Mid-Build Evaluation: On to the hard part-Alignment -Advice?

[Gregg H]

My son is a Bear scout. I posted back in December about "upping" our game a bit. With my oldest two boys we have had success at the pack level, each usually winning his den, and twice the pack race. Three of our cars have set the track record (28' wooden, 3 laner). Then we go to districts and get beaten badly (middle of the places) on the six-lane 42' aluminum track. So this year my youngest, who has raced at districts a few times now wants to win there and go to council. Historically I have invested little in time and money - used lead, basic tools, not done rail-riding, though I have canted the backs, prepped the axles through sanding up to 2500, polished the wheel bores minimally, and typical graphite lube (required by rule).

For this year we have finished the body work - cut it, shaped it, weighted it, and painted it. I have attached 2 pics of the bodies, top and bottom. We are building two cars and going to use the fastest one. We have a stock wheel base by rules, typical 5 oz weight limit. These two bodies weigh 4.35 and 4.45 each. Wheels/axles will get them up to just under 5oz. The main difference in regard to weights are 12 cubes behind the axles on one (COM of 1/2"!), and 10 behind the other (COM 5/8"). I have positioned the weight such that it falls in the "triangle of speed" made by the rear two wheels and the DFW. Weight change to tungsten, and I can immediately tell the difference and know we have picked up some speed there, I just don't know how much. The slightly lower profile helps and getting more weight behind the back wheels. I have usually run with a COM of 3/4", but lead sits higher and the weight is in the axle plane now. He wants to just leave the paint as is (very cool Aqua color) and just buff it up and make it shine (to be done next to last step), but nothing else to potentially slow it down. No problem there. I have shaved 1/16" off the DFW side in preparation for railriding. If anyone sees anything out of whack to this point, I welcome criticism and advice.




Now we begin what I consider to be the hard part, mainly because I haven't done much regarding the wheel bore prep, and alignment. Comments on my process in each of those three areas are welcome.

WHEEL BORE PREP: I plan to have my son polish with Sporty's method using Micromesh on a carbon rod, up to 12,000. Seems straight forward and the videos I have found on it help a lot. He will polish up a bunch of wheel bores (must use BSA with kit wheels or colored) and pick out some good rolling ones. We cannot lighten the wheels, so this is all we can do to them. Is it worth my sons time to make three different types of wheels: 1)rears, 2)Front dominates, 3)Raised front (unaltered)?

AXLE PREP: We have done good axle prep, but not for railriders. I want to bend the front axle slightly. I have a 4 3/8" wheelbase and need less steer. I have drilled positive cant into the DFW hole of 2 1/2 degrees. The rear axles, it seems, play a different role, with the axle heads creating friction. The raised wheel should do nothing, theoretically. I plan to have my son just do a bunch of them right now and pick the best of the litter. So, is it worth my sons time to make three different types of axles? 1)Rear axles (with tapered heads), 2)Dominant Fronts (slight bend), 3)raised front (unaltered) being the three categories, so each can specialize in the different job they have, is my thought. How do others deal with the different roles of the axles during the build? As for axle bending, I have searched and found some older topics on how to bend axles without a special tool. Do the regulars here have a fool-proof axle bending method? Also, I have read elsewhere that coating the axles in Pledge (furniture polish) positively increases the work of the graphite. We can do anything we want to the axles according to the rules, but we must use the ones from the kit. Any opinions on this?

ALIGNMENT: Finally, to wrap up this lengthy post, I have built a little 16' test track and will be shooting for the 1" drift over 4 feet. I read about. I know the theory behind rail-riding, have read on it, and know about aligning the rears first, then adjust the DFW to move to the rail. It seems like a trial-assess-adjust-trial process more or less. Am I missing something? Other secrets to share in this process? I have always done the best I could with my eye, and it has worked out, but I know now that we need to be more scientific to take the next step, and get more finicky about fine details if getting better results at Districts and then hopefully Council, are to be had.

Anyway, rip me apart fellas. I am coachable on this subject. Sorry for the long post.

[whodathunkit]

Also, I have read elsewhere that coating the axles in Pledge (furniture polish) positively increases the work of the graphite. We can do anything we want to the axles according to the rules, but we must use the ones from the kit. Any opinions on this?

Well Gregg H,
Stan Pope once told me to find a way to incress the diameter of the axle.

If you look at the Ingredients that make up Pledge Furniture Polish
you'll notice some differences with there formulas latly.

The old pledge on the axles trick has been around for awhile.. so this tip is not new at all.

Pledge has several different types of furniture polish out on the market.

orange clean in an orange can..
dust & allergen light blue can..
extra moisturizing brown can..
speclalty surfaces in a yellow & silver can..
and even one called favor furniture polish.

If you look at the ingreadients and formulas you'll see some have two types of film formers.

Ingreadients like:
Water (carrier)
PDMS.. Dimethicone (film former)
Octyiphosphonic acid (corrosion inhibiter)
Nitrogen (propllant)
Polysobate 80 (emulsifier)
PDMS..Polydimethylsiloxane (film former)
Amiomethyle propanol (ph adjuster)
Fragrance from SC Johnson fragrance palette (fragrance)
Proprietary Thickening Agent (thickener)
Methylisothiazolinone (preservative)

For the orange clean it has an extra emulsifer know as sorbitan oleate.
It's an emulsifer derived from sugar!
And then the extra moisturizing has an extra (carrier) know as soparaffin.

Well, is it the PDMS that interact with the graphite.
or is the PDMS that in-large the size of the axle?

[Stan Pope]

Also, I have read elsewhere that coating the axles in Pledge (furniture polish) positively increases the work of the graphite. We can do anything we want to the axles according to the rules, but we must use the ones from the kit. Any opinions on this?

Well Gregg H,
Stan Pope once told me to find a way to incress the diameter of the axle.

If you look at the Ingredients that make up Pledge Furniture Polish
you'll notice some differences with there formulas lately.
....
or is the PDMS that in-large the size of the axle?

Good, you are thinking; bad, thin films are too slow to build up the axle diameter.

This is not to say that Lemon Pledge is not a good idea, though... some swear by it, and others just enjoy the scent!

[Shawn Stebleton]

ALIGNMENT: Finally, to wrap up this lengthy post, I have built a little 16' test track and will be shooting for the 1" drift over 4 feet. I read about. I know the theory behind rail-riding, have read on it, and know about aligning the rears first, then adjust the DFW to move to the rail. It seems like a trial-assess-adjust-trial process more or less. Am I missing something? Other secrets to share in this process?

Allow a good amount of time for alignment. Sometimes things go well right away, and sometimes they don't. It's allowing for when they don't that can make the day. We spent about 2 hours aligning due to time constraints, and it showed. Last year, we spent about 5 or 6 hours getting the alignment right on the rears.

The amount of drift will be dependent on CoM, to a degree. The more aggressive the CoM, the higher the drift. My son won 1st place in district last year with 8" in 4' drift, with CoM at a little more than 1/2". His car ran straight down the track, running that rail perfectly. We tried getting less drift (everyone on the board here seemed to agree that we had too much) this year, and his car wobbled all over the place with 3" in 4'. He did have the fastest run of the day by 0.001 sec, even with the wobbles, but the the other two runs were not so good. I believe part was due to the lesser drift, and part due to the alignment not being spot-on in the rears.

We don't have any test track whatsoever and every derby he and his older brother were in was run without testing. We don't have room or funds for a test track, and now that both of my boys are done with Pinewood Derby, we have no need for one. If you can afford a full length track, at least 28', that would be wonderful. I'm sure that if we had had a test track we would have discovered the wobbles problem ahead of time and corrected it by dialing in the drift and/or tweaking the rear alignment. Overall, in 8 district derbies we had 2 1st place, 2 2nd place, 2 4th place, 1 approx 5th place (no timer that year--double elim), and 1 12th place, I think my boys did very well. They had fun building with dad and learned and experienced a lot. That's the best part of it.

If I could set up one single lane track with no space or budget worries, I'd probably get the Challenger plating and set it up in various ways to emulate as near as possible the types of arcs or curves the car would likely race on. This would include mimicking the 2' radius Best Track curve and the Piantedosi/Microwizard Classic and Freedom curve. I might even throw in a bad joint, just to see how cars would handle it.

[Stan Pope]

ALIGNMENT: Finally, to wrap up this lengthy post, I have built a little 16' test track and will be shooting for the 1" drift over 4 feet. I read about. I know the theory behind rail-riding, have read on it, and know about aligning the rears first, then adjust the DFW to move to the rail. It seems like a trial-assess-adjust-trial process more or less. Am I missing something? Other secrets to share in this process? I have always done the best I could with my eye, and it has worked out, but I know now that we need to be more scientific to take the next step, and get more finicky about fine details if getting better results at Districts and then hopefully Council, are to be had.

My recommendation is a bit different from others ... divide the process into two distinct phases: 1. Rears and 2. DFW toe. This leaves the simple assessment / adjustments (DFW toe-in) for such "test and tune" time as your organizer may provide.

Now, first what can you do without a test track? You should be able to align the rears to track well together and to follow the DFW appropriately off the rail without going near a real track. And, if it takes more than 15 minutes, you haven't learned the method yet.

Rears Method: Establish enough bend in the axles to trim the path. It doesn't take much if you have drilled camber, but if you are working from "straight" holes then 2 or 3 degrees of bend will be necessary. Set some DFW toe-in ... not critical, just enough to keep the DFW on the test rail during rear alignment. Arrange to bias each rear wheel in turn to be dominant by temporarily adding weight to cause each rear wheel to carry about a half ounce more than the other. I use clip-on weights so that I can quickly switch rear wheel dominance. Decide on a distance that you want the wheel behind the DFW to run. Drawing a line on a short (e.g. 30") test section will be helpful. Alternating dominant rear wheels, adjust so that the wheel behind the DFW "runs the line." Two consecutive tests, one on each side, that require no adjustment signals DONE! See http://www.stanpope.net/bentaxlealign.htm for ideas on bias weights and more detail on the method.

A recently suggested process can follow the above. Once the rear alignment is really close, then a reverse roll might signal more improvement. See http://www.derbytalk.com/viewtopic.php?f=11&t=7556. I have not needed to do this, since when the alternating bias adjustments above says "DONE", subsequent attempts to improve times on the track by tweaking the non-dominant rear wheel's toe hurts times. If you do use the method, you can pull the car forward to establish the line for the DFW-side rear to follow, then roll in reverse to maximize the distance before the rear wheel deviates more than X inches from the line. As before, alternately bias the rear wheels for dominance, adjusting only the then dominant wheel.

These "rears" methods work well with just about any reasonable amount of camber you want to use. You don't have to worry about the shallow null that the forward/reverse roll test has when dealing with cambers exceeding 2.5 degrees.

DFW Method: (Don't mess with the rears anymore! They are where they need to be!)
1. No test/tune time on any track is available. Set drift on your alignment board to "very small" if your DFW weight approaches 1 ounce, and increase the toe-in drift as the DFW weight reduces toward 1/2 ounce. If in doubt, add a little toe-in!
2. Best - Use the test/tune time your organizations provides to relieve the drift until the car no longer "holds onto" the rail. Then increase the toe-in until it hold the rail on all lanes. If a timer is allowed, use its results to help make the decision, but it isn't critical for good results.

[Noskills]

I have only anecdotal drift guidance for you. You have heard that a more aggressive COM and shorter wheelbase requires more drift. In my extended wheelbase cars with COMs of 5/8th to 7/8th I have used 2 to 4 in over 4 feet. All very smooth. I just moved to stock wheelbase this year and made cars with a COM of 5/8th to 6/8th. Drift was 3 in over 4 feet. 2 wobbled a little, one was perfect. So I would suggest that with a stock wheelbase and a COM on 4/8th that you go closer to 4 in over 4 feet. Just my

Noskills

[whodathunkit]

Good, you are thinking; bad, thin films are too slow to build up the axle diameter.
This is not to say that Lemon Pledge is not a good idea, though... some swear by it, and others just enjoy the scent!

Do some sware by it because of thinking..
that silione film spayed on the axle will cover the fine scratches and that the graphite powder
will be absorbed into the silione film.
And try it because of thinking..
That the results of useing silicone sprays on the axles will also build up a thin layer
of graphite coating embedded in the silione spray on the axles.
And that maybe more heat races can be run:
with the car with less sheading of the graphite off the axles.

This seems to be the theory behind using silione sprays on the axles.

[Stan Pope]

... Lemon Pledge ...

Do some sware by it because of thinking...

Never figured out just why they were swearing so vehemently!

Don't know if the life-span of Lemon Pledge is longer than straight silicone lube. Michael L (IIRC) reported that silicone lube worked very well, but did not have a long life span like graphite.

[whodathunkit]

Your good Stan!
And I was hopeing you would say what you said about it not lasting.

I'd like to see the rules go back to the way it was when it first started..
( no lubes at all..) just good ol' bump and grind racing.

[Stan Pope]

...I'd like to see the rules go back to the way it was when it first started..
( no lubes at all..) just good ol' bump and grind racing.

That would be way too hard to inspect!

[whodathunkit]

What happend to your paper under the wheels tip!
Or to rolling the car over white paper or to useing a paper strip around the wheel bores..
To check for the lubes?

I thought this was a very good idea.

[Stan Pope]

What happend to your paper under the wheels tip!
Or to rolling the car over white paper or to useing a paper strip around the wheel bores..
To check for the lubes?

I thought this was a very good idea.

Okay in your district, but ...

Do you remember every crazy thing I ever said?

[resullivan]

Lol, some of the recommendations on here

[Gregg H]

Thanks for the suggestions here fellas, they will come in handy when we go to tune this week. I am sure I will learn a lot.

Stan, just a point of clarification from you please. When you discussed aligning the rears, are you suggesting that even if I have drilled a 2.5 degree negative cant that I should use bent axles for the rear axles? If so, how much of a bend are we talking?

Cheers,
Gregg

[Stan Pope]

Thanks for the suggestions here fellas, they will come in handy when we go to tune this week. I am sure I will learn a lot.

Stan, just a point of clarification from you please. When you discussed aligning the rears, are you suggesting that even if I have drilled a 2.5 degree negative cant that I should use bent axles for the rear axles? If so, how much of a bend are we talking?

Cheers,
Gregg

Gregg,

My experience with BSA axles is that all come with enough bend that true drilled axle holes are not sufficient to guarantee best alignment. You can probably use the axle's inherent bend to true up the alignment.

If you have straightened the axles with something like a ProAxle Press, there may still be enough bend, but you may have to add a bit. Obviously you would not need the 2.5 (or there-a-bouts) degrees of bend; a half degree or so should do it.

The basis for this observation go back to when I was aligning rears to run straight and level and adjusting axle orientation using shims. There was always a point at which adding one shim caused the car to go from a hesitating start to a free and easy start. That difference translates to a quicker start and to reduced losses on the flat.

Next question is if you are using machined axles... Is alignment best? Probably, if your holes are truly true. If you are after top racing results, then alignment is worth verifying ... and correcting if found even slightly deficient. Some would drill a new body. Since I'm usually working with cars that already have some youngster's significant time investment, I go with showing him how to add some bend to the axle and align what he brought.