Reverse Rail Runner?

cmoney atrain

Pinewood Ninja
Jan 28, 2018
29
6
3
48
So I understand the logic of the straight rear axles with 3 degree negative camber/cant. The dominant front axle is bent at a positive camber/cant position so it can run into the rail and produce a guided straight trajectory.


Has anyone tried to do a negative camber/cant on the dominant front and have the non-dominant wheel or guide pin run the rail? Wondering if there is a benefit of having less friction on the wheel that needs to spin.
 
I can't see this as being beneficial. A properly tuned rail-runner should give you rolling friction on both the track and axle. What you describe here would give you sliding friction on the raised wheel or pin, which would almost certainly be slower, I think.
 
Why do people lump 3 degree rear cant in with rail running? Has nothing to do with it.

Not picking on you, cmoney. I've just seen this a lot lately and wondering why people think the negative rear camber is helping them to ride the rail.

Well, if you look at riding the rail from the perspective of "Always keep the rear wheels off of the rail," I'd argue that the negative rear camber contributes to keeping the rears away from the rail, since it moves the contact points of the wheels further from the rail, and it also causes the wheels to migrate out to the axle heads.
 
Well, if you look at riding the rail from the perspective of "Always keep the rear wheels off of the rail," I'd argue that the negative rear camber contributes to keeping the rears away from the rail, since it moves the contact points of the wheels further from the rail, and it also causes the wheels to migrate out to the axle heads.

I suppose that is an added benefit, but the migration of the wheels and riding on their edges are the actual purposes of rear camber. It doesn't help you steer.
 
If you consider the positive cant of the DFW, it does two things: 1) rolls on the the horizontal surface of the track (like the other wheels), and 2) rolls against the rail (it does not slide along the rail). A car can roll over not only imperfections on the horizontal surface, but along the vertical surfaces as well. A sliding guide pin would absolutely be more friction and that is essentially why a negative cant does not fair well either. A negatively canted dominant front wheel would slide along the rail.
 
Thank you Vitamin. That is what I was looking for. “Rolling friction” vs a more static “Sliding Friction”. I can imagine that my question might have come across as a “Newbie, thinks you’re doing it wrong” type statement. Thank you for seeing past that Vitamin. That wasn’t my intent. I just wanted to be able to explain why the reverse might not be faster. Before your reply, I could not do that.

Skywalker, us beginners lump our new knowledge in related categories (e.g wheels). Unfortunately I can’t yet explain to someone else why a three degree cant on rear wheels with zero toe runs straight but a three degree bend in axle of the dominant front wheel (also with zero toe?) causes the car to curve into the rail.

That might be why we do that. At least that is why I do.
 
  • Like
Reactions: Skywalker Racing
Skywalker, us beginners lump our new knowledge in related categories (e.g wheels). Unfortunately I can’t yet explain to someone else why a three degree cant on rear wheels with zero toe runs straight but a three degree bend in axle of the dominant front wheel (also with zero toe?) causes the car to curve into the rail.

That might be why we do that. At least that is why I do.

Aha, that's where you misunderstand. The bend in the DFW axle gives both camber AND toe. The amount of toe you want varies with a lot of factors, but that's the wheel that steers your car into the rail.
 
Eureka!!!! So there is toe. And you achieve that toe with slightly turning the axle? Ahh, that is why the straight axles in the rear are preferred (with perfect alignment and 3 degree canted holes) because they reduce the chance of toe from the bent axle.

I think I’m starting to get it. B_Regal, your comment was also enlightening. Thanks for expanding out that concept.

You guys are great!!
 
Eureka!!!! So there is toe. And you achieve that toe with slightly turning the axle? Ahh, that is why the straight axles in the rear are preferred (with perfect alignment and 3 degree canted holes) because they reduce the chance of toe from the bent axle.

I think I’m starting to get it. B_Regal, your comment was also enlightening. Thanks for expanding out that concept.

You guys are great!!

Now you're getting it! :)
 
  • Like
Reactions: cmoney atrain