The Classic Opel Forums - View Single Post

bq97 · 02-10-2006

Here is what I’m looking at.

My GT has the stock sized master cylinder, 75 Manta sized rotors and calibers on the front, ¾” wheel cylinders on the back. All the components are new and the booster works fine. This set up is a vast improvement over the standard GT brakes. However, the most braking force is when the pedal is near the end of it’s travel with a single push of the pedal. If I pump the brakes a second time I get better braking force. To me that is an indication there is not enough fluid flow out of the master cylinder for the larger brake components. The system has been bleed repeatedly and there is no air in the lines. The rubber brake hoses have been replaced with new braided steel hoses.

A friend has 78 BMW 320i with a disc/drum setup. The BMW front brake components are the exact same as the ones on my GT. His car is 500+ pounds heavier. The braking distance for the BMW is less than the GTs if I don’t pump the GT brake pedal. If I pump the GT’s brake pedal the stopping distance is about equal. Both cars have the same brake pads.

I know the pedal geometry, tires, and a few other things also play a role in braking force but it would seem to me that since the brake components are the same it might be a good idea to use the same master cylinder as well.

Any thoughts?

02-10-2006	#7 (permalink)
bq97 Member Join Date: Sep 2003 Posts: 217	Here is what I’m looking at. My GT has the stock sized master cylinder, 75 Manta sized rotors and calibers on the front, ¾” wheel cylinders on the back. All the components are new and the booster works fine. This set up is a vast improvement over the standard GT brakes. However, the most braking force is when the pedal is near the end of it’s travel with a single push of the pedal. If I pump the brakes a second time I get better braking force. To me that is an indication there is not enough fluid flow out of the master cylinder for the larger brake components. The system has been bleed repeatedly and there is no air in the lines. The rubber brake hoses have been replaced with new braided steel hoses. A friend has 78 BMW 320i with a disc/drum setup. The BMW front brake components are the exact same as the ones on my GT. His car is 500+ pounds heavier. The braking distance for the BMW is less than the GTs if I don’t pump the GT brake pedal. If I pump the GT’s brake pedal the stopping distance is about equal. Both cars have the same brake pads. I know the pedal geometry, tires, and a few other things also play a role in braking force but it would seem to me that since the brake components are the same it might be a good idea to use the same master cylinder as well. Any thoughts?