Brake fade, potential problems

[monk302]

Just put in the Granada swap with 74 Maverick MC non power or booster. Here is my question. My brakes are very spongy. In order to get some pressure you have to pump the brake pedal several times. At that point the pedal will become a bit more stiff. However, if I don't pump the brakes for a minute, that pressure that just built up will fade and the pedal will hit the floor. Also, now when I bleed the brakes there is no air in the tubing coming from the speed bleeder. I used a suction unit to the bleeder and was pulling the fluid out with the pump from the driver front wheel and when it comes out under pressure somewhere bubbles are getting into the line. I am thinking there is a small leak but I can't figure it out. What do you guys think?

 

[monk302]

Setup consists of the following:

74 Maverick MC non power/booster
Wilwood Proportioning valve
new line to the rear
New line to front driver
Slotted Granada discs

 

[mustang70]

You might want to check around the MC and the firewall to see if there's any leakage. Also, I might be reading this wrong, but you did bleed all four wheels right?

 

[68keyblr]

Just put in the Granada swap with 74 Maverick MC non power or booster. Here is my question. My brakes are very spongy. In order to get some pressure you have to pump the brake pedal several times. At that point the pedal will become a bit more stiff. However, if I don't pump the brakes for a minute, that pressure that just built up will fade and the pedal will hit the floor. Also, now when I bleed the brakes there is no air in the tubing coming from the speed bleeder. I used a suction unit to the bleeder and was pulling the fluid out with the pump from the driver front wheel and when it comes out under pressure somewhere bubbles are getting into the line. I am thinking there is a small leak but I can't figure it out. What do you guys think?

I had the same thing after swapping out my drums for discs from a '79 Granada and a power booster setup. I finally took it into a brake shop and was informed that I needed to "Bench Bleed" the new master cylinder before installing it or would still have air in the lines even after bleeding at the calipers for what seemed like hours! Worked great after the break shop did a vacuum bleed...

Also, it sounds like you could have a leak somewhere - be sure to check all connections for leakage.

Good Luck!

 

[monk302]

I had the same thing after swapping out my drums for discs from a '79 Granada and a power booster setup. I finally took it into a brake shop and was informed that I needed to "Bench Bleed" the new master cylinder before installing it or would still have air in the lines even after bleeding at the calipers for what seemed like hours! Worked great after the break shop did a vacuum bleed...

Also, it sounds like you could have a leak somewhere - be sure to check all connections for leakage.

Good Luck!

I have bled all four wheels. How long does that vacuum bleed take. I think I may get that done soon. I want to get this damn car on the road, the weather is way to nice for it in the garage.

 

[Max Power]

Sounds like a master. If your pedal is hitting the floor, and there are no external leaks, your master is probably bypassing. Is it new? You haven't answered any questions about it.

 

[68keyblr]

Vacuum Bleed

The local brake shop here did the vacuum bleed in less than 30 minutes. Only cost me like $60...

Good Luck!

 

[monk302]

Sounds like a master. If your pedal is hitting the floor, and there are no external leaks, your master is probably bypassing. Is it new? You haven't answered any questions about it.

The master cylinder is brand new. The brakes are working however the pedal still feels really spongy and you have to push it down farther than in the past to have it engage. I am not hitting the floor as of this afternoon with the pedal, but still it feels a bit spongy. I am going to take a look at it now and see if I can figure out anything new.

 

[68GEETEE]

make sure the calipers were installed with the bleeders at the top, 12 o'clock position. Mine werent and as a result I could never bleed all the air out, till I realized the calipers were on the wrong wheels!

 

[Max Power]

Also make sure your rears are adjusted properly.

 

[monk302]

Backed the car out onto the driveway yesterday afternoon and this is what I found. The car will stop but the brakes in order to work need to be pumped several times. Though I stopped it at a 5mph stop, I would not trust it at a 25mph stop at the current setup.

68GeeTee, I will take a look at my bleeders. Right now they are at the top but pointing out at an angle, not straight up. Isn't there only one way you can put on these Granada calipers?

Max Power, my rear brakes were fine when I took off the original drums from the front. Would they have to be readjusted to accomodate the Granada disc's up front?

 

[68GEETEE]

Backed the car out onto the driveway yesterday afternoon and this is what I found. The car will stop but the brakes in order to work need to be pumped several times. Though I stopped it at a 5mph stop, I would not trust it at a 25mph stop at the current setup.

68GeeTee, I will take a look at my bleeders. Right now they are at the top but pointing out at an angle, not straight up. Isn't there only one way you can put on these Granada calipers?

Max Power, my rear brakes were fine when I took off the original drums from the front. Would they have to be readjusted to accomodate the Granada disc's up front?

Sounds like they are on correctly, my bleeders point to the side too, and their location is at the top of the piston chamber 12 noon. It is possible for left and right calipers to be installed on the wrong wheels, but from your description it sounds like you got them on right. Does the car have a small cigar shaped valve next to the distribution block? Mine did, and it was bad. Its called a residual pressure valve, and its designed to keep about 10psi of pressure on the rear brake line to increase pedal firmness. You might see if there is one on your Stang. Master Power brakes sells a 10psi replacement valve for about $30.00

 

[monk302]

There is no cigar shaped valve next to the distribution block. Actually I got rid of the distribution block and have replaced it with a Wilwood proportioning valve to the rear with the front lines breaking apart to each wheel with a T-block.