Center Of Gravity

General topics of interest to racers and race coordinators alike.
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Black Fox
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Center Of Gravity

Post by Black Fox »

Greetings Gents

My sons in the process of building his PWD car for Cub Scout.

Just need a little refresher on the CG. I know 5/8 to 3/4 in front of the rear axle on a standards wheel base is ideal. His is currently a little less that 5/8. I know if its too short your rear end will start to wiggle. So I'm just wonder if I'm pushing it with this CG.

By the way, the weights are 2.8 oz.

Thanks
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Scrollsawer
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Re: Center Of Gravity

Post by Scrollsawer »

We've run several 3/8" COG cars on an extended wheelbase, raised wheel, and rail-riding with no problems. Ours almost always use 1/4" tungsten cubes for weighting. I don't recommend you go this aggressive unless your Pack's rules allow you to drill an extended wheelbase, and even then, I'd be less concerned with COG location, and more concerned with getting as much weight as possible evenly located immediately aft and immediately forward of your rear axle location.

Do you have to use the pre-made slots that come with the wood block, or can you drill your own holes into the block for the axles? COG location, while important, is somewhat dependent on your Pack's Derby rules.

Use the search bar in the upper right section of this site, and search on COG (or 'center of mass'). You'll get tons of good information on what is best for your axle locations.

Good luck!

Scrollsawer
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whodathunkit
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Re: Center Of Gravity

Post by whodathunkit »

:welcome: Black Fox,
Scrollsawer wrote: Do you have to use the pre-made slots that come with the wood block, or can you drill your own holes into the block for the axles? COG location, while important, is somewhat dependent on your Pack's Derby rules.
Nowadays Guys ..
you can also cut and make new axle slots in the block
thanks to the new DW pro body slotter tool thats out.
http://www.derbyworx.com/products/tools ... y-slotter/" target="_blank

If your pack derby rules will allow for extended wheel base cars..
you can cut new slots or drill axle holes.
With the tools that are out now,
I'm curious to see how the rules for extended wheel base might change using the axle slots rule
or if drilling axle holes, will change, or if they even change at all.

Whoda.
What type of automobile can be spelled the same forwards & backwards?
Black Fox
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Re: Center Of Gravity

Post by Black Fox »

We have to use a standard wheel base. And the axle holes have been drilled with the Jewkes block with the rear wheels canted.
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whodathunkit
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Re: Center Of Gravity

Post by whodathunkit »

Black Fox,

Stan Pope, Will tell you as a general rule" that longer tracks will benefit slightly from a less
aggressive weighting... plus the less aggressive weighting reguires less toe-in on the DFW
in order to maintain controle.

Check out the weighting & center of gravity on short vs longer track topic. ;)
http://www.derbytalk.com/viewtopic.php? ... cog#p71333" target="_blank
What type of automobile can be spelled the same forwards & backwards?
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