COG Advice

[Black Fox]

Greeting Gents

I need a quick memory refreshing about COG (Center of Gravity). I know on a standard BSA wheel base the COG is about 3/4~1 inch forward of the axle. On an extended wheel base is the COG still the same?

Thanks

[Stan Pope]

Greeting Gents

I need a quick memory refreshing about COG (Center of Gravity). I know on a standard BSA wheel base the COG is about 3/4~1 inch forward of the axle. On an extended wheel base is the COG still the same?

Thanks

Usually, set the CM at the rearmost location for which you still have control over the car. If you can't keep it from dancing about (by adjusting DFW Toe), then push the CM further forward. Then look for the CM that gives the best time at your track's length. Guys that know say longer track = longer flat = need for less DFW Toe in Resistance = less extreme CM location.

On wheelbase ...
CM location controls the weight distribution between front (DFW) and rear (combined). The weight carried by the DFW, in turn controls how effectively the Toe-in manages DFW off-rail excursions. More weight, less toe-in!

However ...
To extend the wheelbase you may sacrifice some potential energy for the same DFW Weight. The fraction is small, and if extending allows you to move the rear axles farther back, the CM May end up farther back as well. Check out the actuals adn choose between

Also if extending the wheelbase results in too little weight on the DFW, you may have to ease off in order to control the dancing.

On a 32' track you can get by with smaller CM Loc ... Grandson's car liked 0.41" CM loc on the test track, but danced uncontrolably at 0.40". With toe angles adjusted for best times, 0.41" was better than 0.42", 0.43" ... Still, We left something in the car, so we might have been better off to race at 0.42 or 0.43". Dunno ... Given that it was a race of "graphite attrition", there are a lot of unknowns to influence results. The intent was that by the finals, each car was running on memories of graphite!, so axle and bore preparation optimization may have been critical.

[Speedster]

Stan, don't you just really Dislike those "Unknowns"?
Did you by any chance use "Red Rocket" or any other type wax before applying graphite? Did your competition? Do you think wax could be a benefit? Does wax fall into the "Unknown" category?

[Stan Pope]

I'm in the "interested spectator" group regarding Wax with graphite.

The unknowns is what keeps me coming back year after year. That and a list of unfinished "to do"'s. Maybe this is the year I do a "start to finish video of a complete 3-minute alignment" that someone asked for a year or so ago.