29 Jan 2008

Got the wheels today and boy they’re big, and blingy!  These were bought because wheels are next on the list of must-haves after the tire sizes were chosen. These will be for the street, so they ended up more towards the appearance end of the pool as opposed to function. I’m trying to contain costs more than with Kimini so it means going with heavier wheels than I’d like. What I get in return is a stronger wheel so I don’t wince whenever I hit potholes. These are literally three times cheaper than proper race wheels though about 7lbs heavier – but so be it.

The wheels are from Sportmax which are apparently sold to drifters with Nissan 240SX cars. They aren’t perfect but they’ll serve their purpose just fine and at $130 each, it was too good to pass up. Before I hear, “those are way too big, 17″ is dumb”, keep in mind that since the design spec calls out only tire outside diameter; the builder is free to choose a different size. That is, any tire from 14″ – 17″ will work just fine. I chose 17″ because it’s my opinion that it “future proofs” the wheel choice for a long time. This is my reaction to getting bit from dwindling 13″ street tire sizes with Kimini – I don’t think 15″ tires are far behind. Once burned, twice shy. Also, this guarantees that when builders slap on 9″ wide race wheels, they’ll fit just fine.

Looking at another engine for sale. I keep flip-flopping between building a high-reving normally-aspirated engine and a forced-induction solution. Either way it’s going to require changing pistons and rods, and I recently came across a partly disassembled project engine that has neither – perfect. I’d have to take it apart anyway, and with it disassembled, it’s much easier to check out.

25 Jan 2008

Finally tested the coil-over shocks with a proper press and load cell. As suspected, there’s a sizable gas preload pressure before the shock starts to compress. It was a lot of fun, actually, as I rarely have the proper tools to do this. I’m always having to guess or approximate what I’m doing due to not having the right tools, always making me feel bad about doing a half-assed design job. However, when I’ve got the proper tools it’s a really good feeling knowing that the data I’m collecting isn’t “roughly” this, or “about” that – it’s exact. With this data I can confidently design the push-rod suspension, and know it’ll work first time. That’s a great feeling to have even before it’s built.

After 25 years of resisting, I’ve finally given into probably having two sets of wheels and tires, one for the street and one for the track. Given that, I’ve backed off on buying the lightest street wheels possible, since they’ll have to deal with potholes (and bonehead tire installation shops…) Street wheels are far from light but then again they cost less than 1/3 that of a really light racing wheel. So it was a bit surprising to come to terms with purposely buying something that isn’t the best. Yup, today, street wheels were ordered. Theoretically they aren’t needed but they’re invaluable for suspension mock ups and checking clearances. Having CAD is pointless when detailed dimensions aren’t available, which is a lot of the time. Wheels are especially bad in this respect, and it’s a rare manufacturer that supplies accurate cross-sectional drawings. The best anyone gets is bolt pattern and back-spacing.

The ultralight track wheels that cost crazy money will come later after the car’s built and ready for the track.

23 Jan 2008

And so it begins. Having decided on the front tire diameter now the real suspension design begins. Using Mitchell’s excellent WinGeo3  software, I’m working through many iterations, trying to get static FAPs (Force Application Points.) What’s frustratingly familiar is how I can get static FAPs, and roll centers for that matter, but I’m not happy with the camber gain curves yet. I’m not complaining and quite enjoy the iterative process. It’s a good feeling knowing that once this step is done, the car will have a stable, predictable nature to it, just like Kimini has. And like the Mini, it took weeks to gradually settle on those elusive points in space about which the suspension will pivot.