Crazy Alignment Idea:

[Jewel]

Consider drilling small holes about .050 in diameter into the axles down about ½ an inch. The depth should be right at where the axle intersects the car body. Then take a .050 rod, like a drill blank and insert it into the axle and bend the axle into good LBW alignment.

This may be easier than using the shims and you could converge on good alignment faster. The attraction of using the rods is so that you would avoid creating an arc when bending the axle. I think bending the axles for alignment is fairly common, but could this method produce better results than shimming? A problem with shimming is getting the axels back in the car body correctly, they will rotate and you will need to add witness marks to the axle heads to get consistent results. You may also bend your axels and perhaps damage the wheels by removing and adding an shim, and then doing it many times to converge on a good alignment. The many times of removing the wheel, checking and adding a shim opens up the potential for errors.

I think a draw back with this approach is getting good control of the bend, so maybe the drill blanks would help and reduce the number of variables so good results could be achieved.

[RACER X]

Not a bad idea, my only concern would be durability.

A standard B.S.A. axle is around .088" before treatment, a .050" hole would leave only a .019" thick axle wall. I would be afraid that it would not hold alignment.

Maybe, once you have established your alighnment, you could fill the hole with something like epoxy or J.B.Weld or added durability?

Another thought would be to use the larger Awana axle it is .092". It is not a lot bigger, but they are nice.

[DuckBoy]

One "tip" I read, is where a person cut a slot in the nail head so a screw driver could be used to rotate the nail when trying to align the wheels. Not sure if this is what you were lokoing to do?

[Jewel]

Duckboy,

The idea behind the rods inserted into the axles is to be able to accurately adjust toe in and toe out and positive and negative camber. You know when your car is running well when the wheels neither move in or out of the car body when rolled backwards or forwards. The axles are in a neutral position and the wheels can role free in this state. And you want your car to track perfectly straight. If you achieve this condition you have a very fast car. Go read Stan Pope’s book if you have not already, it will help you make the best car that you can.

[Stan Pope]

getting good control of the bend

Control of the bend is a big concern. How do you "add another tenth of a degree? How do you prevent overshoot?

If that issue can be ovecome, then the bend produces another concern. The orientation of the axle in the car body becomes more critical as the bend angle increases. There might also be a concern about increasing the torque that would twist the axle in the hole.

I think that these concerns are better served by leaving the axle straight.

From the point of view of a typical Cub Scout family, every one of them has a friend or acquaintance with a drill press and a willingness to help them drill axle holes. Most of those friends/acquaintances can help them set up so that the holes are "kinda close to perpendicular" and are "pretty close to the right place" and accomplish all of this with acceptable safety risk.

Only a small handful can access general purpose tools to accomplish high precision cutting and instrumentation to measure the precision of their results.

ProTools appoaches the problem with specialized tools at a modest cost and, if I understand the assertions correctly, with results that are sufficiently close to exact that no precision measurement is needed to reach final (i.e. race-ready) state.

Stan approaches the problem by accepting the results that most Cub Scouts can produce with commonly available general purpose tools and applying knowledge (technique) and minimal instrumentation to reach final state.

I think that both approaches have merit. Both produce superior cars.

The answer to the "which is better" question (if one demands an answer) depends on the value that the individual places on various aspects of the process.

[DuckBoy]

Jewel - Sorry, I misread your post. I thought you were looking at a way to rotate the axel in the slot/hole.

[Jewel]

Control of the axle is a pretty big issue in building your winning car. The shim method is great because it is so simple and can produce great results for cub scouts and their parents without using precision tooling. But it can be tricky to get it really good and take hours of testing. I blew out (made oversize) my axle holes after putting in too many shims. I did this because I had a slight bend in my axles and no witness mark on the axles to always insert them with the same orientation. I ended up both shimming and rotating the axles the night before the race to get the car ready, I finally got it pretty good and the car was fast. So I am considering other techniques, or just doing a better job with the shims.

There are other ways besides shimming to control the position of your axle. You could try rotating and bending, and you could try setscrews and rotating around pivot points to adjust the cars alignment.

I am fortunate enough to have access to precision machining and our annual derby is an all-adult race at a manufacturing company, so it is fun to consider other options.

I got a number 60 .040 drill blank out and it is a very stiff piece of material. The axle wall thickness of a BSA .088 axle would be .024, using the 60 drill blank as an adjustment rod. Is a .024 wall strong to race reliably? The rear axle has about 2 oz. Of weight on it and should not hit really rough bumps on the track that will knock the axle out of alignment. The drill blank is about 2 inches long and it should be inserted about .400 into the axle, could the control be fine enough to compete with an excellent alignment done by shimming?

The extra time of making the axles carefully may save hours in getting a great alignment as you prep your car for racing.