Brake Bias and Brake Cylinders

Brake Bias

Brake bias is a straight forward adjustment that you likely already understand, but just for completeness I wanted to add this small section. By decreasing the brake bias number in iRacing you are applying more braking force to the rear tires and less to the front tires. By increasing the brake bias number, you are apply more braking force to the front tires than the rear tires.

If you apply more brake force to the rear tires (i.e. smaller bias number) then the car will oversteer more while trail braking and also will tend to have a slightly shorter braking distance. If you apply more brake force to the front tires (ie. larger bias number) then the car will understeer more while trail braking and also tend to have a longer braking distance.

Having said that there have been some cars in iRacing where I have felt that moving the bias forward somehow gave the car more steering on trail braking, which did not really make sense and does not happen most of the time but try it out for the car you are driving to see what happens.

Brake Cylinders

Larger brake cylinders require more brake pedal pressure to achieve the same braking force, and can be used to tune how you are braking to be more in line with the brake threshold or abs engagement of the car (i.e. where the tires begin to lock). For example, if you are finding that you are hitting the abs or locking the tires easily try a larger brake cylinder as that requires more pedal pressure to achieve the amount of braking force as a smaller brake cylinder.

You can also use different brake cylinder sizes front and rear to effectively change the brake bias and the brake ramp up differential front to rear. For example, if you had a 50% brake bias with the same brake cylinder sizes front and rear and then went to a smaller rear brake cylinder this effectively moves the brake bias more rearward. However, this is slightly different than just changing the brake bias, because of the rate at which the brake forces ramps up is now different front to rear, with the rear reaching a high brake force more quickly than the front. In this example the car would have a more rear bias on trail braking but if you are near the abs threshold (on cars that have abs) the rear would engage abs at that limit before the front tires, giving the front tires more grip.

In general, I have not liked having different brake cylinder sizes front and rear as for me I feel it can create less predictable or at least less intuitive balance behaviours. For me I like using the brake cylinder sizes to reduce or increase the overall braking sensitivity of the car. For example, if I keep getting into the abs, I just go up one size on both the front and rear brake cylinders and that always helps me stay out of abs or reduce locking.

Handling Scenarios

For me I like using the brake bias for balance and the brake cylinder size for brake sensitivity and avoid using split cylinder sizes front to rear, but having said that here are the changes you can make to affect the car handling balance, but I have also added a section for reducing the tendency of getting into abs.

Loose Off Power

• Move brake bias forward

• Increase rear brake cylinder size or decrease front bake cylinder size

Push Off Power

• Move brake bias rear

• Decrease rear brake cylinder size or increase front brake clyinder size

Reduce locking or tendency of engaging abs

• Increase brake cylinder size equally both front and rear.