Electrathon America Forum

Zaine Stapleton · Senior Member

Steering Geometry, Camber angles

Kyle Keenan · Veteran Member

In "full size" car racing, by adding "Negative camber(Wheels leaning in)" we are able to increase the size of the contact patch while cornering.

I too have wondered the benifit to doing so with Electrathon cars, as typically we are not at 10/10ths in terms of possible speed for the cars.

mhodgertt · EA President

I told the guys that build car #110 that they had way too much camber when they were building it. I have found that with the type of wheels/bearing we have that no camber or just 2-5 degrees is 'usually' the best. If you add too much camber (like 110) the sealed bearings in our moped front tires tend to have more drag as they ride on the outside race. These bearings are meant to be used on cycles so are not designed for a 'tipped' wheel. Car #107 did very well with lots of camber this year but I still think they would have been able to travel about 1/2 a mile farther in each race if their wheels had been nearly straight. They are just all very good drivers and their car is very light and well made outside of the camber.

Some teams think that having a large negative camber helps on corners as the outside wheel will 'dig in' more if it is at a strong angle. Instead of this I gave my car a very large (25 degree) rake or caster and my wheels are nearly straight up. This way, when I turn both of the front wheels are at an angle and dig in. I tell my students to have at least a 10 degree caster. If you get much more than this it is harder to get you steering alignment right. Mine is not perfect and I had to play with it a lot to get it as close as it is. But my car corners great.

Hope to see you all at the Eugene Celebration Race August 28th and 29th.

MIke

Zaine Stapleton · Senior Member

If you have heim joints in your steering system where the wheel is held by the kingpin, does it make a difference in how far you can go in a race due to the drag made by the camber you put in? The geometry would change, but would it really have any significant effect in slowing you down? Thought I might ask, I may try it for next season when racing in the adult class.

meangreen · teacher / board member

Resurrecting an old topic here... I'm an old stock car racer and, as Kyle said, camber adjustments are used to increase the contact patch of the front tires in a corner. Not so in Electrathon, though...

To begin with, changing the camber on bicycle tires makes little or no difference in the contact patch because the tire tread cross-section is basically round. When used on a bicycle, the wheels endure very little side-stress; the bicycle is leaned into a corner so gravity and centrifugal force combine to put the stress straight down the length of the spokes. The stress that the spokes "see" is always the same whether going straight or turning. In Electrathon we use the wheels in a situation where they are held in a fixed position (vertically) and forced to go around corners without the ability to lean into the corner. The spokes are "loaded" and "unloaded" relative to their position at any given moment as the wheel rotates. Eventually they may fatigue and break. The reason for negative camber is to relieve some of the stress on the spokes on the outside wheel. Since we can't lean into the corner, negative camber is one type of compromise to help the spokes "live" longer. The cars in my avatar picture have 7* negative camber and 7* positive caster. Mike uses some pretty extreme caster with 0 camber to accomplish the same thing. There are pros and cons to both methods... confuse