1966 Master Cylinder Failure

Hi all. I have a new to me 66. It already has the dual master with the cross member trimmed. It has front and rear drums. At some point I want to change the fronts to disc. But at this moment I just want it to stop.

The current problem is that I can get the rear brakes bled but I can’t get the front to bleed. I can loosen the lines and fluid will come out but no pressure when bleeding.
I think the master is bad. What can I change it out with since the cross member is already trimmed.

thanks
Bill
 

biddle

Forum Moderator
Staff member
As noted in previous message "Ford Thunderbird" is not needed in subject since we are a Ford Thunderbird site. Thanks for posting.
 

57tbird57

Well-Known Member
Hi all. I have a new to me 66. It already has the dual master with the cross member trimmed. It has front and rear drums. At some point I want to change the fronts to disc. But at this moment I just want it to stop.

The current problem is that I can get the rear brakes bled but I can’t get the front to bleed. I can loosen the lines and fluid will come out but no pressure when bleeding.
I think the master is bad. What can I change it out with since the cross member is already trimmed.

thanks
Bill
first thing, a 66 should have front disk brakes from the factory as they were standard equipment starting in 65. a 67 mustang dual master cylinder will bolt right up to booster. can be bought at most auto parts stores.
 
i have a 66 parts car with all the brake systen intact. all i need is to roll onto a trailer to go to recycle sometime soon. this could be an option for you but I would go with a new booster and cylenders. Just thinking because this car is a doner car and is going to be recycled.
 

Ward 57

Well-Known Member
i have a 66 parts car with all the brake systen intact. all i need is to roll onto a trailer to go to recycle sometime soon. this could be an option for you but I would go with a new booster and cylenders. Just thinking because this car is a doner car and is going to be recycled.
Just make sure you strip EVERY thing off first. Especially the trim and dash parts. Don't know where you are But check out T-Bird wrecking yards, It may be that they will take it off your hands at their cost and reclaim everything possible. Some things are irreplaceable.
 
Just make sure you strip EVERY thing off first. Especially the trim and dash parts. Don't know where you are But check out T-Bird wrecking yards, It may be that they will take it off your hands at their cost and reclaim everything possible. Some things are irreplaceable.
Good advice, Im in sacramento area of california dont want any parts to go to waste.
 
Not an expert, but at least the calipers ,rotors, proportioning valve and possibly the spindles. Front brake hoses probably different
what about the brake lines for the swap could they be different diameter for the disc set up verses the drum brakes in discussion with NCMODELA for his disc brake swapnsince i have an intact 66 brake system he may want to use for his car
 

Ward 57

Well-Known Member
I'm no expert on converting brake systems, As you state you have fluid but no pressure. I wouldn't blame the master cyl but look down line. I assume there is a proportioning valve installed, was it properly primed or maybe a stuck valve.
 
Ok. Thank you. I did not think of a stuck proportioning valve. How would I know if it’s a master or valve?

fwiw. This car has been sitting for at least 12 years. That’s why I went to the master diagnosis.
 

Ward 57

Well-Known Member
ward 57, do you think I should save the rear end?
I'm thinking that if you can find a salvage yard not just a crush and recycle the good steel. I'd do my due diligence and seek out some local clubs and ask them. May find some good friends in the process. Don't deconstruct it other than what you need as a donor.
 
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