Technical Lost my brakes 4 miles from home

I finally got my linkage all straightened out on my 1964 Chevy Biscayne and took it for a 30 mile ride. Everything was great until I noticed a spongy brake pedal. A couple of pumps later and the pedal went to the floor. I creeped the car home using the same technique that my dad taught me in 1964. Look ahead a quarter mile, go slow, downshift and shut off the engine if need be, double clutch into first and creep into the driveway.
My question is this, where are the adjusting slots on the backing plate of the mid 60's Chevies? There appears to be no leaking of the wheel cylinders, no leaks at the MC and no leaks at the junction.

 

Internal seal failure on the master cylinder ?

 

some cars had adjuster slots in the drum, that you access once the wheel is off.
you need to pull all the wheels drums and give the brakes a thorough check up. always rebuild/replace anything marginal don't forget an inspection of all the lines.
BRAKES are THE number one priority.

 

Also double check your brake lines and all the connection points. I just had the same thing happen a couple of days ago on my truck and turned-out to be a pin hole in the brake line about a foot away from the hose going to the front wheel.

 

If memory serves, there was a knock out on the drum to access the star wheel on those years. And you will need to make a small hook to pull the adjuster arm off the star wheel if you go too tight. Like said above, adjusting won't fix a soft/spongy pedal. Adjusting will fix a good pedal with too much travel.

 

I tell you an experience I had. Lost my brakes. They have been giving me fits. Checked for leaks and the usual stuff. Everything checked out. My Uncle suggested cleaning all 4 drums with degreaser*. I had nothing to lose so I pulled the drums and cleaned the contact surface and I also cleaned the shoes with degreaser and a brush. After they dried I got some 80 grit sandpaper and gave each shoe a light scuff. Took it for a test drive and the brakes never worked better. Apparently, When working on my front end, I must have got grease on the brake shoes.
*I'm not sure if it was degreaser or brake clean as it was just an unmarked bottle he gave me.

 

If the pedal went to the floor, it isn't the self-adjusters. There is a leak somewhere. Either internal to the M/C, lines, or wheel cylinders. Plan on a complete rebuild. It's easier that way.

 

Look at your backing plates for adjuster slot. Yes, check over the brake system as already mentioned. Pedal does not go to the floor just like that.

 

Unbolt your master cylinder,move it forward if you can away from your booster. If your seal is gone in there you will have brake fluid in your booster than can’t be seen externally.
Without a booster it would normally be seen on your boot.

 

Single circuit MC. No booster. I just checked the brakes again in the driveway. Pedal had some pressure, then completely to the floor again, then some pressure, then back to the floor. MC still has same amount of fluid. No leaking around the drums or connections.

 

Will start looking for dual circuit MC tomorrow. Is there a source for MC out there?

 

That appears to be the symptom.

 

Just looked at the rock auto page, I wish we had a business like this down here!

 

Thanks Moriarity for the info. All the brake lines are stainless and I just replaced the rubber hose to the rear junction. No leaks there either.

 

All sorts of hydraulic cylinders with bad seals will do the same thing. I've got a forklift that would go down a couple feet in 5 minutes with a couple hundred pounds on the forks. But, you could pick up a thousand pounds and it would hold for hours without dropping at all.

I've repaired several things like this in the past, and the seals always look fine from a visual inspection, but when compared to the new seals, the old ones are always noticeably harder.

 

If you need to replace the master you would eb better off to send it out to be sleeved, the new stuff is poorly built offshore, if its not rusty inside then a quick hone and a kit will fix it right up.

 

I think I'd be looking for a DIY upgrade to front discs and a dual master cylinder, rebuild the rear brakes, and new lines.

 

We don't know the history of the brakes on this car. On any car I get, I go through the brakes, completely, so I know what I have. I replace the rubber parts, and inspect the metal parts and replace them if needed, and replace the shoes if needed, turn or replace the drums as needed. The wheel cylinders and master cylinder...they include rubber and metal parts, so the rules above apply to them--new kits, and new cylinders if they are worn/pitted/rusted up beyond repair with just a kit.

Did you do all of that?

Single circuit master cylinder systems can be very reliable, if you maintain them. If you can't maintain them, then I dont know that adding a dual m/c will help...it might, it might not.

 

My brother's 54 Desoto lost its brakes once with a bit of a scary moment. As it is single system I rigged up a remote brake fluid reservoir in the trunk with an alarm buzzer if the level goes down. If it ever happens again he'll have some warning that he may only have one press of the brake pedal's worth of fluid left. Hopefully enough to get out of trouble. Its also easier to keep a check on the level every time he opens the trunk than messing about with the carpet to find the hatch to the master cylinder under the floor.
https://www.carbuilder.com/uk/single-brake-fluid-reservoir-130mm
They do a dual one too.
In my Merc I use an old power steering reservoir to feed my master cylinder, as it looks better under the hood than a plastic container. No warning buzzer ,but easier to keep a check on the level than down the depths of the engine bay.
Most difficult part was getting a seal where the pipe feeds through the master cylinder's cap.

 

Had a master cylinder cup flip once, no visible leaks, rebuilt the cylinder all was well. Just glad you made it home safely.

 

Just looked at the rock auto page, I wish we had a business like this down here!

WE DO.
Rock Auto ship to us in about a week for a reasonable fee. I've got several guys down here using them now.
Check it out with a sample part and they have a shipping calculator option.

 

First thing is switch master cyls for a double master. Look at the master cyl for a 67 Impala and see if it looks like it will fit. Then disconnect the rear line from the junction block and plug it up and run it to the rear port of the master and put the front line in the front port.
That way the next time you loose pressure half the braking will still work..

 

It might, if there's enough pedal travel...some times there is, some times there isn't. Make sure to test the system by opening a bleeder on the front, and see if you still have brakes. Then close it, make sure it's bled again, and open a bleeder on the rear, see if you still have brakes. With a dual system, it's important that you keep the brakes adjusted, so they will pass this test, if it has manual adjusting brakes. Otherwise, the excess travel will take away all the safety you thought you bought by adding dual.

 

Nah, once you add that tandem master cylinder there is no more brake maintenance necessary, solves all the problems you could ever have....it drives me nuts that it is the first suggestion for every brake problem, mid matching components is far more dangerous than a properly functioning single master system...

Fix the master cylinder and happily drive the car for years to come.


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But, but, but the first suggestion was to properly diagnose the problem(s) and buy a new fruit jar master cylinder.

There are a lot of unknowns/variables to consider. OP's intended usage of car, condition of all brake components, money/investment, etc.

If the entire system is corroded and drums out of spec, what's the cost comparison of stock replacement versus a potential upgrade?

If the OP is saying he wants to get a dual m/c and just add that to the existing (stock?, original?) system, that might be a problem. Were all dual m/c disc/drum? Did they come into existence with front disc brakes?

Only fixing the single m/c might be a problem.

I imagine there are bolt-on caliper brackets available, and instructions for off-the-shelf components, where the total cost might be cheaper than stock replacements. Or maybe it's worth the extra money. But maybe the stock wheels would no longer fit on front.

So, back to paragraph two.

 

Have a look at how many threads there are with “my brakes don’t work after I installed this kit” just because it’s sold as a kit doesn’t mean it’s right, the factory parts work almost like they were designed for the car they came on...

Most factory systems in good working conditions are perfectly fine for everyday driving.


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