Is it Magic?

[Brant]

Last night I was up at the local track for a test and tune session with my son. I had some new bodies I wanted to try out. The first was a .007 JK Lola Judd. I had been running a .010 JK Lola Judd, but my son wanted it back.

The track is a 60's American Orange and on the black lane my best time had been about 4.18 sec. with the .010 body. With the .007 body my time droped to 3.96 sec. That is a 5% change!
It held in the donut like it was on rails.

I'm new to this stuff, and it appears as magic. Does anyone have an explaination as how this works? Or do I have to write off the lower lap times to the alignment of the planets?

[Slotracer152]

if I'm not mistaken...the thinner body is much more flexible and almost acts as another pan....it basically allows for tighter handling

[Dan P]

Lighter bodies also give you a lower center of gravity, = a less "tippy" car.
Simple as that.

[Speedshop]

No serious racer would use a .010 body. Lighter is faster because of the lower center of gravity along with more body flex transfers weight on to your rear tires. When we choose race bodies we will check each body for lightness (not all .007 bodies are the same) and pick the light .007s. We even paint our cars with the lightest paint on the back to keep the weight down up high. With Gary King bodies that's black.

[Slotracer152]

personally I like a good .015 body on my FCR....it lets it slide around the corners well

[Dan P]

Lonnie, why not switch to a hard body on your FCR? And some old Cox hard rubber tires? Then you'd REALLY slide!!!!

TOO much fun !!!:D

[Brant]

Dan P.,

On the issue of the less weight of the .007 body, I went home last night, and with my kitchen scale, the .007 body measured in at 4 grams and the .010 measured in at 6 grams. The chassis and motor, a turbo flex with aluminum pan and falcon motor weights 92 grams. So the car weights 2% less with the .007 body.

Speedshop,

At first that didn't hit me as significant, but it is 2% more weight up high which would make the car tip or slide more easily, and reducing the weight did improve cornering significantly.

Slotracer152,

The .007 body is extremely flexible, but I don't understand your comment that it acts like a second pan. In fact I don't understand why the floating pan works better, but as an experiment I've tape the pan so it would not move relative to the chassis, and the car did handle terribly. So I know by experience that the pan has to float. Why, I don't know!

[Phil I.]

Taping the pans is a tuning device. If you need to loosen a car up, so the rear slides. A 1/4 by 1/2 peace on each side of the pans in the rear can help. I have a GT 1 car that doesn't handle with out taping the back & the body, depending on the track.
Phil I.;)

[Aubin 3 sixteen]

I've even seen some of the big name racers do the following. While the fron wheel wells do not need to be cut out, what they did was punch a small hole with a hole punch where the center of the front wheel (wheel, HAHAHAHAHA!!) would be, then cut a straight line up to the hole. This (it was explained to me) allows the front of the body to flex even more. It seems especially effective on higher bodies like NASCAR.

[wayne h]

imho, the thinner body lets the chassis do what it was designed to do - that is, flex. a stiff (thick body) is kind of like adding tape to the chassis - it restricts movement. also, the interior (how heavy it is and how it is mounted) and bullet-proofing (where and how much) also affects handling. just try running a body with no interior or bullet-proofing and you will quickly see just how important these items are.

wayne h.

[Speedshop]

With flexi cars (they should be called stiff cars) your pan must move to create a slide in the turn. With no pan movement your car would either tilt or chatter. With this slide your car becomes much more forgiving and faster through the turns. This slide is created by pan movement. When your car gets to the turn and starts to turn the pan slides over and allows the tires to slip and slide some through the turn. The tighter or less movement your pan has the more traction your car sill have. Of course everything is a trade off and a tighter car will be less forgiving.

For a loose track with less traction we tape the front of the pan to the front chassis ears on a Champion Turbo Flex chassis to reduce pan movement to only up and down movement in the back. This gives us more traction. When the track tightens up with more traction we remove the tape, loosen the pan and your car becomes more forgiving. We also tune the pan by restricting it's up and down movement. For more traction place a piece of King bullit proofing on top of the pan under the cotter key. This restricts the up and down movement. I never tape my chassis at the back of the pan as it doesn't work near as well. We also use .050 steel tubing in place of the body clips to isolate our body from the chassis creating more body movement. This will make your car more forgiving without losing speed. There is a lot more to flexi car racing than it appears at first glance.

[Brant]

Thanks to all that have contributed to this thread.

Speedshop,

You said a lot in those last two paragraphs. I've made a hard copy of your post for reference. It will take me a few sessions at the track to try all that you offered.

Brant

[Quickerthanu]

wow.. way to dig out an OLD THREAD! LOL

The tubes will float! Some of the Sonic retainers soldered to the tube will keep tube independent from the chassis.
This means the body is mounted to the tubes, and not persay to the chassis, thus allowing the body to flex and move much more then if the body clips were used.
How should the body meet the chassis for best handling? That depends on the track, body, chassis, etc.... Sometimes you want the body as forward as possible, and sometimes as far back as possible... Thats up to you to figure out!

[Quickerthanu]

Do you grind out the holes in the chassis for the tubes? No

How far from the chassis do you solder the retainers to the tube? 0.030"-0.050"

How much side play should the tube have? Just a little bit

What do you do when the motor is in the way of putting tubes in? Like the cheetah 11? You bend the tube to go around the motor.. A little less movement then normal, but none the less it still works

Do you have any photos? Sorry i do not, havent raced Scale cars in about 4 years

Josh B.