Brake Linkage. Pedal goes to the floor

M

mavmavv

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Nov 21, 2007

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Nov 26, 2008

#1

• Nov 26, 2008

• #1

So I recently replaced my MC and Brake booster. Car stops a little better, but the linkage is all out of whack. The car doesnt even start stopping until the pedal is almost to the floor. I messed with the little pin coming out of the booster a little bit, but im not sure if thats the proper way to adjust things.

And yes, I bench bled the MC before installing. I do need to do a proper bleeding of all 4 brakes, but I know this is a different problem than just air in the lines. The actual linkage is just a little fubar.

What is the proper way to adjust this?

 

trbkrb

Founding Member

Jun 4, 2001

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Houston, TX

Nov 26, 2008

#2

• Nov 26, 2008

• #2

There is a template floating around that gives you the correct setting dimensions for the acorn nut on the booster. Basically it should be right at the piston on the MC. If you can measure the distance from the MC mounting surface to the piston at rest, and then adjust the nut and shaft to the same dimensions, that should be pretty good.

 

M

mavmavv

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Nov 21, 2007

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#3

• Nov 26, 2008

• #3

So snug should be sufficient? Thanks for the quick reply too.

I dont want to spend my Thanksgiving Holiday messing with all this junk

 

trbkrb

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Jun 4, 2001

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Nov 26, 2008

#4

• Nov 26, 2008

• #4

As long as it is not pressing on the piston, that would be like riding the brake pedal.

Good luck!

 

Mr. Rustypwnz

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Jun 1, 2005

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indianapolis/ valdosta ga

Nov 27, 2008

#5

• Nov 27, 2008

• #5

bleed the brakes dude..

 

93 LX

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Nov 27, 2008

#6

• Nov 27, 2008

• #6

+1 bleed the brakes

 

Beasty306GT

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Dec 19, 2002

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#7

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M

mavmavv

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#8

• Nov 27, 2008

• #8

Ill be bleeding the brakes once I get the pedal adjusted properly. Thanks for the help guys.

 

V

v8only

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Jul 3, 2003

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Nov 27, 2008

#9

• Nov 27, 2008

• #9

come on guys, we don't need cookie cutter responses in triplicate!!!

My pedal in my 86 went to one inch off the floor for 12 years straight. During this time, I replaced every brake component at least twice, including the booster and m/c..and Bled it a dozen times.

It was so bad, that I could BARELY fit my big toe under the brake pedal when stopped at a signal. It was that bad, and that's just how I thought it was supposed to be.

then I swapped in a 94/95 m/c into my 86, and suddenly it's a night and day difference. the pedal starts now at the top, and not the bottom.

There is a ford procedure for adjusting that rod. Assuming you know how to bleed the brakes, that adjustment is your problem.

 

hotcobra03

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Nov 29, 1999

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poteet,tx

Nov 27, 2008

#10

• Nov 27, 2008

• #10

If after all this and you are sure everything is right their is one more thing that could cause low pedal.proportioning valve. If you clamp off front brake hoses and pedal is rock hard than its your problem

 

M

mavmavv

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Nov 21, 2007

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Nov 27, 2008

#11

• Nov 27, 2008

• #11

Well, I adjusted the rod, that made a pretty weak difference, rebled the master cylinder, then bled each wheel. I can live with the performance, but the braking doesnt really start until half stroke down. Once there, it stops pretty good.

 

V

v8only

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Jul 3, 2003

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#12

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• #12

interesting. then indeed it was the m/c I put in that made all the difference in the world. Mine stops at about an inch or two off the top.

I swapped out to a 94+ v6 master cylinder, though I think the early sn95 v8 cars had the same setup.

If you've got an 86 or older, just grab a 94/95 master cylinder, and grab the two lines from an 87-93 car that go from the m/c to the 2 port valve under the m/c...that's all you need, the m/c and the 2 aero lines.

If you car is an aero, you'll need a three to 2 port valve on the bottom...maybe an 86 valve would work,...search here, it's common for 5 lug swaps to use a 2 port valve.

that m/c should provide the difference you're looking for, and it's a $20 junkyard item

 

Black1987Stang

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Aug 22, 2004

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Nov 27, 2008

#13

• Nov 27, 2008

• #13

I always bleed the fittings that hold the brake lines into the master...sometimes youll get some air out of them too.

 

MustangLX-5.0

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Nov 27, 2008

#14

• Nov 27, 2008

• #14

Oh how I dread putting the MC and BB back in my 92.The BB is new.it had a core charge so it's gone.I have no idea where the BB rod was set at on the stock BB.

And how do you bleed a MC? This one had all the fluid drained out so it wouldn't piss all over.

 

hotcobra03

Active Member

Nov 29, 1999

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poteet,tx

Nov 27, 2008

#15

• Nov 27, 2008

• #15

Also rod between mc and pb is to adjust freeplay.with car off push on pedal til vac is gone than check pedal freeplay .also when bleeding brakes most like to pump up mc than release bleeder screw that is wrong.open bleeder than push brake .pumping pedal makes air.

 

V

v8only

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Jul 3, 2003

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Nov 27, 2008

#16

• Nov 27, 2008

• #16

hotcobra03 said:

Also rod between mc and pb is to adjust freeplay.with car off push on pedal til vac is gone than check pedal freeplay .also when bleeding brakes most like to pump up mc than release bleeder screw that is wrong.open bleeder than push brake .pumping pedal makes air.

Click to expand...

lol...do that and you'll never in a million years get your brakes bled right.

the braking system is closed looped. This means that air cannot and will not get into the system if everything is tight and all your lines and hardware are in good shape.

therefore, air gets into the system when replacing components and opening a line. Pumping up the brakes will NOT introduce any air into the system. you pump the brakes with the bleeder closed. THis will force the fluid from the master brake cylinder, down the lines, and collect the air at the end of the lines.

your foot MUST have pressure on it when you crack open the lines, or more air will be introduced into the system. If we bled brakes by cracking the screw loose, then pressing the pedal, all we'd be doing is letting more air into the system.

 

hotcobra03

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Nov 29, 1999

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poteet,tx

Nov 27, 2008

#17

• Nov 27, 2008

• #17

Been in brake business for 30 years from basic car to mack trucks.anyone who knows yes air enters the system when opened or pumping pedal with no fluid.your fluid pushes trapped air in line.pumping pedal makes bubble go back and forth.a power bleeder pushes fluid and a vacuum pump pulles fluid.never heard of a brake pumper?most everyone does it different FWIW