Brake Grab

MY1978TOY

MEMBER
1978 FORD THUNDERBIRD
84,356 MILES

I just got a 1978 Ford Thunderbird (Jubilee Edition)about a month ago.
The front brakes started to grab just as I pulled onto my exit, then the car just wouldn't move, so I cut one of the flex lines to get the moving.
The next day I went & replaced both front calibers, pads & flex hoses, bled the system, the brakes worked fine for about 20 mins of testing & again they started to grab, so I checked the proportioning valve & found that the 2 (piston like valves)weren't working properly so I gutted the proportioning valve & they work for about a day. Now after about an hour of driving the brakes are starting to grab again. I don't know what else to do outside of doing a complete up grade which going to cost a couple of grand or just junking the T-Bird. Please help !

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4 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Check the pedal to booster push rod clearance. There must be some free play to allow fluids to return, failing which pressure would build up in system when brake fluids heats.

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Sunday, October 7th, 2012 AT 1:39 PM

CJ MEDEVAC

MECHANIC
11,004 POSTS

GUTTING THE PROPORTIONING VALVE MAY NOT HAVE BEEN A GOOD IDEA EITHER

THE MEDIC

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Sunday, October 7th, 2012 AT 1:48 PM

MY1978TOY

MEMBER
2 POSTS

Thank you both :)
I'll check the clearance :)
I had to gut the valve to get the car moving for now & put away for the winter, but I will replace it with an OEM.
Once again thank you both :) :)

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Sunday, October 7th, 2012 AT 2:14 PM

CJ MEDEVAC

MECHANIC
11,004 POSTS

ALTHOUGH I LOOKED IN MITCHELL I FOR YOUR RIG, IT DOES NOT LIST IT

BEST BET IS GET YOUR INFO FROM ONE OF THESE

https://www.2carpros.com/questions/2007-ford-taurus-tune-up

THIS IS NOT YOUR VEHICLE.....THIS IS NOT YOUR VEHICLE.....THIS IS NOT YOUR VEHICLE.....THIS IS NOT YOUR VEHICLE.....

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

THIS IS A DIAGRAM FOR (IF I REMEMBER RIGHT) A 2004 F-150 TRUCK

HIS TRUCK WAS HAVING ISSUES WITH THE FRONT CALIPERS LOCKING TOO

I FOUND THIS DIAGRAM IN MITCHELL I FOR HIM----TURNED OUT SOMETHING WAS WRONG WITH HIS COMPUTER.......YOURS DOES NOT HAVE ONE

I JUST WANTED YOU TO UNDERSTAND....MY PIC IS A "GUIDE" (SHOWING A MEASURING TOOL) FOR WHAT NEEDS TO BE DONE. THE "ACORN NUT" IN THIS DIAGRAM IS THE "ADJUSTER"....YOU NEED TO FIND "YOUR MEASUREMENT" AND CHECK IT OUT

THE MEDIC

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