So... I replaced the Clutch Master Cylinder....

[nbk13nw]

As stated, I replaced the clutch master cylinder in my 05 GT. Man what a pain. Regardless, I got it done. With there being no way to really bleed the clutch (Seems it is self-adjusting / bleeding) I figured that the soft pedal would pedal would be gone in a day or so, after countless pumps and a tired leg.

Anyway, here it is three days later and I am getting a really irritating squeal when depressing and releasing the brake pedal while running. Imagine a person letting the air out of a balloon while pulling the opening to vary the pitch, same noise.

No noise when depressing or releasing the clutch, only the brake. Seems like the clutch cylinder may be pulling and pushing air. Anyone ever seen / heard this before? I read that even though the clutch and brake use the same fluid reservoir that the compartments are separate.

I have ordered a new vacuum pump (Cant find my old one) and will try and pull the air out again this week. I did try the trick of jacking the rear drivers side a bit to help while pumping the clutch with the cap off to allow the air to escape. Does not see to help. Any thoughts?

 

[stkjock]

bleed the system using a mini-vac is the best way, it's been discussed on the board many times, that should have been done first.

a soft pedal is not going to just go away.

IIRC you're supposed to jack up the driver's front to allow the res to be at the highest point in the system.


quick search:

http://s197forum.com/forum/showthread.php?t=121527&highlight=bleeding+clutch

http://s197forum.com/forum/showthread.php?t=111792&highlight=bleeding+clutch


many more out there

 

[nbk13nw]

Thanks. My searches came up blank. Guess it was just my search terms.

I ordered a new pump and it should be here this week. Just not sure what to think about getting that noise on push and release. I expected a softer pedal but not the noise.

 

[Eel Mit]

The oring that seals the booster to the master is most likely leaking...thats your air leaking out a balloon noise.

 

[702GT]

The oring that seals the booster to the master is most likely leaking...thats your air leaking out a balloon noise.

This.

The clutch shares the fluid resevoir with the brake system, but there is no way for air to enter the brake system from the clutch. You'd have to run the resevoir out of fluid for either.

As for the Master cylinder, it is important to bench bleed the master just like the slave cylinder before install. The air in the clutch line should be the only air in the system. Once everything is installed, you should vacuum bleed before pushing on the clutch pedal. As stkjock pointed out, air in the system will not resolve itself. I prefer gravity bleeding when it comes to the brakes, and then grab a buddy for a few brake pedal bleeds to ensure no air is trapped in the high spots (ABS). Works like a charm for me.

 

[nbk13nw]

The only thing to add is that the squealing noise seems to originate under the dash itself and not in the engine bay. It can easily be heard inside but not outside. But that could be due to engine noise. Also, it does not occur when the engine is not running, at this time the brakes are solid and not very compressible. Once started, the brakes still seem mushy and of course the noise is present. So it is sounding more like seal on the booster. I wonder if there is a rebuild kit out there or if the seal itself (o-ring) can be replaced.

 

[nbk13nw]

So I found the issue.

There is a hose from the top of the cylinder leading to the fluid reservoir. On the factory cylinder the fitting on top is plastic and firmly attached to the cylinder, on the replacement it is a plastic bard fitting pushed into a rubber grommet.

When I removed the pedal assembly this morning I found that the hose was pushing up against the body of the pedal assembly causing the bard fitting to stand about 1/3 out of the rubber grommet. I used a dremel and widened the hole in the pedal assembly plate and also made some extra room in the sound insulator since it was also causing it to bind up.

Re-installed and no more balloon squeals. Bad design for a replacement.

Still begs the question of the brake and clutch operating on separate compartments. I had absolutely no noise from the clutch pedal but the brake was constant as long as I was driving. Sometime without using the brakes the squealing would start. And I could only modify the sound with the brake pedal (High or low pitch depending on pressure and speed applied), but nothing with the clutch.

 

[ColeStang_GT]

So I found the issue.

There is a hose from the top of the cylinder leading to the fluid reservoir. On the factory cylinder the fitting on top is plastic and firmly attached to the cylinder, on the replacement it is a plastic bard fitting pushed into a rubber grommet.

When I removed the pedal assembly this morning I found that the hose was pushing up against the body of the pedal assembly causing the bard fitting to stand about 1/3 out of the rubber grommet. I used a dremel and widened the hole in the pedal assembly plate and also made some extra room in the sound insulator since it was also causing it to bind up.

Re-installed and no more balloon squeals. Bad design for a replacement.

Still begs the question of the brake and clutch operating on separate compartments. I had absolutely no noise from the clutch pedal but the brake was constant as long as I was driving. Sometime without using the brakes the squealing would start. And I could only modify the sound with the brake pedal (High or low pitch depending on pressure and speed applied), but nothing with the clutch.

This is because the brakes was dragging. They was somewhat applied because they didn't have enough "pressure" from not bleeding them to travel back to there full returned position so to say. So you hit the brake pedal, which applies the brakes, release it, and they didn't return fully due to the air being in the system preventing them from doing so.

Prolly what that is IMO

 

[nbk13nw]

Yeah. I am going to bleed them again this weekend. No more noise but occasionally the brake feel soft and at the sale time the clutch goes soft as well. I am assuming there is still some air in there.

 

[nbk13nw]

Final update:

The replacement / aftermarket design is really flawed. It still is allowing air to be sucked into the system, regardless of the install procedure. It does not hold a vacuum.

I grabbed Ford replacement from Tasca and everything is working beautifully. Ended up returning the aftermarket part to O'Reilly's for a credit towards some new plugs.

 

[james432]

How do u bench bleed the clutch master cylinder?I'm about to put in a 2013 shelby one in my 06 gt?

 

[702GT]

The way I did it was using a spare hose on the inlet/outlet nipples of the MC and put the other ends of the hose into a bottle of brake fluid. Then press/depress the plunger of the MC til bubbles stop. Once fluid has filled the MC, I put the rubber plug caps back on the MC and proceed with the install. You will lose some fluid throughout the process, but once the install is complete you hook your mighty vac (or whatever you're using) back up to the brake resevoir and put the clutch back under vacuum. Any remaining air wont take long to bleed.

 

[pics06gtstang]

I did try the trick of jacking the rear drivers side a bit to help while pumping the clutch with the cap off to allow the air to escape. Does not see to help. Any thoughts?

You jack the drivers FRONT tire not the rear .
8" /10" tire from ground ,let it sit overnight pump 10 times and you should have a pedal