Derby Talk is a forum for Pinewood Derby, Awana Grand Prix, Kub Kar Rally, Shape N Race Derby, Space Derby, Raingutter Regatta and other similar races where a child and an adult work together to create a race vehicle and a lot of fun and memories
Thanks again Speedster. It's unfortunate that I have to do this with bent axles, and the 4 wheels touching rule is just plain stupid!
Not to beat a dead horse but you said:
Speedster wrote:If you have Positive cant on both front wheels you will also have toe-in. They will be fighting each other all the way down the track and riding the rail.
Why do the fronts have to be fighting each other if I do positive cant on both? Can't I just set the more dominant one for toe in and the other front for slight toe out?
We have an "all 4 wheels touching, all across the tread" and "no bent axles" rule as well. But since our pack track has no center rail, we are just choosing to gamble it and tune for straight as possible. Our District is a month after the pack race, and it has a center rail, so we will decide then if we will try to make any changes (even though the district rules state "no Rail Riding" as well), I agree, the those rules are stupid! lol
In order for the four on the flour method to work right and be fast, when u have to do 4 wheel touching.
You have to have the front right wheel drift to the rail. At least doing 60% of the drift to 70% .
The non dom left front wheel. Has to do at least 10 to 20% toe out drift . To hole the car to the rail.
This also is c onnected with the axle bend. If you do to much axle bend on the right front wheel. The left wheel will not touch or work right. Giving you poor performance.
You do not want the left wheel to push into the car body as it roll s. Down the track.
Btw, I got terrible text typing lag, as I do this reply. Why is this ?
Due to new site?
In order for the four on the flour method to work right and be fast, when u have to do 4 wheel touching.
You have to have the front right wheel drift to the rail. At least doing 60% of the drift to 70% .
The non dom left front wheel. Has to do at least 10 to 20% toe out drift . To hole the car to the rail.
This also is c onnected with the axle bend. If you do to much axle bend on the right front wheel. The left wheel will not touch or work right. Giving you poor performance.
You do not want the left wheel to push into the car body as it roll s. Down the track.
Btw, I got terrible text typing lag, as I do this reply. Why is this ?
Due to new site?
I feel like I have a good understanding of what I need to do with the degree of drift for each front wheel but I am still curious about what cant/camber you're using for the front wheels. In my earlier post I linked someone's 4wheeler that appeared to have positive cant on both fronts.
Nelvis wrote: In my earlier post I linked someone's 4wheeler that appeared to have positive cant on both fronts.
That could be a "rail hugger" configuration. Both fronts rolling. Both tuned to run straight. Both indented.
If you look through his build photos though http://www.derbytalk.com/viewtopic.php? ... oor#p73578 you can see that he only indented one side. I'm wondering if the positive cant on both fronts makes it easier to keep both front wheels touching.
Got your message. What we did was build a 3 wheeled rail rider first. I then bent the "raised wheel" axle. We turned it so that it was touching just enough to be considered a "4 wheeled car." If you were to push the car to make it roll all four wheels would move. If you pushed the car from the back only 3 wheels would roll with the 4th only occasionally making contact.
Great thank you for the response. Did you find it easier to get the "raised" wheel to touch the floor slightly with the positive cant as opposed to a negative cant? Also did you put any toe out on the "raised" wheel or did you just keep it neutral? I think I'm going to try your method for the adult/sibling race and then stick with Sporty's method for our scout car. If I am understanding Sporty correctly I think he used a negative cant for the less dominant wheel and then added a very slight toe out to keep the car on the rail.
I do not remember paying attention to which way the wheel was canted. The wheel touched so slightly that I am not sure that it mattered. I do remember that we wanted the inside of the wheel to touch vs the outside of the wheel.
Assuming the right front wheel is the DFW, he built a 3 wheel rail rider. He then inserted the 4th wheel with a bent axle and had the inside of the wheel touching. That is Negative Cant. I'm assuming the head of the nail was at 12 o'clock when he started which would be Negative Cant and No toe. He then said, "We turned it so the wheel was touching". If he turned it backwards between 12 and 3 o'clock he would have Negative cant and toe-out. When he reached 3 o'clock he would have No Cant and maximum toe-out. If he turned it forward between 12 and 9 o'clock he would have Negative Cant and toe-in. When he reached 9 o'clock he would have no Cant and maximum Toe-In. It would be better to have Negative Cant and toe out because that would help the DFW stay on the rail.
This can be fun demonstrating it to your scout. I put some tungsten putty in a wheel bore and shove the nail through the putty and pack it a bit. This stops the wheel from flopping around because of the slop in the bore. Put the nail in a Pin Vise and slowly rotate the wheel and the scout can easily see the movement of the wheel.