Keeping track of things

Being a nerd, I like to keep track of things. Excel and I are on a first-name basis. So it's natural that I'd want to accurately document my build.

Even though the Spartan won't be an absolutely low-cost locost, I still want to keep track. Some have suggested that this is a crazy idea, as it gives my wife real numbers to yell at me about. Fortunately for me my wife is really cool about this obsession of mine, so I feel comfortable keeping a budget spreadsheet with the actual figures for my build.

I'm going to count the full purchase cost of partial items. That means if I use 10% of a $4 tube of grease, it'll be $4. I don't want the pain of tracking how much welding filler wire I've used. The spreadsheet will also break out shipping and tool costs and list sources for each item. I figure that may help someone else understand how I got those figures.

While I've been waiting to start my build I've been reading like a banshee. I've also scoured the internet for anything I can learn about building a car. Along the way I've made lots of decisions about components and specs for my car. I've decided to keep a specification spreadsheet (xls) listing what I plan on incorporating into the Spartan.

Both documents are now on the sidebar, and they'll be constantly updated as I go along. You're free to copy and use them as you see fit.

And so it begins...

My first ever component just arrived. Behold, the Spartan's steering rack!

I was alerted to a good deal on Ebay by an astute member of the LocostUSA forum. I'm not entirely sure it'll be what I need, but at the price I picked it up for it was too good to pass up.

Here are the details:

Appleton p/n: 7010410
18.25" width, tapered ends
2.5" travel per turn
4.5" total rack travel
17 lbs.*

The factory specs say that this unit weighs 17 lbs., but the shipping label says it's 14. I'll have to get a scale to make sure.

If you've been reading this blog, you'll remember that I'm not inclined to cut and weld a normal automotive rack. It's not that I think it's a bad practice, I would just rather spend a little more and know I've got a reliable unit. Losing steering control at speed doesn't sound like fun.

This rack isn't as nice of a unit as a Woodward rack, as you have to replace both the outer housing and the steering pinion to change the ratio. There also seems to be a bit of friction in the system, possibly due to the fact that the rack and pinion spacing are determined by the manufacturing tolerances of the housing, not some fine adjustment. I may be off base, but Staniforth claims that a good steering system will allow you to move the front wheels with one finger. Maybe he's a little used to high-buck purpose-built cars. I'll wait until I can inspect a stock Miata rack before I pass final judgment.

In any case I got such a good deal on it I figure I can still recoup most of my costs by selling it on Ebay if it doesn't work out. Besides, I've come to learn that a companion hobby to working on cars is collecting car parts.

Even if it's only one part, I'm still pretty excited about what this represents - my first tangible component of my car. It's all uphill from here!

Comparing Dimensions

I've been reading the excellent Lotus Seven & the Independents, and one thing I'm struck by is how much variation there is in the critical dimensions of various Sevenesque cars.

I've compiled various measurements for the two common Locost platforms as well as for three baseline Sevens and a few lightweight sports cars. I've also thrown in weight and horsepower numbers for reference.

Car	Overall			Track		Wheel base	Ride Height	Weight	HP
	Length	Width	Height	Front	Rear
1962 Lotus Super Seven Series II	131.5	56	39.5	47.5	48.5	88	6	924	85
Haynes Roadster (Gibbs)	129.5	67	46	56	57.5	94	3.9	1309	105 est.
Keith Tanner's CMC Miata-Locost	128	65.5	42.5	51 est.	56.2 est.	92	4 est.	1279	175
FM Westfield	131.5	63.4		55.5	56.2	91.5	5.75 est.	1300	125
2006 Caterham CSR Superlight	129.9	66.3	40.0	59.3	57.7	91.1	3.9	1245	260
1993 Mazda Miata	155.4	65.9	48.2	55.5	56.2	89.2	4	2222	116
1974 MG Midget 1500	141	60	48.3	46.3	44.8	80	4	1631	65
2003 Ariel Atom II	134.3	70.8	47	63	63	92.3	3.5	1005	220
1957 Lotus Eleven LeMans	139	60.5	31	45.5	47	88	4.5	1360	84
2000 Lotus Elise	147	67	45.2	56.7	57.9	90.6	6.3	1574	143
1964 Austin Mini Cooper S	123	55.5	53	52.8	46.9	80	6.3	1250	70

Click on the car's make and model for the sources for my data.

The first thing that jumps out to me is how tiny the original Seven Series II is. The Caterham is nearly 10" wider than the original car. Of course a lot of this is wider modern tires, but it's still significantly smaller than anything on the road.

The other thing is how much longer the wheelbase is on Gibbs' Haynes Roadster vs. every car in the table. If you look in the Haynes book, the front wheels actually stick out past the front of the nose cone! Since my frame design is based on the Haynes Roadster, reducing the wheelbase to 90-95" is going to be one of my design priorities.

I'm going with the stock Miata front and rear track on my Locost (as of right now), so the width of my finished car should be in-tune with the rest of the pack.

Update 6/22/08 - Chris Gibbs has contacted me with corrections to my table. It appears that the figures I had before for the wheelbase were way off, as many have commented. Now with the correct dimensions, it appears that the Haynes Roadster isn't as big as the discussion forums would have suggested. This makes me feel much better about using the design as a starting point!

Update 4/14/09 - It appears the Haynes Roadster wheelbase figures are in dispute again. I've received word from a reader who very adamantly states that the wheelbase is actually 94". The reader states this is what he got in CAD when modeling up the frame. Gibbs himself on his forum states it is 92", so I'll chalk that up to the book not completely representing the actual car.