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my chassis design ur comments please
johnston - 19/12/02 at 09:37 PM

ok started meausreing up my donor

and as im not goin the u book route my thanx to aln b and stevie g for puttin ideas in to my head.

i'm startin to lay down the basics for the chassis design but for reasons i'll not go into now im goin to put wat could be best be described as "side pods"

now im tryin to decide which way to do it

pics of basic ideas here

idea 1 is the book chassis with the side pods as extensions basicaly as supports

idea 2 is usin the side pods as the chassis

idea 3 is just to add strength to front if the chassis is to be wider

p.s pics not to scale


jollygreengiant - 19/12/02 at 10:02 PM

In reality I think you would be better of creating a marriage between 1 & 2. Reason: In 1 the pods would just be extra weight & no other real function other than (to quote american, sorry alan) "Fenders".
In 2 & 3 you would loose the available space to put you front suspension/effective steering.

If you use narrow front & then extend the front nose rails back to intersect your wider sides then you end up with usable width but you would loose I think a fair degree of your torsional stiffness.

But hey this is designed to be self build & self expression.


Enjoy.


stephen_gusterson - 20/12/02 at 12:26 AM

hi

Im not gonna vote yet as I dont quite understand what you are trying to do....

Are you trying to get

1. A wider car with more passenger room

2. Decorative side pods


I Think you are trying to do 1 ?

Bear in mind im not a mech or structural engineer.


Having made a wider car, 6 ins wider - I made it 6 ins at the body, and 4 ins at the front. However, just that extra six ins makes a LOT of difference to the appearance.

When I see my car and compare to a locost it looks BIG. (The rear is also about 4 ins higher, to get the morgan look).

So, its taken as read that its not gonna look 'right' if its to be a wider locost.

The thing I found most important is how you are going to do a back axle and front suspension. The book car runs the wheels almost at the drivers sholders, and OUTSIDE the 'tub. So, if you make the car wider at the driver, you have the hassle of IRS suspension and special shafts. If you dont make the body wider at the front you will also have unweildly long suspension arms and a problem mounting the shockers at a decent angle and position - bearing in mind the lower point of the shock must go close to the ball joint end of the 'bone will be more stressed.


If this is a full 'custom' design, it might help you if you put the rear wheels in board to the chassis - but thats gonna complicate things a lot - and make the car longer still.

I would sketch your drawings taking into account suspension dimensions and wheel positions as it could well affect your future plans.

Doing things different adds lots of time and pitfalls - but dont be discouraged.

If the side pods are decoration, they could be quite flimsy, and just bolt on. However it might make getting in and out a bit hard.

How much wider do you want to go?

I wonder if its possible to add more bracing, make the tranny tunnel more structural, etc. Make the std car say 4 ins taller at the sides as well as wider? Use 30mm x 2mm section and just scale up the existing chassis?


I used a lot of continuous welding and X sections on the side of my car to make it stiffer.

Im not the one to rely on here - wheres cymtriks when U need him!

Can you give us more details of what you are trying to do?


atb


steve













[Edited on 20/12/02 by stephen_gusterson]


interestedparty - 20/12/02 at 03:53 PM

I don't see how a design can be assessed until it is in three dimensions. Major considerations will be twist and sag, and it's the triangulation in the third dimension that will have the most effect, and the floor plan the least. Could you have a go at an isometric view?

John


johnston - 20/12/02 at 07:32 PM

i'm just tryin to get an idea of were to start

and yes steve its goin to be a gd bit bigger than a locost and therefore i can put the driving seat a bit further foward and not siting on the axle but the "side pods" are a bit exagerated in the pics (i aint to gd with paint programs) but they will be to use and end just in front of the rear wheels the actual interior will prob be about the same as a standerd locost

the car will look wide and low full bodyed inspired by alan b's (i curse the day i saw ur site) if u look at some of his pics but bring the sides out level with the outside edge of the front wheel arches you'll get some idea of where im goin with the body shape

the term "side pod" is just cos i cant think of a better way to explain em and its maybe a bit of puttin if ur thinkin of them in the f1 sense


stephen_gusterson - 20/12/02 at 08:01 PM

Just beware of making it too wide - the difference between a mini and a range rover is probably a foot or less.


Another way to have a go at a design is to buy some 3mm balsa strips and build a scale model.

I was tinkering with a different design a few months back. However, once I developed the idea on paper, it was clear the dimensions would be all wrong.

The locost is a simple well proportioned design.

atb

Steve


johnston - 20/12/02 at 08:46 PM

im stickin wit donors original track and wheel base so no what size it will be (donor size minus over hangs)

was thinkin of gettin the girl friends da to make it out of balsa im useless at anythin like that and he's very very gd (scratch built a model of stingray and the titanic as she sits on sea bed from pics in nat geographic mags) the trouble is he can be a bit annoyin and hard to listen to