Frame design question

Ok so since I am unemployed right now and I have nothing to do except apply for jobs and sometimes work on my motorbike and Triumph (hard to do when you have no money) and I have a copy of solidworks, I was thinking about designing a frame for an idea that has been in my head for a while (a Jag XJ6 based locost with a Model A or something body). My question is how can I go about figuring out some of the variables I need to work about like the width of the body, the size of the engine and transmission without having a donor car yet?

use the google

since you've got time, try to find one in a junkyard to measure. Even if it's not usable as a donor measurments are measurements.

I've seen dimensioned drawings of Model A and 1932 Ford frames over on the Jalopy Journal board (a '32 frame under a Model A is a popular hot rod swap.) Even though you're talking about designing a tube frame, that would give you some overall dimensions to start from.

Find a copy of "Racing and Sports Car Chassis Design", by Costin & Phipps (Yes, that's Costin as in Cosworth). Will answer all of your questions.

93EXCivic wrote: I was thinking about designing a frame for an idea that has been in my head for a while (a Jag XJ6 based locost with a Model A or something body).

A locost-derived frame with a 1920/1930s body? Seems perfectly reasonable to me.

My question is how can I go about figuring out some of the variables I need to work about like the width of the body, the size of the engine and transmission without having a donor car yet?

For a Model A, you should be able to find nearly every dimension you ever dreamed of. (...and as noted above, the HAMB has posted all of this in the past.) If you PM me, I'll send you some Model A schematics and blueprints that I collected from the HAMB over a few years before I started on the Datsun. You probably won't need to do what I did (and am doing.) For the record, though, this is how I approached a similar problem; i.e. an L24-powered locost with a 1932 body:

I started with the best side image I could find.
From the limited information available I knew the wheelbase of the car.
Next, I used photoshop to measure the number of pixels of every dimension I wanted to know. With the actual wheel base and the pixels of the wheelbase, that gave me the ability to cross multiply and get the actual value of anything I measured. The right column exists because the L24(e) engine from my donor 810 wagon needed a 42 inch engine bay, which meant that I needed to scale the entire car up in size to keep things proportional. (The original car had a 77" wheelbase; a car that neither the engine nor I would have fit in. The above sketch shows a 93" wheelbase. What I ended up building was a 95" wheelbase.)
I then spent some time making lots of compromises (e.g. using the stock wheels with the rear axle to keep the cost down, despite the fact that those wheels are too small to be proportionally correct.)

BTW, if you're going to do a Model A-locost-thingy, you may be interested in this sketch I did after I learned about locosts but before I had settled on the idea of the Datsun replica.
Basically, I was trying to capture the locost/lotus proportions (especially the long nose) with the shapes of a Model A.

I like those, Joey.

Thanks. If I had not found the 810 wagon donor, the second one is what I would be building right now. (my HAMB profile still says that I want to build a model A.) After I knew I was going to use the L24 in an odd looking replica, it seemed reasonable to base it on a datsun

In reply to JoeyM:

That looks great and unique too.

BTW, I've been meaning to ask you, do you have a plan on how you're going to make the fenders for the Datsun replica? If not, has it kept you up @ night? I know it would me

Everything is hypothetical until I actually have a functional part (e.g. the metal embossing for my grill shell being done with a bead roller instead of with a wheel like I had first planned) but what I currently expect to do is

Rear fenders: drum from clothes drier
running boards: metal bookshelf
Front fenders: Not sure yet, but probably shape them with a shot bag, mallet and english wheel

93EXCivic wrote: My question is how can I go about figuring out some of the variables I need to work about like the width of the body, the size of the engine and transmission without having a donor car yet?

I was just re-reading the OP, and thinking about the question of car width. Size the body width to what you and a passenger will be comfortable in....that's true for both cockpit width and length. (Ever sat in a stock Model A....the only time I did, I was amazed at how cramped it seemed....and not in an "I'm wearing this elise" sort of way. More of a "I'm stuck in a box that's plenty wide and tall, but not nearly long enough")

The engine compartment should be sized to the engine. I'd suspect that these guys could answer any engine-dimension questions you have. If not, though, do what I did.....go to car shows and autocrosses with a tape measure and ask permission to take measurements. (Now, once I found my 810 wagon donor, I ignored those and started taking measurements off the wagon.) Once you have the length and width of the engine, determine a few other things like the width of your radiator, the width of the cockpit to comfortably seat you and one other person, etc. Then draw some sketches and use some algebrato get your total width at the firewall.