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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 33461
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I put a M2300K (93 Cobra-R) brakes on my car. They seem fine

Customer Question

I put a M2300K (93 Cobra-R) brakes on my car. They seem fine unless you panic stop. Then there is a 1 second delay from the time to press the petal to the brakes engage. Otherwise all seems normal. 3 different shops have bleed the brakes.
Submitted: 5 months ago.
Category: Ford
Expert:  Ron replied 5 months ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

The problem you are describing sound like you may have a failing master cylinder, all pressure to the system comes from it. I would start with having them recheck it and the pressure coming from it to the breaks.

Customer: replied 5 months ago.
Hey Ron,I was thinking MC as well. If I remember correctly I was getting 700psi at my portioning valve. Does that sound like enough? Note that under all other conditions, brakes seem normal. You wouldn't notice there is a problem.I read an article I read yesterday, they were testing hawk brake pads. They said the plus brakes seemed grabby and bit hard. Could it be the stock brake pads from the Cobra R. I'm not looking for grabby but maybe that's the issue.
Customer: replied 5 months ago.
I'll re-test the brakes and see what psi I'm getting. It's been a while since I ran the test. Guess that means I have to open the valve all the way and reset the proportioning once I'm done. Let me know if you'd like me to do this test as I'll need to get someone to watch the pressure while I pump the brakes.
Expert:  Ron replied 5 months ago.

Yes I would do both, the master should produce pressure as soon as it pushed no matter how fast that is done.

Customer: replied 5 months ago.
Hey Ron,I'm getting 700psi. If I hit the brake it jumps to 400psi for a fraction of a second than raises to 700. This video show it. Note that the video is after I reduced the pressure a bit on the back brakes via the portioning valve.
https://dl.dropboxusercontent.com/u/11733585/IMG_2855.MOV
Expert:  Ron replied 5 months ago.

So are you still getting the delay? Even at 400 PSI the brakes should grab.

Customer: replied 5 months ago.
still getting delay.
Customer: replied 5 months ago.
Note this even happens at slow speeds. First noticed it when I was doing about 15mph and had to stomp on the brakes as I wasn't paying attention to the car in front of me.
Expert:  Ron replied 5 months ago.

Something dose not make any sense here. Im not sure what is could be if the master is building good pressure beside the portioning valve hanging .

Customer: replied 5 months ago.
Let me see if I can video what's happening so you can see it.
Expert:  Ron replied 5 months ago.

Okay.

Customer: replied 5 months ago.
Hey Ron,The video didn't come out well. I didn't have a mount for the camera. I'm wondering if it could be the booster? My vacuum appears fine. Note that when I first hit the brakes, it's like hitting a rock. Just for a second then it goes down. Probably half a second.Don
Expert:  Ron replied 5 months ago.

If the pedal is hard as a rock its is a possibility. In most cases if the booster has good vacuum and its not leaking it will do its job, Are you sure there nothing binding?

Customer: replied 5 months ago.
It's only hard as a rock for that split second. What do you think would be binding? Do you mean the petal? I'm leaving on vacation here in shorty, but can check something when I come back. I watched this guy on vacuum assist brakes and thought maybe a seal or something isn't closing or opening at the right time. Just speculating. I added the instructions the mech would have used. If you want me to verify a step, let me know. They don't talk too much about adjustments.https://www.youtube.com/watch?v=LThrL8Jjsgc
https://performanceparts.ford.com/download/instructionsheets/FordInstShtM-2300-K.pdf
Customer: replied 5 months ago.
a google search using "brakes hard in panic stop" is bringing up some stuff. Thought I have to start packing for the trip. I'll look look through the search later.
Expert:  Ron replied 5 months ago.

Okay .

Customer: replied 5 months ago.
Hi Ron,
I'm back from vacation. I found this link. I've completed step 3, checked the booster check valve which was good. Today I'll do step 2. The hose is a fuel hose, so I'll replace with vacuum hose and retest. Though the BB hose is pretty new and stout, I'll replace. Would make sense that the hose collapses for just a second then reopens, causing my symptoms.http://www.mpbrakes.com/techtalk/how-to-series/how-to-diagnosing-a-hard-brake-pedal
Customer: replied 5 months ago.
Oh and I did step one as well. Don't recall the exact number but the needle was well in the green range. I'll get the exact number after I replace the BB hose.
Expert:  Ron replied 5 months ago.

The vacuum supply line dose need to be vacuum line but I have never seen one suck shut. Nothing to loose by at least replacing it and see.

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