Brake Upgrade

[Knexo]

Car is a 93 Cobra. I'm in the process of upgrading my front brakes to 73mm pistons and slotted rotors. The calipers are 88 Mark7's with steel pistons. I'm also putting Russels stainless braided lines on the ends. I haven't touched the rears. I've tried bleeding the front caliper for over an hour now starting with the right and then the left. The pedal will come up to the top, but as soon as I start the car in goes to the floor. I've gotten alot of air out of the system. Does anyone please have any ideals of why the pedal keeps going to the floor upon start-up and why its taking so long to bleed them. I've been checking the master all along and have never let it get lower then half full. I'm at work so probably wont be able to respond until tonight.

Thanks,
Lenny

 

[sled]

bleed the master cyl first.

 

[Knexo]

How do you bleed the master cylinder? Sorry if this is a stupid question, but I've never done tat before.

Lenny

 

[kcp203]

If you are installing a new M/C, or if you drained the M/C reservoir dry when bleeding the lines, you need to bench bleed the M/C.

Here is a link.

http://www.misterfixit.com/brakbld1.htm

 

[Knexo]

Thanks guys. I'm going out to work on it right now and I'll let you know how things go.

 

[Knexo]

Sorry I haven't replied in awhile. After hours a bleeding the master and line, come to find out one of the calipers was broke. Took them back and got 2 new and I now have a pedal, but its very soft. My car has 112,300 on the original master cylinder. With the 73 piston calipers, I'm pretty sure I only need a 1 inch master. As far as I know, the Cobra came with a 1 inch master. I adjusted the booster rod, and have found what I think is the happy medium between drag and pedal feel. Any help with te soft pedal would be helpful.

Lenny

 

[93Cobra#2771]

If you pump the brakes, and the pedal gets firmer, then you still have some air in the system...