brake problem

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Jan 20, 2012 | 07:44 PM

Paul Davis

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brake problem

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9; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} </style> <![endif]--> I am having a weird problem with my brakes. I have searched the forum for this same type of problem and I don’t see anything familiar with gas powered trucks (I did see similar problem with diesel trucks).

My truck is a 1994 Ford ¾ XLT
460 engine
2 wheel drive

The problem is when I touch the brake for any reason, stop sign, traffic, stops light or any time. The brakes lock up no matter how light I tap them. The brake pedal is sucked to the floor. And I have to pull the brake pedal back up with my foot to release the brakes. odd thing is after about 10 miles or so of this, THEN the brakes work fine.

This has happened 2 times now at various times. It does not happen every time I drive the truck. When the pedal is stuck on the floor I can’t even pull over to the curb out of the way. I’ll give it full throttle and it will spin (SMOKE) the rear tire, in drive and/or reverse! I will not drive the truck now until I fix it.

Thanks for any advice

Jan 20, 2012 | 10:45 PM

rla2005

Fleet Owner

Joined: Oct 2005

Posts: 20,789

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From: Kentucky

As a test pull the vacuum line to the power brake booster, see if you still have the same issue. From what I gather you may have bad booster, aka "over-active".

The brake pedal will be very hard, but it should not drop to floor and stay there if it is a booster issue.

Jan 21, 2012 | 12:33 AM

Thumper19

Elder User

Joined: Oct 2008

Posts: 550

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From: Colorado

did you do any routine brake maintance?

Forget to bleed a line?

It seems to me it would be in the master cylinder and or brake booster

Jan 21, 2012 | 09:49 AM

Paul Davis

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Joined: Jan 2012

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thank you for input.

i replaced brake booster last Apr (that is when i bought the truck) diaphragm was bad. and replaced rear brakes and all hardware. bled entire system. truck was braking perfectly until last week.

the problem is when i touch brake pedal for any reason...they go to the floor and lock up (my foot is off the brake pedal and they "suck" themselves to the floor). i then have to pull back pedal with my foot to release brakes.

dunno... has anybody heard of this type of problem on a gas powered vehicle?

Jan 21, 2012 | 10:45 AM

Lazy K

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Joined: Jan 2005

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There is no difference between a vacuum booster on a gas truck and one on a diesel, only difference is the source of the vacuum supply.
My guess is that your booster is bad. Pull the master cyl forward and see if you have a brake fluid leak from the rear of the master cyl. Brake fluid can eat boosters.

Jan 21, 2012 | 02:06 PM

rla2005

Fleet Owner

Joined: Oct 2005

Posts: 20,789

Likes: 1,753

From: Kentucky

Quote:

Originally Posted by Paul Davis

thank you for input.

i replaced brake booster last Apr (that is when i bought the truck) diaphragm was bad. and replaced rear brakes and all hardware. bled entire system. truck was braking perfectly until last week.

the problem is when i touch brake pedal for any reason...they go to the floor and lock up (my foot is off the brake pedal and they "suck" themselves to the floor). i then have to pull back pedal with my foot to release brakes.

dunno... has anybody heard of this type of problem on a gas powered vehicle?

And now it is January and you have a new problem. Just because the booster is new, rebuilt perhaps, does not mean it is functioning correctly now.