DFW: Positive Cant vs Negative Cant

[CivilWarTalk]

When I first set my son's car as a rail rider I mistakenly set the steer with a cant that I believe is considered positive, the bottom tread of the wheel was angled away from the rail.

I was surfing the forum and discovered that you guys all run a negative cant if I'm remembering correctly, this puts the angled tread pointing into the rail.

So I corrected this a re-steered my son's car, and he ran a great race.

So why would you use one cant over the other?

I have my own ideas why this is faster, but I'm interested to hear your point of view!

 

[561 racing]

I believe it's causes the least amount of friction when contacting the rail.

 

[Vitamin K]

Positive Cant = Bottom of the wheel closer to the car than the top of the wheel.
Negative Cant = Bottom of the wheel further from the car than the top of the wheel.

Positive cant is applied to the DFW, because this moves the point-of-contact of the wheel towards the center of the car. This, coupled with narrowing the DFW side slightly, ensures that, if the car is steering away from the DFW side, the inner edge of the DFW is going to touch the rail before anything else ( the negatively canted rears ) are able to come into contact. Thus, the lightly-loaded front dominant wheel ends up as the only part of the car to actually touch the rail.

 

[Crash Enburn]

Simplerer/Clarifyier:

With Positive cant (wheel like this: \-[ ), it will roll along the rail.

With Negative cant (wheel like this: /-[ ), it will roll on the track, but drag on the top edge of the rail.

 

[ngyoung]

All assuming you're on a center rail guided track,
Rear wheels should be negative cant:
/---
Front dominant wheel positive cant and a raised wheel:
dfw->---|
or what many do is DFW canted positive and NDFW negative:
dfw->---

 

[CivilWarTalk]

Ah so it sounds like I had my terms backwards, got to remember that.

 

[GravityX]

So why would you use one cant over the other?

Another reason why not to run a negative cant angle at the DFW and to add to what Crash Enburn said. The wheel will be riding the top edge of the rail and by riding this top edge the wheel will be constantly trying to "climb" the rail. Eventually it may get a good grip and actually climb it and then jump it. The result may be something spectacular.

 

[derby freak]

also if you use a pos cant on the dfw then its possible your rear wheel on the dfw side was contacting the rail