Do I Have Power Brakes or Not?

I recently overheard an exchange taking place at a car show about whether or not you could make drum brakes into “power brakes.”

“Aren’t drum brakes always manual and disc brakes always power?” the one fellow asked.

“That’s right, it’s why they have disc brake conversion systems,” a second fellow chimed in.

“Whoa – not so fast!” I said, as I stopped to jump into their discussion for a second.

brake-booster-instalation-1 On the one hand, you have brakes that have NO POWER ASSISTANCE TO THE PEDAL (we all call them manual brakes) and brakes with power assist making the pedal easier to depress (aka power brakes). A classic or hot rod car can have manual disc brakes or power assisted drums.

“I thought a power booster was required equipment with disc brakes,” said one of my new buddies.

“No, is the short answer. Even though a power booster gives you a good pedal feel, manual disc brakes work fine,” I explained.

The real differentiating point between power and manual brakes is whether or not the master cylinder has a power brake booster attached. Simply put, a power booster helps assist the master cylinder piston apply force when you press the brake pedal.

All the brake hardware at the wheels will be the same, power or manual.

The booster is typically using vacuum pressure from the engine or a vacuum pump to help you apply pressure to the brake pedal. The reason people like a power booster is that you use less foot pressure on the pedal to get firm braking action. Originally presented as a new car feature “for the ladies,” the addition of a power booster meant you didn’t have to use every last ounce of leg power on the brake pedal to stop on a dime.

Converting your classic or street rod to employ a power booster along with new master cylinder (replacing your current manual master cylinder) is a simple bolt-in installation.

Safety First – We are going with a Dual Master Cylinder!

Many cars prior to the 1970’s used a single reservoir master cylinder. This is not the safest of situations. If a master cylinder should fail and there is only one line and reservoir, you will effectively lose brakes on the entire vehicle. With a dual reservoir master cylinder, you have the security knowing that after converting with one of our kits, the front and rear braking systems on your car are completely separate from one another. It doesn’t matter whether or not your car came with a single or dual reservoir master cylinder to begin with, we have safety in mind in our conversion kits and always provide a dual reservoir master.

Upgrading to a dual reservoir master cylinder should be the first upgrade you make if your car is a daily or frequent driver and currently equipped with a single reservoir master cylinder.

Article Courtesy of: Master Power Brakes

  • (will not be published)

29 Responses to “Do I Have Power Brakes or Not?”
  1. Curt

    I have a 63 Corvette that I’ve owned for 45 years. I’ve always driven it a lot, and still do! About 30 years ago I was attempting an easy stop at traffic lights, on a slight downhill grade, and my brakes failed completely. I only saved myself from plummeting into traffic, by gearing down into 1st and turning the car into a sideways slide. Very lucky! I had manual single-cylinder drum brakes at the time. I immediately switched to a dual cylinder power-brake system but kept the drums. At the time there were no conversion kits available as there are now, so I used a system out of a 70’s Chevelle. The cylinder was dual, but much smaller, and it bolted in very nicely. It was even smaller than the original! After that, I had way more positive braking, with way less effort, and of course, way more peace of mind. It’s still in the car, working as beautifully as ever. I even still do a lot of Autocross every summer! You only need to lose the brakes once, to realize that sometimes an upgrade, even though not OEM, will truly save your life. I saved the old parts in case I want to put them back for some collector. But I’ll have to be really old and senile before that ever happens! I’m still just having way too much fun!

  2. Etienne Davis

    I want to convert my 1966 Buick Lesabre to front disk brakes. Any good kits around?

    • Mike

      I used the MC and booster out of an 86 Chevy S-10 in my 57 Chevy. I would be willing to bet that the same parts can be made to work well in your buick. You will not need a proportioning valve if you use the 4 wheel drum set up. Likely a little bit of creative parts sluthing will either get you a spindle that will bolt in to hold front disc and calipers. I also own a 65 GMC and the spindles out of a 69-86 chevy or gmc truck are a direct bolt in with no modifications required.

  3. Larry

    I have a 68 Chevellle I switched to 4 wheel disc with the dual master cylinder and power booster.
    However when I step on the brake pedal, the pedal feels fine but the brakes are weak at best. In my opinion if I want to go 80 mph and lock up the brakes it should lock up. I recently ordered a new balance valve to see if that helps.
    Is the a correct size for the brake lines that would make a difference on the stopping power?
    The air has been blead 4 times, that part is fine. Just not able to hard brake.

    • Customer Service

      Hi, Larry. Thanks for the question, from my own experience brake issues can sometimes require more than just a little head scratching. That is why we reached out to the folks at Master Power Bakes to assist us in answering your question. Here is the advice I received from Mark Chichester at Master Power Brakes ( There are a few things that come to mind with this scenario. The first would be the apply system and what is there. What is the bore size of the master cylinder? How big or small is the brake booster? Is the pedal ratio correct? Any of these things can cause that issue. The bore size too small would lead to not enough volume of fluid being transferred to the calipers. The booster being undersized could be not providing enough assist through the system and therefore not generating proper line pressure. For the pedal ratio, if this was a manual brake car, did the new booster pushrod get located properly on the brake pedal to obtain the proper ratio and therefore the proper movement of the system through the pedal. Once determining those things, you would have to start looking at what are the actual line pressures at the calipers. Determining that would tell you where the problem might be. As you can tell by Mark’s reply there are nearly as many questions as there are answers within it… This is common, and the more information you can provide the probability that the answer you receive will solve your problem will increase dramatically.

      I hope this helps, Wrench Safe, Mark

  4. Jerry

    Sorry for the spelling, resubmitted———-1967 olds 442 with 4 wheel manual brakes. I installed a PBB and new MC, replaced all 4 wheel cylinders, bench bled MC and all 4 wheels, completed all vacuum hookups. Brakes are ther but no power, replaced PBB and MC, reveled everything, no power brakes, checked all line hoses no leaks. Start car push brake pedal, it suppresses 1 to 1 1/2 inches but no power brakes, What’s up with this? I’ve never added PPB and MC, in 30 years, and had an issue like this, any advise?

    • Customer Service

      Hi Jerry. Sorry you’re having so much trouble with your brake system upgrade.
      From what you’ve described, and the process you’ve gone through so far, I would initially suspect there may be an issue with your vacuum source.
      Are you sourcing your vacuum from the back of the distributor or off the intake manifold?
      Have you checked your engine vacuum? High performance and tired original engines can have issues developing enough vacuum to properly operate power brake boosters (pbb).
      You mentioned you checked for vacuum leaks, are you certain there are no leaks anywhere in the system.
      “WITH CAUTION, AND OUTSIDE” unlit propane gas or starter fluid can be used to locate vacuum leaks.
      With the engine running, expose leak areas (hose connection, intake gasket area, etc.) to either and a change in engine idle speed indicates a leak.
      I hope this helps but also, I am going to share your question with a few Brake System Pros, and get their insights to share with you as well.

    • Customer Service

      As I mentioned previously, I shared your situation with a few other brake system professionals; one of them was Mark Chichester at Master Power Brakes (
      Here is his reply:
      A couple of things come to mind and there isn’t a clear cut “fix this” and it will solve everything. The first thing I would check is engine vacuum. Any brake booster will require 18” of vacuum. Any less than that will result in a pedal that is harder than desired. If there isn’t enough vacuum pulling on the diaphragm within the booster, pushing the pedal will only result in trying to push through the diaphragms. A way of checking that is to depress the pedal several times with the engine off. On the last push hold the pedal and start the engine. The pedal should drop between a 1/4″ and a 1/2″. This would typically indicate that the booster is working. Once checking that, I would look at what size master cylinder bore the system has. We would typically recommend a 1” bore master cylinder when using four wheel drum brakes. If using a larger bore, the pedal travel will be significantly reduced and therefore create a much firmer pedal and one that will feel like you don’t have any power assist. This can be measured by pulling the master cylinder forward and measuring the inner piston bore.

      This should give you a few things to check, Let us know if you have continued problems.

  5. Diesel Dan

    Great discussion !!! I too so enjoy some the discussions I “overhear” at car and truck rally’s and as to the others requests for “kits” an such , my response is as long as you didn’t build the car from scratch , the manufacture has something already figured out that will fit your car , all you have to do is the research to find that “part” even if that means an afternoon at the parts /salvage yard with a tape measure in hand !! (been there!!) and Do consider replacing the entire rear axle with the brakes you want already installed on them , this saves loads of time !!! also don’t automatically expect your vintage wheels to fit after you have upgraded the brakes , ive seen to many tears shed at having to buy bigger wheels/tires after a brake upgrade !! hey disk brakes take more real estate than drums do !! but hey they will half your stopping distance !! so its worth it !!!

  6. Arun

    Is it safe to say that all the cars have brake Boosters installed in them now a days, i mean the cars which were produced from 2015 onwards. Or still there are car models with only Manual discs installed.

    • Customer Service

      Hello Arun,

      I would agree, most modern cars are equipped with some sort of brake assist. Whether the braking is assisted by vacuum, electric or hydraulically can vary be vehicle, but most are assisted. Can I say ALL are? No. I have been a car guy long enough to know there’s always something out there that defies the common logic.

      Wrench Safe,
      Mark CCRC Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special offer for your first year membership.


    Would love to convert my 1974 1.2 MGB-GT brake system to power. First is it possible to convert to power? How?

    • Customer Service

      Hello George,

      Yes the conversion to power brakes is pretty straightforward.
      You’ll need a brake booster and power brake master cylinder. available through most auto parts stores.
      Once installed you’ll need to connect a vacuum hose from the power brake booster to a port on the intake manifold.
      You can expect to spend about $250 on the conversion.

      Best Regards,
      Mark CCRC Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first year membership.

  8. JR

    I have a 1935 Cadillac coupe with mechanical drum brakes with power assist. Factory original. Just saying power assist has been around a few years!

  9. Lee

    Yes some of the older car with Drums has POWER BRAKE System, My 1957 Ford Thunderbird has power brake system with four drum system. Would I go with the dual master cylinder on it, No because it will down the price of the car, I have the Parking Brake working very good in case the brake fail. But the Dual master cylinder is nice but I like to keep the car the same as it was new. Thank You Lee Larson

  10. Robert Raduechel

    Great article and good answers. One thing in the article you referred to the booster using vacuum pressure. Vacuum is the opposite of pressure. I know you know the difference. Just a reminder. Keep up the good work. RR

  11. Ken

    Can I replace the single brake reservoir with a dual on my 62 Olds F-85? If so what product do you recommend?

    • Customer Service

      Hello Ken,

      This is a subject that some avid car restorers disagree.
      I stand on the side, that dual reservoir masters are just plain safer.
      And when I drive ANY classic car safety comes first.
      There are many options for master cylinder replacements for your car and I’ll leave a few possible links below.
      You failed to mention whether your car was manual or power brakes, or if you were considering a front disc brake upgrade in the future also.
      those factors must me taken into consideration when making your final purchasing decision.
      But here is an option to consider:
      For a straight master switch a dual master from a 1964-1972 GM A-Body (Chevelle, LeMans/GTO, Cutlass or Gran Sport), should work as well.
      and save you a few dollars, although you’ll need to source proportioning valves and misc hardware connections and tubing.

      Wrench Safe,
      Mark CCRC Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first-year membership.

  12. bob gibson

    I have a 1969 olds cutlass with front disc brakes, rear drums. have installed 4 master cylinders, 2 power brake boosters and something I bought off internet that attached to the brake booster and brake lines. pedal still goes past half way down and requires pressure as if no power brakes. anybody??

    • Customer Service

      Hello Bob,

      We just completed a brake upgrade on a 1968 Cutlass, the cars brakes could not stop the car car quickly even when pressed hard.
      After the upgrade the brake pedal moves about an inch and locks up all four corners when pressed hard.
      The owner now has full confidence in his braking system.
      We used a kit from Master Power Brakes with a 1-1/8″ bore master cylinder and 9-inch dual diaphragm booster.
      Here is a link to the video.

      Wrench Safe,
      Mark CCRC Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first-year membership.

  13. Marty phillips

    I recently installed a 7 inch double booster, dual reservoir on my 54 MERC. There was a good improvement. I had new linings in back ,but older linings that were not worn out in front. I noticed that the new linings seamed to have more friction, so I installed new linings in front too. Now the brakes will easily “stop on a dime”, without converting to disc brakes.

  14. Mike

    You could have any possible combination of brakes. ’57 Chevrolets were available with power assisted brakes and they only came with 4 drums. I took apart an ’88 ford ranger pickup that had a manual master cylinder and discs up front an drums in the rear. I later used that MC in a t bucket with 40 ford hydraulic brakes and is stopped very nicely,

  15. liu

    We are a professional manufacturer of brake discs for antique cars & classic cars. We can make all kinds brake discs according to your samples, designs, or drawings. Any needs or questions, please feel free to contact us at

  16. Ray

    Have installed a complete front brake system. The brake pads are very tight and the wheels don’t want to turn. what did I do that was not right. Ray

    • Customer Service

      Hello Ray,

      If I understood correctly… You performed a disc brake upgrade to your car, and the pads are really tight to the rotor, so tight they prevent the rotor from turning.

      If this is the case, somethings not right.

      My first suspect would be the pistons in the calipers were not fully retracted when assembling the brakes. To remedy this remove the calipers and pull the pads.
      Using a caliper compressor tool (available online or from auto parts stores) compress the pistons fully into the caliper. If the pistons compress the pads should now fit properly.
      If the caliper pistons do not compress any further, then there is a problem with your kit and I would contact the manufacture to discuss the problem you are having.

      I have had some budget kits that weren’t engineered correctly that I have had the rotors turned to get clearance, but this is an absolute LAST resort.

      Wrench Safe,
      Mark Classic Car Restoration Club Video Membership

  17. Zach

    Hey! Working on my first restoration!
    I have a 1960 AMC Rambler American.
    Running on manual drum brakes.ive been working with a local shop and they were unable to find any kind of disc brake conversion kit that would match up. Was wondering about other options. I guess before 1961, all the braking equipment is under the car and changed through an access point in the floor. Any recommendations on where to go next? Not sure if a power will work or fit. Also not sure about switching to a dual cylinder system for the same reason. Any help? Safety is my #1 as I’ll be driving it fairly regularly.
    Thanks in advance!

    • Customer Service

      Hello Zach,

      Scarebird makes a disc brake conversion bracket to fit your car…. it was recently revised to fit back to 1955 AMC’s.
      Here is a link:

      You can keep your master under the floor and upgrade to a remote dual reservoir master cylinder.
      Willwood makes a good one and if you want power brakes you’ll need to install a remote power bake booster in an area with enough clearance.

      Hope this helps,

      Classic Car Restoration Club Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first-year membership.