Thread: Brake troubles

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In my case the discs are very close to the same size, so no advantage. The point I was trying to make is that in many cases, street rods are built using what parts are available or will fit. That doesn't mean they are going to work together.

In the case of GM metric calipers, typically they have a 2.496 bore in the front. The rears can range from about 1.88 to over 2". Choose the wrong bore and you can wind up with a situation that has the front brakes stopping the car, while the rears never do much of anything. If the fronts are too much larger than the rears, the line pressure required to allow the fronts to stop the car will be too low to allow the rears to offer much clamping force. In most cases, you're never going to want more braking on the rear that the front, but you do want a relationship that allows complimentary action. Bore size, for me, is just a convenient way to compare.

My Ford calipers are actually closer in bore size than some combinations of GM parts. I agree that area is a probably a better description, but bore size will work as long as you understand that bore size will determine area.

Originally Posted by Hotrod46

. If the fronts are too much larger than the rears, the line pressure required to allow the fronts to stop the car will be too low to allow the rears to offer much clamping force.

1st thing to check!