Streetable Formula Car

[NetKev92]

I'm about two months and $700 into a street legal formula car project. My goal is something like a single seat Ariel Atom crossed to a Formula SAE. I was busy in the airplane building college competitions, so I wasn't in on FSAE and Baja. I'm hoping to pop up every so often to ask questions.

Right now, I'm working drivetrain design and figuring out how far to take things. Power will be a '99 Yamaha R1 engine which I bought for the job. Is an ATV differential up to the loads from a 150 hp screamer? The Honda Rubicon limited slip is interesting. Otherwise I'll borrow from a car.

http://www.cardomain.com/ride/2276782

I figure fast for something that I can drive to the track to play with, but slow for a car that will fit almost nowhere but A-Modified for racing.

[NetKev92]

I'm about two months and $700 into a street legal formula car project. My goal is something like a single seat Ariel Atom crossed to a Formula SAE. I was busy in the airplane building college competitions, so I wasn't in on FSAE and Baja. I'm hoping to pop up every so often to ask questions.

Right now, I'm working drivetrain design and figuring out how far to take things. Power will be a '99 Yamaha R1 engine which I bought for the job. Is an ATV differential up to the loads from a 150 hp screamer? The Honda Rubicon limited slip is interesting. Otherwise I'll borrow from a car.

http://www.cardomain.com/ride/2276782

I figure fast for something that I can drive to the track to play with, but slow for a car that will fit almost nowhere but A-Modified for racing.

[Igor]

Did you check out the Rocket from The Light Car Company?
Maybe you can steal some ideas from that one.

Igor

[NetKev92]

The Rocket is one of my comparison points. It is very close in size class to what I intend. I also called Weismann/Power Products to ask about the gearbox they used on the back end. They used the gearbox in the Yamaha engine case, but they had two forward reduction ranges and reverse in the secondary gearbox sharing a case with a differential. They wanted $6500 for the unit which is far too much for my budget. My secondary gearbox layout though is roughly similar to theirs. I just plan to ditch any attempt to shift between more than two gearsets, and I'm doing a bit of dumpster diving looking for a differential. Besides cost, I'd also love to reduce the diameter of the angle cut drive gear on my diff. The more compact the arrangement, the easier it is to fit within my 90" target wheelbase.

If I can't create my own shifting hardware and it costs too much to buy/adapt, I may scrap any ability to shift with gears and make it just a gear reduction box to feed the diff. I could do like the Honda Goldwing for reverse. They use a small electric motor for the occasional backwards driving.

[NetKev92]

A second quick note -
I know that a number of FSAE cars use diffs out in the open without sealed oil-filled cases. I expect the typical FSAE doesn't get many driving hours per year, but do you see evidence of wear on the typical external diff. A direct chain drive would be simpler than any of my other current arrangements.

[drivetrainUW-Platt]

why didnt I think to use a Lego Drivetrain.....all those years as a kid, that would be soooo light and compact, plus if something breaks I could just dig through the bin and find another piece, that is if hasnt been sucked up in the vaccuum!

I would get ahold of a cad program before you do any serious designing...make life easier in the long run.

[NetKev92]

I'd love to play with CAD, but the prototype should be more informative and it's buy parts for the car or buy a CAD package. Besides, I could play with CAD at work in my freetime, but I'd rather spend my freetime getting my hands dirty. Excel's good enough for now.

I broke down and took my next step though. I bought an open diff from a Mazda Miata. You'll all pobably burn me at the stake, but I'm gonna use Miata halfshafts, uprights, hubs,brakes, and wheels. They're heavy as lead bicks for the job (50-60 lb per corner for all those parts and the A-Arms). Until I can assemble my own machine shop though instead of borrowing one, I really don't have the resources to make custom uprights within my time constraints. I'll focus my machine time on the diff case/reduction gearbox. Downsize the corners later.

[Faterooski]

Check into dune buggy building parts. Lots of companies motorcycle engine-driven drivetrains that are slightly more reliable than race stuff. Do you research and you'll quickly find lots of Hayabusa powered single seat dune buggies. All I can say is wow. Imagine going much faster than FSAE cars over bumps and hills. I want one.

[Bryan Hagenauer]

Something I caught glancing through your posts on cardomain: You mentioned a raised footbox causing visability problems.

Almost universally, the first words out of someone's mouth when they sit in our car for the first time is "I can't see forward"

From looking a picture of me driving with no seat padding, the front rollhoop is just under nose height. I have NO problems driving the car. If you are ever looking closer than 50ft out, you have bigger problems... The first time you try to park against a curb might be a different issue, however. So when that mockup is sitting still indoors, don't be suprised to think you need more visability.

[NetKev92]

I'm kinda coming to the same conclusion about visibility. If I want more, I'd be forced to raise the driver's rear. The Ariel Atom pops the driver's seat up about six to eight inches and the footbox is at the bottom of the car. It provides more visibility and it also keeps the front to rear dimension of the cabin a little smaller, but it makes everything taller.

In further experiments, I've found that the steering wheel obstructs as much forward view as my feet do, even in the raised footbox position. Visibility over my feet may be the secondary problem and not worth worrying about. I'm thinking a 200mm or 250mm steering wheel will make my life a lot easier. I would like to make it a detachable wheel for ease of in-out, but I'm not sure if it would be legal for street use.

I'll have to start looking more at the dune buggies. I have seen a couple with some fairly nice parts.