Imperial Home Page -> Repair -> Brakes -> Losing Brakes
Question from Dennis (1953):
I finally got my '53 registered, headlights working, and cleaned up for the first run out of the yard. Everything seemed to be going well until I realized that the brakes were not stopping the car well. They worked fine about the first half mile, then when I stepped on them the car would start to stop but near the end of the stop the car continued to roll even with strong pressure on the pedal. It would finally stop. I did smell burning coming from the brakes and brought the car home. I had the booster rebuilt last fall and it seems to be ok. I am under the impression that the brake shoes simply are so old that they are no longer able to provide the friction and are burning instead of gripping. One of the rear brakes seems to be gripping too hard and that wheel even locked up. The car has what I believe to be 32,000 original miles and I think these are probably the original shoes and wheel cylinders. Nothing appears to be leaking and when I had the drums off to do the wheel bearings everything looked good. When I hold the pedal it stays up and it needs no pumping to operate the brakes. Does anybody have any suggestions?
Replies:
From Quint:
At first blush it sounds like the brake shoes. Since you've already had the booster reworked and you get pressure on the pedal to the metal anyway, it sounds like the most obvious...brake shoes. 32K original miles for a '53 seems really low....might not that odometer be going around for the 2nd time? And if it is the second time around...then it's probably brake shoes.
From Currell:
I had the brakes done recently on my 53, and I had the same problem. You can adjust it out right at the master cylinder. You turn the plunger, as I recall. I haven't looked at it recently, and can't describe the actual processing detail
Mine don't drag now, but I notice that the brake lights sometimes stay on, after I have turned off the motor! A few minutes later, they cool down, and the lights go off. This is a deal where we adjusted it just enough to stop the dragging, but not enough to keep the lights off.
So, more adjustment for me.
From Roger:
I too bought a low mileage original car that was stored for 30+ years. When it came to the brakes I soon found that the slave cylinders at the wheels where full of rust. The car acted like yours does when I first tried to drive it. What the problem is caused from is moisture in the brake fluid, do to condensation. I would replace every hydraulic brake part in the car to be safe. This would include all wheel cylinders, hoses, and shoes if needed. Pay close attention to the anchor pins on the brake shoes. They need to aligned back to the original positions. This will make the car safer for your family and those around you.
From Kenyon:
I agree with Roger very strongly.
Your car is 50 years old and on a single circuit brake system. Redo all of the parts and any rusty brake lines so that you personally KNOW that there are no rotted parts. This is your hide that you're risking riding around in that car. This advice is hard-won on my part and I would not like to hear about any of the 10+ seals on your brake system failing and causing loss of control for you.
I redo brakes on all 20+ year old cars that I get. You can't trust anything but yourself on this point. I'd suggest belts and all hoses while you're at it.
Question from Dave (1958):
I recently replaced all 6 wheel cylinders and brake shoes on my '58 Southampton. Brake pedal pumps up to a good hard pedal and braking is good. But... my first pedal stroke on the brake goes way below the pumped height so I have bled all the wheel cylinders three different times to try to eliminate this issue but I still get the same result. Is my problem the master cylinder? Should a rebuild/kit suffice?
Replies:
From Dave G.:
I think you need to go back and *carefully* re-do the brake adjustment. It is very critical on these types of brakes, and if not perfect, will do just what you describe.
From Ian:
I agree - on most cars there is a special order in which to bleed the cylinders and so forth in order to ensure that you do not allow a bubble of air to remain in the system, I cannot remember whether it is typically nearest to the master cylinder first or farthest away first - but is is there for a good reason. The symptoms that you report indicate that there is a gas bubble in your system somewhere.
From Paul:
This symptom can mean (among other things) that the brakes need to be adjusted.
From Dennis:
It is generally foolish to do a brake overhaul and not do the master cylinder. It just leaves a weak link in the system and that can lead to an accident, which not only will destroy your car but the worst case scenario is loss of life. If you take the master out and inspect it you can determine if a rebuild will suffice. I just did my whole system on my '54 and the master cylinder was not as old as the rest of the system so I was able to rebuild it and save well over $ 100. Brakes are easy to do, but generally in these old cars everything should be replaced or rebuilt. My only dilemma is that I now would like to use dot5 brake fluid, but some of the info on this silicon fluid is a little scary, so I think I will go with the dot4 and just bleed the system each spring to avoid moisture problems.
From Chris M.:
One way to eliminate the master cylinder question would be to remove the line to it and put a plug in the hole. The M/C should give you a very hard pedal almost immediately.
The brakes being out of adjustment is definitely a factor too.
I broke down when I was refurbishing the brakes in my '62 and bought the Motive Products power bleeder (About 50 bucks). It consists of a garden sprayer looking bottle with a pressure gauge, a long hose, and a cap designed to fit over the M/C. You fill up the bottle with brake fluid, and pump it up to 10-15 psi. Then you get under each wheel and let the pressure do the work for you as you loosen up the bleeders. What's nice about it is that you don't have to mind the M/C since the bottle is feeding brake fluid under pressure. All you have to worry about is making sure the bottle has enough fluid in it!
Question from Raffi (1962):
My brakes have been feeling a bit spongy of late, and they seem to be getting less effective. They work but they don't work with as much ease as they used to. In fact, the other day, I could hear one of them dragging: I came to a stop, pulled my foot off of the brake and heard that metal screeching sound as the car lurched forward. This has only happened once, but it concerned me enough to check the master cylinder. Sure enough, I was low on Brake oil. The brake oil that was in there was also quite dark. Anyway, I next checked for leaks, on the inside of the tires, and I haven't been able to find anything yet. There are no leaks coming from the master cylinder itself. Is it possible that the leaks are going into the vacuum booster unit? I hear a hissing sound when I put full pressure on the brake pedal, which usually indicates a leak in the vacuum booster. Maybe this is what is giving me less than standard brake performance. I am no mechanic and this is the first car I have ever owned, so any helpful opinions would be great!
Also, my Imperial sat in a garage for 16 years without being started once. I got the car going last year with my uncle, and we checked the original brakes, everything seemed to be in good condition, except the master cylinder, which we replaced. Could the brake cylinders have corroded just sitting there?
Reply from Bob:
Yes, regular brake fluid absorbs moisture, which causes corrosion in your brake system - cylinders, pistons, lines. That is the primary reason why it's recommended to flush & replace all brake fluid every 2 years.
Question from Brandt (1963):
My brakes have been spongy and making a hissing sound and going all the way to the floor on my '63 LeBaron. I looked under the hood and saw some rubber tubing that looks like it touched the exhaust manifold and melted. This tubing is not coming out of the brake booster but below it and inboard coming out of the bulkhead. There is a thicker tube about 1/2" diameter and two thinner ones about 1/4" diameter...what are these tubes? and where do they go? they're all loose tubes.
Reply from Eric:
The smaller hoses would be for the heater box vacuum actuators / heater switch. The larger hose is for the automatic parking brake vacuum actuator. Neither of these hoses would cause a brake pedal that is spongy or goes to the floor. The 'to the floor' condition would be more akin to a failed master cylinder or a failed wheel cylinder in the braking system, or it could be one of the 3 rubber brake hoses has failed. A 40 year old rubber brake hose should be tossed on principle alone. If you have melted or detached hoses, you'd be hearing vacuum hiss from these, and likely have a less than optimal running motor. Hesitation on acceleration from a standing start, rough idle, and poor mileage would be some of the symptoms of vacuum leaks. Replacing all the vacuum hoses on the engine compartment side of the firewall is a recommended procedure on a 40 year old car. I've just done that on my '63 Crown. Be sure to utilize the factory holding ties on the firewall to keep these hoses away from the exhaust manifold. I had hoses that weren't secured and they were melted, too.
Question from (1966):
Had my coupe out yesterday. The mornings here in central Ohio have been in the low 40's of late and when I rolled out of the garage, I noticed the brakes took quite a while to get up to pressure. Could this be indicative of a tired booster diaphragm? Is this an easy/cheap repair, something I can do on the kitchen table with the right rebuild kit?
Reply from Paul:
I doubt that your foot is so sensitive that it could perceive a weaking rubber power brake booster diaphram. I would expect that you would notice if it was going bad since that usually results in a signinficant vacuum leak.
The first signs of this are a slightly rough idle once the car is warmed up, and especially when you step on the brake. If the booster is bad enough, the vacuum leak will cause the car to run badly, if at all.
In some older Imperials (1955), a bad diaphram will also result in brake fuild being sucked into the engine.
From the sound of it, I would recommend that you check the fluid level and have your brakes bled.
Question from Greg (1967):
Here are the symptoms with my '67 (naturally, front disks and rear drums). I press on the brake pedal and there's quite a bit of pedal travel and a noticable hiss from the pedal area when I do so. The pedal will go to the floor with little effort and the brakes will finally grab, but at a minimal amount. The pedal is not "hard", it simply goes to the floor. No amount of pumping the brakes makes any difference at all. The hiss stops as soon as I reach the floor (only hisses while the pedal is in motion). The "brake system" light comes on. Once to the floor and the car has stopped, the brakes will hold it stopped indefinitely as long as I keep my foot on the pedal (no gradual slip like a bad master cylinder). What on earth is wrong with my brakes now?
Here are the things that have been done: The following items have been replaced: master cylinder, all metal brake lines, rear wheel cylinders,
rubber lines up front from the metal line to the brake itself. No leaks anywhere under the hood and no drips at any of the wheels. No loss of brake fluid; Master Cylinder stays full. I recently had the brake lines bled when I purchased new tires, but I am not exactly confident in the quality of their work. Still air in the lines? Bad Power brake booster? Bad "new" master cylinder? Can pads or disks or drums be the culprit? What sort of thing would result in so much pedal travel with so little result in braking? The convertible starts every time and rides like a dream... but that won't do me any good if I can't stop!Replies:
From Demetrios:
The "brake system" light should turn on for a sec every time you start the car. Does the "brake system" light turn on every time you hit the brakes? This supposedly compares the pressure between the front and rear system, and it alarms the driver if one of the two systems failed. My guess is that there is air in one of the systems. Get yourself a $5 bleeding kit and bleed everything. The bleeding kit allows you to do the work yourself without putting any strain on your MC. Its essentially a check valve (composed of a little cup that fills w/ fluid).
From Mark:
I don't think it's the entire problem, but if you are hearing a hiss when you hit the brakes, it's probably the vacuum leaking from the booster. But when I had that problem, the pedal was hard (no assist) until the vacuum from the engine compensated for the leak.
From Dick:
The hissing means that either you have had a snake curl up under your dash, and he is upset by the fact that your socks don't match (he can only see them when you step on the brake pedal), or that you have an internal vacuum leak in the power brake booster. Try putting your foot on the floor alongside the brake pedal. If there is no hiss now, you can bet it's the second option (be sure to do this before you change your socks).
The pedal going to the floor means that you have to displace an inordinate amount of fluid from the master cylinder before the pads or linings move all the way to the friction surface. This means that either your self adjusters are not working (probably not put together right last time the rear brakes were serviced) or that the system has trapped air bubbles in it. Another possibility is that you habitually don't use the parking brake - this will keep your brake adjusters from doing their job as well as they should.
The warning light lighting when you step on the pedal means that the pressure is building up in one half of the system but not in the other half - which also indicates that one half of the system is working sort of right, and the other half isn't. In the bad self adjuster scenario, the rears would be the ones that are not developing pressure while the fronts are sort of OK.
How to fix it in 3 steps:
1. Replace the power brake booster.
2. Bleed the system with a power bleeder - if you don't have access to one, take it to a real actual brake person to do it for you.
3. Inspect the rear brakes, paying special attention to the brake adjusters. One common error is to put the right side adjuster on the left side of the car, and vice versa - this makes them into brake misadjusters, at no extra cost.
Question from Bill (1968):
I have a 1968 Imperial Crown Coupe with brake problems, which is not the usual '67 & '68 caliper or rotor problem, but the pedal, which will sink to the floor with steady strong pressure. There is no apparent leak in the system, brakes have been bled, master cylinder has been replaced once from a parts car, then two other times with rebuilt master cylinders from NAPA. The pedal will pump up, but with steady pressure on the pedal it will sink to the floor, with the "check brake" light coming on. The pedal seems to pump up quicker and stay firm longer with the engine off than on. I would appreciate any suggestions concerning this problem.
Replies:
From Dick:
This is the symptom of a failed master cylinder. I found that new master cylinders are readily available, and have used them now on 3 of my boxcars - all successfully. I also get these from NAPA.
From Roger:
Check your hose/vacuum connections.
From George:
Check your portioning valve. It is located where all your brake lines come together. it will have a wire which is attached to a switch on the valve. The valve should have a small pin which must be reset tio the center position. This should solve your brake pressure problem as well as put out the light.
From Mike:
Did you remember to bleed the master cylinder BEFORE connecting the brake lines to it? For anyone who doesn't know, you connect two metal brake lines about 12" long each to both outlets of the M.C. Then you bend them back into their respective reservoirs and fill the M.C. with fluid. You then take a rod and push the plunger of the M.C. all the way in and release it all the way out. Do this repeatedly until you see NO bubbles in the fluid. You have now bled the master cylinder.
Question from Jason (1971):
I have almost no brakes. The pedal is rock hard...it won't even go to the floor. Could it be my brake boosters that are causing the problem? I changed my pads about 3 to 5 months ago...or maybe a bleed problem with my master cylinder?
Replies:
From Elijah:
There's about a 99.9% chance that it's the brake booster. If the brake booster is bad, the pedal will be very hard, but the brakes WILL still work -- it'll just take a LOT of effort to engage them.
New boosters are available, and there are sources.
From Chad:
I just replaced the booster on my 73 Imp with a rebuilt unit. My pedal was very hard and I could hear a slight hissing from under the dash. I believe a bleed problem like air in the lines would cause the pedal to be mushy as would a bad master cylinder, wheel cylinder and busted brake line. If one of your lines is collapsed or the proportioning valve is bad (I was told it is possible) you will also get a hard pedal. I learned not to purchase my booster from AutoZone as the one I bought from them was as bad as the one I was replacing. The rebuilt unit cost me $100 and has worked great for the past couple of weeks.
From Steve:
I also experienced pretty much the same problem with brakes in my 62 LeBaron when I was bringing it home from Pa. We discovered the only thing wrong was the Rubber hose leading to the brake booster had hardened from age and when the car warmed up a little the hose pinched shut and cut off the vacuum . Maybe you could luck out and it would only be hose trouble worth checking out if you haven't already.
From Asa:
Brake booster is most like the problem. Either that or it's not getting any vacuum or the check valve is bad or the unit itself is leaking vacuum internally. Usually it's a hose so check that first! Also, the booster needs vacuum to work, so make sure you check that before contaminating the booster.
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