Soft Brake issues

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Mar 31, 2008 | 09:40 PM

#16

CoachRobb

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Joined: Dec 2003

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From: THE SOUTH

my problem was a bad m\c and brake booster from the auto parts store

Mar 31, 2008 | 09:55 PM

#17

Bern_F150_4x4

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From: Maryland

Quote:

Originally Posted by dpellicone

I cannot find this pin either. My next thing is to look close at the metal brake lines. There is air in there somewhere!!

The Pin is on the underside of the proportioning valve on my 86 F250 HD. it seems that it can be pushed in but I haven't seen instructions on how to bleed the system using the pin... I can get a pic if the rain stops tomorrow.

Apr 3, 2008 | 03:04 PM

#18

dpellicone

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Bern,
If you can get us a Picture that would be great. According to the Hayes book the pin is opened during bleeding of the front breaks to allow the valve to Proportion the fluid properly. We shall see!

Apr 3, 2008 | 11:05 PM

#19

Bern_F150_4x4

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From: Maryland

No problem, I'll get the pic as soon as the rain stops

Apr 5, 2008 | 01:05 PM

#20

zukes 466

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Ok. The Other Day, I Took Off The M/c. In The Manual, They Say Make A Tool Out Of Cardboard And The Distance The Pin Should Be Sticking Out Is .980-.995 Of An Inch. It Was Correct In Mine. So I Adjusted The Rear Brakes Until They Would Not Turn Anymore, Then Backed It Off Until It Would Turn. That Gave Me Excessive Pedal Pressure, Almost As If The Booster Could Be Bad. And The Truck Still Does Not Come To A Screeching Halt Like It Should With 12x3 Rear Brakes, Dual Pistin Calipers, And The Dual Servo Booster. In My Manual It Says To Prop The Proportion Valve Open On The F-150, And Push It In On F-350 To Bleed The Valve In Order To Properly Bleed The System. Right Now I Believe I Have Too Much Pedal Pressure. So The Booster Is In Question. I Did Hook A Vacuum Guage To The Booster Valve And Run It Up To 15 Psi. And There Was No Drop, What So Ever. But Im Not Sure If That Nessesarily Means The Booster Is Still Good. I Will Continue This Battle, And If I Find Something, I Will Post It.

Apr 5, 2008 | 01:22 PM

#21

zukes 466

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Try This. Remove The M/c, And Make A Gauge Out Of Cardboard, In The Shape Of A C, The Top And Bottom Of The C Should Sit Flat Against The Booster, The Center Of The C Should Be .980-.995 Of An Inch. Use A Micrometer To Measure The Cardboard And Cut It Out. Measure The Distance The Rod Sticks Out Of The Booster. It Should Be .980-.995 Of An Inch. If It Is Less, The Pedal Will Have To Travel Farther Than It Should. The Booster Pushrod Is Adjustable. Its One More Thing To Eliminate Anyway!

Apr 5, 2008 | 01:24 PM

#22

Franklin2

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From: Virginia

What do you mean by excessive pressure? Adjusting the shoes up in the rear took the travel out of the rear system, giving you a higher pedal. If you can pump the brakes, and the pedal gets higher, then it's usually the rear brakes too far away from the drums. You have to keep pumping the pedal to get them out to the drum.

If the pedal is hard to push, with apparently no assist, then you might have a booster problem. What I would do is try them with the vacuum line pinched shut, and then try them with the vacuum line hooked up, and see if you are getting any assist.

The guy with the locking brake in the rear; I have had that happen for mainly two reasons. The parking brake cable is sticking on that side, or the shoes are contaminated with brake fluid or rearend oil. Once the shoes soak up the oil, they get gummy and stick once you fix the fluid leak, so they are pretty much ruined and you have to buy new ones. When I was in a pinch, I have taken a torch and heated the shoes to drive the oil and fluid out. But this is only for emergencies.

Apr 5, 2008 | 01:39 PM

#23

Kylet8020

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some trucks dont have the pin to push or pull it would be on the front of that valve under the m/c look at that valve there is a switch on there that can leak its for your dummy break light easy fix is to put a pipe plug. becouse that valve is about 209$ with fords abs kit that switch will make your breaks fell very soft till right near the end just might wanna check