Wheel Alignment Problem

[Jungle Jim]

Without arguing all the details, I don't see this "aligned" definition transferring to PWD cars. You are defining almost, but not quite, best target states for camber and weight distribution.

Just giving a simple lesson in pertinent geometry.

My observations indicate significant friction and tracking superiority when alignment is "dead-on", and significant time advantage when weight distribution matches track's geometry but stays just within the wheel's traction limits ("death rattle" avoidance).

Are you stating that "dead-on" (and I guess this to mean all angles 0 and squared) is the superior choice?

However, I am happy for my opponents to follow your direction to the letter, so I won't argue vehemently.

Even though I no longer have children who race (they are both in a troop now), giving out inclusive advice is not something I usually do. Merely I will try to explain to someone what he or she can accomplish, how it will make their experience better and send them on their way. This way they live it for their self.

And on another note: when we were building cars to race, for one year for each boy (they are 2 years apart) I made sure that every possible details was covered. On those years they not only won every race at every level, but the wins were quite decisive. I'm talking to the tune of car lengths. And quite honestly for myself it was embarrassing.

[Barga Racing]

I noticed that when you run the drill bit through the Pro-body tool, there is a bit of "play". Before I first used the tool, I assumed there would be no play whatsoever.

While you guys are discussing the Pro Body tool let me caution you not to do what I did. I tried to drill my holes with a dremel instead of taking the time to walk to the shed and get my drill. A dremel does not have enough power to drill at low speed. So I had to run it pretty fast and it induced vibration into the drill bit. It then wallowed the holes in the tool out considerably, so as I had to get it replaced. Just my $.02, but I found a variable speed drill works best.

[Stan Pope]

Just giving a simple lesson in pertinent geometry.

I questioned the pertinence of transferring all of the process for aligning internally powered, steerable vehicles to externally powered (coasting) straight line vehicles. Something more than reassertion is appropriate.

My observations indicate significant friction and tracking superiority when alignment is "dead-on", and significant time advantage when weight distribution matches track's geometry but stays just within the wheel's traction limits ("death rattle" avoidance).

Are you stating that "dead-on" (and I guess this to mean all angles 0 and squared) is the superior choice?

For this type of car, yes, that is my experience.

(References to my humor removed)

And on another note: when we were building cars to race, for one year for each boy (they are 2 years apart) I made sure that every possible details was covered. On those years they not only won every race at every level, but the wins were quite decisive. I'm talking to the tune of car lengths. And quite honestly for myself it was embarrassing.

We have comparable stories. The anecdotes don't prove superiority, one way or the other. They do indicate that further study is probably justified.

On the question of weight distribution, your equal weight distribution guideline might be correct for a particular track design (e.g. extended track length or very slick track surfaces), but it is not correct for most. From physics we know that car specs (rules), track and traction dicate optimum weight distribution. For the most used track style (the 32 foot style shown in the Cub Scout Leader's How To book and as implemented by Piantedosi) equal weight distribution on all weight-bearing wheels is inferior in theory and in practice.

[Jungle Jim]

Just giving a simple lesson in pertinent geometry.

I questioned the pertinence of transferring all of the process for aligning internally powered, steerable vehicles to externally powered (coasting) straight line vehicles. Something more than reassertion is appropriate.

I am not particularly interested in trying to sway someone into my way of thinking. And the lesson given is absolutely pertinent to PWD cars and does not work (or at min. works poorly) in automotive applications.

My observations indicate significant friction and tracking superiority when alignment is "dead-on", and significant time advantage when weight distribution matches track's geometry but stays just within the wheel's traction limits ("death rattle" avoidance).

Are you stating that "dead-on" (and I guess this to mean all angles 0 and squared) is the superior choice?

For this type of car, yes, that is my experience.
[/quote]

So how do you get the wheels to remain neutrally staged? And what do you do to keep the car from wanting to lead-off?

(References to my humor removed)

Nothing meant by the deletion.

<another snip ... just 2 guys yappin'>

On the question of weight distribution, your equal weight distribution guideline might be correct for a particular track design (e.g. extended track length or very slick track surfaces), but it is not correct for most. From physics we know that car specs (rules), track and traction dicate optimum weight distribution. For the most used track style (the 32 foot style shown in the Cub Scout Leader's How To book and as implemented by Piantedosi) equal weight distribution on all weight-bearing wheels is inferior in theory and in practice.

Ahhh, now I see the rift I wrote earlier: "The other thing you want to make sure of is that the vehicle is properly planed. There should be an even amount of downward force being applied to all the wheels (3 or 4)." What could be, and most likely was, interpreted in this statement is that each wheel should have the same amount of load-bearing weight on it when the car is race ready. Of course most of us know this is untrue.

[Jungle Jim]

While you guys are discussing the Pro Body tool let me caution you not to do what I did. I tried to drill my holes with a dremel instead of taking the time to walk to the shed and get my drill. A dremel does not have enough power to drill at low speed. So I had to run it pretty fast and it induced vibration into the drill bit. It then wallowed the holes in the tool out considerably, so as I had to get it replaced. Just my $.02, but I found a variable speed drill works best.

Bummer

[ExtremePWD]

My variable speed drill did a fine job of wallowing out the holes without the help of a dremel. Speed could be a factor as you suggest but I think there are at least two other factors that aggravate the problem. The first is drill bit wander sideloads the bit into the tool. The second is three young kids that can't hold the drill straight while making multiple cars.

[Stan Pope]

So how do you get the wheels to remain neutrally staged? And what do you do to keep the car from wanting to lead-off?

A lot of the car's desire to lead-off arises from steering torques that arise from different wheel coefficient's of friction (Cf). If the Cf's are equal, the steering torques disappear from the equations.

Ahhh, now I see the rift I wrote earlier: "The other thing you want to make sure of is that the vehicle is properly planed. There should be an even amount of downward force being applied to all the wheels (3 or 4)." What could be, and most likely was, interpreted in this statement is that each wheel should have the same amount of load-bearing weight on it when the car is race ready. Of course most of us know this is untrue.

I shall search your words for other, less obvious, meanings.

[Barga Racing]

My variable speed drill did a fine job of wallowing out the holes without the help of a dremel. Speed could be a factor as you suggest but I think there are at least two other factors that aggravate the problem. The first is drill bit wander sideloads the bit into the tool. The second is three young kids that can't hold the drill straight while making multiple cars.

If the tool was made of stainless I think it would alleviate this problem. The only problem with that is I bet it would double or triple the price and I don't think too many people would want to pay that for it.

[RACER X]

If the tool was made of stainless I think it would alleviate this problem. The only problem with that is I bet it would double or triple the price and I don't think too many people would want to pay that for it.

Heck, we lowered the price this year by 40% and people still say it is a bit high. Stainless would more than double the price due to many things other than material, ie. tooling, CNC run time and freight just to name a few.

I have 2 Pro body tools on my work bench that were used last season during a P.W.D. workshop. The 2 did around 40 cars and thay are not in too bad of shape. All I can say is "Slow down" the tool was designed for a standard hand drill. I have even done them by hand with a "pin vice", it is only pine.

[ExtremePWD]

I guess the only speeds I know when I am working around pinewood derby cars is fast and faster. I'll have to work on the slow part.

[Jungle Jim]

So how do you get the wheels to remain neutrally staged? And what do you do to keep the car from wanting to lead-off?

A lot of the car's desire to lead-off arises from steering torques that arise from different wheel coefficient's of friction (Cf). If the Cf's are equal, the steering torques disappear from the equations.

You state: "If the Cf's are equal, the steering torques disappear from the equations." While this is certainly a true statement, we are not racing on a computer. As such, its practical relevance is somewhat diminished.

We know the car is going to be subjected to changing conditions on its way down the track. We know that these conditions will affect the cars ability to track properly. And we know that an object is most susceptible to outside forces when it is balanced and supported at only one point.

So I'll ask this question in a different way. How do you get the car to overcome these inherent forces, and the wheels to remain "neutral" with your "dead-on" alignment approach?

Remember Stan, I'm not trying to task you to intolerance, just seeing how sound a couple of ol' derby racers idea are