Here we go again with brake problems

[Tommy]

Tom,
You don't mention what "poor brakes" means, so I will assume it means you cannot apply enough pressure to the brake pedal to lock the brakes at 40 MPH on a dry, clean road.

My EM is very different from yours, but it also has manual brakes and stops fine. Here are some things to consider in sorting out your brakes. To begin, you can ignore all the stuff between the brake pedal and the calipers. The basic laws of physics are that the force you apply to the pedal multiplied by the distance it travels is equal to the force applied by the caliper pistons to the brake pads multiplied by the distance the pistons travel. Of course the balance bar and differences between the front and rear calipers will distribute that force and motion differently between the front and rear, but the totals will all add up. One thing that can reduce piston travel is expansion of your brake lines under pressure. If you have any rubber lines that are expanding when you apply the brakes, they will decrease your braking effectiveness.

The clamping force of the calipers on the discs can be affected by the types of brake pads and the size of the discs. One of the first things I would suggest is to get more aggressive pads. These can cause side effects such as excess brake dust and rapid wear of parts, but they will stop better. Mounting the calipers farther from the centers of the wheels on larger diameter discs can improve the stopping force, but it can also increase the angular momentum of the wheels/tires/discs that the calipers have to stop. Keep in mind that the brake actually stops the disc that stops the wheel that stops the tire that stops the car. If you have especially large or heavy wheels or tires, your car will not stop as well.

Finally, a few words about the balance bar. If you cannot press the brake pedal hard enough to lock either the front or rear tires, it doesn't matter where it is set. As the front tires do about 70% of the braking in a hard stop, you want the balance bar initially set to apply more pressure to the front. It is also widely accepted that it is safer to have the front tires lock up before the rear in a panic stop. So in making any adjustments to your brakes, I suggest you focus on the front system first.