Weighting tips for standard base

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
Post Reply
Topspin.D
Master Pine Head
Master Pine Head
Posts: 183
Joined: Wed Jun 13, 2012 12:10 am
Location: Kirkland, Washington

Weighting tips for standard base

Post by Topspin.D » Sun Jan 25, 2015 3:02 pm

Image

We're doing a few fender cars this year with standard wheel base. Because we're doing full fenders (think nellie faye style) the wheels will be about the normal slot locations. This means there's room for more cubes behind the rear axle. Any advice on weighting this style car? Go with three rows or two in front and two behind like a extended base car?

Thought about adding to Sporty's thread but didn't want to detour that.

Thanks



User avatar
pwrd by tungsten
Master Pine Head
Master Pine Head
Posts: 723
Joined: Wed May 24, 2006 1:51 am
Location: Seattle, WA

Re: Weighting tips for standard base

Post by pwrd by tungsten » Mon Jan 26, 2015 3:49 am

I would try for a COM of 5/8" to 3/4" with the weight as close to the rear axle as possible (leave a nice amount for a solid rear axle of course) and likely evenly placed between front and back of axle. You will have to measure with the car and wheels. On a new build I make two cars and sacrifice one to get the weight placement nailed. Really not necessary here. Tape the weights in and then measure the com with wheels and axles in place. I usually use spare wheels and axles for this (just be sure to not place an unfinished axle in a wheel bore).


W Racing!!!!

Topspin.D
Master Pine Head
Master Pine Head
Posts: 183
Joined: Wed Jun 13, 2012 12:10 am
Location: Kirkland, Washington

Re: Weighting tips for standard base

Post by Topspin.D » Tue Jan 27, 2015 12:11 am

Thanks... we have done very well in the past with extended wheel base cars and 1/2"-3/4" COM where we've got 2 oz behind and 2 oz in-front of the axles, but the one standard wheel base (same as slots) car I built with the aggressive COM was really really bad.

I'm thinking of cutting out the full 3/4" behind the rear axel and playing with moving 2 - 3 oz between an aft pocket and 1-2 oz in front of the axles. Thanks for the suggestion about tape. I'll give that a whirl on the test track (provided my wife approves re-assembling it this far before the race... 6 wks out).



User avatar
pwrd by tungsten
Master Pine Head
Master Pine Head
Posts: 723
Joined: Wed May 24, 2006 1:51 am
Location: Seattle, WA

Re: Weighting tips for standard base

Post by pwrd by tungsten » Tue Jan 27, 2015 3:40 am

With a standard wheel base car you really want the COM between 5/8 and 3/4. You don't want to be more aggressive than that. The sloppier the build the longer the COM. Many cars simply do better at 3/4" and that is at the PRO level... though many PRO cars are at 5/8.


W Racing!!!!

User avatar
Noskills
Master Pine Head
Master Pine Head
Posts: 787
Joined: Tue Jan 31, 2012 1:37 pm
Location: Bellevue, WA

Re: Weighting tips for standard base

Post by Noskills » Wed Jan 28, 2015 5:51 pm

Dave,
Our district winner last year was a extended front end car. Based on a suggestion by Sporty I went with less weight behind the rear axel. Two rows of 5 cubes. Then 13 in front. Forgot our COM. Look up my post on "Stampy cat" car. We had picks and details.
Noskills


"Nunchuk skills... bowhunting skills... pinewood derby skills... Girls only want boyfriends who have great skills!"
Napoleon Dynamite

Post Reply