Diagnosis and Repair Information for Your Imperial's Master Cylinder

Imperial Homepage -> Repair -> Brakes -> Master Cylinder

Tip from Mark on converting your Imperial to a dual master cylinder set-up:

For safety reasons, I converted my '66 Imperial to a dual master cylinder. It is easy enough to do as the rear brake system on my Crown attaches to the front right in the engine compartment. A simple replumb to bring the rear system to the mc while leaving the front system intact was simple enough.

How to Bench Bleed your Master Cylinder:

After successfully rebuilding a master cylinder (or when fitting a new one) it is a good idea to bench bleed the MC before installing it in the car. This will fill the master cylinder with fresh air-free fluid and in effect "prime" it for integration with your car's hydraulic brake system, making your on-the-car brake bleeding a little easier.

The basic idea is to create mini hydraulic system on your bench. You can use old brake line fittings if you have them but I didn't so I purchased a master cylinder bleed kit from my local auto parts store. A new master cylinder may include the necessary parts already. The kit should consist of a number of plastic fittings which are designed to fit in the outlets (usually two, front and rear) of your master cylinder. One end of the fittings will be threaded and the other will have a round smooth hose adapter. Thread the appropriate fittings into the outlets on your master cylinder. The kit will also contain a length of plastic hose. My kit had black hose but I found some spare clear hose and used it instead - this will allow viewing of the air bubbles passing through the hose. My kit also had a plastic clip used to hold the two pieces of hose together and clamping to the edge of the fluid reservoir.

Clamp the cylinder firmly in a bench vise so that the cylinder area is level. If it is pointing upwards the air will remain in the cylinder. Slide the hoses onto the fittings. Cut the hoses just long enough to reach into the reservoirs and remain submerged - the shorter the length of hose the better. Place the other ends of the hoses into the fluid reservoirs (you'll probably have hold them in place somehow because once you start pumping they'll want to flail around in the air and spray brake fluid everywhere). If you can get a helper that is ideal.

Fill the reservoirs with new brake fluid, and pump the piston slowly and evenly, full strokes. I used a big Phillips screwdriver because its tip doesn't damage the piston and the handle gives you something to lean against. I would not worry about the fluid getting recirculated because it is brand new and you are creating a temporary hydraulic circuit with the hoses which will not become contaminated with dirt. The air which is still in the system at this point will be bled out. Pump the cylinder until the tubing contains no more air bubbles and no new ones emerge from the master cylinder on the down stroke. On my master cylinder this took about 15 strokes some may require more, some less. Keep going until the air stops as this will make the task of bleeding the brakes in the car much simpler. When all the air is out, mount the cylinder in the car. Here you have to be careful to prevent the fluid still in the hoses from spaying your car and any other painted objects nearby - brake fluid is a great paint remover! If you decide to remove the hoses before installing on the car, make sure to plug up the fittings - I just held the hoses up while transferring from bench to car. Once the master cylinder is mounted in the car, remove the fittings and connect the brake lines. You'll lose a little fluid but the check valves in the cylinder should stop any major leakage. Now you are ready to bleed the brakes in your car and it should be a lot easier than if this step was avoided.

Tip from Jeff:

I was lucky enough to get a copy of Tony's WONDERFUL!!!!!!! Video of the Senora meet and I noticed a couple of the 57-59 Imperials had an aftermarket master cylinder filler neck or something. It looked wonderful. Anyone who has ever added Brake fluid to a 57-59 (maybe later) Imperial will find the power booster is located directly above the master cylinder which makes it ALMOST impossible to add fluid. On the tape I saw a couple of different styles which bring a neck out of the way of the power booster. Does anyone know where to get one of these or if they work well? [I used to have one of those years ago - Bill Fuller (now deceased) had a bunch of them. Unfortunately, this was before I switched to the chemically-inert DOT-5 silicone brake-fluid, and the old-style DOT-3 fluid devoured the plastic reservoir, dissolving the plastic into the hydraulic system - It never seemed to harm anything, though. I would NEVER trust one of those devices unless I also had DOT-5 installed as well.

Question from Kenyon:

When installing the plumbing for a dual MC on my originally single MC car, do I: Run 1 line to both front wheels and 1 to the rear? <> Run the lines like an X with 1 line to RF/LR & 1 line to LF/RR wheels? I am assuming that the first is correct. ----- Should I get a proportioning valve if I do the front/rear deal? If so, how do I determine at what point to set it? (yes, they probably do come with instructions, but I haven't gotten that far yet.)


From Brian:

One line for the front and one for rear, and do use a prop valve. If you get an adjustable valve, set it for more front than rear to start and then drive carefully to a country road or road with very little traffic and test stop. Brake hard enough to lock them up and adjust so that they lock at the same point. Others can probably tell you a little more on them, but thats the basics.

From Ron:

There is a stop on the piston that will operate the front brakes without rear pressure. This was one of the main reasions the car company's switch to dual master cylinders. It also workes in reverse. I used a mid-80's Dodge van masters on all my Imperials and Desotos...no proportioning valves needed because you have 2 slaves up front and one in the rear per wheel.

From Bill:

I've done this swap a couple of times now. Use an all-drum master cylinder from the '67 model listing. Mopar always fed the front wheels with the rear reservoir, and the rear wheels with the front reservoir, until going to X-systems in the front wheel drive cars. Run one line from the rear master cylinder outlet to the present junction block. Leave the lines from the junction block to each front wheel as they are now. Plug the junction block outlet to the rear axle line with a flare plug (not a pipe plug). Run a line from the front master cylinder outlet to the line going to the rear axle, using a flare union to connect the two. You should not need a proportioning valve to stay with all drums, I haven't had any problems at all without one.

Question from Kerry:

What year Imperial was the first to have a dual master cylinder? Did it still have drum brakes? Was there a proportioning valve? My 57 needs a new master cylinder. Since I'm not stock anyway, I thought I'd replace it with a dual unit. I'm hoping that the first dual units would bolt up and I'd only have to run a few brake lines.


From Ron:

Which power unit do you have, bellows or piston? We do a few dual conversions a year (highly recommended for daily drivers) and you have several choices, but it depends on the power unit. All you need to change is the master, and maybe fabricate an activator rod, you don't need a proportioning valve on drum/drum systems as that is built into the sizing of the wheel cylinders.  

From Peter:

If the car is being restored for show it makes sense to leave it stock, however if it is to be driven on a regular basis the added safety of the redundant dual is very real. Brake leaks do occur even to the best and most fastidiously maintained cars. Think of it as a social responsibility, after all look at the size and power of the 50's Imperial. I have performed this modification on a 1965 Buick Riviera, it should be similar for the Chrysler cars. The master cylinder must come from a car with drum brakes, disc brakes use much less cylinder area. Obtain a master cylinder just like the one in your car. Go to a wrecking yard. Take the master cylinder with you. Probably a dual master cylinder from an early sixties Chrysler full size will work but you must make sure the distance between the mounting studs is the same, the diameter of the end of the master cylinder boss is the same ( most are ). The rod from the pedal may differ in length, it's best to take that as well. Make sure the tube flare fittings fit both master cylinders. And take the proportioning valve. This is the most important part of the conversion. Both front brake lines connect to it as well as the thinner rear brake line. You may need flare fitting adapters to fit your cars lines to the later models proportioning valve. The valve should be located close to the master cylinder. Take it and the connection lines along with the new master cylinder.  Remember the make, model and year of the DONOR CAR! Install all of this on your car. You may need a cheap tubing bender to help reroute the lines a little. If it all fits and works properly go to the car parts store and buy a NEW master cylinder and install it. The auto manufacturers changed parts and suppliers a lot, don't be surprised if the first master cylinder you choose doesn't quite fit. This is actually quite an easy conversion and well worth the effort on any older car that will be driven on a regular basis.  

From Lawrence:

A source for this is Hot Rod World Wide.  Here is a portion of the email I received from them:

"I have a kit that will fit the 65-70 Dodge & Plymouth. It is a dual master cylinder for drum/drum and comes with a combination valve, bracket and lines. The M/C that you need is $179.95 (MC11571) the valve that you need is $79.95(VL3526)

David Cantrell
Hot Rods World Wide
4876 Lakewood Drive
Acworth, GA. 30101

From Ron:

How to convert a brake system from a single to a dual reservoir master cylinder:

Donor car: 1968 Chrysler Newport w/ drum all around, but dual circuit.  Receiving car: 1962 Chrysler 300 2 dr also 4 drum, but single circuit  FROM 1968 NEWPORT: Remove master cylinder, and all brake lines in engine compartment.  This includes both lines from master to distribution block, dist. block itself, and brake lines to both front wheels. Only line staying on Newport is brake line going from distribution block to rear...  1962 Chrysler:  Remove master cylinder, line down to dist. block, and both front lines.  Install dual master, lengthening the rod coming out of booster a little bit; it's adjustable. Need to measure one master versus the other as far as length of rod needed...  Install distribution block, in stock location, and plug in the lines from master to block. Minor bending necessary. Install lines to each front wheel. Plug in line to rear wheels to distribution block. Bleed brakes - you're done... Reason for using front brake lines to Newport is that they are a bit  longer - in your application you might be able to keep your front brake  lines...  result: dual circuit drum brakes; something blows, and you don't lose it  all!  Hope this has been helpful - let me know how you make out... 

Question from Bobby:

I decided to replace the check valve on the booster before swapping out the entire unit. The old one seemed to have a little restricted airflow. A new one was only 3 bucks at Autozone. Well, it wasn't the problem. The pedal is still hard , all the time now. So I'm waiting for my booster with master cylinder to arrive. What I want to know is how hard is it to install. Are there any surprises I should know about or any rules of thumb that should be followed. Also, how much bleeding is necessary? I remember changing a master a few years back and I didn't have to bleed it at all. Is this possible when changing them both?

Reply from Steve:

Does your car still use a hydraulic brake light switch? If it does I would go ahead and replace it now with a new original type unit. Andy Bernbaum has them and I am sure others do to. They seem to be more durable than the general replacement units. Before installing your new master cylinder you need to bench bleed it. Many times the stuff you need to do this does not come with the new master cylinder. "Help" makes a good little kit for this that contains all the fittings and hoses you need for any master cylinder and it is all reusable for around $5 cost. If you aren't familiar with this company there is usually a little section of there stuff in most parts stores. They make a lot of generic type replacement parts and automotive tools. Your master cylinder should contain the instructions to bench bleed. If it does not then put a fitting and hose on the lines out of the master cylinder and loop them back into the master cylinder then fill the master cylinder with fluid. Pump the master cylinder until all the air bubbles disappear. I usually pump the cylinder an additional 20 or 30 times just to make sure all the air bubbles are gone. After this is done carefully reinstall the master cylinder (remember that brake fluid will eat your paint!) and then bleed the rest of the system from furthest away (passenger rear) to closest (driver front). Make sure you do not let the master cylinder run dry during the bleeding process or you have to start all over again (and if you are anything like me great amounts of profanity can be heard throughout the house at that point). If you don't have another person to assist "Help" also makes a one man brake bleeding cup that can be a life saver. I would bleed all the wheel cylinders at least twice and probably three times to make sure no bubbles are hiding in the system. Once you get done bleeding check the brakes to make sure they are all properly adjusted. Take this opportunity to check all your wheel cylinders / calipers for leaks and check your rubber hoses for cracks and bulges. Many times marginal components will fail after the master cylinder is replaced. I don't know whether this is because the new cylinder can exert more force or because the gunk in the lines gets stirred up.

Question from George (1955-converting to dual master cylinders):

I've been getting my new '55 Limo road ready, I've title & tagged it, I've touched it, sat in it, looked it all over, read & re-read the books and manuals, I've got to know it very well. As much as I want and need to keep it all original, I've run into a challenge with breaks, specifically the new single master cylinder failed (I fixed it) then it failed again, during this latest cold snap. It's no fun to have no breaks in a 5000# car! anyway to my point...I'm changing over to a dual master cylinder. I found a bolt in replacement from a early '60's era MoPar with non-power breaks bolts right up to the fire wall, it even has the require 1" piston. I'm now measuring for the placement of the dual lines down the fire wall to the point at which they will need to split. One of the reservoirs in the dual cylinder is slightly larger so it will be for the front with the rear running thru the stock lines to the back. Also this job is a little easier since this Limo has the disc break set up so no power booster. I didn't want to do this, but at least I'll have double the chance of always having the ability to stop. Has anyone else made a similar modification?

Reply from John:

What are you using for the proportioning valve?

Response from George:

That's a great question, however, the answer may be different for you than it is for me. For me, since my '55 Limo' has 'Dics' brakes all around, of the design that is self energizing, enabling the omission of any power booster...I don't need one...That said, it requires further information. For you, (depending on your car & brakes) ...any proportioning unit from any American car that is new enough to have a dual master cylinder and old enough to not be metric thread will work. But, you most likely would want to use a unit from the era of the master cylinder you pick. Now, I do intend to install a proportioning unit, I've chosen to use a adjustable unit of the design that has a 'set screw' to adjust it (as once set, it won't need readjusting) this also will serve as the split for the two lines going forward and the single line going back. In other words two new lines from the new master cylinder (for front and rear) go to this unit, out of this unit go the two lines for the right front and the left front, also the line to service the rear. This unit also has a port for a unequal pressure switch that I could use to light a brake warning light if I desired.

Reply from John:

I've been thinking about the conversion to a dual mc the next time I have a brake job to do in one of my cars. The '57-'61s (drums all around) have the mc located under the power brake booster so clearance is a big issue. It looks like a tandem mc from a '67 Chrysler might do it (and the setup also includes a hydraulic switch as you describe below).

Follow-up Responses:

From Remco:

I have converted my '57 Imperial to dual master cylinders.  Here are the steps I took:

I used the master cylinder off of a Dodge W-200.  The first problem I encountered was that it was too high and also did not clear the valve cover. I cut about 1 inch off of the top of the master cylinder, otherwise the power booster was in the way.  I welded in a small pipe through the lid with a flexible hose so that refilling would be simple.  Now when I need to bleed the brakes, I just use a pressurized bottle for refilling... I just have to open the bleeding plugs on the wheel cylinders... no need to pump the brake pedal any more.  I bonded the lid onto the master cylinder with the same type of glue used to glue in windows.  Do not use silicon-based glues.

On the engine side of the master cylinder were two lumps of metal.  I grinded these down to get about an 1/8 inch clearing with the valve cover.  

I took the proportioning valve off of a Camaro, but any other will also work.  

I think the brake light switch on a '57 is on the master cylinder.  There was no brake light switch on the master cylinder of my W-200, so I made just a small switch on the brake pedal.  I took one from a Japanese-made car. The pushrod from the brake pedal to the master cylinder had to be made a bit longer, but there was no need to be exact, as the pushrod is adjustable.

I also made an adaptor plate on the firewall as my original master cylinder is fixed with 2 bolts.  The W-200 is fixed with 4.   It's not a very complicated job to do.  I think most 1 1/8 bore master cylinders with the brake lines on the fender side can be made to fit, but be careful when working on brakes for a 5000 lbs car!!

Quesiton from John (1955):

Have a question about the master cylinder cap seal. One day while driving my car I had to use the brakes very heavily several times and all of a sudden didn't have any brakes. After I got the car home I took the cap off and noticed that there wasn't any seal at all under the cap and all of the fluid had dripped down the side of the master cylinder. I made a seal for the cap and it works fairly well, but under hard braking this still leaks. Is there anybody who sells remanufactured seals for the master cylinder cap?


From Dave:

A couple of years ago I managed to get a master cylinder R/B kit, the cap seal was not included in it. How ever when I was in Jacksonville I managed to get a proper one off Automobillia. They are very helpful.

From Roger:

It is the only master cylder made of that type. The loss of the ring is a good question? If you let some one else service your car I would switch people. They do come off easly when taken off. Murphy was right it always goes to the center and hardest part to reach. Ford ring is the same and so is the cap.

Question from John (1956):

I have noticed that I now have a brake problem.  The problem is that when you touch the pedal it goes down to the floor, if you pump it once or twice it will stop the car, but if you keep pressure on it it goes down to the floor again.  I have checked the fluid level and it was just a little, little bit low.  I have bled the brakes and found no air.  There is some indication of brake fluid near the top of the brake pedal. 

Reply from Peter:

You've described classic symptoms of master cylinder failure.

Question from Philippe (1957):

Brake problem on my 57: I don't know if it's a problem or not. I have an excessive  travel of the pedal before brake apply. The brakes are efficient only in the last 1/3 of  the travel (but the pedal don't touch the floor) with or w/o the brake booster and the distance between no brake and wheel locked is closed. I have adjust the master cylinder rod according to the FSM but I don't feel in security with all this "gap". Do you think I must lengthen the rod by adjusting the nut rod ? Or is it a problem of bleeding ? I use silicone fluid.

Reply from Dick:

I'm not sure if anyone else has responded to your question about the brake push-rod adjustment. There should be just a little free travel of the pedal before it contacts and begins to move the piston in the master cylinder. No more than 1/2 cm, at most, as measured AT THE PEDAL, not at the rod itself. But there must be some free travel, so that the pressure relief port in the master cylinder is opened up after each use. If your pedal is too low, but otherwise everything is OK, it sounds to me that you just need to do a normal brake adjustment at the wheels. Your car doesn't have self adjusters. Just go through the normal adjustment at each wheel (tighten each wheel until it cannot be moved by hand, then back off 8 clicks), and see if this helps.

Question from Tony (1957):

Although my brakes were working fine, I noticed that my master cylinder was weeping from the back (behind the brake pedal). To avoid any potential failure, I replaced the M/C with a new one. I have followed the manual, slackened off the shoe adjusters, bled the brakes and M/C then re-set the shoe adjusters three times. Despite this, the pedal still goes to the floor even if I pump it. What am I missing? For what it is worth the M/C is actually for a Dodge truck, but the interchange manual shows it as identical to the Imp part. It certainly looks the same. Could the push rod be lengths be different? (Mine is a non-adjustable rod)  How do you bleed the master cylinder ? On mine (57) there's no bleeder screw ..

Reply from Leo:

Did you bleed the master-cylinder before you installed it?

Follow-up question from Philippe:

How do you bleed the master cylinder ? On mine (57) ther's no bleeder screw ..


From Leo:

Usually you get the bleeder tubes with the rebuilt master-cylinder. Put the master-cylinder in a vise, attach a tube from the outlet port or ports into the reservoir. Fill the reservoir with brake fluid and keep depressing the piston all of the way with a dowel until no more bubbles appear in the fluid. This only applies to a new or rebuilt master-cylinder. On used ones, only depress the piston part way, otherwise the corrosion in the untraveled portion of the cylinder. will damage the piston cups.

From Steve:

You attach a plastic tube from the brake line connection and route it back into the brake fluid reservoir. There are kits available in most part stores for about $5 with all the different connectors and the plastic tube. These kits are made by a company called "Help". Once attached use something like a wooden dowel to cycle the master cylinder. Do this with the master cylinder clamped down to a table and as close to level as you can get. Cycle the master cylinder until all the bubbles have disappeared (I usually do this for about five minutes even though the bubbles cease around one minute. Leave the hoses in place and install the master cylinder in the car then quickly switch over to the regular brake line. Start bleeding the wheel cylinders from the furthest to the closest (passenger rear, driver rear, passenger front, driver front). Be very careful not to let the master cylinder run dry! If your 57 is like my 59 then it is very hard to tell how much fluid is in there because the power brake booster blocks the view. If the master cylinder does go dry you have to start all over again. I usually repeat the bleed process for the wheel cylinders three or four times to make sure I have gotten all the bubbles.

From John:

I have a K-D pressure bleeder tank that is similar to if not the same as the Snap-0n tank. The tanks are a great tool and if used correctly do a much better job than vacuum bleeders, check valve bleeders, etc (I've tried them all). I have a few cars with the master cylinder (single round 2-3/4" bowl) mounted under the power brake booster and none of the commercially available adapters I have would fit. I made my own master cylinder adapter by soldering a length of 1/4" copper tubing through a scrap master cylinder cap. A short length of clear plastic hose connects the tube to the bleeder tank. To get a good seal between the cap and the master cylinder bowl, I use a gasket that was made to seal a toilet tank to a toilet bowl and clamp the cap down with a rubber washer under the cap bolt. I tested this at 25 PSI with no leaks so nominal bleeding at 15 PSI is no problem. You don't say what kind of master cylinder you have so I'm not sure if my solution for the round master cylinders will work for your car. Don't run with any more pressure than 15 lbs and dial down to 10 or 5 lbs if you needed to stop leaks. The lower pressure will just slow down the bleeding time a bit. Regarding corrosion, DOT 3 glycol based fluids will eat through anything given enough time and they suck water so will pit master cylinder and wheel cylinder bores on cars that sit or fluid not changed often. I've seen some nasty looking used bleeder tanks for sale on E-Bay and elsewhere. The bleeder tank is a pressure vessel so the tank is heavy gauge metal (stainless?). A plastic or composite tank that could withstand up to 45 PSI (at which point the pressure relief valve goes) without blowing up like a balloon would be bulky and/or expensive. To get away from the corrosion problems I use DOT 5 silicone in my bleeder tank and I'm switching all my cars over to DOT 5 as they need brake system rebuilds. I've had DOT 5 in one of my '63s for over 5 years and the master cylinder both inside and outside show no signs of rust or other crud.

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?


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 Rex (1959):

To replace the front cylinders recently I practically had to remove and dismantle the entire wheel to get the cylinders out. I am sure there must have been an easier way. I know I need a shop manual, but I am wondering what the "quick" method for removing the cylinders would be?

Reply from Dan:

After you wrestle the brake drum off, you see the shoes and all the springs and things. If you take the top springs off and maybe even the bottom one s(?), (I am not sure about how an Imperial is set up). Lay the brake lining to the left and right and the front part should be done. You then have to crawl under the car and remove the cylinder. The hardest time I have ever had is trying to keep the lines going to the cylinder from twisting around and in half. I suppose a person should break the line loose, then take the cylinder off, then finish the cylinder removal. That sounds a lot simpler than it is.

Question from Tim (1960):

The 1960 manual refers to a compensating port on the master cylinder. The picture of the master cylinder only shows inlet port and outlet port. Which one are they referring to. It says that could also cause a hard pedal.


From Mikey:

The compensating port is a small drilled hole inside the master cylinder, its NOT one of the external ports that the lines are connected to. When you look down inside the master cyl, youll see several small drilled holes in the bottom of the reservoir, one of them is the compensating port.

From Pete:

There are 2 holes at the bottom of the brake master cylinder fluid reservoir. The forward one is, I think, the compensating port. The compensating port is uncovered when the piston retracts completely (brake pedal released). When the port is uncovered, brake fluid from the wheel cylinders and lines can flow back into the reservoir, reducing system pressure to zero.

Question from (1961):

Is the master cylinder under the brake booster on a '61? If so how does one fill it?


From John:

The master cylinder is under the booster on the '61, same as my '60 is. I use a small funnel with a short piece of rubber hose attached to add fluid. To remove the cover on the master, the tool of choice is a 7/16 offset box wrench. If you try to use a flat wrench, you'll most likely round off the shoulders of the bolt.

From Kyle:

Yes, the master cylinder is under the power booster on the '61. I fill mine by first unscrewing the small bolt on top, then jimmying out the coverplate, bolt and rubber gasket at the same time. The last time I filled it I used a measuring teaspoon and filled the spoon then sticking it under the booster and pouring it in to the resevoir. its small so it dosent take too many times. Then replace the coverplate gasket, making sure the gasket is pushed back into the plate, and the bolt sticking out the top and riglle it back in to place and tighten bolt.

From Ted:

I filled my '61 by Kyle's "remove the cover" method, but instead of a spoon used a rubber hose with a small funnel to pour the fluid in. make sure it doesn't run over! It will remove paint. Retracting the booster is the best idea. You will need a cooperative wife or buddy, hopefully they are one and the same!

From Clay:

I have found that a turkey baster works great for both sucking the brake fluid out of the container ,and depositing it into my '60's master cylinder. It's easy to control the amount of fluid you need to add. I wouldn't try to sneak the baster back in the kitchen drawer though .

Question from Greg (1961):

Just had the master cylinder replaced on my '61 4 door.  Should I go ahead and have the brake linings checked? replaced?  I would appreciate recommendations on where to get the brake kits if this is not something they still have at NAPA?  I asked a few shops about redoing the brakes and the uniform response was  "No way, we can't get the parts."  A friend, fortunately, did the master cylinder but further work is out of  his line.

Reply from Dick:

The master cylinder really has no impact on the condition of the brake linings, so your decision is really independent on this subject. It is always a good idea to pop off a drum and inspect the brake linings (and cylinders) if it has been a long time or you do not know the condition of them. It is child's play to inspect the fronts, most places do it free, if you are not comfortable doing it yourself. The rears, on your car, require a puller, which is probably why the mechanic you asked wasn't willing. The linings are readily available, you might have to send in your old cores and have them relined, but there is no problem getting it done, at least out here in sunny California. The local NAPA will be delighted to take care of it for you. Also, if you need your wheel cylinders rebuilt or replaced, this is no problem to a professional brake shop, they do this all the time. I think maybe you need a better mechanic?  

Question from John (1962):

Is there any difference between pre'62 & post'63 master cylinders?  Installed a known good '66 master cylinder on my '62 Crown and  couldn't get a pedal. Aftermarket parts books seem to differ in opinion.

Reply from Joe:

I tried a '63 master cylinder on my '62 Custom Imperial and found the same thing. The units looked identical externally, but, internally the '63 master cylinder had a smaller diameter piston. From '62 to '63 they went from the old system with total contact brakes to a newer Bendix system which had only one wheel cylinder at each front wheel like the rear axle wheel cylinders. The '62 and older units required a larger piston because of more pistons & piston travel on the older design brakes. After '63 (probably in '67) the Imperial went to a totally different system with the dual braking system approach. Also at some year they offered front wheel disk brakes (the Budd system). 

Question from Timothy (1962):

I've been busy over the last three weeks puttering away on a brake job on the sixty in my "spare" time.  Here's the situation... No pedal! no matter how many time you pump it.  We have replaced the front shoes and hoses, rebuild the front wheel cylinders, took apart the back drums and realized that the have already been done in  the not to distant past and left it at that for the moment and adjusted everything, then gave it a try.  When that didn't work we checked for leaks and air and decided that the master cylinder was leaking out the back. Yanked it and rebuilt it, reinstalled, rebled, readjusted, and still nothing.  The car slows down and will sort of stop if it's not on high idle or pointed downhill.  I have a new rear hose which I am still meaning to install but I can't see how a hose that's not leaking could cause the problem.  I am rather frustrated and having trouble coming up repair ideas.  Anybody got any less volatile ideas???


From Paul:

After all that you have done, try going back and readjusting all the brake shoes.  If you turned the adjusting cam in the wrong direction on just one shoe, then your brake pedal will go to the floor as you have indicated.  Use a 7/16 inch six sided socket, of 3/8 drive to adjust the shoe cams.  Six of the eight tighten in the forward direction of the wheels.  The rearmost two, which are most frequently adjusted wrong, are tightened by turning in the reverse direction of the wheels.  After you have properly adjusted the cams, that may solve the problem. But if it doesn't, then be sure to bleed the brakes in the proper order: right rear, left rear, right front lower, right front upper, left front lower, left front upper.  Right and left are as you sit in the driver's seat of the car.

From Dave:

Had a similar problem with our '60.  The problem is due to the master cylinder, if you disassemble it the bit that goes in first is a spring with a valve on the end of it.  Very often it is a residue that is trapped between the rubber and the metal pressing of the valve as over the years it has gone hard and basically causes the valve not to work properly.  The remedy is to disassemble, leave the valve soaking in some alcohol (no its not a waste of alcohol) for a couple of hours and then reassemble and refit, etc.

From Mikey:

I have been following this thread,  it looks like everyone has covered most of the possibilities......there is one thing I would advise is to NOT adjust the length of the pushrod between the booster and master cylinder.  I only know because I switched boosters once, and was about to do just that when I read the notice.  I agree that if its too long the cylinder won't be able to fully return, and if it's too short  there will be wasted motion before the cylinder starts to apply the brakes.  I'd go back and double check the adjustment and maybe even double check the bleeding.  That's a long distance to push an air bubble around.   Also, I would double check the check valve in the master cylinder.

Question from Michael (1962):

I have noticed that in the last number of years, my brakes have gotten more mushy and need to be pumped to stop. I have  had them bled and worked on. I most likely need to change the brake master cylinder and booster. Should I just have them rebuilt or are they available already rebuilt or NOS.

Reply from Jeff:

I have done both. It is not difficult to rebuild maters cylinders if you need to but I have had very good luck finding them rebuild although I often  have to try several different parts places and I try to avoid "the new guys" at the parts counter. I believe your 62 uses the same one as several other 50s and 60s Imps.  

Question from Brandt (1963):

I've removed the booster/master cylinder assembly from the '63 LeBaron. I need another one because this one went bad. I tried Autozone, they're out of stock. Pepboys had no idea, as usual. Napa wasn't too helpful either. Then I was in the San Fernando Valley and stopped at Performance Auto Warehouse (P.A.W.) and they said we do not carry brake boosters. What a let down from PAW, seeing that they had the hugest part shelves I'd ever seen. I tried overhauling the booster myself but the booster I have is not shown in the service manual...only Bendix and Midland Ross were shown. But the booster I have did not have 8 bolts holding the vacuum together, it was more like one piece with the metal welded together. So I could not take it apart to get inside. Most of the ones I did get a chance to look at new had the two-bolt on master cylinder; my master cylinder requires 4 bolts, its a single cylinder with one brake line for drum/drum application. Please help me find a replacement that works.


From Larry:

Try calling Power brake Booster Exchange, Inc. They are knowledgeable and friendly. I got a booster for my '67 from them.

From Chris:

Looks like a similar path taken by my 62 this summer. Not many people stock our boosters - that was my epiphany too.
Most places will take your booster and rebuild it which is what I had to do. Yours sounds very similar to mine which is a Bendix with the 4 bolts for the master cylinder.

Try these folks. They are very knowledgeable, and they did a super job on my hisssssssssing boossssssssssssssssster:

Power Brake Booster Exchange
4533 SE Division St
Portland, OR

503 238 8882

Kanter sells a beautiful re-casting of the master cylinder. Might as well change it too if you're going through all of that trouble to begin with.

And that leads to another super handy tool, the power brake bleeder from Motive Products. It will save you a lot of time and hassle. And it's worth every penny of the 60 or so bucks with shipping.

Not that there is anything wrong with a friend or neighbor helping you pump up the pedal, but when they forget to tighten the master cylinder cover and then you get brake fluid all over your freshly painted valve cover... Well, you get my drift.

From Eric:

I can attest to good service at the Portland, Oregon shop, Power Brake Booster Exchange. "Booster Dewey" as he is known there, sold me a new booster this summer for my '72 Newport. I watched him even do an adjustment of the level of assist. I think he could help you if you cannot find a local supplier.

Question from Lance (1965):

On my '65 and my '66 I have leaks coming from I believe the bottom of the master cylinder. I have to put brake fluid in every month! Do I need to replace this part or can it be easily repaired?


From Phil:

You probably need to replace or overhaul the master cylinder, I expect the seal in the rear, where the brake rod goes into the master cylinder, is leaking. Replacements shouldn't be too hard to find.

From David:

Replace it. Even if there is a rebuild kit available it is quite possible the bore is worn and the new seals may not seat properly and it will still leak. Don't forget to make sure you get all of the brake fluid that leaked out of the master cylinder out of the booster.

Question from Brian (1966):

If you remove the brake lines on your Imperial, will you have to re-bleed the wheel cylinders? I replaced the lines on my '66 Crown and the car was fine. Now I'm losing fluid somewhere and have to fill up the master cylinder after a few days.


From Paul:

The loss of fluid means that the car needs additional brake work. Rather than doing half the job, the best advice is to go through the brakes and eliminate all of the problems at once.

From Chris M.:

Yes, you would definitely have to bleed the cylinders all over again, but at least you'll have peace of mind knowing that your M/C is in proper working order.

There is one caveat about pumping the brake pedal on a M/C that has been operational for some time. You don't want to pump the pedal all the way to the floor board since it forces the piston of the M/C to bottom out in a region of the bore where there is corrosion. This can damage the seal causing it to leak through.

Question from Loyal (1966):

Does anyone know if a duel chamber master cylinder from a '71 Imperial will fit on a '66? I need to switch my single chamber master cylinder with a dual chamber, but I'm not sure which one is compatible.

Reply from Gary:

I installed a Napa # 36221 (late 60's full size mopar w/all drums) M/C with excellant results. It bolts up to the booster w/no problem. You will need fittings available new and a junction block from a late 60's mopar w/all drums.I got my block from a junkyard.I replaced everything (hoses, lines, whl.cyls and shoes over two years ago w/ no problems since.The Auto pilot bracket may need work or removal for the m/c lines. Good luck, it's worth it.

Question from Stu (1966):

Does anybody know where I can get a new or used master cylinder for my 66 Imperial?  This will be the 3rd one since new.  I can get a rebuild kit from NAPA but I would like to have one on hand for a latter date. I heard that you can put a later date master cylinder with two reservoirs... does anybody know what year I need?  If I go that way I know I need one for drum brakes and I know that I have to change the brake lines because you have 2 lines coming from the master cylinder instead of one.


From Mark:

A business colleague of mine is doing this with his '65 Polara.  I remember the single master on my '63 Fury and it was kind of scary.

From Jim:

Interesting point...when I had my '66 Chrysler it seemed like a good idea to go to dual reservoir. Instead, I added a vacuum booster and replaced all the hoses and master cylinder. Easy job, good brakes (for drums, anyway) and no more paranoia of failure. The thought of 2+ tons of American steel going down the road just short of ram recovery speed with failed brakes is indeed unpleasant.

From Bill:

I am not where I need to be for this, but I think Year One has them and possibly Kanter. Try 1-800-yearone and if they don't, ask them who to call. They are usually very helpful in supplying competitors names and numbers if they don't have something. I know they have have the rebuild kits, also as I just overhauled mine with their parts. Normally, unless you have stripped some threads or have a crack in the casting, you should not need the actual cylinder. I may be wrong but in reality only "x" amount of fluid will go through the system and as long as your reservoir has the capacity needed a single or double well won't make a difference.


I suggest that you sleeve your master cylinder. I prefer stainless in that it does not wear out like brass can. I have had excellent work from the following. He is reasonable and gives good turnaround on you cylinder. Imperial Machine 621 South 112 St Lincoln, NE 68520 402-488-9450

From Curt:

Have you tried your local Chrysler/ Plymouth dealer? They have a computerized parts locating system that works well extremely well. I found a dealer with a new master cylinder for my 68 imperial and found a power brake kit for my 71 challenger this way. I would recommend you go to the dealer instead of calling because its a fair amount of work to pull out the old books and track down the part number and to put it on the system. Most dealers just blow you off if you are calling by phone.

Question from Don (1966):

I just put new brake shoes, good drums and rebuilt the wheel cylinders on my 66 Crown Coupe. The original problem was very low brake pedal-almost on the floor. I power bled the system after all the work and with the car sitting there the pedal was rock hard and very high. When I started the car and stepper on the brake pedal it went almost to the floor-as in before the brakes were done. One thing I found when I was doing the brakes was that the rear wheel cylinders were seized solid-I could not free them up even with a hammer and punch. I ended up replacing them both. When I bled the brakes using a pressure bleeder, the front wheel cylinders squirted out a healthy flow of brake fluid while the rears just dribbled a small steady amount. Is this normal? Or is it indicative of a restriction in the system as in the single brake hose at the rear axle?


From Phil:

I'd check the rubber brake line that goes to the rear axle. I've had the rubber lines go bad in internally before on different cars. Once I had one go so bad, it would lock the wheel temporarily, after applying the brakes. To look at it on the outside, you couldn't tell anything was wrong on the outside. But the inside of the line had somehow with age, managed to swell shut and also, become clogged with small bits of corrosion. You should have the same amount of flow out of the rear as you do the front when bleeding. If changing the rubber line doesn't help, check all the lines going to the rear of the car for dents or bends, anything that could cause a restriction.

From Bill:

The flow of brake fluid should be pretty much the same front & rear. Also, too many times the brake hoses are ignored when repairing the brake system. I never assume they are OK just because they "look" good on the outside. If in doubt as to how long they have been on the car, replace them. In addition, when opening a brake system for repairs I always bleed out all the brake fluid, then fill the system with denatured alcohol and continue to bleed that out until the fluid coming out at each wheel is clear or clean looking. Then proceed to do your usual rebuild or replacing of wheel cylinders, master cylinder, and brake hoses.

From John:

If the rear cylinders were seized for some time, you may find that the rear lines are full of rust also. Either take off & clean or replace them as well as the rear hose. If the pedal still goes to the floor after this, most likely the master cylinder is bad.

Question from Matt (1966):

Does any one have a source for a gasket for the resevoir on the master cylinder. I guess we can make one but what would it need to be made out of?

Reply from John:

They are easy to make -- just get some paper gasket sheet at any auto parts store. Gary Goers www.garygoers.com has them.

Question from Mark (1968):

Can anyone give me the part# for a 1968 master cylinder?

I have found a used rebuild kit on a MC a long time ago, but I was wondering what the opinion of the list is on doing this. is it as good as replacing the whole unit? The unit I have is leaking. But it looks good and is not rusted or corroded, so I'm just going to try the kit. It's $5 vs. $125 or thereabouts.


From Dick:

NAPA has these in stock - I don't recall the part number, but it is listed in their catalog so any counterman can look it up. I have installed new (not rebuilt) master cylinders in all my "boxcars" without any drama at all. NAPA United Part 36259. This is for a new 1967-68 Imperial master cylinder, bought this spring sometime (May 03?).

If you have a brake hone, and if your master cylinder bore shows no etching from water damage, the kit should allow you to get a few more years out of it.

From Tristan:

Just thought I would mention to you that a master cylinder for a 1974 Chrysler Newport works great in 67/68 Imperials. That's what I bought for mine when it needed one. It is a little bigger than the original, but looks almost exactly the same and bolts up nicely. It was also used on some Dodge trucks I think, but the newport listing should get you one. Most places have one in stock. This master cylinder also makes a nice bolt on for converting an older Imperial to dual brakes.

Question from Jody (1968):

Here is my story about problems with my braking system on my 68. If anyone has feedback or suggestions I'm open to it as the story may not be over. I am on my 4th master cylinder on my Imperial in about 250 miles. The one on the car when purchased failed several months ago. I took the car to a mechanic near my house (it was convenient) whom I knew but not that well. He put a master cylinder on it. It lasted about 100 miles and the pedal faded to the floor. Took it back to him and he replaced it (no charge). It lasted about 50 miles and the pedal went to the floor. He told me that the MCs he put on were rebuilt and perhaps they had been sitting a while and the seals did not hold up. At this point I decided to take the car to a mechanic who has done lots of work for me and whom have a good deal of confidence. He put an MC on it. Told me it was not rebuilt. Within 50 miles, the pedal was on the floor. This was the third time. The Imp has been in his shop for a little over a week now. Called him today and he said he put another MC on it (up to 4 now) on Tuesday. He had called me last week and asked me if I added fluid to the system. I had not. Today he told me that the fluid was contaminated. Had something floating in it. He totally flushed the system when he replaced the MC Said he wants to keep it another day to drive it a little and see if the pressure holds.  Anybody ever heard of such an experience or had a similar problem?   


From Mark:

I have never heard of anything like that! 4 master cylinders in 250 miles?! Sheesh. How, I wonder, does the fluid get contaminated? Is this guy saying something in the fluid was eating out the master cylinders? Hmm. I have only changed one master cylinder in my life - so far - and I had to replace most of the brake fluid (or a lot of it) in the system when I did, so I am dubious as to this explanation. How could a contaminant stay in a system through 4 changes??? Maybe I'm missing something, but are you sure you do not have a leak somewhere else? Have you noticed any little puddles of brake fluid around the tires when you park it? If you are losing pedal, it may be that you have a leak in the system somewhere other than the master cylinder. (Do Imperials have cylinders at each wheel? I guess not if they have front discs, but otherwise yes? I would check there as well.)

From Dale:

I would have the mechanic check for a leak. My '68 did the same pedal trick on me. Not a fun experience when the 5000 lb car is rolling along!!! I found that the right front caliper was leaking fluid. You know those darn '68 calipers are not all they are cracked up to be. So maybe give it a really thorough leak check.  

From Mark:

A suggestion: before you pick up your Imperial, make sure the guy checks out your emergency brake. I have not had brakes go out on an Imperial (thank God), but it did happen on my Mustang, and the only reason I am still here is I had a good working emergency brake. But - don't yank HARD on the emergency brake if your brakes all go out - that could lock up your rear wheels and cause you to lose control. Just put enough pressure on the e-brake pedal to stop you. Most people think e-brakes have only 2 positions - on and off - but if you are careful, you can apply them a little bit at a time (at least, in a Mustang you can - help, anybody???). AND DON'T PANIC!  

Follow-up from Elijah:

This technique works especially well in an Imperial with the automatic emergency brake release. Since the vacuum canister is effectively holding the stop mechanism open, you can gently press down on the brake -- and quickly ease back up if you give it too much. I found this out about 10 years ago when the master cylinder went south on my blue '71 Imperial.

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