How To Repair Hard Brake Problems On Your Imperial


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Question from Ray (1950):

I urgently need a full set of wheel cylinder rubbers for 1950 Chrysler Imperial ( New Yorker chassis ) 2 for each front wheel and 1 for each rear wheel looks like Im going to have to replace everything to find the problem :

My front brakes grab one-sided so that the car always pulls violently to the right when braking. I stripped everything down, cleaned it all and put it back but it still does the same - cant see anything obvious.

Replies:

From Arran:

Check the adjustment on your brake shoes, if its grabbing it means that the brake cylinders are working somewhat. This is a single circuit brake system, if one wheel cylinder goes the whole system looses fluid. If one set of shoes is adjusted too far in, meaning that they don't even contact the drum, you will have a lurch to one side. Find a shop manual, Motor or Chilton will do, and follow the adjustment procedure. If there was a wheel cylinder was bad it would be self evident; take both of the front drums off and have someone sit inside and push the brake pedal while you watch. If you can see the shoes move, the wheel cylinder is fine. If one doesn't move, gushes fluid, you have found your problem. Contact Pro-Antique auto parts, or look up another company selling parts for old Chryslers on the internet, they shouldn't be hard to find. Too bad that you're not over here, you could order them from almost any auto parts store.

From Ernie:

You mentioned that that you disassembled everything, did that include the wheel cylinders? One probable cause, if the problem started abruptly, is a bad brake flex hose on the side opposite the pull. Try swapping them if you can, this will either prove or disprove them as the culprit

From John:

I saw a reply to this problem in a publication for another make I happen to also have an interest in. Replace the brake hose on the opposite wheel from the side that is pulling. Sometimes there is a problem with deterioration from the inside the rubber brake hose, and you end up with a blockage which restricts the flow of brake fluid to the opposite side, so you get full effect on one side--the one that pulls, and little effect on the other side. If this works, replace all of your brake rubber hoses. You should probably do this every 5 or so years simply because OLD rubber is bad news.

From Terry:

Do you have the original disk brakes??

What is the diameter of the rubber disks which you need? I'm thinking one inch but haven't had mine apart for a while. Are you adjusting the self adjusting setup correctly? Took me a while to understand it when I worked on mine a number of years ago and it pulled and tried to lock up also.

Anyway the cups shouldn't be a big deal at any parts house. At least those around here stock an assortment of all normal diameters. Of course yours may be in the dreaded metric sizes and be a problem.

From Roger:

I just went through this problem on my '55 Imperial. All wheel cylinders are the same from 1955 to 1949 or so I am told. Desoto, Dodge and Plymouth used the same ones so they are easy to come by. EIS sells both the kit or the cylinder. Hoses and master cylinders as well as brake shoes are a different matter. I had to reline my brake shoes don't let them ware to the metal or you can't do this. Also don't neglect the lower pin shoe adjustment. This is hard to set without the proper tool. I adjusted mine until the shoe started to drag then backed off until I could not hear it any more. Others have said to cut a hole in the backing plate and use a feeler gage. I chose not to do that one due to water and snow build up on the shoes (I like to stop in the rain). Parts are hard to find for these Imperials but check the internet for specialty catalogs and you will find them. I also wonder if you are bleeding the system right. There are to bleed screws on the front end.


Question from Philippe (1957):

Last weekend I made a 250 miles trip with other cars to a car show. All was fine except my brakes! When cold (i.e. after 1 night) the first braking is VERY hard, the left front wheel locks immediately if the speed is very low (under 5 mph). And, as expected, the car goes left.  If I lift my left foot lightly off the brake for 10 seconds, the problem disappears (because the lining is now warm?).  When warm or hot, the car remains unsafe because on strong braking, it goes to the right. I'm always very nervous at "3 digits speeds".  The braking remains too hard, especially at low speed and I feel that the drums are not perfectly round. At very low speed the braking locks again the front wheel(s).  It seems that the drums must be (again) turned, but why are the brakes so efficient?  It seems that either I've a light braking (with light pedal pressure) or a "lock" braking with strong pedal pressure. I know that the power assist system could be adjusted at the "bellow" rod but do you think it's the solution. Maybe also a lining problem: too soft so too efficient?  The brake parts are new (only 2 years old). What do you think of old "NOS" or "NORS" lining and shoes, often seen on ebay? How are these linings (glued..) after 20 or 30 years?

Replies:

From Phil:

I wonder if your shoes got contaminated with something in the past, either grease or brake fluid. This always causes them to grab, and is impossible to clean out. The fact that the left grabs at first, then becomes in effective leads me to believe that the shows on that side are contaminated. What with or how, I can't say, but once apart , check your wheel cylinder very carefully. Grease is also sometimes a problem, but not near so much as brake fluid when it comes to lining contamination.

From Dick:

I've not worked on Mopar brakes of this era since I sold my '57 New Yorker in 1962, but I can say that anytime a drum brake grabs when cold, I have found some contamination (either brake fluid or wheel bearing grease) on the linings, so my advice is to take the drums off and very carefully inspect for a leaking wheel cylinder or hub seal.

I can offer no insight on the booster performance, as I've not worked on this type, ever.

Some boosters of that era were prone to over-boost which makes the brakes lock up at very slight pressure, regardless of temperature or environment - the Bendix "Treadlevac" as used on many cars of the 50s is famous for this problem. The cure is to carefully clean and calibrate the pressure amplifier part (AKA trigger valve) of the booster control system - in fact I have a 55 Packard which is about to get this exact treatment - it will put you though the windshield if you are not feather-footed! However, I do not know if the Mopar booster has this tendency - perhaps someone who as actually rebuilt the boosters himself (rather than simply sent it out to a shop) can comment on this and give you some guidance.

But the first thing to solve is the grabbing on one wheel - this cannot be related to the master cylinder/booster system, it has to be a problem at the involved wheel. If you find no contamination, then I suspect a loose suspension part allowing the wheel to get a little crosswise to travel when the brakes are applied (but this would not be variable with temperature).

As I'm sure you are painfully aware, the braking performance of a heavy car of the 50s is never going to be up to modern standards, and if your car has 14 wheels, the drums are really too small by design, making the fading problems worse.

From Russell:

I had a similar problem on a Brand X car once and found it to be a bad front wheel brake hose on the opposite side of the wheel that locks up. I just replaced both hoses and cured the problem.

From Paul:

I have a lot of experience with these brakes. I have five Imperials with Center Plane brakes. I have driven them a lot of miles and had them for a long time.

The symptoms that you describe are indicative of your car needing a complete brake job. A brake job on our cars does not simply mean new shoes.

The brakes must be completely disassembled. The backing plates must be cleaned and the rubbing surfaces polished. The drums need to be checked for roundness, and possible "over-turning" during the many years of repairs. The wheel cylinders need to be replaced with new (not NOS that have been sitting around for a while) or rebuilt as new. The fluid lines need to be flushed and replaced with new fluid, and all of the flexible lines need to be replaced. The linings must be replaced if they are worn of contaminated.

The brakes need to be reassembled, bled, and adjusted precisely as outlined in the shop manual. It is absolutely imperative that the brakes on your car be in top notch conditon or you will run out of brakes in an emergency stop with your Imperial. Some say that the brakes on our cars were never good enough to stop a car of its size. I believe if they are in perfect condition, and the car is driven responsibly, they work well enough for you to enjoy your Imperial.

They require adjustment FREQUENTLY. I adjust mine every time the car is on a lift, or every 2,500 miles, which ever comes first. During high speed stops you should gradually pump the brakes to avoid overheating the shoes, and thus glazing the linings.

I have chosen to use DOT 5 brake fluid since my cars have been known to sit around a lot and moisture in the lines has been a problem. Dot 5 will correct this condition. Some say that DOT 5 results in a mushy pedal. I have not found this to be true, but that may be because the brakes are otherwise in perfect condition.

There are no brakes on the planet that work very well at 80+mph. That is why it is necessary to make sure that they are working as well as possible.

If you Imperial's brakes are acting up, your car is not safe to drive.

From Roger:

I would jack up the car on that side. Spin the wheel and check if the brake is dragging. If it is re-adjust and test drive. If not jack it up again use a bar and check for up and down motion (wheel bearings and other parts. Then tear down and inspect. From what I see in my manual wear points are critical on the spring guides and spring links. That center plane system looks funky.

From Joe:

You're having the same problem myself and others at the power company I work for are having. The brakes on my company truck would grab hard the first few times I applied the brakes after the truck sat overnight. The mechanics told me it was moisture getting into the brake linings. A lot of brake linings are no longer built with asbestos in them so they are made of a moisture absorbing material. The environmentalists at work. I suggest trying to find someone who will reline your brake shoes with original lining and I'll bet the problem goes away.

Follow-up from Philippe:

This afternoon I've removed the two front drums from my '57 Imperial (remember that I've 2 problems: one is locking left wheel when cold, 2nd is pulling left when hot, see previous posts). Joe send me this post:

You're having the same problem myself and others at the power company I work for are having. The brakes on my company truck would grab hard the first few times I applied the brakes after the truck sat overnight. The mechanics told me it was moisture getting into the brake linings. A lot of brake linings are no longer built with asbestos in them so they are made of a moisture absorbing material. The environmentalists at work. I suggest trying to find someone who will reline your brake shoes with original lining and I'll bet the problem goes away.

And I think this was right.

But I've found other interesting thing. First, no leaking, no grease or oil on linings, no fluid in the wheel cylinder boots. All the parts are perfect (don't know about the return springs). As someone gave me a "comparator" (don't know if it's the correct word) I took some measurements on the 4 front drums I have (2 from my car and 2 from my "donor parts car"). Surprisingly the two drums from my car (which has been turned 2 years ago because the car pulled to one side) are badly out-of-round !! - # 1: (the original right side which was replaced by one from the parts car some months ago, see # 3 ) has 0.0060 out-of-round (FSM says: max 0.0040). Now i know why i replace it ! - # 2 (which is the left side on my car): 0.0027 inside and 0.0047 outside !!!! So the drum is cone shaped ... It's the "locking" side. As i said these drums were turned by a professional 2 years ago !!! - # 3: The right on my car (which was one from the parts car and it's original) has 0.0015 out-of-round - # 4: The left from the parts car (which was on a shed and also original): 0.0019 out-of-round. So I've removed the "conical" drum and put the 0.0019 which is a little "grooved" but I think it's better than a cone-shaped drum. Now I've the 0.0015 and the 0.0019. I've not tested the car.

Philippe's pictures are available at his site:

http://www.ifrance.com/c-i-f/brakes.htm

Follow-up responses:

From John:

I see at least 2 things that look wrong to me. One is that the lower pistons appear to be rusty. If that's so, it will cause them to stick. Another is the back plates also appear to have rust & no white grease on the contact points.

I don't know how the drums can be so far out of round if they were turned correctly, since they mounted on center in the machine. The entire surface should even out. I had some drums on one of my 60's that the drums were turned to the point that the ridge at the outer edge of the drums was almost flush with the rest of the surface & they still worked well. Based on that, it looks like they could still be turned again.

The conical shaped lining will take a while to even out & make full contact with the drum. That should increase the braking power on that wheel.

From Dick:

If you are not using white grease on your brakes, I am concerned that you may be using the wrong grease, and that this could be the source of some contamination. White grease is a sort of shorthand name for lithium brake grease (which is, in fact, white or at least a light cream color), specially compounded so that it will not melt and run even at very high temperatures. Be sure the grease you are using is specifically made for this purpose.


Question from Philippe (1957):

Today I've removed the right front drum (I know it was the right wheel because I made some hard braking in my wet courtyard and the right wheel left some black rubber "stamps" ..). All was fine, no broken parts, no play on the shoes, no leaking brake cylinders, no grease or fluid elsewhere. So I decide to install my spare left drum (the one with the 3 spring brackets). I tested the car and had perfect braking, no grabbing, no wheel locks (except if I brake very hard) and no "out-of-round" feeling just before the car stops. When I have the two drums on the ground, I measured the internal diameter and the "culprit" drum is 12.008 inches in diameter and the "new" one is 11.98 inches. Seems that it wasn't ever turned.

What do you think of installing a left one on the right side? (according to thread studs). I've put some Loctite on 2 nuts ...

Reply from Dick:

Rather than do that, why don't you take the unmachined (probably NOS?) drum to a brake place and have them turn it to standard size (12.000?).

If you'd rather use the left drum, you can remove the left handed thread studs and install right handed thread studs with a press - but this can be tricky - be sure the press operator knows how to avoid warping the drum.

If your drums have threaded inserts, rather than studs, I suppose you can do the same thing but I've no experience with that.

Leaving left handed threads on the right side of the car is inviting future damage, unless you paint on a big sign warning mechanics about it. It also theoretically means that your wheels may work loose, although I think that danger is overstated, if the lug nuts are securely tightened to the torque spec.


Question from Steve (1961):

While driving, the brake pedal is hard as a rock although it stops the car fine; when parked and turned off, the driver's side brake light comes on and the brake is stuck so that the car cannot be driven, until after a while when the pressure apparently eases and the brake light goes off. I've had the master cylinder and the wheel cylinder (and pads) replaced but without success.  Any ideas?

Replies:

From Kerry:

Steve, it sounds to me like the master cylinder is not releasing. I know you just had it replaced.

Couple troubleshooting things:

1- Do ALL 4 wheels lock up. If so, it pretty much has to be the master cylinder

2- If only 1 wheel locks up it would indicate that wheel cylinder OR the flexible hose. I have heard of conditions where the flexible hose can deteriorate and hold pressure on the wheel cylinder.

3- Don't understand why only one brake light comes on unless the other does not work at any time. If they both work normally and only one in this condition than I would get someone to perform an exorcism.

From Bob:

Check all your flexible brake hoses to the drums. Sometimes these start to break down/disintegrate internally, preventing the brake fluid from "returning" after the pedal is pressed and holding the brakes on. It should be an easy, not expensive "fix" and worth doing anyway.

From Timothy:

If it is all four wheels locking up, something exactly like that, except both brake lights lit up, happened when I put a 66 master cylinder on my 60 just to see if my master cylinder was bad. The brake pedal just didn't back off enough for the newer master cylinder. The moral of the story are you certain that you have exactly the correct master cylinder, because they don't look much different at all.


Question from Canu (1962):

I have a 1962 Chrysler with drum brakes on 14" rims and drive it about once every 15 days. My front left brake grabs and at highway speeds it jerks the car to the left violently. At slower speeds it is manageable with anticipated counter steering to the right. Still, it is a major pain. The problem exists even after driving a bit. What can I do to correct the problem?

Replies:

From Paul:

It is probably time to rebuild the brakes on this car. If they are recently rebuilt, it is possible that they have been adjusted incorrectly. The shop manual fully explains the brake adjustment on these cars. Malfunctioning wheel cylinders or dirty brake fluid can also cause this problem.

Your should pull the drums and take a look, although not all problems would not be visible to the eye.

Driving it with the knowledge that the brakes are not functioning correctly is not a good idea. The problem is not going to correct itself, and could result in a serious accident.

From Denis:

I had the same problem with my '58 until they found out that the rubber hose to the other front wheel was collapsing and all breaking power was going to the wheel that pulled violently. If you are like me and mechanically challenged , find a good break shop to check it out.

From Bob:

It would appear that your left front brake is not "sticking" but is grabbing. The first thing I would look for is a leaking wheel cylinder. Brake fluid on a brake shoe commonly causes this problem. There may be no need to rebuild all the wheel cylinders but I would check all of them out. Peel back the rubber boot around the cylinder and look for wetness.
If this is the problem, you can't use the fluid-soaked shoes--you'll have to replace them (in axle pairs.) Front brakes, because of the increased weight nearly always wear more rapidly that rear brakes.

Rebuilding the wheel cylinder might solve the problem.


Question from Tim (1967):

I've recently noticed that when I drive my '67 very slowly, such as in a parking lot, it feels as if the brakes are on slightly. The car doesn't pull to one side or the other though, and it doesn't happen when I'm in reverse. I don't notice it at all at normal driving speed, and there's no burning smell or anything like that.

Maybe the emergency brake is failing to fully release? Setting and releasing the pedal doesn't seem to help.

I'll take the car to my trusty mechanic in a few days -- he's familiar with old cars but not Mopars in particular. Can anyone give me a clue or two to relay to him?

Replies:

From John:

If it is the emergency brake , it could be that one of the cables is sticking.

From Demetrios:

Take the rear wheel covers off and after a moderate drive, feel the temperature of the rear wheels compared to the fronts. If the rears are warmer, may be the emergency brake sticks. Then, take one of the rear wheels off and try to remove the drum. If the drum does not want to come out only with minimum effort, that is an added indication that the emergency brakes is grabbing. If the drums come right off though, that's not it.


Question from Don (1968):

My problem is the front brakes don't release-I don't know what the rear brakes are doing but definitely the fronts won't release. Today I parked the car in my driveway which has a substantial slant to it. I put the car in NEUTRAL and I could not budge it. I put it back in PARK, separated the master cylinder from the booster and put the car in NEUTRAL and it started to roll down the incline unassisted. I put it back in PARK, reconnected the master to the booster and put it in NEUTRAL one more time-it would not move! So, is there a push rod adjustment somewhere or am I looking at this illogically?

Replies:

From Larry:

Yes there is an adjustment to solve the problem you described. On most cars the rod from the brake pedal to the booster (it goes through the firewall) is adjustable. Some cars also have an adjustable rod between the booster & master cylinder. There should be a little free play when the pedal is all the way up. If these adjustments don't work, you may have some mismatched parts. I have seen the wrong master cylinder mounted to a correct booster and the wrong rod at the pedal.

From Kerry:

I've also heard of the brake hose breaking down and causing a symptom like this. Apparently what can happen is that a flap of rubber inside the hose comes lose and acts as a check valve by not allowing the fluid to move back to the master cylinder.


Question from Bruce (1971):

The mighty '71 Imperial has a strange braking problem. When I apply the brakes, they don't release for anywhere from a half a second to about 3 full seconds. This happens with brakes cold and hot, but seems worse when they're hot. Everything in the system has been recently replaced, including master cylinder, vacuum booster, calipers, shoes, wheel cylinders. Shop originally said problem was in the master cylinder and replaced it, but the problem is not solved. I have not taken it back yet, so I suppose if it's supposed to be a master cylinder problem, then the replacement one could be defective. Any suggestions??

Replies:

From Elijah:

It's possible that the replacement master cylinder is bad. However, did the shop replace the soft (i.e. rubber) lines at the front and rear? These lines can collapse internally, which prevents the brake fluid from releasing pressure to the calipers and/or wheel cylinders.

From Kenyon:

I had something similar happen when the spring that returns the brake pedal broke. Had to apply and then use my toe to pull the pedal back.

That's an easy one to check visually, however unlikely it is. Spring attaches to the pedal arm and goes to a frame above the pivot point of the brake pedal.

From Dick:

You don't list the brake hoses as having been replaced. These are so cheap to do that they are often overlooked in the shop's haste to sell you expensive parts. Your symptom sounds to me like bad brake hoses. Replace all of them, not just the front two. If one has failed, the others are close behind.

From Stevan:

You didn't say if the front brake lines had been replaced and if they haven't there's a real good chance that's your problem. What happens is the hoses get rotten and will collapse internally not allowing fluid back to the master and keeping the front brakes applied. We've run into quite often especially on older vehicles.

From Roger:

About a year ago, I replaced the power brake booster on my '65 Crown Coupe. I also replaced some of the wheel cylinders as there was leakage evident. For a while, I had the most annoying problem of driving for a short while and having the brakes lock up. I had to wait for the brakes to cool off before I could drive it home. I finally took the booster off and went back to the parts house to exchange it and upon comparing, found that the mounting hole for the brake pedal arm was located farther away from the booster. So, the brakes were applied all the time until they heated up and expanded--and locked up. With the correct booster, all is well. You can't rely on your parts house to always come up with the correct part. It's called caveat emptor--let the buyer beware.

Check your booster to make sure it's correct.


Question from Joel (1972):

I have no pressure for the brake. I'm having to use the parking brake to remain stopped at lights. It gradually faded. When I first got the car three months ago, they actually gripped too firm. No I have to depress the pedal all the way down and stand on it just to keep from rolling. Is the problem the booster or something else?

Reply from Kenyon:

IF you can keep the car still when in gear and the pedal is stiff and not bottoming out or spongy, then you have a bad booster. Easy to install yourself in 1-3 hours depending. If there is spongyness or the thing bottoms out, you have a failed system or may have one circuit dead with a leaking hose, line, or something.

PLEASE NOTE: If you do not know when the last time was that your car had the system flushed, new components installed, or whatnot, you would do well to consider 3 new soft hoses, new calipers/wheel cylinders, and a new master cylinder. It is probable that the soft lines at least are original and are now over 30 years old!!!

Please consider redoing the system now that you're there.


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