2nd Year Head Scratcher...

[Allagash]

Hi Everyone,

This is my son's second year participating in the Pinewood Derby. Last year as a Tiger...he placed in the pack derby and went on to win the regionals. I was amazed. His best run (on what I believe was a 42' Best Track aluminum track) was 3.04 at the regionals. I credit his success to my purchasing David Meade's book and following the principals outlined within. We used no "specialty tools" such as the ones listed on David's website (last year). We did not bend the rear axles and tune them for the wheels to ride out to the axle heads...however with a screwdriver and a hammer we did bend the dominant front wheel axle a bit to make a rail rider that drifted about an inch or two per 5' of travel on a level wooden board. We raised the right front wheel so as not to touch the track. We polished the axles up to 2500 grit. We polished the inside of the wheel hubs with pipe cleaner and tooth paste. We had never built these little cars before and blindly did what the book told us to do...and it worked. We actually built two somewhat identical cars and raced them against each other at the Tiger derby (before the pack derby) and the faster one he raced with at the pack derby and the other one his sister raced at the open derby after the pack derby and won. They were almost as fast as each other.

This year, I figured we'd take the principles in the book and use them again only I would purchase some of the specialty tools off David's site: Body Jig, Hub Tool, Rail Rider Tool, Axle Press, Outer Hub Shaver, and Wheel Mandrell. I also purchased from various sources off of eBay and Amazon sand paper in the grits of 3,000; 4,000; 6,000; and 8,000.

My son and I used all of these tools to the best of our ability. We put the finishing touches on the car the other night and raced it against last years winner on a board and last years car beat the pants off this years car! On a 5 foot run on a level board lifted three inches at one end, last years car was easily 3/4 car length ahead. My son was dissapointed to say the least. I assured him that the pack derby isn't for a couple of weeks and that we had time to keep working and figure it out. I also told him (as I have all along) that just because he came in first last year didn't mean he would even place this year but we would try our best and have fun either way.

Some of the things we did differently this year that I have questions about are:

We used the hub shaver tool to cut off that little edge on the outer portion of the hub. I feel as though we may have shaved off too much of that little edge on the wheel and made the outer wheel hub not as round at that edge as they would have been had we left them alone.

We bored out the wheel hubs with the bore hub tool. I felt weird doing this as I feel (however I'm no engineer) that a tighter fit of the hub on the axle would allow for less wheel wobble. Last year we did nothing to the hub except run the pipe cleaner with toothpaste through it for five or ten seconds.

We polished the axles to 8,000 grit.

We used the Raid Rider Tool and axle press to bend the rear axles 2.5* and the dominant front wheel 1.5*. We tuned the axles with needle nosed pliers per David's instructions.

We used David's formula of graphite that he sells on his site in a little glass jar. It's called Bullet Lube. Last year we used fine graphite purchased at the hardware store.

Last year we followed David's method of "breaking in" the car by trying to brush graphite down into the hubs with a small paint brush once the car was together and then spinning the wheels with a dremel tool and soft buffing wheel. This year I thought I'd take it one step further and do this before we put the wheels on the car. We took each wheel and polished axle combo and poured graphite into the hub loosely filling it and then pushing the axle through the graphite. My son then held the end of the axle that was not polished and spun the axles with the buffing wheel. He did this for probably 3 or 4 minutes per wheel axle combo refilling the hub with graphite every minute or so.

When I spin the wheels on last years car, they spin extremely quietly and for a long time with no wobble or chatter at all. When we spin the wheels on this years car they seem to chatter and wobble and don't spin very quietly. I think my problem is with the wheels. I'm considering trying different wheel combos to test how long they spin and if they seem to spin true.

Is there a better way to polish the inside of the hubs?

Should we not "break in" the car the way we did it this year?

How important is it to use matched wheels from molds 2,8,12, and 15 such as the ones sold off David's site? Can good results be had with any wheel number combinations?

We will humbly and graciously take any and all advice you guys can give us. Also, is there a thread on here that gives a step by step guide to what the more "modern" approach to building these fun little cars is? I keep reading how David's book is a great foundation to get you going but that in the past year or two, you guys have come up with some fresh ideas to car building that have made the book a bit intiquated.

Thanks!

[Speedster]

A place to start would be in the Post, Graphite selection/testing? Go to the end and find Sporty's technique in preparing the wheels. Others will give you better advice than I on other things.
Best of Luck.

[FatSebastian]

Allagash! If you are using Meade's book as a starting point, I refer you to this post which outlines how advice on DT deviates the book (and includes a link to Sporty's bore-prep process). Keep in mind that the BSA redesigned their wheels starting in 2009, and much of Meade's advice applies to the pre-2009 wheels.

Hopefully your questions will stimulate a lot of added discussion, but for now...

We used the hub shaver tool to cut off that little edge on the outer portion of the hub.

Opinions vary on the necessity to remove the stepped hub. IMO you are probably okay to leave it intact as long as you polish and lubricate the underside of the axle head and wheel.

This year I thought I'd take it one step further and do this before we put the wheels on the car.

Generally speaking, excessive graphite "break-in" can abrade the wheel bores. It is possible to lubricate too much.

When I spin the wheels on last years car, they spin extremely quietly and for a long time with no wobble or chatter at all. [...] I think my problem is with the wheels.

Wheels from last season were from earlier stock, with more and more people are reporting that the quality of wheels are getting noticeably worse over time.

We bored out the wheel hubs with the bore hub tool.

This is probably unnecessary on the newer BSA wheels, and may even mess up the bore.

[Aron]

I would agree....Check out Sportys bore prep process. I use it....works great. I would also be careful using needle nose pliers......you could damage the axles, i would suggest getting axle pliers from max v

[sporty]

Allagash,


I am glad that the book and the products helped you and you're son.


I am always glad when any product or book or video can hlep families improve there skills and performance in Pinewood derby.

However,

There are more than a few of us, that feel. Much of the information and some of those products sold. were at the expense of others who put in the hard work and time and testing. Then only see the credit go elsewhere.

Thats about all I am going to say, or I will end up on a venting spree.


Welcome to Derby Talk.

Here you will find lots of information and help, To further improve your skills and knowledge.

Sporty

[Allagash]

Thanks for the replies guys. Just a few more questions...

Is there a video or post with pictures of Sporty's wheel prep process?

Do you guys recommend using the old style wheels if I can? I have a bag of wheels to choose from and I think some are the old style.

Thanks!

[FatSebastian]

Do you guys recommend using the old style wheels if I can?

Some have theorized that the older (heavier) wheels might "out-last" the newer (lighter) wheels, but unless you are racing on an abnormally long track, I cannot imagine a benefit in using the old-style wheels.

[sporty]

Allagash,




http://www.derbytalk.com/viewtopic.php?f=11&t=4995" target="_blank

[pgosselin]

Welcome to the board.

I've been in your shoes. Had a son who won the entire Pack and got 2nd place at District his Tiger year. Then had two not-so-good years. Then won the Pack again this year thanks to the help and advice on this board.

There are a number of things that could be affecting your son's car. I think you are wise to suspect the wheels. I'd get a matched set and prepare the bores using Sporty's method and see if that makes a difference. If you did well without shaving the wheels down last year, why do it this year? If you're correct, you should see a major improvement.

Since you are racing them down an inverted board, you're not seeing how they transition to the flat part of the track so you don't know the whole picture. It could be better on the straightaway than the old car.

I'd also look closely at your rear alignment to make sure that it's running perfectly straight and one or both wheels aren't toeing in our out. That can slow you down out of the gate. Sporty has a pretty simple method for checking that. He's also posted some videos of it.

Good luck.

Paul