Setting rear axle Negative camber

[Speedster]

If you must use the standard axle slots. The rear of the car needs to be at least a 1/2" over the rear axle slot. Drill a tiny hole up through the axle slot at the area where the point end of the nail becomes round. Drill a 1/4" hole from the top of the car down toward the axle slot leaving enough of that tiny hole for a screw to hold solid. Insert a #2 x 1/2" round head brass screw (Lowes) into the hole and screw it in until you see the pointy end come out in the axle slot. Remove the screw and grind the pointy end flat. Insert the screw back into the hole until the flat end of the screw is even with the top of the slot. Remove the spacer on the Pro Axle Guide. Clamp the Pro Axle Guide to the car. Don't worry about scratching the paint with the clamp. It will be covered with a decal later. Insert the rear axles using a drill press if possible. Do not remove the Pro Axle Guide from right to left wheels. Notch a credit card for wheel to body clearance. Hopefully the rear axles are now straight. Remove the Pro Axle guide. Turn each screw 1/2 turn and test car so wheels stay out against heads of nails while rolling forward and backward. Keep turning screws 1/4 turn until you get what you need. Don't go any farther than you have to and your wheels should still sit flat if your rules state they must. Glue axles. Cover the holes with your favorite decal. I recommend Skull and Crossbones, Black Widow Spiders, or Coffins if your car is going to be named "The Undertaker". OK.... Just Kidding. Good Luck.

[FatSebastian]

[Speedster]

This will never hang in the Toledo Museum of Art. Hopefully this will help those who do not have the skill (Me) to drill angled axle holes.

[rpcarpe]

Here I've been using The Block to drill angled axle holes.
The upside... our rules allow extended wheel base.

[Stan Pope]

Interesting discussion!

I've observed that very small errors in axle orientation can have severe effects on performance. Typical Cub Scout axles come "out of the box" with enough "lack of straightness" to have those "severe effects." Even "straightened" using commercially available tools, those Cub Scout axles still leave toe error even though the holes and/or the adjustments (alignment screw in initial post) are themselves true. The screw adjustment affects one dimension of axle orientation: camber. Toe still depends on trueness of the hole/slot AND on straightness of the axle.

For those of us who must run Cub Scout axles, we still need to be able to tweak camber AND toe, OR we must have multiple finished axles to swap in so as to pick the best.

The popular "twisting bent axles" approach to alignment is still a one dimensional adjustment, but it works well for those who are permitted to have camber, since the "null" for optimum camber is quite wide, allowing the sharp null for toe to be satisfied. The screw adjustment in the initial post gives the builder one more alignment mechanism to adjust within that broad camber null.

The suggested "glue in" after alignment is complete is probably a really good idea since the screw adjustment appears to leave substantial unresolved tension within and between components.

[Speedster]

Once again I'm thankful I'm not racing in Mr. Pope's District. I will admit I have never used a nail out of the box. Speaking of nails, MaxV has nails made. Has anyone with the equipment ever tested a few of them to see how straight they are, their circumference?
Thanks to everyone on DT for all your help.

[Speedster]

My wife just told me my 1st sentence in the previous post sounded sarcastic. If anyone took it that way, Forgive Me. It was meant to be humorous. I admire Stan Pope.
Bill Klingler

[whodathunkit]

Speedster,

Are the brass screws you're useing corse thread or fine threads?
For finer negative camber adjustments i'd go with the fine theads.

Whats the thread count on the brass screws you're useing?

Seen lots of cars with this type of set up where alot of them were useing a corse thread set screws.
Would a finer thread be easier to dial in for adjustments?

Whoda.

[Noskills]

Speedster,
Interesting idea here. Looks simple enough that I might try it. I will admit that I am worried about trying to drill axel holes. I did buy the Silver bullet but it is not intuitive how to use it. Also it seems like slight errors in axel holes can wreak havor. I have watched all of Sporty's videos and so far I am still confused. Need to practice with the drill press I guess.
Seth

[FatSebastian]

Some might also be interested in the DVD Physics and the Pinewood Derby, which recommends an alignment method involving precision set screws.

[Speedster]

A quick history. My friend, Wil, who taught me this, is out of the pinewood derby. His son took 1st place in the District 4 out of the 5 years he raced. He was beaten the 5th year by another rail rider. The rail rider that beat him was caught with bent axles. I gave him a set of raw axles out of the box. The Head judge and I watched him push the axles into the car and the car was then impounded. We were not allowed to use graphite at the time so I don't know what he had on the wheels. I watched the car take 1st place. Wil's son took 3rd. Another friend from my Pack took 2nd place and was using Doc Jobe's oil.
The brass screws are a coarse thread. There are 5/16" of threads on the 1/2" screw and as nearly as I can count there are 7 threads. I do not open the axle slots before building the car. The axles goes in tight. I don't know if a fine thread screw is available or if it would hold in the soft wood. The two cars I have built so far seems to have given me what I want the first time. I have not yet tested them on my track. Stan Pope has told us the "toe" is more critical than the amount of camber and that's true. However, setting perfect "tow" on the rear axles gives me nightmares. For those builders who depend a lot on the straightness of the slot, this one simple adjustment might give them an advantage over a car that has the wheels bouncing around on the nail. With our rules we cannot go very far with camber and this technique gives a controlled way to hopefully give my scouts a bit of an advantage. I guess Time will Tell.
Cheers,
Speedster