Vintage Mustang Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
803 Posts
Discussion Starter · #1 ·
How do you know if your master cylinder is bad? I have drum brakes all 4 corners, the drums look good and the brake pads look good, brake fluid is full, the brake cylinders dont leak. so why doesn't my car want to stop?? im thinking master cylinder bad ? air in the lines? it has been sitting several months. any ideas?
 

·
Registered
Joined
·
4,197 Posts
Ok, probably not too bad a situation but we will need some more info....

Do your have power brakes?
Is the pedal firm/soft, continue traveling down when pressure is applied?
Describe exactly what happens when you attempt to stop and it acts like it doesn't want to....how much longer does it take to stop in the same distance?
Does the car or steering wheel pull to one side?
Do any of the brakes wnat to lock up when applied?
 

·
Registered
Joined
·
803 Posts
Discussion Starter · #3 ·
no on the power booster.
brake pedal feels pretty soft.
pulls slightly to the right when brakes are applied.
none of them feel like their locking up.
if i had to make a quick stop in a short distance i dont know if i could. pretty unsafe
 

·
Registered
Joined
·
409 Posts
Sounds like normal operation of 4 wheel drum brakes, really they are unsafe at best for real world driving.
You should consider front disc brakes as one of your upgrades.

Don
 

·
Registered
Joined
·
4,197 Posts
Ok,
1. Sounds like there is air in the system. Completely flush/bleed the brakes starting at the farthest point.

2. Pull all the drums, check for leaks at all the wheel cylinders and ensure the brakes are clean, not glazed. Re-adjust and reinstall. A slight pull to one side is typically a minor adjustment..either tighen the left a click or two or loosen the right the same amount.

3. If all is ok, brake pedal is firm, still doesn't want to stop, the incorrect shoe lining (co-efficient) was installed. The OEM had a co-efficient of around .30, most if not all of the shoes sold by dealers and part stores are rated 25 or less....and don't stop worth a &%$^&&! Contact Hawk or CarboTech Engineering (web site). They have linings rated at .36 or better...this is the equivalent of the Velva Touch linings installed on the Shelby's, Hertz specials and used in NASCAR through the early 70's. Drum brakes can stop a vehicle very well and very comfortably. If I lay on the brakes hard, I can easily put a front passengers head into the windshield (to give you an idea of the braking capacity).
 

·
Registered
Joined
·
10,286 Posts
Testing for a bad master cylinder is easy.
Put your foot on the pedal (not hard) and lightly push down. Does the pedal continue to allow your foor ti sink to the floor? If yes, bad master. If not, Master cyl is OK.
 

·
Registered
Joined
·
4,197 Posts
Thanks Roddster...I forgot that!
 
1 - 7 of 7 Posts
Top