to get my ideas on paper first, then into the computer.
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Badger_McLetcher
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| posted on 24/4/09 at 07:39 PM |
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I tend to use a combination of both- lay it out with sketches and use cad to get it exact.
And I only have cad 'cause I'm a scabby uni student
If disfunction is a function, then I must be some kind of genius.
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brianthemagical
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| posted on 24/4/09 at 08:16 PM |
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Solid works is one of the easiest CAD softwares to use, and if you get the right copy it'll have rendering, FEA and CFD packages built in.
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Benonymous
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| posted on 28/4/09 at 09:08 AM |
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Software
The problem with software/CAD is that not only do you have to learn the package you then end up having to do your design the way the software wants
you to do it. 
This can be extremely frustrating and I would say, if you are not committed to your project, it will easily kill your enthusiasm
I'd like to add a vote for purchasing the "non negotiable" parts then building a work table (nice and level) then start assembling
using nothing but air for the chassis!
When I did my first chassis in Solid Works I leaned back to admire its brilliance and then decided to add a "driver" model to my chassis
to see how the proportions had worked out. Imagine my surprise when I discovered a chassis tube passing through the chest of the driver!
If you seriously want to use CAD, I'd treat learning it as a separate project.
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