No Brake Pedal: Part II
03-30-2013, 06:54 PM
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Location: Valley Forge, PA
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No Brake Pedal: Part II
Sadly, my '87 Carrera still has no brake pedal.
What I experience is:
1) No brake pedal for 1-2 pumps (goes down to the floorboard).
2) Some to semi-solid 1/2 brake pedal in 3-4 pumps.
3) After 3-4 pumps, the brake pedal will hold with no fade.
4) All four calipers are providing braking.
5) Once the brakes are release, it's back to no brake pedal
What I've done is:
1) Replaced the master cylinder (performed a good bench bleeding)
2) Bled the four brakes lines repeatedly in every way known to mankind (honest)
What might the following convey?:
1) At the master cylinder, I remove the brake line connection to the front brakes and insert a plug into the master cylinder. Doing this gives me an extremely solid brake pedal (almost zero movement).
2) At the master cylinder, I remove the brake line connection to the rear brakes and insert a plug into the master cylinder. Doing this gives me no brake pedal.
I have pretty good confidence that the master cylinder is good (hours and hours of work and testing leads me to this conclusion). I've bled the brake lines in every conceivable way with various pressure applying devices, etc. No part of the braking system is leaking.
What's not working? What am I missing? Is there something to consider other than the master brake cylinder and brake lines? A regulating value? Something? Anything?
Any guidance will be greatly appreciated.
Thanks.
Dan
What I experience is:
1) No brake pedal for 1-2 pumps (goes down to the floorboard).
2) Some to semi-solid 1/2 brake pedal in 3-4 pumps.
3) After 3-4 pumps, the brake pedal will hold with no fade.
4) All four calipers are providing braking.
5) Once the brakes are release, it's back to no brake pedal
What I've done is:
1) Replaced the master cylinder (performed a good bench bleeding)
2) Bled the four brakes lines repeatedly in every way known to mankind (honest)
What might the following convey?:
1) At the master cylinder, I remove the brake line connection to the front brakes and insert a plug into the master cylinder. Doing this gives me an extremely solid brake pedal (almost zero movement).
2) At the master cylinder, I remove the brake line connection to the rear brakes and insert a plug into the master cylinder. Doing this gives me no brake pedal.
I have pretty good confidence that the master cylinder is good (hours and hours of work and testing leads me to this conclusion). I've bled the brake lines in every conceivable way with various pressure applying devices, etc. No part of the braking system is leaking.
What's not working? What am I missing? Is there something to consider other than the master brake cylinder and brake lines? A regulating value? Something? Anything?
Any guidance will be greatly appreciated.
Thanks.
Dan
03-31-2013, 05:45 PM
#2
Rennlist Member
First, I trust your statement that you've comprehensively gone through each step repeatedly. We've all been there.......
But I think you've answered your own question in the Part 3, Number 2--plugged the port to the rear brakes, and don't have pedal pressure. By this exercise, I read it that you have the front brakes hooked up. So something is going on in the front circuit. Whether it's the master, or in a caliper, I guess you can plug both master ports, and bleed from the plugs. Still soft/no pedal? Nothing left in the system at that point BUT the master.
But I think you've answered your own question in the Part 3, Number 2--plugged the port to the rear brakes, and don't have pedal pressure. By this exercise, I read it that you have the front brakes hooked up. So something is going on in the front circuit. Whether it's the master, or in a caliper, I guess you can plug both master ports, and bleed from the plugs. Still soft/no pedal? Nothing left in the system at that point BUT the master.