SLOT CAR HANDLING & TIRE SELECTION
For maximum performance and control, the rear end of a slot car must break loose and "drift out" a little in the corners. This "power on" slide enables you to take the corners much faster than if the car just tracks following the slot.
THE "LOOSE" CAR - NOT ENOUGH TRACTION...
If the rear tires don't provide enough grip, the rear of the car will slide out too easily, or it may "fishtail" making it very difficult to control the car. The car will slide out until it can go no further because the guide flag is locked all the way to one side. At this point the car leaves the slot. This de-slot is the result of having not enough grip or traction.
THE "TIPPY" CAR - TO MUCH TRACTION...
A slot car can indeed have to much traction. When this happens the rear end of the car cannot "break loose" and slide out in a controlled power slide. The rear tires track tightly following the slot. But if the car is driven too fast, the car will suddenly tilt and the guide flag tips out of the slot. When a car is tilting out of the slot it usually will head straight into the wall. This happens very suddenly and makes it very difficult to race the car without de-slotting.
Another way a slot car can de-slot is when it is bouncing or chattering on the rear tires. This chattering can sometimes become so severe that the car actually bounces out of the slot. The chattering is very undesirable. It is usually caused by a broken chassis or motor mount, a bent wheel or axle, or worn out bushings.
THE "HAPPY" CAR...
When the car is set up properly, it will drift out into a controlled power slide. If you drive improperly, it may tilt out of the slot or it may slide out. It won't always de-slot in the same way. It will be much easier to drive and race than a car which always slides out or always tilts. By observing just how your car is de-slotting when you race it, you can tune it by changing things to make it run better.....
car swings out to easily.....
Try grippier or wider tires.
car tilts to easily....
Try firmer tires or narrow the width of the tires.
Try adding lead weight up front.
Are you using the proper size of tire? Tires that provide the minimum legal clearance will work best. Taller tires make the car tippy.
Remember that no combination or set up will work for all tracks. You must be ready to adjust and make changes on your car to suit the conditions you find.
Narrowing tires…. How? Why?
Adjusting the width of the tires is a very important tuning method to get maximum performance from your cars. The narrowing of tires is often necessary when your car has more than enough traction. In this condition, the car will tilt out of the slot. (The guide flag comes out first and the car won’t take the turn… it goes straight.)
Too much traction is common in glue racing, but it may also occur in spray glue or even in no glue racing.
The tire width should be adjusted by trial and error… just a little bit at a time until the cars’ rear end drifts out just a little in the corners as power is applied.
Trimming the tires…
The easiest way to do this is with one of the “tire machines” make for trimming and truing tires. These machines will rotate the tire as a cutting tool (a blade or needle) is forced into the rubber, taking a bit off the inside edge of the tire. It can also be accomplished by chucking an axle into a rotary tool or drill, and using an exacto to trim by hand. The tire machines are very nice because tires can easily be trimmed to exactly the same width. After the cutting, the square inside edge is rounded off by sanding it as it rotates with a fingernail sanding stick. Make the inside edge of the tire about the same radius as the outside edge. Some racers will prepare several sets of tires in this way at different widths to be prepared for any track conditions.
The amount of trimming will depend on the firmness and stickiness of the rubber as well as the amount of glue on the track. Start by trimming off just a little... you can always go back and trim off more. But if you make the tires too narrow, it’s impossible to put the rubber back on.
It is common to see Box 12, Cobalt 12, even 27 car tires trimmed so much so that part of the rim is exposed on the inside edge. Trimming tire width is an important tuning procedure that every slot racer should understand.
Some advantages of “properly trimmed” tires…
It reduces tilting and popping in the glue… can make a car easier to drive and race… often faster too.
Trimming tires reduces their mass, causing faster acceleration, better braking, and lowers the center of gravity of the car.
Trimmed tires will be faster on the straights – especially in glue.
Properly trimmed tires will allow your motors to run cooler and longer.