Wheel alignment

[drew_351]

So many posts about alignment and revolve around my question, but since many are old I thought I would start my own. Per what I am reading, it sounds like the rear wheels should be canted upward (top closer to car than the bottom) at about a 3 degree angle.

For a 3 wheel rail rider car, people are saying to have the front drivers wheel (DFW) downward canted (bottom of the wheel closer to the car) as that would have the least amount of drag, and then also have the axle turned slightly inward so the car steers toward the rail slightly to prevent any bouncing around on the track.

What angle should that DFW be canted downward? Should it be about 3 degrees like the rear wheels, but obviously it is the opposite direction of the rear?

What angle inward should the DFW be to have it turn in just enough? I am planning to experiment with this as many people suggest. But looking at ranges or approx people have had most success/fastest car/least bouncing. I have read testing a car on a slightly slanted board going about 4 feet and the car moving about 1", but I have also read like 6" which just seems like it would be a lot of drag wouldn't it? Again, wondering what should be a goal here.

Thanks for any help!

 

[Loud2ns]

it sounds like the rear wheels should be canted upward (top closer to car than the bottom) at about a 3 degree angle.

Yes, this is called negative can't.

people are saying to have the front drivers wheel (DFW) downward canted (bottom of the wheel closer to the car) as that would have the least amount of drag,

Yes, this is called positive cant.

and then also have the axle turned slightly inward so the car steers toward the rail slightly to prevent any bouncing around on the track.

This is called steer.

What angle should that DFW be canted downward?

4-6 degrees is typical

What angle inward should the DFW be to have it turn in just enough?

Put a slot in the head(k-house groove) of the axle so you can twist it with a screwdriver to adjust steer.

I have read testing a car on a slightly slanted board going about 4 feet and the car moving about 1"

1" wouldn't be enough, the rule of thumb is start at 4"/4 feet.

 

[drew_351]

Yes, this is called negative can't.


Yes, this is called positive cant.


This is called steer.

4-6 degrees is typical


Put a slot in the head(k-house groove) of the axle so you can twist it with a screwdriver to adjust steer.

1" wouldn't be enough, the rule of thumb is start at 4"/4 feet.

Thanks for the response! This is a huge help. Any suggestion on what degree angle the positive cant would be on the DFW?

Per the rules I need to follow, I can't bend the front axle so having the slot in the head of the axle to twist will not do much (unless I can find a naturally bent axle...but when proper polishing happens not sure how much that will help).

 

[DerbyDad4Hire]

You will have to drill the proper angle in. I offer predrilled blocks to achieve what you are looking for and there is no time spent to align the car. Your child could build it and it fairly cheap.

 

[DerbyDad4Hire]

https://derbydad4hire.com/Plug-N-Play-Precision-Drilled-Rail-Runner-Pinewood-Derby-Block-BL-PNP.htm

 

[Loud2ns]

Thanks for the response! This is a huge help. Any suggestion on what degree angle the positive cant would be on the DFW?

Per the rules I need to follow, I can't bend the front axle so having the slot in the head of the axle to twist will not do much (unless I can find a naturally bent axle...but when proper polishing happens not sure how much that will help).

I didn't realize you needed straight axles, but it looks like John has you covered.

 

[drew_351]

I didn't realize you needed straight axles, but it looks like John has you covered.

I appreciate what John has offered and I plan to buy the block and test with it. But I also hope to experiment with my son to try and see what we can attempt ourselves. Just was trying to figure out some approx to start around based on others success. Figuring out that steer degree will be the trick.

 

[drew_351]

Set your drill angle at 6 degrees positive cant. Rotate your workpiece 15 degrees clockwise ( for a right side dfw). I’ve had some success in scout races using this setup.

Doesn't "DFW" stand for drivers front wheel? I am confused then when you say for a right side dfw? If I understand the 15 degrees correctly, it is higher degree turn because of the positive cant...I am assuming the 15 degrees ends up being more like a 6 degree steer but sounds larger because of the cant? Or am I way off? Haha, not sure.

 

[Brian Stanley]

DFW = Dominant Front Wheel - is the wheel on the front that steers in a three wheel rail rider set-up, most often this is the front right wheel.

 

[ClarkstonStrong]

Is there a jig out there that will do the front positive cant? I have one for the back (bought before I found this form). For steer should you have a bent axle or will you be able to tune without it?

 

[DerbyDad4Hire]

Bend your front axle with a straight drill.