Check out my pinewood derby car.

[David]

Ever since I was a kid, I looked forward to building a derby car for the dad's (and mom's) class. My son is moving to boy scouts soon (and I won't be cubmaster anymore!!!) so this is my last chance to build the car I've thought about for so long (my son build his own). I haven't decided on paint yet, but I'm leaning toward red due to time constraints:

[RickM]

Very nice job! Putting decals on?

[M.D. Holloway]

For your axle lube, go with dry moly instead of graphite - let me know if you need some. Nice job by the way! (White would look great as well)

[johncj8989]

[Overpaid Slacker]

Nice! Then again, with plans and drawings THAT serious, it should be nice.

JP

[David]

My original plan was to use a CNC machine, but I've only used basic power tools. I couldn't find a 962 model for decals, but I did find a 996 GT3 model so I'll have some cool decals.

[911pcars]

A Dad's or Mom's class is a great idea. That should leave some kids the opportunity to build their own and provides parents a chance to revisit childhood with modern woodworking tools at their disposal.

Have fun,
Sherwood

[mede8er]

Don't forget to put some 'lead' in the nose......

[David]

Originally posted by mede8er
Don't forget to put some 'lead' in the nose......

Actually, since the car starts on an incline the back of the car is the highest point so that's where the weight goes. Remember Potential Energy = mass * gravity * height. Mass and gravity are fixed by rules and laws of nature but you can maximize height. Another tip, lead has a density of 0.41 lbs/in^3 and tungsten has a density of 0.697 lbs/in^3, with tungsten you can get the weight farther back. Just don't put it so far back that the car does wheelies down the track like the dragster I made two years ago.

[gaijindabe]

What about the underside?? I see you are keeping that secret...

Everyone knows ground effects are the cutting edge in pinewood derby.

[David]

Due to some horrific crashes last year we've outlawed side skirts but rear diffusers are still legal.

[M.D. Holloway]

What about your axle lube? Any consideration on molybdenum disulfide?

[asphaltgambler]

Holy s--t!! Are those the blueprints for the car?? Looks like build plans for the stealth bomber!

[David]

The prints are for a piece of crap 30 year old circulator pump case we're working on.

I've alway thought molybdenum disulfide was better suited to high temp applications. I don't have any data comparing graphite to moly. I've always used micro graphite lube, but there's another engineer in the pack that works for Exxon and I've always suspected he has a better axle lubricant.

This is all the detail I used for cutting the wood:

[M.D. Holloway]

Exxon! Blast you man! Don't you know those guys are devil incarnate! Just kidding - actually, graphite has better high temp performance but moly doe a great job of plating onto the metal surface and is real tough to get off. PM me you shipping address and I shall send you out samples of each and let you make up your mind - do you perfer powder form or an aerosol?

[David]

Mike, thanks for the offer but the race is Saturday. Do you recommend a product and brand I could buy locally?

[red-beard]

Originally posted by LubeMaster77
What about your axle lube? Any consideration on molybdenum disulfide?

Swepco?

[M.D. Holloway]

no no no, Swepco won't do - to bad I didn't have an extra day I could have over-nighted you some. Not sure you can find any at the local hobby store - maybe the Grainger store front or Motion Industrys store front.

[David]

Here's the final car. I wanted to do a historically correct paint job but I didn't have the time or the decals. It ran pretty good, it came in second in the pack's masters class. The car that beat it was a thin pure speed car.

[klaucke]

Congrats.