Author Topic: Brake drag/slow pedal return  (Read 181 times)

Offline 68NordicCat

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Brake drag/slow pedal return
« on: March 29, 2017, 12:54:44 AM »
12/67 SJ built 68 Cougar - power front disc rear drum brakes. Rebuilt booster, reconditioned original distribution block, repro proportioning valve (which I hear now might not be much count). Have bled the system, but brake pedal still feels squishy from time to time. Bigger problem is very slow pedal return. From what I've read the most likely culprit is the booster, but I've also heard it could be the proportioning valve. I now have a rebuilt original block and valve assembly which I could change out (easier than the booster). Question - is there a way to diagnose the specific problem without just continuing to purchase and swap out parts (or resorting to a bungee cord :P)? Thanks.

12/67 Built SJ J code 4sp Cougar

Offline Murf

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Re: Brake drag/slow pedal return
« Reply #1 on: March 29, 2017, 11:32:54 AM »
Typically the booster is the cause of a slow return.  Many times it is caused by the rear seal of the master cylinder leaking brake fluid into the booster and swelling a certain part.  In some cases the brakes will not release until you hook your toe under the pedal and force it to return to the "off" position. 
John Murphy

1965 "K" GT fastback Honey Gold exterior, Ivy Green and White Pony interior, many options
1966 Conv., high option, removeable hardtop, thermactor "C" engine, AC, Springtime Yellow exterior, Black Pony interior
1968 California Special, "J" code, ,many options, white with red interior

Offline preaction

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Re: Brake drag/slow pedal return
« Reply #2 on: March 29, 2017, 05:04:34 PM »
Dan, don't hesitate to give WCCC a call they work on issues like this every day and are happy to help.
8R02S125064- January 6 1968  SJ   7F93S591808 - April 28 1967  Dearborn   7F91S544039 - December 17 1966 Dearborn

Offline rockhouse66

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Re: Brake drag/slow pedal return
« Reply #3 on: March 30, 2017, 10:52:07 AM »
How old are the brake hoses?  These have been known to look great on the outside but swollen on the inside, acting like a one-way valve.  This will cause drag and slow release or even complete lock up in some cases.
'66 GT FB, '69 Mach 1, '69 Grande