Lost Brakes!

[UncleOtis63]

I pulled in to a conveinent store this afternoon and parked my car. Everything seemed fine. When I back out, I went to step on the brake pedal and it resisted. The pedal didn't hit the floor but in fact felt very tight. It was weird. They worked fine before I went in to the store. Also, I noticed when I press hard on the brakes, the engine hesitates. What could this be? Does this mean I lost the power brake booster? Could it be possible that it is as simple as the vacuum valve on the booster? You guys are always so comprehensive in your answers. Please advise once again. Thanks in advance.

Shawn

[Alan H. Tast]

Yep. Something failed with the booster. Disconnect and plug the vacuum line from the manifold to the booster, run the engine and apply the brakes. Pedal will still be hard, but you probably will not detect a change in the engine's sound or performance. Don't forget that vacuum for the transmission modulator is also pulled through the booster - if you disconnect the vacuum to the booster, there will be no vacuum to the modulator unless you jury-rig another vacuum source.

Why did it fail? To be honest, I don't remember why the pedal gets hard, but it's pretty much assured that something is FUBAR inside the booster. Pull the master cylinder off the front of the booster and see if it's wet inside of the booster, which would be a symptom of a leaking master cylinder. If the rubber bellows in the booster came in contact with brake fluid (DOT 3) and the rubber is mushy, consider the booster shot and get it rebuilt. You don't need to disconnect the brake lines from the master cylinder, unless you need to remove the MC for a rebuild.

It's probably a good bet that both the master cylinder and booster need to be rebuilt. Thankfully, it can be done, but the combination if sent out will probably cost you around $200 plus labor. The booster is a bear to take off from the front of the firewall, but it can be done. There is a clip and pin which retain the push rod for the booster to the lever arm located between the booster-to-firewall brackets that will have to come out, then remove the four nuts which retain the booster to the firewall bracket.

You can exchange the booster and/or master cylinder, provided they're rebuildable, for a rebuilt one through most of the T-bird vendors who advertise in VTCI's Thunderbird Scoop magazine. There are no home rebuild kits for the booster, but there are rebuild kits for the master cylinder.

You can make the removal part of the job easier if you're willing to crawl under the dash, unpin the brake pedal, take off the four retaining nuts for the brackets and pull the whole thing off. This would allow you to also replace the special seal for the rectangular push rod, which on a higher-mileage original car will most likely be shredded. Don't send the bracket with the booster - you'll need it for the rebuilt unit. Pulling the whole thing off will also allow you to clean up the brackets and repaint them while the MC and booster are being refurbished. I just did this with my '63, including replacing the firewall seal, and it was worth the effort. The firewall seal uses a C0AA- part number, as it was also used on '60s full-size Fords and early Mustangs. Some of the T-birds parts houses do not have it.

[UncleOtis63]

I pulled the MC took a screwdrive and compressed the cylinder through and got juice out of all three brake line connections. I assume that the MC is fine on that note but will have it rebuilt anyways. I'd probably be better off purchasing a new one.

I unclipped the pin under the dash from the pedal lever assembly. Remove the 4 nuts from the booster side between the booster and the bracket (vs bracket and firewall). The bracket is still attached to the firewall and there is a pin and rod attached to the bracket. It got dark while I was trying to locate how to detach that rod. Did you say that to avoid having to disassemble the pin and rod that is connected to the bracket, I can remove the entire bracket? I just re-read that and I'll have to take a look at it again tomorrow. I guess I'm doing it right.

When I pulled the MC away from the booster, there is absolutely no fluid in the booster. All the rubber was virtually dry. When I stepped on the pedal while the MC was detached from the booster, it felt almost normal. I also noticed as I was backing it in to the garage that the brake lights were 'NOT' working and I just installed a new brake light switch. Could this be inherant to a bad booster or bad MC? Even though there was no fluid in the booster, could there still be a problem in the booster? A clogged line or bad MC would 'NOT' cause the engine to defunct when I press the Brake pedal, would it? I think I'm getting paranoid. Heh

Please advise!!
As always, thanks in advance!
Shawn

[UncleOtis63]

Success!!! I finally got the booster off and took it to San Antonio Brake and Clutch here in SA, TX. Fortunately, they had the kit in stock and put me back together in less than a day. It cost me about $129.00. $119.00 for the kit and then where the Rod came out of the back of the booster, there is a hard plastic sleeve like device that sleeves the rod. That was mysteriously broken. He said that it was probably a result of my standing on the brakes after the booster failed. That part cost about $10 since he used a used one that he had to cut to length. In any case, sure enough, there was a hole right through the diaphram in the booster. First I painstakingly unthreaded all 4 nuts from the back of the booster but I couldn't get the clip undone if you can believe that so I took ALAN TAST's advice and crawled up under the dash with my ratchet and a swivel joint and removed the 4 nuts off of the bracket. After removing the 4 bolts from the cross members (from shock to firewall) the booster came right out. Went in just as easy. I bled them and Uncle Otis and I were back in business last night.

Thanks again for your advice.
Shawn

[Alan H. Tast]

Glad my advice helped. Do you have any info on the plastic insert for the push rod going into the booster? I had a remant of some plastic around a groove in the rod, but not sure if this was supposed to retain the rod in the diaphragm. I'd like to get a replacement piece if possible.

[UncleOtis63]

The only thing I know about it is what the tech that rebuilt the booster told me. He said that it probably cracked when the booster failed and I stood on the brakes with all my weight and force. He had extras but none that were to specs for my car so he had to cut one down that came from a different application. Sorry but that is really the only thing I know about it.