Rail rider pulling opposite way? How to fix it?

[Slalom]

HI. So we have car built, looks really sharp good aggressive COG, aligned rear wheels using sporty's technique with front wheels off, some scotch tape and lube under the front. rear wheels aligned, ride on axle hub back and forth, sanded off 1/8th inch from DFW. Still even with DFW just kissing the rail, rear wheel does as well. So I did stan's technique of accomodating by toeing rear wheels. Once past threshold that brought rear wheel off the rail, the DFW had to be toed out in order to get even semi reasonable drift to rail. This seems to be not a good situation with the front and back fighting hard and twisting to maintain good alignment. SO I shaved another 16th inch or so off the DFW side, re aligned, and exact same thing....what am I missing? Pictures to follow

[Slalom]

[Slalom]

[Slalom]

[Slalom]

[Slalom]

[sporty]

Thanks for sharing. The pictures, reveal, Some canting issue on the rail rider wheel, not enough cant and not enough drift.. But the rears Show some alignment issues, toe out issues on one of them, looks pretty far out of alignment.

Id recommend, doing a new car and starting over at this point. Your can try fixing it with turning and rotating axles to fix issues. but likely bent axles needed to use to try and correct. However looks pretty severe to me on that one rear,.

Sporty

[Slalom]

Thanks!, they are bent axles, so maybe, i will try to tweak. Race is tomorrow. I use a level tuning board and an 8 foot track. The axles are grooved so it is diificult to adjust the angle without bending within the groove which would obviously be bad, maybe i will swap out axles, and start over. The axle holes in the car are all true, so I don't think I need to rebuild the car itself.

Again...thank you very much for your expert opinion.

ned

[Slalom]

i think that possibly the toe out issue on the right rear may be whats pulling the left rear into the rail? The confusing thing is that when doing the thumb tack front wheels off thing the car goes straight as an arrow for 5 feet, the car has even weight distribution.

[Stan Pope]

The alignment adjustments needed here are part of my "5-minute tune-up" aimed at rear AND front misalignments. Of course, the "5 minutes" applies becasue I have already spent the half-hour or so to construct the tools!

The details are at http://www.stanpope.net/camalign.php?rail=right.

When working with youngsters, it is much better to help them bring their car "up to snuff" than to tell them to "start over"! The difference between the two methods is not in the resulting performance ... it is in being able to pull an axle and replace the axle without rechecking alignment!

[sporty]

ya, best guess that left rear axle needs some real tuning adjustment, but your rail rider wheel, needs more cant, its not near enough, if needs to be and likely some of your trouble of getting the drift right. The axle needs to be bent more and down more, It should almost look like the outside of the edge near the knubs is the only area touching the track.

Sporty

[JSG]

Another thing to look at is that the rears stay at the axle head (away from the body) when rolling the car forward AND backward. If the rears are towed out and you only check the forward roll you'll think you have good alignment. But when you roll the car backwards they'll go into the body telling you they are misaligned.

[Speedster]

I've noticed a few times advice was given to put a piece of tape under the nose when setting rear wheel alignment. The car is now at an angle. When you raise the car to put the front wheels on you now change the toe on the back wheels. I don't see how you could ever get satisfactory alignment this way. I measure the distance from the ground to the bottom of the car with the micrometers with the DFW on. I then file a push pin so the car sets the exact height, with a piece of scotch tape and graphite on it, as it does when it is setting on its wheels. Rear wheel alignment then stays exactly where I've set it. This has always worked well for me.

[Slalom]

Thank you guys we have districts today.


Problem: rear wheels aligned with negative camber (bent axles). DFW positive camber with perfect toe-in. DFW inset at least 1/16th inch. Non dominant rear wheel still rides rail lightly. this can be overcome by adjusting dominant rear wheel to steer the car. Does this slow car if steering is occuring from the rear and not the the dfw? I straighten the DFW toe so that the car is not "twisting"

[Stan Pope]

Ned,

Rear wheel steering does not necessarily slow the car.

What happens is this: So long as the DFW stays on the rail, the rear axle which carries the most weight will steer the rear of the car left or right until the axle is perpendicular to the rail. The other rear wheel will go along with it, willingly or unwillingly, depending upon its alignment, with little effect upon the car's direction. The more willingly that off-side rear follows, the better the car will perform.

I provided a method to perform bent axle alignment which is less sensitive to the degree of bend in the axles than the "forward/reverse roll" in my web page at http://www.stanpope.net/camalign.php?rail=right.