Am looking at commencing building a STR class car, initially with a relatively small motor and perhaps stepping it up each year once I gain more experience. Now I'm a fan of doing things once and doing it right. I really would appreciate some input in relation to the choice of front end. Is a dropped I beam the best route or should I consider an aftermarket independent set up. My ultimate gaol is 200 +, perhaps as an A or AA engine. The other thing to consider is it will need to maintain a roadworthy status when not on the salt. Thanks.
There is nothing wrong with a dropped axle except that most of the components, axle, drag links, spring and wishbones or 4-link are all on different planes, so you have a lot of components that are out in the wind and increasing frontal area.
One of the earliest approaches that I've seen to over come that is the famous Beatty lakester. The picture above shows what he did to overcome the bad aero you can get with a dropped axle. He took an "A" axle that has the least amount of drop in it and turned it upside down and re-bent the ends to get the camber and scrub radius correct again. That also further straighten the axle so it is almost like a straight axle. Then he reversed the spindles and bent them so the drag link across the front is right in front of the axle. Then by working with the spring perches he aligned the spring pretty much behind the axle. Finally using split wishbones they are also behind the axle and have less vertical height than say hairpins or 4-links. I don't see why you couldn't even run this on the street, but if it was me I would do this for the salt and have a second dropped axle for the street. I was going to do this for my lakester and picked up a couple "A" axles, but then decided I wanted to do something yet different for the lakester. The A axles can be had pretty cheap as everyone wants a dropped axle.
Here is a newer approach and is on the beautiful Kelly & Hall lakester. It uses a straight tube axle with the other components out of the wind as much as possible.