Imperial Parking Brake Repair Information

Imperial Homepage -> Repair ->  Brakes ->  Parking Brake

Tip from Dick:

The parking brake also operates the rear brake adjusters on some vehicles.   People who never use their parking brake are always having problems with brake balance front to rear, and wondering why.   The parking brake also relieves the driveline of steady pressure against all of its moving parts, if properly applied.

Tip from Thomas (1961):

The parking brake light (on the instrument cluster) is suppose to flash when the brake is engaged. 

Tip from Peter (1970):

 

'70 Imperials don't have a regular parking brake release handle. The parking brake releases automatically when you move the shift lever out of Park. The release is operated by a vacuum motor under the dash. There IS, however, an emergency release for the parking brake (in case the vacuum release fails.) This is a little lever mounted to the left of your left foot when you are sitting in the car. It's pretty small, painted black, and not obvious. Use caution when using it because your hand can et smacked by the pedal on its way up. You shouldn't need to use it though.

Question from Zan (1962):

 

How do I adjust the parking brake on a '62 Imperial?

 

Reply from Paul:

 

The '62 parking brake is a drum brake located on the back of the transmission. To adjust, buy a brake "spoon," open the dust cover on the front button of the assembly, and rotate the star wheel down by moving the brake spoon up until the shoes lock up the drum, then back off just enough to free the drum. That should do it, however there is also a cable adjustment nut where the cable goes into the drum assembly, but adjust the shoes first before you try that. If none of that works, you can remove the parking brake assembly by disconnecting the drive shaft, and removing the nut from the end of the transmission shaft, where it passes through the parking brake. Wrap a strap type big pipe wrench around the drum to lock the transmission, and use a big socket to get the nut off. Back off the shoes, and remove the drum to see what's going on.

Question from Erik (1963):

On my '63 Crown's auto parking brake release, I noted that there were no clips securing the vacuum line to the vacuum diagram, and this 40 year old hose fits loose enough to allow air passage. A new hose is on the to-get parts list. Can anyone confirm that clips were or were not used to secure this hose to the diagram?

Clay, for that issue with a non releasing parking brake, it sounds like the diagram is stuck in the release position or the manual emergency release lever is being held in the release position.

Though it isn't a huge problem, the parking brake has never worked on my Crown Coupe. It plain doesn't do anything. The pedal won't even stay down when you press on it.  Any suggestions on how to repair this problem?

Replies:

From John:

I've owned 4 '63's & none of them had any clips or clamps to hold the vacuum lines on.

From Paul:

There are no clips holding the hose on the parking brake release in my '63 Imperial. I accidentally pulled the hose off of the unit when I had the instrument cluster out the last time. I didn't realize it until I had everything put back together and started the car. The hissing clued me as to what I had done before I even tried to operate the release. I was able to re-attach the hose without taking the instrument cluster out again, but I re-routed the speedometer cable so that it wouldn't happen again the next time I was servicing the cluster. It probably wouldn't hurt for me to also replace the hose, although the old hose doesn't leak any vacuum.

Question from Bruno (1964):

Since I had my transmission worked on my 64 Imperial, the "Park" lever would not function properly and also when I start the car and put it in gear the emergency brake normally would release automatically. Now nothing works anymore and my mechanic doesn't' know what to do.  

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From Jay:

I had the same problem in my '66 after I installed rebuilt brake booster.  Check to see if you have a loose or broken vacuum line under the dash or at the booster.   If you start the engine and put the tranny in reverse or drive, you might notice a sound of rushing air coming from under the dash. The automatic parking brake release is actuated by a vacuum operated diaphragm under the dash. If the line to this diaphragm is loose or broken, you will hear escaping air and the parking brake will most likely not automatically release.  There is a manual parking brake release lever. If you haven't found it already, it is a small lever mounted very close and to the left of the foot pedal lever.  Make sure that your hand/fingers are clear of the main parking brake pedal when you release it manually. (It really has a strong kick!)  

From ???:

The parking brake release is vacuum powered. You might need to re-connect the vacuum hose under the dash; when the Park lever is pushed up, it activates the vacuum release. (There's an emergency release switch on the side of the emergency brake pedal.) When I had the seals replaced on mine, the neutral safety switch was occasionally out of alignment; this would prevent my car from starting. (The transmission thought it was in reverse when it wasn't.) You might have a similar problem with the Park pawl not hooked up properly.

Question from Tim (1965):

 

I don't even know where the parking brake release is on my car.   

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From Chris:

To Tim and everyone (post-'64 only, of course) who feels that the Park position is good enough for parking, I strongly recommend that you apply the parking brake as well, unless your Imperial is going to sit for a long time. Anytime you rely on the parking pawl (a mechanism inside the transmission) to restrain the car on a slope, even a gentle one, you take that much more out of the parking pawl's life. (Put it this way, if it's hard to get the lever out of Park when you need to drive away, you are straining the parking pawl too much. And if the car rolls more than a few inches before the pawl catches and holds the car, then it's already begun to wear from this practice.) BTW, the correct procedure is to stop the car, and with your right foot on the gracefully large brake pedal, use your left foot to firmly but never forcefully depress the parking brake pad. THEN shift into Park (so the brake's holding the car, not the parking pawl), and THEN take your feet off the respective brakes. Besides, using the parking brake regularly helps to keep it operational should you someday need to rely on it as an emergency brake. It also motivated me to fix my automatic parking brake release, which is a special treat every time I shift from Park.   All Imperials of your vintage and later had an automatic p-brake release, which is why there's no obvious handle in sight. But if you look under the dash you'll see a small flat black horizontal lever about 4" long in the upper left corner of the foot well, kind of directly above the high-beam changer button. Use a flashlight if you need to, but it's not that hard to find. If your automatic release does not work, pressing this lever (the idea is that you do it with your foot while seated) will mechanically release the parking brake).

From Nancy:

This is a trick I have learned with most MOPARS that have a parking brake that is engaged with the foot. Put your hand on the parking brake then follow the piece it is attached to with your hand as it goes up under the dash. As you go up the parking brake you will feel something sticking out. Reach out for it with you fingers and you will feel a small lever. Press on it and your parking brake will release. This is the only way I have been able to find them. By the way - one day the parking brake on my '82 Imperial wouldn't release at a gas station and this method even worked on it. I guess they kept that same general design for a long time.  

Question from Brian (1966):

The emergency brake does not release automatically either. How does that work?

Reply from Paul:

The emergency brake release is controlled by a vacuum motor and a switch that is activated by the transmission lever. If the brake doesn't release, the switch could be out of alignment (or leaking), the vacuum motor (or diaphragm) could be leaking, or vacuum source (or hose) could be disconnected or leaking. Assuming that you are able to release the brake with the manual assist lever, there isn't too much else to go wrong.

Follow-up question from Brian:

When I put the car in gear I can here a slight hiss under the dash. The manual works fine.

Reply from Paul:

That would lead me to suspect the diaphragm in the vacuum motor or actuator. The hiss means that the switch is probably functioning. Check to see if the vacuum motor will hold vacuum, and also make sure that the linkage is connected properly to the parking brake.

If the hiss is continuous, there is a leak. If it only happens briefly during the time that the shifter is being moved, its normal.

Also, check to make sure that the hose hasn't come undone from the vacuum motor. This can happen accidently when you are reaching around under the dash.

Question from Clay (1967):

The parking brake has never worked on my Crown Coupe. It plain doesn't do anything. The pedal won't even stay down when you press on it. It has also never made any sort of vacuum hissing noise. I always thought it was a gizmo, or bracket, that had to be replaced. 

Replies:

From Bill:

On my '67, when you shift into drive the parking brake releases. Of course, don't use it much in the flatlands of the Arkansas delta.

From Brad:

I had one mechanism where the pedal would not stay down and it was just that the mechanism was so rusty that the parts would not move freely. This prevented the little cog that holds the pedal down would not engage. I replaced the entire assembly.

Question from Carl (1968):

I've been working on the Imperials and the NYB a lot lately and I have a question. The automatic parking brake release doesn't work on my 68 sedan so I decided to tackle that last weekend. I investigated the situation and noticed the following things: The vacuum line was disconnected from the vacuum tank at the engine, the vacuum line to the vacuum valve was disconnected, the line from the valve to the actuator was also disconnected and the vacuum valve was loose. So, starting at the engine, I reconnected the vacuum line to the vacuum tank since the hose was still in good condition. Next I applied the parking brake and mated the two lines that go to the vacuum valve to check the release activator. As soon as the two lines touched, the brake released. So, I next went about looking at the vacuum valve. It has three spots to be mounted on the steering column and an actuating arm with one helleva spring. I took the valve off the column, disconnected the wires attached to it and tested it to see if it could regulate a vacuum. When I pushed the are against the tension, the vacuum shut off so I'm assuming it works, or is it? But I'm not really sure how it works. Does the steering column contain a "slot" for the actuating arm that triggers the vacuum when the transmission is shifted into "R" and "D"? Or is the vacuum triggered by the electrical connection with the arm performing an ancillary function? The FSM is a bit vague on the parking brake vacuum valve and since I can't see behind the steering column where the valve is located.

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From Dick:

Yes, there is a mating slot on the shift column (inside the steering column bracket) that engages the tang on the moveable plastic thingy that gates the vacuum off and on depending on which gear you are in.  This same assembly also contains the totally separate and unrelated electrical switching function of turning the backup lights on in reverse.   Do not, I repeat DO NOT take the electrical switch assembly apart, it is nearly impossible to get all the tiny parts and springs back where they belong.  The vendor must have had a horde of trained monkeys and  $1,000,000 in tooling to assemble these things.  

There is a special procedure to reinstall this assembly on the column, it is well described in the shop manual.   You need the ability to work upside down, in the dark, with your nose roughly 2 1/2 inches from your fingers, for about 2 hours, to accomplish this.   If you are thus qualified, it's easy.  If you're like me, take a sedative before beginning.

From Michael:

I've had to do this on my '68 also.  It is mechanical - an arm positions something (it's been too long to be more precise) on the piece attached to the base of the steering column.  As I remember, the sammechanism contains the switch to the backup lights.  I'd suggest you check to see if they function correctly.  If so, vacuum is more likely the problem. If they don't work correctly, the combination switch would be my bet.  I do remember that you have to position everything just so in replacing the switch, and I think there is some lateral adjustment for fine-tuning.

Question from Tony (1971):

I was thinking the other night that my auto parking brake release on my '71 Imperial has never worked since I have owned it. I was wondering where I should start to look to correct thhis problem..

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From Dick:

Take a look at the vacuum diaphragm device on the left kick panel, the one that is connected to the brake release. See if the vacuum hose is connected to it, and to the control valve on the base of the steering column. If not, there must be a stub of a hose or some other device to prevent vacuum leaking from the control valve, otherwise you'd hear a lot of vacuum hissing under there when you shifted into gear. I'm assuming you don't, and that your backup lights work. If this is correct, the release device is either disconnected or failed in such a way that it doesn't leak (it is rare that they fail in that mode, usually the failure is that they begin to leak, and the owner disconnects them).

From Kerry:

There is a vacuum can up above the mechanism under the dash. They leak a lot and frequently (usually??) the hose gets disconnected and plugged either under the dash or at the back of the motor where it branches off the vacuum tree.

Question from Robin (1972):

On my '72 Imperial I have noticed a vacuum like noise if I shift to neutral. I did not know there was anything vacuum related linked to the shift mechanism. Anyone know what may be?

Replies:

From Chris:

It's your automatic parking-brake release, which is most likely leaking either at the diaphragm in the canister that's attached to the top of the parking brake pedal, or at the valve behind the regular brake pedal which opens when the gearshift is placed in R, D, 2 or 1 (if adjusted properly).

How to test if it's a problem: Put the car in Park. Set the parking brake. With the motor running, shift to R or D. The parking brake should release (sometimes this takes a few seconds). If the brake release works properly, you can probably ignore the hissing sound for a long time.

If it does not release, there is a small manual-release lever intended to be operated by poking your foot up under the dash above the parking brake pedal.

In neutral, as in Park, the valve (a small plastic or nylon assembly with two hoses connected to it) remains closed. In one of the "moving" gears, the valve opens, sending vacuum to the canister above the parking brake, which then pulls a lever connected to the parking brake pedal to release it.

It's a fairly simple system that is prone to a few faults:

1. Leaks are possible in the hoses, in the rubber diaphragm inside the canister, or in the valve assembly behind the brake pedal. Such leaks can cause hissing (and the fact that it only occurs in neutral really doesn't eliminate any of these as the problem) and also reduce the vacuum to the canister so that there's not enough strength to pull the lever. You can usually find the leak by crawling under the dash with the engine running and listening (provided you can set the parking brake while the car is in neutral, so you can do this safely... be careful NOT to move the gearshift into D or R while doing this, and I recommend blocking the front and rear wheels first).

2. If the valve, which mounts to the steering column above the brake pedal, is misadjusted (or if the PRND21 indicator needle is inaccurately positioned, you can adjust this back into position with some trial and error. I think the valve body also holds the contact for the backup light switch, so chances are you can get all three features (PRND21 indicator, brake release and backup lamps) to work properly by adjusting the valve position properly. The valve rarely leaks unless it is broken... you can pull off the hoses to see if their fittings on the valve body are cracked or broken off.

3. If the leak is inside the canister, there's little you can do except find a good canister in a junkyard and swap them out. The 1969-73 canisters are interchangeable, I believe, and with some creativity you can modify one from a '67-68 or '74-'78 to work. You can also use one from any '69-73 fullsize Chrysler, Plymouth or Dodge that was equipped with this option (it was standard on Imperial).

4. If the leak is in a vacuum hose, these are easy to replace as vacuum hose is sold by length at any auto parts store. Cut off a quarter inch at the end of one of the hoses and bring it in to match it up.

One final note: your parking brake is also your only emergency brake. It is vital that it be in proper working order, even if the automatic release doesn't work. Many people ignore the brake's very existence, and that causes the pedal assembly, the cable to the rear brakes, and the mechanism inside the brake drums to freeze up or rust. It's worth the effort to make sure the p-brake operates freely and is adjusted so that it can stop the car yet doesn't bind or drag when released.

From James:

I don't know if the system is the same as in '76, but if it's working properly it will hiss when you shift into neutral or park, but only for a few seconds, this is just the mechanism doing its thing so you can apply the parking brake (which can't be done in RD21). If yours keeps hissing, then you have a problem.

From Ross:

That could be the actuator for the automatic parking brake release. I had the same noise on my '78 NYB and it kept getting louder. As it turned out, the actuator went bad and caused a vacuum leak. It's now temporarily disconnected until I find a new unit.

Question from Tony (1977):

My '77 NYB 440 seems to be having a case of sticky emergency auto-brake release, it eventually pops up, but sometimes I have to go back and forth between Park and Drive 4 or 5 times before it will release.......... has anyone else experienced this, or does anyone know an easy-fix ?

Reply from Chris:

The actuator valve for the automatic parking brake release is mounted to the steering column, so that it moves relative the the position of the gearshift lever. If the brake releases (it should do so in D or R), it suggests that the vacuum canister and hoses are generally OK, but that the actuator might be out of adjustment. Crawl under there and try adjusting it (it's a rotational adjustment along the arc of the steering column) so it releases cleanly when the gearshift is moved into D or R, but not when it's in P or N. The actuator is easy to spot... it's a rectangular metal and nylon thing about 2x3" with vacuum lines attached to it.

A slow-to-release brake (one which just takes its time once you leave the lever in D or R) suggests a leak in the line or the diaphragm inside the canister. Try just leaving it in D for about the same time it takes you to shift back and forth from Park to Drive 4 or 5 times (in other words, wait rather than shifting back and forth), and if the brake eventually releases, it's just a matter of weak vacuum. (If not, see above, as it's likely the adjustment). If you hear a hiss while the car is in gear, then try replacing the vacuum hoses. If it's a leaking canister diaphragm, you have to replace the canister (meaning you'll need to find one in a junkyard, most likely).

In the meantime, there is a manual release lever under the dash (atop the canister, on the left wall of the foot-well). It's intended to be reachable by sticking your left foot up there, but Chrysler certainly seemed to hide it well in the NYBs. I can find it by feel in my Imperial without a problem, but I practically have to use a flashlight and my hand if I want to use the one in my NYB...

Question from Bob:

Has any one had trouble with the automatic parking brake release? My diaphragm has a bad vacuum leak in it.  Right now I have the vacuum line plugged and working the parking brake manually. It looks like the whole parking brake assembly has to be replaced. I am thinking of installing a push-button type vacuum switch under the dash to power the diaphragm to release the parking brake.

Replies:

From Dick:

I don't know for sure how the auto-parking brake release works on a 66. On the 67's and 68's, there is a curved switch assembly attached to the steering column at floor level (another nice thing to service!) The switch has a protrusion that enters the steering jacket and engages a rotating sleeve that moves with the gear shift lever. The switch has wires to control to the backup lights (do they work OK?) and a vacuum valve that closes off vacuum to the brake release diaphragm in Park and Neutral. By the way, this is often the mysterious source of vacuum leaks on these cars. If you hear some hissing in the driver's seat, that is a good place to look and listen. Anyway, when you shift from P or N to a gear, you should hear a momentary hiss while the diaphragm is getting its air sucked out, then the noise should stop.   

From Chris:

Before blaming the diaphragm in the vacuum unit, try a few things. With the car running and have a trusted friend safely hold the regular brake pedal down and shift to D or R. Crawl under the dash and listen for a hissing sound that would indicate a vacuum leak, and find out where it emanates from. The leak could come from the vacuum hoses themselves (a pinhole, perhaps), from the valve that is actuated by the gear selector (which one of your cars are we discussing here?), or from the diaphragm in the canister itself. Also, wear in the pivot point for the p-brake pedal actuator rod (the rod that goes into the canister) can make it hard to release even with correct vacuum. One last test: patience. My old p-brake release would finally do its job if I waited about 90 seconds. I've since found a replacement canister in a junkyard, put washers on the pivot to reduce the free play, and replaced the leaky actuator valve. Now it releases within three seconds. Vacuum canisters differ by body series but often the only difference is the angle of the rod attachment, which you can bend into the correct shape in a vise. And, once again, you should always apply the parking brake when parking, before you shift into P and before taking your foot off the regular brake!

Question from Tony:

Today, in the process of searching for an annoying intermittent rattle, I removed my prop shaft. Since it was off, I thought it would be a good chance to examine the parking brake and, as I suspected, the linings were worn down to the rivets. I would like to get them re-lined, but the material they are made of is something I have never seen before. It appears to be a mixture of fiber and metal with a surface texture like the back of a woven rug. Is this what they call composite lining? More to the point, is it necessary to replace it with the same material or can I use regular ferodo linings.  Any advice would be much appreciated.

Reply from Mike:

In the past I have had good luck getting the oddest brakes re-lined at some NAPA's and if not, look for a commercial brake reline outfit near you.  

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