Looking for Alignment board suggestions

[rsebring]

Everything after 3 or 4 feet is extraneous

Having pondered this year to replace my 4 ft board with something longer I came across this. I had a wiggle last year that seemed imperceptable on my 4 ft board and thought (erroneously?) that a longer board might have revealed the problem.

I may build it anyway since I failed to do the research before having the Home Depot guy cut down an 8 ft piece of melamine to 6 ft because if fit the back of my pickup easier.

I've also searched hours for the general guidlines for drift on various length boards and that seems to be a widely varied measurement. Generally I came across 2 in 4 and 4 in 8 as common goals. In my mathematically challanged mind I calculated 3 in 6 as a swag. I saw your calculator but honestly not sure if it tells me how much drift over 6 ft for a standard wheelbase or how much toe needed to achieve an particularly desired drift. (see told you mathematically challanged)

Thanks ahead

[Stan Pope]

rsebring, I'd be really surprised if you could see the so far invisible cause for your wiggles on an 8 ft tuning board.

Th translation from 4 ft to 8 ft is not simply proportional. The car's pathway is a circle, starting, ideally, "straight down the hill". The farther you go, the faster you go away from that "straight down the hill" line. Which is why I wrote that calculator page!

The point of the calculator page is to allow kids who aren't quite ready for Trigonometry yet to perform the translation between board lengths. Recommend that you go back to the web page, plug values that you know and see what it seays.

[rsebring]

Thanks Stan. So if I wanted to know what the comparable drift of 4 in 8 was on a 6 ft board I would leave 89 and 4 for the given test surface data and input 65 for the available? The answer being 2.13 which is obviously considerably less then my swag. Your calculator page may be useful for adults that aren't quite ready for Trig also.

[Stan Pope]

By George, hi's got it! Well done!

There is a small error component which, for the slope angles, toe angles, and directions we're working with, will be very, very small: The source of the error is that when the car turns from straight down the slope, the "down slope" tends to reduce the effect of DFW toe angle. We don't even want to think about solving that equation!

For communication purposes, you can translate your optimized drift to some more commonly used base. For instance, through a series of test runs you find a toe adjustment that gives the best time on a particular track. Then you put the car on your 6' test board and see a drift of 2". While you could tell your friends that 2" drift on a 6' board is good for that track, if you know that he has a 4' board and is really scared of the math, you could plug those values in instead of the 8' board, yielding 0.8".

Expressing drift using more than two significant digits is probably useless, given the difficulty in staging the car accurately.

[rsebring]

Excellent. Thank you for the example. Very helpful.