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Line locks and master cylinder failure
#1
I dropped my car off at the mechanic to install the line lock as I generally prefer to leave brake works to someone else.

They had a problem bleeding the brakes and pulled the master cylinder and found it leaking into the booster.

The master cylinder was replaced less than 5,000 miles ago.

The prior master cylinder had failed after the conversion of the rear brakes to disc

I replaced it with http://www.streetortrack.com/Master-Cyli...23771.html this master cylinder.

Two questions

Could improper installation or bleeding have caused this failure?

And with the brake booster full of brake fluid, is it likely that it will have been damaged?

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#2
Bleeding no , and the brake fluid should not effect the diaprahm in the booster.

There is a rod between the booster and master that connects to the pedal assembly, if that rod is not adjusted correctly then when you push on the brake pedal all the way down it may damage the push rod in the master.


Also what type of brake fluid are you using, dot 3,4,5.1 or converted to silicon dot 5?
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#3
dot 3 iirc

thanks I am not expierienced with hydraulicss

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#4
we hear stories about the newer dots causing seals to fail, but dot 3 would not cause that unless the break system had a contaminate in it or dirt that would ruin the O ring.
since your brake system is no longer stock i don't know what effect the rear disc is having. in the manual there is a section talking about the correct pushrod length between the master and booster. you would have to pull the master out to get to the pushrod, then there is a way to measure the length. it may not be the problem.

its very possible the new master wasn't 100% from the start. may of them are refurbished units and maybe the bore wasn't good inside to start.
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#5
Well the master I had was a scott drake part. I spoke with my mechanic about pushrod length and he said that if it was too short or too long the brake pedal height would be either high or low and he felt that this is not an issue.

I think I have found a rebuild kit for the master, though it is a bit hard to tell til I get it in hand.

perhaps it was a manufacturing defect, but my prior master failed after the rear brakes were installed

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#6
I know the MC form SOT says for 4 wheel disc brakes. However, if they did not remove the 10# residual pressure valve from the MC output port for the the rear brakes it may cause some problems. I would think the symptom would be rear brake dragging (no 2# residual valve required for high mounted MC). It may be a stretch but......
The rubber valve and spring are behind the brass seat in the MC output port in case you want to look. Just an idea. Chuck
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#7
I was planning on doing that if the rebuild parts arrive, but they did not today. I am not completely lost when it comes to brakes, I have over the years replaced pads, rotors, shoes, wheel cylinders, drums and even have rebuilt one master cylinder, but I purposely stay away from working on them now and that is part of what is so frustrating.

I wish I could find a factory part from another year that would bolt up and work with no major headaches! Looked at a 1995 Mustang GT MC and the bore size is right, but the ports are on the opposite side and not sure if the pushrod length would be something close

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#8
I don't know Jeff you seem pretty talented at fabrication. Go to a pick and pull and grab the MC, booster, and peda off a 95. Who knows what you may come up with? Cool

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#9
marks73;86711 Wrote:I don't know Jeff you seem pretty talented at fabrication. Go to a pick and pull and grab the MC, booster, and peda off a 95. Who knows what you may come up with? Cool

Um . . . . hell no! If I could use the MC on my booster and pedal set up and just had to bend some custom lines, maybe, but I like the way my brakes felt and really want to keep it close to where it was.

Now a pull a part would get me the pushrod and the lines and fittings. . . hmmm

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
  Reply
#10
I did a disc conversion in the rear as well, I ditched the old school steel capped MC for one out of a early 90s Crown Victoria. It bolted right up to the stock booster and works great with the discs all around.

"BOSS 331"
73 fastback
331ci stroker
wide-ratio toploader
power discs front & rear
9" trak-lok axle w/ 3.70:1 gears
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