nice to see you stick to it

Just picked up two of these bad boys.. slightly used, great shape, great fit.

I'm going to mock the cock pit up with 1x1" wood to see what it's really going to be like to get in/out and ride in this thing. Should get a nice proof of concept for < $100.



Question:
Does anyone know why inboard shocks are so preferred? I'm guessing it has to do with unsprung mass + adjustability. But it does seem kind of like a fad to me, needlessly complex, when the shock could just be mounted between the lower A-arm and chassis. "Outboard" setups do pose a problem when there is a drive axel going through where the shock would. Inboard shocks use a push rod which can be at an odd angle to get around the axel. Or you could just mount the "outboard" setup to the upper a-arm. Or like the lambo, use two coil overs on the lower a-arm to strattle the axel. I'm just not sure why everyone is so set on inboard. They do look pretty dern rad though. Inboard vs. Outboard

Apparently one of the finer points is that inboards are usually a "rocker" setup. With the cam shaped like it is, it offers progressive spring and dampening rates. Where as a vertically mounted outboard shock is more or less a single rate through the entire travel. Hmph.. why did this have to go and get way more complex..

[Edited by - bzroom on September 17, 2009 12:41:33 PM]

Current state of the chassis design:


The tubes weigh ~200lbs as drawn.

Anyone want to help design a body for this chassis? Just print out the orthogonal blue prints and lay some pencil on it. Currently there is no provision for a windscreen or door, but i've added them into my body design and may integrate them into the chassis. So basically, there are no restrictions, just completely knock yourself out. (and then send it back to me :))

Orthogonal blueprints





Edit: whoops forgot the blueprints url.

[Edited by - bzroom on September 23, 2009 7:21:59 PM]

Quote: Original post by bzroom
Does anyone know why inboard shocks are so preferred? I'm guessing it has to do with unsprung mass + adjustability.

Pretty much. Also look around the net for "DPcars.net". Its mainly just a engineer trying to build race cars...might prove inspirational, definelty at the high end F1 performance potential. His main focus is produceing the DP1. A 500hp all wheel drive single seater gocart like race vehical that weighs 800lbs.

It looks good - my only concern is that mid- and rear-engined cars tend to be a handful to control at higher speeds if you're not paying attention. Also, I don't know what kind of seatbelt setup you're going for, but you should probably check to make sure the chassis frame is adequately spaced and sized to hold onto the restraints. The seats are a good choice.

I should really have gone in for mechanical engineering in school. This kind of stuff would be really fun to do if I ever manage to figure out how to weld, set up suspension and remember Ackerman's principle.

If I were designing the body for a car like this, I'd probably go with something similar to the Shelby Daytona body. That was a body-on-frame setup as well, and looks absolutely gorgeous even with plexi windows. You probably can't pull it off with an engine in the rear; in that case I'd go with a "stubnose" racing design like a GT40.

It's quite a lot to keep in mind. I've been reading this book and it has helped a ton. Basically the first chapter talks about different types of frames. The second chapter looks at ~20 real race chassis. The 3rd talks about what is handling and what affects it. The 4th goes over ~20 different suspension configurations. The 5th talks in depth about starting from scratch. Then it goes to an appendix which works all the math for an example chassis. It's very brief and extremely to the point http://www.amazon.com/Racing-Sports-Car-Chassis-Design/dp/0837602963

Anyways, here's the body i've been drawing up. I should have done all the sketches on an overlay like the front. I want the body to look cool but still be functional. I dont want a lot of extra vents and things for no reason. which is hard when you've got a mid engine. I've got the large hole in the front for the radiator, which vents out the top. But in the lower sides of the front i feel like the styling calls for more vents but they have no purpose. It would only increase drag. The rear vents will feed the intercooler and oil cooler (it's a split vent, with a carbon louver in the center). The rear deck lid has louvers to vent that air. The exhaust will come out a stainless tip somewhere through the body work there. And yea, the front fender needs to be reduced a little.

You're completely mad!







...Can't wait to see it whizzing about! [grin]

I started a website to track the progress from here on out. I'm sure i'll still bump this thread occasionaly when i make significant advancement.

www.designedtwodrive.com

Bump in your trunk.