A rookie needs a little advice...

[beadlock]

Hello folks,

I'm a newbie so go easy...

I've been a reader to this forum for a while and now I need some advice from the pros. I guess it's time to jump in with all four feet.

This is my second year in Boy Scouts with my grandson as well as Pinewood Derby racing.

Last year we both had a blast building and competing with our PW car. He finished 3rd in his pack race and went on to the Scout-O-Rama where he finished 41st out of over 230 cars. I thought we did alright for neither one of us knowing what the heck we were doing. Needless to say, we were both hooked.

After reading this forum I decided that we should build (2) cars for this year and use the fastest of the (2) for competition.

We have finished both cars and I heard about a local AWANA event that was held tonight at a local church. I took both cars and after watching all of the competition, They were happy to let me take a couple of runs on the track with our (2) new cars. We have no other outlet for testing our cars.

Sorry for being so long winded but here's my situation:

We tried to build both cars as identical to each other as possible with the only difference being where we placed our weight. I went thru over (40) wheels and axles to come up with the best (8) for these cars. We straightened, polished and tapered the heads of the axles on both sets. We coned the hubs and polished the inside bores of the wheels. I feel that all (8) wheels and axles are as close as we could get them to each other. Both cars have a 3.00 oz tungsten weight inserted into the bottom of the cars. Both cars weigh exactly 5.00 oz on my scale.

Car #1 - We have a COM of 1.10" in front of the rear axle.

Car #2 - We have a COM of 0.90" in front of the rear axle.

The only other difference is when I used the PRO BODY TOOL to drill my axle holes in the slots provided, Car #1 ended up with the right front wheel slightly raised. All (4) wheels touch on a flat surface, but the RF axle rests against the upper portion of the wheel bore, so I guess you could say it sort of has a raised front wheel?

I only got to run these cars tonight (2) times swapping lanes for the second run. The track was a wooden track, 36 ft. long with about a 16 foot slope and only about a 20 ft. flat stretch.

Both runs were the same result. Both cars came down the incline together, with Car #1 pulling away in the last (4) or (5) feet to win by about a 1/2 car length.

Here's question #1 - Do you think the little bit of raised wheel effect I have on Car #1 offsets the weight displacement enough to be the faster car?

Question #2 - With our pack race coming up this Saturday, on a new Aluminum track with a much farther flat run out, which car would you experts use?

Keep in mind, at our pack race, they allow NO PRACTICE runs what-so-ever. You check your car in, it goes thru tech and then hits the track for the first time in qualifying races.

Again, sorry for the long book, but I wanted to explain the whole situation so I can get your expert feedback.

Thanks for reading and hey, this sport is addictive.

Any help would be greatly appreciated...Beadlock

[Sappington R]

Greetings Beadlock, welcome to the forum. It was a great idea to find a local Awana Race to test on. Track testing is definitely the way to go, however, there are some pretty fast builders (league) that don't use a test track.

To address a few of your questions, I would need to ask a few.

1. Are you allowed to run an EXT wheelbase? If so 3/4" seems to be about the right spot in front of the rear axle for C.O.G.

2. Are you required to have all four wheels down? If not, then the coefficient of friction will be reduced by 25% simply by raising a wheel.

3. Are you allowed to lighten the wheels by removing material from the inner walls? Lighter wheels will always perform better out of the gate (moment of inertia).

As you know there are many, many other factors in play, such as rail riding, and canting axles.

I believe that the two most critical speed tips that I ever learned from the experts were:

a) Raise a front wheel and steer the car by bending your front axle slightly on the down wheel into the rail so that the car migrates a couple inches to the center rail over about 6 feet ball park (so the dominant wheel touches the rail). When you are "table top" tuning, make sure that the rear wheels stay off the body in both a forward and reverse direction- this can be done by drilling straighter holes and by adding slight negative Camber- At first you may spend a lot of time "tuning" but as you get better it should go a lot quicker. One last thing: Make sure that the front wheel base is slightly more narrow than the RWB, like 1/16" on the FDW- this will ensure that the rear wheels don't touch the rail.

b) Don't be bashful or apologetic about asking alot of questions on the Message Board- it's a great resource and a lot of people will share info freely (as long as you aren't in their district )


Sapp

[beadlock]

Sapp,

Thanks for the reply.

To answer your questions:

1. We have to run the 4-3/8" wheel base slots that come with the car.

2. Yes, all (4) wheels must touch the track, and they do tech.

3. No, we can not lighten the wheels. We can cone the inside of the hub and polish the inside bores but nothing else.

Thanks again...Beadlock

PS - Boy this is a tough crowd. I already have a (-1) karma!

[derbydominator]

Hey Beadlock,

You're even on Karma now. No one should start behind. Weird, though. As far as your race is concerned, did you see any noticeable wobbles as it reached the flat stretch for either of the cars. If so, then, alignment needs to be worked on. Your COM's are pretty good for a wood track, but not as aggressive as you could be for an aluminum track if you could incorporate the rail rider technique. Not much time to do a lot of changes though obviously. A half a car length is a fair amount to make up so unless you see some significant alignment issues with the second car that could be addressed, the #1 car is the obvious choice. Did you get an idea of how your car compared to the others that ran that night? That will tell you as much as anything about your cars. If car 1 was pulling away right at the last, then that would suggest either you did a better job on the wheels and axles for that car or alignment is better and the second car was being overly impacted by speed wobbles. The difference in the COM's would generally be seen earlier in the flat section although one may be just noticing it a bit later. Best of luck to you on Saturday. Let us know how you do.

[beadlock]

Well, I was off on my dates. Hearing must be the first thing to go when you get old...

Our pak race is not until this next Saturday. Anyway, we went to visit my son-in-law in Nebraska this weekend and took my grandson's cars so he could sneak a peak to satisfy his interest. While we were at a Campfields store looking over their PWD inventory, we bumped into a gentleman with his son and he informed us that his pak was having their PWD races on Sunday, (today). He invited us to bring our cars and said we could run them in their adult open class.

We did just that. It was another wooden track, about (36) feet or so. They had (6) adult open cars and they ran them all at once on their (6) lane track. They ran (3) heats changing lanes for each one. Our car #1 won all (3) races and our car #2 was a close second on each heat. I guess Car #1 is the car we will use at our pak race.

I do have a question. We have now run (5) races and I am wondering if I should relube with graphite before our pak race this Saturday or leave the cars as is. There were no timers at any of these events that we just ran so I have no idea if our cars were beginning to slow down or not.

Any rule of thumb about how often a person should relube?

Thanks for any information...Beadlock

[beakerboysracing]

Mar 15, 2009 19:33:28 GMT -6 beadlock said:

Well, I was off on my dates. Hearing must be the first thing to go when you get old...

Our pak race is not until this next Saturday. Anyway, we went to visit my son-in-law in Nebraska this weekend and took my grandson's cars so he could sneak a peak to satisfy his interest. While we were at a Campfields store looking over their PWD inventory, we bumped into a gentleman with his son and he informed us that his pak was having their PWD races on Sunday, (today). He invited us to bring our cars and said we could run them in their adult open class.

We did just that. It was another wooden track, about (36) feet or so. They had (6) adult open cars and they ran them all at once on their (6) lane track. They ran (3) heats changing lanes for each one. Our car #1 won all (3) races and our car #2 was a close second on each heat. I guess Car #1 is the car we will use at our pak race.

I do have a question. We have now run (5) races and I am wondering if I should relube with graphite before our pak race this Saturday or leave the cars as is. There were no timers at any of these events that we just ran so I have no idea if our cars were beginning to slow down or not.

Any rule of thumb about how often a person should relube?

Thanks for any information...Beadlock

I like to lube and then run the car twice on the track before a race. I find my cars are at optimum speed after two runs and will start tailing off after 8 more runs. After about 30 or 40 runs, I take everything apart, clean, polish and relube again. Graphite will build up after allot of runs.

Definately relube, and spin wheels for a couple of minutes each if no track to run on.


Scott

Beakerboys