Mushy Brakes question

[GTG]

Hello, this thread is directed to those with 00R brakes. A couple of weeks ago i swapped 00R brakes onto my 97 Cobra. At the time of installation I lost a good amount of fluid when each caliper was being swapped out. After they were installed we did a good job bleeding them until there was no air. The pedal feel was mushy up top and the stopping power is kind of disappointing. Well, thinking there is still air in the lines I had the brakes bled by a shop. Still a mushy feeling until the pedal is depressed about a third of the way. The dual pistons pbr's had good pedal feel before the swap. I have checked for leaks and haven't found any.

Is there air in the master cylinder? Do I need to upgrade parts to accommodate the 4 piston calipers? I tried searching with no luck.

Thanks,

Gary

 

[ac427cobra]

Hello, this thread is directed to those with 00R brakes. A couple of weeks ago i swapped 00R brakes onto my 97 Cobra. At the time of installation I lost a good amount of fluid when each caliper was being swapped out. After they were installed we did a good job bleeding them until there was no air. The pedal feel was mushy up top and the stopping power is kind of disappointing. Well, thinking there is still air in the lines I had the brakes bled by a shop. Still a mushy feeling until the pedal is depressed about a third of the way. The dual pistons pbr's had good pedal feel before the swap. I have checked for leaks and haven't found any.

Is there air in the master cylinder? Do I need to upgrade parts to accommodate the 4 piston calipers? I tried searching with no luck.

Thanks,

Gary

Gary:

It sounds to me like you left the system open for an extended period of time? A braking system should only be opened long enough to swap the brake line and that's it.

If that's the case:

For starters you'll need to bleed the master cylinder. Then rebleed the entire system. Then if your brakes are firm enough to drive the car, go somewhere where you can activate the ABS. Either a rainy street or a gravel road. Then rebleed the system. If that doesn't do it you'll need to have the system pressure bled.

Hope that helps.


:thumbsup::coolman::beer:

 

[GTG]

Gary:

It sounds to me like you left the system open for an extended period of time? A braking system should only be opened long enough to swap the brake line and that's it.

If that's the case:

For starters you'll need to bleed the master cylinder. Then rebleed the entire system. Then if your brakes are firm enough to drive the car, go somewhere where you can activate the ABS. Either a rainy street or a gravel road. Then rebleed the system. If that doesn't do it you'll need to have the system pressure bled.

Hope that helps.


:thumbsup::coolman::beer:

It does help, thank you. i did leave the system open for too long and lost a lot of fluid. This was my first time swapping calipers like this. But.... I'm a dunsky, how do you bleed the MC?

 

[ac427cobra]

It does, thank you. But.... I'm a dunsky, how do you bleed the MC?

Just like you bleed a caliper; pump up the brakes, open one of the lines at the MC, let the pedal go to the floor, close the line, pump the pedal up again and repeat! Go to other line and do again!

 

[Jimmysidecarr]

Just like you bleed a caliper; pump up the brakes, open one of the lines at the MC, let the pedal go to the floor, close the line, pump the pedal up again and repeat! Go to other line and do again!

I'm going to go out on a limb here and say that a bench bleed of the master may be in order.
The steep angle the master cyl is at when installed and the lack of bleeder in the high spot, is what prompts me to recommend this.

03/04 Cobras have a bleeder in that high spot. I got air up in there once and it drove me nuts! I was bleeding till the cows came home, and no improvement. Fortunately I didn't get any in my ABS unit. One of my Cobra club buddies heard me talk about it an MSR event I was at and came over and suggested trying "that bleeder right there".

5 minutes later rock hard pedal!

If it's in the master, a pre 2003 SVT Cobra will likely need the master leveled out to get rid of the air in it completely.

If it got in the ABS it is a bit more involved as Bruce mentioned. We can cycle the ABS unit via computer manipulation while bleeding at a Ford/Lincoln/Mercury dealer.
There have been many success stories of grassroots go getters improvising the cycling of the ABS to get the air through and out of the system, but it is time consuming and can attract the attention of the local po po, if you are not in an extremely rural area.

I would try the master cyl line bleed first, followed by a standard 4 wheel brake bleed and see what you have.

If that didn't get it, do the master cyl bench bleed, followed by a standard 4 wheel brake bleed and see what you have.


If you still have a soft pedal, you got it in the ABS, and will need to address this issue.

Seriously....
Take a look at the angle that master is mounted at, and tell me if you think any air could get trapped in there.
It happened to me also.:beer:

 

[GTG]

I'm going to go out on a limb here and say that a bench bleed of the master may be in order.
The steep angle the master cyl is at when installed and the lack of bleeder in the high spot, is what prompts me to recommend this.

03/04 Cobras have a bleeder in that high spot. I got air up in there once and it drove me nuts! I was bleeding till the cows came home, and no improvement. Fortunately I didn't get any in my ABS unit. One of my Cobra club buddies heard me talk about it an MSR event I was at and came over and suggested trying "that bleeder right there".

5 minutes later rock hard pedal!

If it's in the master, a pre 2003 SVT Cobra will likely need the master leveled out to get rid of the air in it completely.

If it got in the ABS it is a bit more involved as Bruce mentioned. We can cycle the ABS unit via computer manipulation while bleeding at a Ford/Lincoln/Mercury dealer.
There have been many success stories of grassroots go getters improvising the cycling of the ABS to get the air through and out of the system, but it is time consuming and can attract the attention of the local po po, if you are not in an extremely rural area.

I would try the master cyl line bleed first, followed by a standard 4 wheel brake bleed and see what you have.

If that didn't get it, do the master cyl bench bleed, followed by a standard 4 wheel brake bleed and see what you have.


If you still have a soft pedal, you got it in the ABS, and will need to address this issue.

Seriously....
Take a look at the angle that master is mounted at, and tell me if you think any air could get trapped in there.
It happened to me also.:beer:

Thank you for your input also. I see a brake type bleeder towards the rear of the cylinder, top dead center. Would this be the right valve to open?

 

[tomshep]

How could you get air in the master cylinder and NOT get air in the ABS module if the lines were opened at the caliper? I have not had any experience with bleeding the ABS or the MC, but I would think if air is in the MC due to the calipers being disconnected the air would have to go through the ABS.

Someone espain dis to me.

Tom

 

[ac427cobra]

How could you get air in the master cylinder and NOT get air in the ABS module if the lines were opened at the caliper? I have not had any experience with bleeding the ABS or the MC, but I would think if air is in the MC due to the calipers being disconnected the air would have to go through the ABS.

Someone espain dis to me.

Tom

Bubbles travel UP!! ;-)

 

[Jimmysidecarr]

Thank you for your input also. I see a brake type bleeder towards the rear of the cylinder, top dead center. Would this be the right valve to open?

I'm not that familiar with the 96-98 master cylinders, so, if you do have a bleeder at the high point (which would be toward the front of the car) of the tubular shaped center section of the master cylinder, then I apologize for the inaccurate "pre 2003" statement.

If you do have a bleeder at the high point of your cylinder, by all means, give it a try.

I did a little searching and it appears in this pic that you may have a bleeder there after all. SORRY! Can't tell for sure from this pic though.

The 2000 Cobra R cars I have seen did not have this.

 

[wheelhopper]

I had the same problem. Bled the MC and all was well. There are fittings on the MC like the calipers. bleed the air out and I bet you'll be good.

 

[GTG]

I had the same problem. Bled the MC and all was well. There are fittings on the MC like the calipers. bleed the air out and I bet you'll be good.

Is it at the back and top center? I think I found it, but it doesn't look exactly like a caliper bleeder. Thanks for the reply.

 

[Jimmysidecarr]

I had the same problem. Bled the MC and all was well. There are fittings on the MC like the calipers. bleed the air out and I bet you'll be good.

He has a 97, I don't think the back top center is the high point.:shrug:

 

[tomshep]

Bubbles travel UP!! ;-)

Then why does everyone say you have to cycle the ABS unit to get all of the air out? To me that means the air is somehow trapped in the ABS. If all it takes is bleeding the MC that could be done separately from the ABS.:??:

Tom

 

[ac427cobra]

Then why does everyone say you have to cycle the ABS unit to get all of the air out? To me that means the air is somehow trapped in the ABS. If all it takes is bleeding the MC that could be done separately from the ABS.:??:

Tom

Tom:

MANY people leave a brake's hydraulic system open for a couple days, a couple of weeks or even longer while they wait for parts or decide what direction they want to go. During this time, brake fluid slowly drains out of the system all the way from the MC down through the ABS control module and eventually exits at the loose line by the caliper. As the fluid comes out, this creates a void for the air to enter.

If people would only learn to open the hydraulic system just long enough to change a caliper or line, we'd never even have to have these conversations.

FWIW

:thumbsup::coolman::beer:

 

[tomshep]

Tom:

MANY people leave a brake's hydraulic system open for a couple days, a couple of weeks or even longer while they wait for parts or decide what direction they want to go. During this time, brake fluid slowly drains out of the system all the way from the MC down through the ABS control module and eventually exits at the loose line by the caliper. As the fluid comes out, this creates a void for the air to enter.

If people would only learn to open the hydraulic system just long enough to change a caliper or line, we'd never even have to have these conversations.

FWIW

:thumbsup::coolman::beer:

Oohhh. When I read all of those posts I thought they had swapped a line or something and had it open for a short time and just a few bubbles caused all of those problems.

I didn't realize they were leaving it open for extended periods and actually letting the system drip empty.

Now I understand!!!:banana::idea:

Tom

 

[Philcsag1]

Many times when the MC goes low on fluid air enters the rear brake system.

If you have a Mushy Pedal be sure to bleed all 4 corners of the car.

I removed and replaced many 94 to 96 ABS modules there is no special way to bleed the system because it has ABS.

And I have never needed to activate the ABS to bleed the system