Axle and wheel alignment

[alaroche00]

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!

[PinewoodPerformance]

2.5 to 3 deg is a good angle to set most cars up at. Remember, the negative camber in the rear only helps if the toe angle is 0 deg, its is not a set-it and forget thing like most think. Your rear toe is effected by the ride height of the car over its total length. if the front is higher then the rears will be toed out and if the front is lower than the rear it will be toed in (toe and adjustment is shown in the Derby Worx Pro Rail rider video) there is a lot of speed in the rears to be gained or lost that is greatly overlooked. Take your time and learn to make the proper adjustments.

On the front dominant wheel, 2.5 to 3 deg is good as well, if it is a smooth track, use positive camber (top tilted out) and set your steer at 3.5" to 4" over 4' with a CG of 5/8" in front of the rear axle.

This will give you a very solid / basic rail rider alignment that should run very well.

[ginger1990]

You have the angle direction correct for front and back. 2.5-3.0 degrees is a ballpark on rears. Having rear axle holes drilled perfectly aligned from each other is a great start but does not deliver perfect alignment of wheels/axles. You have to account for the clearance between axle journal diamiter and wheel bore diamiter when weight on wheels. They will settle in being out of sync with each other. To compensate, having slight bend in axle with a tunning groove, you can make small adjustments that will provide HUGE speed gains. My cars in every class of fat wheel cars run best when rear angle is very shallow. If wheel quality isnt very good, a steeper angle may be required. The front angle in general needs a little more angle and that depends on type of wheel and the finished surface on inside tread edge. Once rears get dialed in, play with slightly different front angles. You'd be surprised how much speed you pick up when the sweet spot is found. The better the car is tunne the less steer you'll need. Majority of all my non bearing cars have between 1 3/4" to 2.5" of steer over a 40" distance of travel on tuning board. They can run faster with less on my single lane track but you must account for dirty airflow from cars racing next to yours, thus, little more steer to keep on the rail. CG on all my cars are as far back as I can make them, about 1/2 inch. My DF axle hole is drilled .032 higher than rears for a 5" wheel base. Lower for shorter wheel base. I personally build to be slightly lower in front to no more than perfectly even. Being slightly higher in front is a speed killer.

[RacerX]

Spot On Ginger 1990!