66 Mustang brakes gone, master cylinder cap rubber gasket has grown in size?

Got a buddy of mine's 66 Mustang over here to troubleshoot no brakes, among other problems. Manual drums. Been sitting for several years. Master cylinder empty, front drivers brakes all dirty and gunked up, looking oily, so I suspect wheel cylinder slight leak. No other obvious leak points, though the metal brake line going to the back looks so heavily rusted I wouldn't trust it, especially with the single reservoir master cylinder. I put fluid in the old master cylinder and there's absolutely no pedal firmness, though I haven't bled any wheel cylinders yet. I did let some fluid out the little allen plug on the front bottom of the master cylinder. The brand new fluid immediately turned dirty opaque brown after pumping the brakes. And to top it all off, the rubber gasket will not fit back inside the cap now. Do these things grow in size or is there some trick to installing them (and which way is up)? My inclination at this point is to buy a new or rebuilt master cylinder and front drivers wheel cylinder. Any comments?

Reply to
hillpc
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They swell if they get contaminated with any type of petroleum product. I would replace the master, ALL rubber lines and all wheel cylinders. Also you will want to look over the steel lines REALLY close. If they look rusty replace them. Being a popular vehicle there are all stainless kits available as bolt on items to replace the lines. Not really cheap bust for a pony car I'd spend the money.

Keep in mind that a car is rather difficult to stop if the brakes fail. How much is your friends life worth?

Reply to
Steve W.

What Steve said. The swollen gasket is a sign that you should not trust ANY rubber in the system, period. it's time for a full brake job including hoses. If the shoes are not contaminated you can reuse them but everything hydraulic should be cleaned and rebuilt - or just buy new wheel cylinders if you don't feel comfortable doing them yourself (probably not a bad idea, at least 50% of the time when trying to rebuild you will find at least one cylinder with pits that won't hone out.) Replace all hoses, replace or rebuild the master cylinder, and consider buying a new brake hard line kit for the vehicle - being a popular model you can probably get new all stainless lines from any number of vendors.

You probably can get "driveway brakes" by bleeding them; the fact that one front wheel was oily tells me that it leaked all the way down so there's tons of air in there. I wouldn't drive more than in and out of the garage like that though.

Now is a good opportunity to remove the backing plates, bead blast and paint them, weld up any grooves that have formed where the shoes ride, and repack the wheel bearings.

good luck

nate

Reply to
N8N

Forgot to mention...

also disassemble and clean the star wheels and put a good coat of anti- seize on the thread. If these have self adjusters replace them if they look too grungy or if any of the cables have broken - they're generally not expensive at your FLAPS. A shop manual will likely tell you to replace all the springs and "nails" as well - I don't always do that, but again, they're cheap and I definitely would if any of them look weak or overly corroded.

nate

Reply to
N8N

I concur with the others. The entire brake system should be replaced. If you replace just the master and wheel cylinders you will be flushing crud from those rubber hoses and steel brake lines for a long time and may have to re-replace the wheel cyliners.

Reply to
John S.

Thanks guys. I appreciate the help and will recommend these items, though I may consider keeping the front metal brake lines, since those look pretty new. If we do keep these I'll be sure to thoroughly flush them.

Reply to
hillpc

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