Pack Winner- but looking for Speed Advice!!!

[tkp]

Thanks again to you all for helping us over the last 4 years!!! (although we finally created a profile in 07- but read most posts on this site prior)

2009- lucky again- 1st in Pack!!! On to districts….

We raced on a Super Track- (plastic) his av time over 4 runs was 3.05.
We want to break 3.0 for next year but meanwhile he has to focus on Districts!


Approaches

• Baked block- to lighten it
• Final wood only body roughly .5 oz.
• 3 wheeler- right front wheel- 1-2 mm off ground
• 1 inches COG in front of rear axle
• Aerodynamics/smooth finish and rounded everywhere- took our time on sanding.
• Axles- deburred, sanded, polished
• Wheels- deburred, hub rounded, graphite, letters sanded off lightly for friction and less weight used 1.6 g wheels, but are the approved wheels.
• Canted rear axles-very slight helped with stability some
• Alignment- dead on frontward’s and backwards!
• Graphite- Hob e lube-
• Low COG- bottom of car and centererd-low as possible-very low- can’t get lower.
• 1/16 space between wheel and car body.
• Dense COG- tungsten all in the same area- 3.5 oz
• Tungsten weights-7 cylinders. Put 6 just in front of rear axle on bottom of car and then put the other 1 in the back of the real axle- ie another .5oz. The weight with both should now be 3.5 oz. However, he also uses a well underneath to add weight on race day- we added about .25 Total added weight 3.75.
• Used spray on paint this year and was much lighter
• Also used clear coat spray and again much lighter
• Broke in car wheels/axles with soft dremmel head- wheels could easily spin over 20-25 seconds and not touch body with the spin of your finger. (not bad for lighter wheels!)
• Ran it down our test track a few times- flat and slope testing etc.
• No shimmy on track from car- ran fairly smooth.
• Graphited the heck out of the body, wheels, axles, etc- hob e lube
• Total weight 4.95 oz.
• Could not extend wheel base.
• Could not extend/move wood in any fashion
• Could not move axle slots or use drilled holes
• Plastic Super Track- had to prepare for spot on alignment and of course had to prep the outside of the wheels as there was no middle guide rail. We lightly sanded, polished and graphited the heck on the outside tires/lettering.



Areas of improvement for next year/Districts:
• Use 7/8 or 3/4 COG
• use more canting
• perhaps tighter wheel/body relationship- ie 1/32
• ensure the tires ride all the time toward the axle head




Questions
• Does graphiting the Tread help?
• Could go lighter wheels but in testing- but we wore 1 wheel out and had to replace?
• What other items can we do to decrease our times?
• Does turning the car around and having short end on the front provide any advantage? I noticed the 2nd place car did this.


We feel we have done about all we know of to date.
We still feel that for Districts in order to crack the top 3, we are still roughly a car behind.
What can we do to pick up the needed 6 inches to get in the top 3?

Any advice would be much appreciated!
We'll post a pic soon,

thanks in advance,

One happy cub and dad.

[roosclan]

Mar 21, 2009 18:40:34 GMT -6 tkp said:

T
Approaches

• Baked block- to lighten it
• Final wood roughly ,5 oz.
• 3 wheeler- right front wheel- 1-2 mm off ground
• Weight 1 inches COG in front of rear axle
• Aerodynamics/smooth finish and rounded everywhere- took our time on sanding.
• Axles- deburred, sanded, polished
• Wheels- deburred, hub rounded, graphite, letters sanded off lightly for friction and less weight used 1.6 g wheels, but are the approved wheels.
• Canted rear axles-very slight helped with stability some
• Alignment- dead on frontward’s and backwards!
• Graphite- Hob e lube-
• Low COG- bottom of car and centererd-low as possible-very low- can’t get lower.
• 1/16 space between wheel and car body.
• Dense COG- tungsten all in the same area- 3.5 oz
• Tungsten weights-7 cylinders. Put 6 just in front of rear axle on bottom of car and then put the other 1 in the back of the real axle- ie another .5oz. The weight with both should now be 4.0
• Used spray on paint this year and was much lighter
• Also used clear coat spray and again much lighter
• Broke in car wheels/axles with soft dremmel head- wheels could easily spin over 20-25 seconds and not touch body with the spin of your finger. (not bad for lighter wheels!)
• Ran it down our test track a few times- flat and slope testing etc.
• No shimmy on track from car- ran fairly smooth.
• Graphited the heck out of the body, wheels, axles, etc- hob e lube
• Total weight 4.95 oz.
• Could not extend wheel base.
• Could not extend/move wood in any fashion
• Could not move axle slots or use drilled holes
• Plastic Super Track- had to prepare for spot on alignment and of course had to prep the outside of the wheels as there was no middle guide rail. We lightly sanded, polished and graphited the heck on the outside tires/lettering.



Areas of improvement for next year/Districts:
• Use 7/8 or 3/4 COG
• use more canting
• perhaps tighter wheel/body relationship- ie 1/32
• ensure the tires ride all the time toward the axle head

Good job on the win! Do you have a picture of your car?

Does your District use the same plastic track or do they use something better? It looks like you've done just about everything you can for your situation. Your speed beat my oldest son's fastest time last year on a Best Track (3.060s) and he won Grand Champion in our District.

Questions
• Does graphiting the Tread help?
• Could go lighter wheels but in testing- but we wore 1 wheel out and had to replace?
• What other items can we do to decrease our times?
• Does turning the car around and having short end on the front provide any advantage? I noticed the 2nd place car did this.


We feel we have done about all we know of to date.
We still feel that for Districts in order to crack the top 3, we are still roughly a car behind.
What can we do to pick up the needed 6 inches to get in the top 3?

Any advice would be much appreciated!
We'll post a pic soon,

thanks in advance,

One happy cub and dad.

Do not turn the car around. You want the wheels as far back as possible, as this will keep your CoM as far back as possible. There is debate about graphite on the tread. On some tracks it seems to help, on others it doesn't. I have no idea if it has even been tested on a plastic track.

If you are a full car length behind, then you are really far behind. Move your CoM back to 3/4" if the slope of your track is a gentle one.
Get some tungsten putty and get your car right up to 5.0 oz. Our cars run 4.996 - 4.998oz.
What kind of prep did you do on the wheel bores? Polish them and then burnish them with graphite.
Other than canting the wheels more, lightening the wheels more (to 1.1g) and really fine tuning your alignment even better, I can't think of anything else.

[tkp]

Not the greatest pics, but this will give you an idea.....

[tkp]

Thanks for the advice. What makes it tough is that now our District uses a wooden track and of course rail riding would be the way to go. Not sure we want to spend all of the time to reconfigure.

But we will use the tungsten putty idea for sure.

Also to clarify, every time we go to districts my son's car is "about" a car length behind the champion. We'll see how this car fairs up. We basically are right on their rear bumper- so to speak!

In the past he can crack the top 6-10, but cant seem to get in the top 3.

Can you tell me about "burnish with graphite". We graphite it up prior to putting the wheels on and of course after etc, but not sure what burnish means.

One thing that would be easy to do for districts however, is that I can move .25 oz of (race day weight) and move it back further.

This may get him slightly under 1 inch cog- maybe 7/8!

This will be our first time on a wooden track as typically they used the Super Track in the past.


thanks again!

[khouse]

I would move the COG to 1/2 inch. Then when you rail ride there is less friction. Turn your car about 6 inches in 6 feet. Like said above. Get closer to 5 oz. Cant the rear wheels 2 to 2.5 degrees. Make sure you adjust your rear wheels where they ride to the axle head in BOTH forward and reverse. That is very important! That plus all the others tips will get you below 3 seconds! Burnishing - Take a polished axle and chuck it and your wheel to a drill or drill press. I use 600 rpm. Then load it up with graphite. While spinning the axle hold the wheel. Without turning the wheel apply pressure from the wheel all the way around the axle. This will burn in your graphite and polish the hub too. Try it on a bad wheel first for practice.