How To Repair and Replace Your Imperial's Brake Boosters

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Tip from Tony:

I'm passing along a copy of a private discussion I've had with somebody who rebuilds the power-brake boosters for what appears to be ALL relevant years of Imperials - Up until now, I have been very dissatisfied, because nobody would touch the bellows-style, oval brake-boosters
(manufactured by Kelsey-Hayes) and provided by the factory on some 1956-1962 Imperials (as opposed to the Bendix-built canister-style units
that were also installed, depending on availability of parts, I'm guessing).

Organization: KARP'S POWER BRAKE

Subject: Re: Brake Rebuilding

> >We are a Brake rebuilder in the U.S.A. We make the K/H bellows and parts for power brakes if you need any thing let us know.

Tony Lindsey wrote:

> Thanks, and I have some questions - WHICH Kelsey-Hayes bellows units?  The
> oval ones or the round ones, or both?  This is very good news, and thank
> you - Is there any way you could send me a list of the Imperial-specific
> items that you work with?
> I want to send you a lot of business, believe me - The K/H units have been
> a real burden, particularly for me!

Mr. Lindsey:

We have the 105-1300 K/H unit in stock.  This unit fits 1955 Chryslers.  We also have parts for the K/H oval unit.  Including the bellows.  The
unit part numbers are 40300, 41582  and 42241.  We also have those units in stock.  We sell them exchange only.  We also have the shaft on the
K/H unit which is usually broken.  We had new ones C&C'd out.  Even if the unit is broken we can still rebuild it. Our turn around time on
rebuilding any unit is one day.

We also stainless steel sleeve cylinders and shaft with 304 stainless.  From 5/16" to 2 1/2" in diameter up to 14" long.

Please give me a call a 1-909-985-0800 if I can be of further assistance.

Ron Karp

Follow-up from Roger:

I've recently had several power brake boosters rebuilt by Karp's Power brake in Upland, CA. Check their site at . I had two '55 boosters and two '59 oval canister boosters done, and I'm impressed by their knowledge and their unwillingness to do anything but a complete rebuild. They mold all the rubber parts for the '55's, as well as the bellows for the oval boosters. So far, the only one I've gotten back into service is for the '55 DeSoto, and I'm liking what I see. This unit was rebuilt several years ago by Power Brake Exchange in San Jose. That unit failed as well as the rubber parts my mechanic and I installed obtained from a man in Minnesota. I cannot recommend Power Brake Exchange. As far as the two oval canister boosters, I'll have to wait until those are installed to report.  

Question from Dennis (1953):

I finally took my '53 imperial out on the road. At first everything seemed fine. Then the brakes started to not work properly and the car would barely stop, even at low sped. The brakes felt like they were not grabbing. I put a rebuilt booster in last fall and the car has not been driven except in my yard and not often. I called the rebuilder and he told me if you do not use the booster at least once every 3 weeks it can go bad. This seems illogical to me. Does anyone know of this to be true? i was told to check the vacuum, it should be 17 pounds or higher. I just got a guage so i will check that as soon as i can. the rebuilder said he will redo it for me if needed since i was not informed about the three week rule. I know that is a nice gesture but the labor involved is something i do not look forward to. Any suggestions?


From Paul:

What is the condition of the rest of your brakes? The booster only provides power assist. It makes the brakes a little easier to activate. A bad brake booster should not keep the car from stopping. I have driven cars with a hard pedal, no booster problem, and still no stopping power. In this case, the linings may be saturated or just plain stale. Although a very different design, when the booster on my '55 Imperial failed, I bypassed it temporarily as well. I found a rebuild kit (Jim Fredrick), but in the meantime I was able to stop the car just fine to get it home. If the brake system on our cars is in otherwise excellent condition, they should work very well. This is not recommended as a long term solution, but rather as a temporary emergency measure.

From Kenyon:

When a booster goes out, you must increase the pressure applied by your foot as the booster is no longer boosting your muscles' power. This could make you feel like they are tougher to actuate, but they should still work, you'll just be red in the face as you try to stom down on the pedal. Boosters are not made out of jelly or some other substance that goes bad after 3 weeks of inactivity. If that were true, think about how many people would be writing into the list or talking about it at the barber shop or whatever. There would be tests to be performed every time that you even thought about driving the car!! The rebuilder is feeding you a line, I'm afraid. If you are driving your 1953 with a new booster and nothing else done, it could be something else. EVERY car that I get gets new brake hoses, master and wheel cylinders installed immediately. Before I drive it. If one seal goes on your system, you're not going to have any brakes. You will still have steering so you'll have choices about where you land, but thats about all you'll have going for you. If you have had everything else done, inspect all lines and wheel cylinders for leakage/failure. Open the MC and see if it's out of fluid. If it's low or empty you have a brake system problem. If full and the pedal's hard, you have a booster problem. Could be that you have a booster rebuilder problem too.

From Paul:

When I rebuild the brakes on Eisenhower, my '54, the booster was bad and rather than having it rebuilt, I just bypassed it. The symption was that the brakes would lock up. Without the booster, the car stopped fine. A little more leg was required but not anything that was uncomfortable. While the power booster was standard on Imperials it was an option on New Yorkers which was an identical car except for trim.. On these cars the booster is just that, a booster. It sits between the master cylinder and the wheel cylinders and amplifies the pressure produced by the master cylinder. It is designed to fail in the 'pass through' position so you still have manual brakes. I've never heard the three week thing. I doubt it was designed that way. The booster is pretty simple, a few check balls, springs, and a diaphram. I suspect your master cylinder is bad. If your pedal is hard, you probably don't have air in the lines. If your pedal goes to the floor you have air in the lines. Bleed them and try again. It's a pain to bleed these brakes because the master cylinder access is under the drivers foot and you have to pull the carpet back. I made an adapter and pressure bled mine with a homemade bleeder made from a garden sprayer. The master cylinder is so small you have to be careful not to let it run dry during the normal, pump and open valve approach.

Question from Philippe (1957):

Does someone know if overhaul kit (seals, "o" rings etc..) are available for the bellow unit (57-59) ? It seems that mine needs an overhaul: sometimes when i push the brake pedal i've nearly an engine stall (vacuum leak ?). After , when the unit is "poised", no problem. But since three days this failure has disapeared and the system works well ...

Reply from Jeff:

Try Power Brake Exchange 260 Phelan Avenue San Jose, CA 95112 Phone 408-292-1305 They have done several brake boosters for me in the past, and are currently overhauling an oval canister type booster off my 60 Imperial Crown. The cost is around $200.00.

Question from (1959):

Is the booster very hard to remove? I hate playing around with the brakes, since I have always liked my cars to stop when I wanted them to.


From Richard:

Read the manual. The process involves putting a block of wood up under the dash, marking the boosters location on the firewall (I use red paint), and unbolt it from the firewall. I remember this going fairly quickly and smoothly so I do not believe it is too difficult.

From Philippe:

You must remove the master cylinder, then the booster / mc plate assembly because the booster is bolted onto the plate. Place a wood block under the pedal extension to avoid the brake pedal extension goes too forward through the booster opening (beware of loosing the plastic bushings at the end of arm). When I removed the booster-master cylinder plate assembly, I cut this plate (horizontally) to have two plates: a booster plate and a master cylinder plate. Now I can remove the booster or the master cylinder without removing the other ...

Don't forget to plug the hose which goes from the engine to the brake tank.

Question from Ken (1961):

Is there a difference between the two brake boosters on the 1961 Imperials? Is the bellows style for LeBarons or Crowns? Or are they just two different ones made that year for no reason? The '61 I am looking at has the bellows design but I'm not sure what make it is yet. Also are flight sweep decklids standard on 1960's and 1961's? Or are they just an option. The Imperials I am looking at one has the Flitesweep and one doesn't.


From John:

The bellows style and the metal oval type boosters are from two different suppliers. They were used in all makes and models -- you got whatever was in the parts bin feeding the line when the car was built.

The Flitesweep decklid was optional from '57-'63 except for '62 when it wasn't offered as a factory option

From Roger:

For both the bellows style and the oval canister style booster, I recommend Karp's Power Brake of Upland, CA. They have a site at They make the rubber parts to rebuild them and can also anodize the end plate of the bellows booster to look like new. I've also use Power Brake Exchange in San Jose, CA and cannot recommend them.

By the way, I've also found that there is no rhyme or reason as to which cars got bellows and which got canister boosters. I've got high end and low end cars with either. Go figure.

The man at Karp's said the 300 guys like the bellows style, and after thinking about it, it occurred to me that the only reason they would is because the gold anodized end plate dresses up the engine room more than a black painted oval.

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 Jaako (1963):

Does anyone know if  '63 Imperial brake boosters can be replaced with some other Mopar booster, or if the membrane (film ?) is available separately somewhere on this planet earth. My '63 crown convertible has vacuum membrane damage, and I need to have them replaced.


From Elijah:

Brake boosters can be rebuilt -- the vacuum diaphragms are the most common cause of booster failure, but can be replaced. Visit the IML web pages for a list of recommended sources.  There are also many sources for this service listed in Hemmings Motor News. One that comes to mind is Brake Booster Dewey.

From Mikey:

My '62 and '63 use the same booster, NAPA had one available for about $250 outright, no core needed and that was with new master cylinder.  You may be able to get a rebuild kit but I doubt it, they are kind of difficult to get unless you are a re-builder of them.  The diaphragms get old and exposure to gasoline fumes doesn't help. 

From Brad:

I ordered a booster from Autozone for my '66. They were able to get it within a few days. Yours shouldn't be a problem.

Question from Keith (1968):

Just a question about power boosters. My '68 4dr crown's brake pedal just got REAL hard to push this morning. I've checked the fluid and all is well (other than it being a little brown), would this be the booster?


From Marcus:

Very good chance... I had a 68 New Yorker that blew the bag inside the booster and that is what it felt like. My current 67 has not yet blown the bag but the brakes will not lock up at any speed and at any speed over 40 I have to put both feet on the pedal to get any stopping resistance at all. We have had ungodly heat here and this seems to precipitate, more rapidly, the failure of these components. Thanks to Bills suggestion I found a place here in Dallas that will rebuild boosters for $85.00 with a two hour wait - American Power Brake & Clutch 10330 Harry Hines Blvd. Dallas Texas. 214-358-3481. They specialize in collectible car boosters.

From Dick:

Sounds like a lack of vacuum problem to me, did you verify that there is good vacuum at the booster end of the hose? If you have a good supply of vacuum (how's that for a poor choice of words?), and the pedal is still extremely hard to push down, yes you have a bad booster, 99% sure.

Question from Bobby:

Today my brake pedal was very hard at start up. It got softer as I drove a bit but after coming out of the store it was pretty stiff for the duration. I can hear a hiss around the brake pedal and it seems the idle goes down a little when the pedal is fully depressed. The service manual points to the booster. Since it works totally from the manifold for vacuum and power, could a clogged line or valve be the problem before buying another booster. Or could there be another culprit?


From Brad:

If you hear hissing, you have a leak, not an obstruction. This is consistent with your changing idle symptom. Also, the increased vacuum at road speeds would improve performance of the unit. Before you go changing out the booster, check to make sure all of the vacuum connections are tight. Make sure all of the vacuum hoses are soft and not cracked. Finally, check the rubber sleeve that covers the brake pedal pushrod, where it goes through the firewall under the dash. If this is the source of the hissing vacuum sound, I'm afraid a booster rebuild or replacement is in order.

From Steve:

I'd like to add onto what Brad from Cedar Rapids said by giving you a couple of experiences I had with leaky boosters.

 1) I had a '69 NY'er that had a booster that "hissed" under the dash, in the brake pedal area only when it was cold outside. I never replaced it...and it never got worse. The car ran great and the "hissing" went away after a few minutes of use and the pedal returned to normal. 

2) When I bought my '75 Imp 9 years ago, it ran ok but skipped on the passengers-side rear cylinder. It turned out to be a bad brake-booster...which gets it's vacuum from that very same cylinder that was skipping. I unplugged the hose that goes from the booster to the intake runner for that cylinder...and plugged the vacuum port with my thumb...and the skip went away!! I found it strange that the booster (which didn't hiss) worked fine but caused the cylinder to skip. Replacement of my Imps booster solved the problem. That was 9 years ago...and I have never had a problem with the brakes OR that skip since. I would think that replacing your booster is in order also.

Question from Bill (1968):

Is it possible to determine if a brake booster is good or bad without installing it on the car? The booster in question is for a 1968 Imperial.

Reply from Brad:

You can test the seals by connecting it to a vacuum source. You need to depress the plunger to test the rear seal. I tested one once before installing it but I neglected to test the rear seal before I installed it, I regret that now.

Question from Dale (1968):

I may need to have the power booster for my '68 worked on.  Is this an item that I can rebuild or does it  have to be sent to someone? Or are there new ones available? I have not done this project before so I am looking for the place to begin.

Reply from Paul:

NAPA parts stores will send your power brake booster away to be rebuilt. I am sending the one from my '62 some time this year. It is my understanding that the booster and the master cylinder must be brought in together, as an assembly, and they will come back both rebuilt. The boosters are not rebuilt separately. I don't remember the cost, but I would expect to pay between $125 and $225.

 Question from Brad (1972):

Can anyone tell me an easy way to determine whether my 72's brake booster is a single or dual diaphragm unit. The aftermarket price difference is about thirty dollars, but I'd like to get the correct one for the application. Symptoms are a hard pedal and no pedal drop at startup.

Reply from Elijah:

Your Imperial has a dual (tandem) diaphragm. In fact, all Imperials of the Fuselage vintage (and many other years as well) use the tandem diaphragm booster. A hard pedal is definitely a symptom of booster failure. There are services who rebuild brake boosters for around $80 to $100. Several sources are listed on the Imperial Web Pages.

Question from Steve (1972):

Can somebody tell me briefly what is involved in removing and reinstalling a power brake booster in my '72 . She is coming home from storage tomorrow! It was leaking and loosing vacuum before I put it away for the winter, I plan on having the master rebuilt along with it.

Reply from Matt:

The brake vacuum booster is held on by 4 bolts( studs) through the firewall. You'll have to work upside down under the dash to reach them.  Be careful-very cramped under there with many rough sheet metal surfaces-easy to get cut.  From the brake pedal trace up until you reach the 90 degree junction with the rod going into the booster .I think the pedal assembly is attached by means of a fancy thru-bolt (could be a cotter pin affair, I don't recall).  Search for 4 nuts symmetrically located around the rod (9/16 or 1/2 inch I think) Loosen them all (sounds easy but takes time in a crowded space) and you're ready to move under the hood.  Unhook vacuum lines and brake lines to master cylinder and remove as a unit.  (I'm assuming you're having both the booster and the master cylinder rebuilt at the same time.)  It may take gentle prying to get it to come away from the firewall after resting there for some 20 years-you may wreck the foam gasket between the booster and the firewall-if you work slowly you can peel it away and save it.  I think it was there for sound deadening mainly.  I've reused the old gaskets with no ill effects.

Question from Tony (1973):

I just purchased a '73 Imperial and the seller tells me the brake booster doesn't work, so although it will stop you have to have lots of room. I thought I might have it towed to a garage and have it repaired before trying to drive it home (don't really trust my own work yet when it comes to brakes). Then the thought struck me that it may not be as easy as that. Can anyone tell how big a job fixing the booster on a 73 Imperial might be? If I take it to a garage are they likely to be able easily fix it or is this one of those items that requires something special? I figure this surely has to be easier than on my 58 though.


From Chris:

Napa-online shows a new booster with master cylinder for $214,or one without M/C for $144,since the M/C has to be removed to replace the booster, I'd buy the one for $214,and be done with it, I'd suggest ordering the booster and cyl from your local NAPA store, take it along with you, since it's almost a sure thing they'll have to order it...You'll be very pleased with your '73 there's nothing quite like a "fuselage" Imperial...

From Steve:

Congratulations on the new purchase. The new brake booster is still available but not normally a stock item. I would go ahead and have the part in hand when you take the car to get it fixed. You can stop it without the power brakes but it sure isn't fun!

It would probably be a good idea to go ahead and replace the master cylinder at the same time.

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