canting front wheel

[pgosselin]

My son and I are already scheming for next year's Pinewood Derby. Up until now, we've tried to produce straight running cars, but want to experiment with rail runners. I've read through the rail runner sticky. If I understand the process correctly, I negatively cant the rear wheels (so the heads are up and wheels roll towards the heads. This helps keeps them away from the rail. I'm a little more murky on the DFW. Am I reading correctly that I positively cant it (the nail head is down) so the wheel rolls in towards the body? I would think the friction between the hub and the body would be a bad thing. Or does this relationship change the minute the DFW hits the rail--pushing the wheel back to the nail head? Or do I keep the DFW axle level and just bend it so it toes in?

Slightly confused,

Paul

[FatSebastian]

I'm a little more murky on the DFW. Am I reading correctly that I positively cant it (the nail head is down) so the wheel rolls in towards the body?

Repeating something posted here, rubbing contact between the rail and wheel for the DFW is more advantageous versus negative camber in that it has the potential for inducing less friction. The hub against the body also acts as a shock absorber against rail defects. I don't believe that positive camber for the DFW is explicitly mentioned in the well-circulated Rail-Riding Method by Jay Wiles (available here in clear text and here as pdf).

[sporty]

RR riding can be done without cant ! We do it eacxh year for our pack races, 4 wheels touching.
We are not allowed canting.


Sorry to toss that out, but I wanted to mention it.

Because canting in the rear, does not have anything to do with RR, but more for better alignment, speed, less wheel friction on the track surface and wheel migration out to the axle head.

The Front RRm the cant is the same way, there is less wheel surface touching the track versus the entire wheel.


Even though this cant, causes the wheel to go towards the car body, the drift (toe in) of the bent axle, has that wheel pushing into the rail, and that pushed the wheel out to the axle head while the inside edge of the wheel rides the rail down the track.

Cant does effect steering, alot of cant, can mean toe out issue and more friction issues on the axle head in certain places, if say you had 5 degrees of cant.



So there is a point of when to much cant is a issue.

many are running 2.2 to 3 degrees of cant in the rears and 3 to 5 degrees of cant in the front and then the toe in, which is created by rotating that bent axle to add the toe in or adjust it.

Now, almost always for a brief second, from the slop to the transistion, that shift, can cause the wheel to come in on the RR and touch the car body for a very brief second.

the faster way is when the rules allow for canting, versus just toe in only.

Sporty

[pgosselin]

many are running 2.2 to 3 degrees of cant in the rears and 3 to 5 degrees of cant in the front and then the toe in, which is created by rotating that bent axle to add the toe in or adjust it.

Sporty

Really, 3-5 degrees on the front? I thought the rail rider tool recommended 1.5. I was thinking I need to approach a figure more like that on the front even though I was thinking about drilling the hole instead.

the faster way is when the rules allow for canting, versus just toe in only.

Sporty

Our rules are vague. They say the axles have to be installed "parallel to the track." I'm not interpreting that as canting being illegal. Do you all? Many people in our pack bend their axles to get the cant. Or they install them crooked and unintentionally end up with a cant. Why not just drill a hole at the proper cant? One to two degrees on the back shouldn't be that noticeable and is approximately parallel.

[FatSebastian]

Our rules are vague. They say the axles have to be installed "parallel to the track." I'm not interpreting that as canting being illegal.

Paul, what then do you interpret "parallel to the track" to mean?

Do you all?

I would say "parallel to the track" intends to make axles tilted up and/or down illegal, but tilting fore and aft (to generate toe) is legal. (This is not to say that I favor such a rule, or that it is even easy to enforce; rather I do not think it is vague.) But it sounds like that the rule is not enforced this way?

Why not just drill a hole at the proper cant?

I believe that is for the most part the subject of this topic.

[pgosselin]

FS,

I am always amazed at how fast you can put your finger on those other links. Very interesting reading. Makes my head hurt because I'm not a physics wonk. Still, I'm very good at grasping concepts.

So I may be indulging in a bit of wishful thinking, eh? Parallel to the track means exactly 90 degrees to the body of the car. Wow, these are Cub Scout races. I don't know how they could enforce such a rule because so much weird camber is going to happen because of sheer inexperience of father and sons building these things. Heck, I've been helping my sons with this for five years now and this is the first time I'm finally starting to pay attention to it.

Still your point is taken. We're not here to cheat in any way. We're scouts, after all. Our goal is to exploit any legitimate advantages. So I may have to try what Sporty suggested as a non-canted rail rider.

Glad I have you all to bounce these thoughts off of before my son and I start building cars in the workshop.

Paul

[pgosselin]

As for the parallel thing, I was interpreting as they didn't want me to put the axles in at an intentionally severe angle, something like a 45-degrees.

Paul

[Rukkian]

One other possible, would be that that if you drill holes, they need to be parallel, meaning that the holes could not be canted. If the rules state that the axle needs to be installed parallel, then that could be done, as the bend would be after that. The rule does not state that you need to have straight axles, or that the entire axle needs to be parallel. If the portion inside the car were straight, that should satisfy the wording of the rule, even if it does not follow the intent.

This is one of the issues with rules like this.

[pgosselin]

RR riding can be done without cant ! We do it eacxh year for our pack races, 4 wheels touching.
We are not allowed canting.

Sporty

So how do you do it without canting? Keep the back wheels rolling in the middle of their axles, then toe in the DFW?

Paul

[pgosselin]

One other possible, would be that that if you drill holes, they need to be parallel, meaning that the holes could not be canted. If the rules state that the axle needs to be installed parallel, then that could be done, as the bend would be after that. The rule does not state that you need to have straight axles, or that the entire axle needs to be parallel. If the portion inside the car were straight, that should satisfy the wording of the rule, even if it does not follow the intent.

This is one of the issues with rules like this.

That is exactly how I did things this year. It was just so time consuming trying to get the right bend in the axles. I was at it for hours upon hours. I was hoping to simplify the process for next year.

Paul

[Stan Pope]

So how do you do it without canting? Keep the back wheels rolling in the middle of their axles, then toe in the DFW?

Paul

You got it in one!

[FatSebastian]

Why not just drill a hole at the proper cant? [...] Very interesting reading. Makes my head hurt because I'm not a physics wonk. Still, I'm very good at grasping concepts.

This comment by RacerX in that thread may do well to sum up one motivation - adjustability.

It was just so time consuming trying to get the right bend in the axles. I was at it for hours upon hours. I was hoping to simplify the process for next year.

It can also be time consuming getting canted holes drilled perfectly. If it helps, if you have a Derby Worx rail-rider tool, you can incrementally adjust the amount of nail bending.

I don't know how they could enforce such a rule because so much weird camber is going to happen because of sheer inexperience of father and sons building these things.

You may want to inquire of the "controlling legal authority" of your race rules regarding the intent and enforcement of the "parallel axles" rule. Perhaps your inquiry might have some influence on having an unnecessarily restrictive rule removed.

[Stan Pope]

You may want to inquire of the "controlling legal authority" of your race rules regarding the intent and enforcement of the "parallel axles" rule. Perhaps your inquiry might have some influence on having an unnecessarily restrictive rule removed.

!!!

Part of that inquiry might be words to the effect that you discovered that the better you taught your son to skillfully satisfy the words of the rule, the worse his results in competition. You found that he got better results when you sent him back to try again when he built too well! In other words, the rule is counterproductive.

[sporty]

you can drill a 1.2 degree cant for the rears and still be legal.

Sporty

[pgosselin]

I've got an email into the guy who wrote the council rules. Of course this is the same guy who has a mantra about wheels: "out of the box, onto the car." I hate the fact the wheel bore is the only thing I can prep on the wheels. I'm not hopeful.

Paul