Posts Tagged ‘Kelsey Hayes Brake Booster’


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After a long search, I found a 1957-1958 Ford Fairlane Kelsey Hayes Brake Booster on craigslist.  I paid more than I wanted to for it, but I lost out one one on Ebay and decided I should just get it.

I also found a rebuild kit available for this Kelsey Hayes Brake booster.  It included a bellows & all the bushings/seals to make it functional. I purchased mine from The Bird Nest, a Thunderbird Parts supplier in Oregon. The Kelsey Hayes booster was available on 1958 & 1959 Thunderbirds as well. The only difference is the end mounting bracket is different than what is used on a Full size Ford. No matter, as the bellows and seal are all the same.  Their website is , the price was $69.95.

The tools you will need are basic. Standard screw driver, 7/16 socket, extension, and ratchet &  snap ring pliers. You will to pry out a pressed in bushing, but I will leave you to decide what you need for that. You will also need a tube of white lithium grease.

The dismantling process included removing the three 7/16 nuts off the end of the bracket plate.

   Once those are taken off, and the washers beneath them taken off you can remove the

plate/bracket assembly from the booster by pulling it straight off the booster.

   Once the bracket is off, you can now squeeze the bellows together and see the shaft of the booster.

On the end of the shaft is a metal clip. Slide the metal clip off the side of

the shaft. Once the clip is off, you can now remove the cone shaped metal air filter that is pushed down the center of the shaft.  Once that is removed, you can now remove the snap ring that is on the end of the shaft.

  Once removed, a washer and seal can then be taken off exposing the bare shaft.  This next step

is a little tricky.  The bellows has a large spring that is under tension that is  slid over the shaft     and each end of the spring is pushing on each metal plate on the top and bottom of the bellows.

With the shaft aimed away from you,  and a firm grip on the plate, carefully peel back the rubber bellow from around the plate.  Work your way around the plate pulling the rubber back allowing the plate to come away from the bellows.  Once the plate is free,  slowly release the tension on the spring by lifting the plate off the shaft.


Now that the large spring has no more tension, pull it off the shaft, and set it aside, along with the plate you just removed.

Next we will need to remove the 3 bolts located at the bottom of the shaft plate in the bottom of the bellows area. These bolts have a 7/16 size head. You will also need an socket extension to reach to these bolts through the bellows.  Once these bolts are removed, you can carefully pry the outer plate located on the backside of the bellows away from the shaft plate that is still inside the bellows.

Set the plate aside, and move onto removing the large bellows plate that has the shaft all the way through the bellows. Carefully lift up on the outer lip edge of the bellows surrounding the plate.  Pull back on it, moving all the way around until the plate is free. Pull it out and set it aside.





The only thing left you have to remove now are the three metal diaphragm rings located inside   the center 3 grooves of the rubber bellows.  These rings are there, to make sure the bellows does not collapse or deform from the air vacuum that is going through it when you press/depress the brake pedal. These can be a pain to remove, but you can save yourself a bunch of time if you just cut them out of the old bellows. This will not spare you the agony of putting them into the new bellows!

Now you have successfully dismantled a 1957-1958 Kelsey Hayes under dash booster used on 1957 – 1958 Ford cars.

Now lets rebuild this:

  On the back side of this plate, you will see a small spring. Remove the spring, and set it aside.     With the spring out,  you will see a rubber donut ring that you will need to remove. I just use a flat edge screwdriver and carefully work my way around the edge,  lightly prying up on it.  Soon the seal will come off, revealing two metal pieces on the back side of the rubber seal, and a spring.








Find the new seal from in the kit, and carefully take the metal pieces from the old seal, and coat them with a light smear of white lithium grease on both sides. Put them into the new seal, and give the internals of the new seal a light smear of white lithium grease as well.


  Next, grab the tip of the small shaft that is left protruding out of the plate you just took the seal off of, and put it straight out.  On this shaft you will see a small rubber donut seal and a white plastic button. The button is pushed onto the end of the seal. Carefully grab the button with a pair of pliers and very lightly pull the button off. If the button is stuck on, carefully twist it back and forth until it loosens up. Do not crush this plastic button with too much pressure from the pliers!!  Once it is off,  you can remove the donut seal. This one was really stuck on there  hard, so don’t be afraid to get aggressive with the seal. It has turned hard over the years and mine almost felt like plastic rather than rubber. Take note that the seal his goes on one direction, with the hollow area pointing toward the button.  Grease the shaft with white lithium grease and push the new seal onto the shaft. Then push the white plastic button back on with your fingers.

Once back to together, grease the shaft and put the piston back into the plate. Grease the end of the shaft, put the spring back on, and push the new seal with the recently placed metal pieces back over the spring and onto the palate. Make sure the new seal gets pushed down far enough that the outer lip grabs the edge of the new seal and holds it all in place. Set t his plate aside.

Next, get the new bellows out and inspect it for any defects. Look around each rib in the seal, making sure there are no cracks,  or areas where air can leak out of.  Next, put some white lithium grease on the end of your finger and wipe it into every groove in the bellows.  There are 5 grooves in the bellows, so this will take some time. Once this is done, grab the first large diaphragm ring and feed it into the bellows and carefully work it into the center groove. You will have to get an edge into the groove and work your way around pulling and tugging the bellows in order to get the ring in place.  Complete this step until all 3 inner bellows grooves have a ring in them.

Next, clean up the plate that has the long shaft on it. Insert it back into the bellows, shaft side first. This plate sets in the outer groove of the bellows. Work the outer bellows over the end of the plate.  Clean and grease the shaft with a smear of white lithium grease.  The exposed back side of the plate that has a large cupped area in it should be cleaned as well. Once clean, put a smear of white lithium grease in the area,  and make sure some gets into the little hole in the bottom of the cupped area.

Now you can take the plate that has the newly regreased and resealed piston assembly in it, and bolt it back onto the bottom of the bellows plate with the shaft that you have just put into the bellows.  Make sure the plate lines up correctly so that all 3 bolts can be bolted from inside the bellows easily.

Now you can set the large spring over the shaft inside of the bellows.  Set it aside, and we can now move onto the other plate.

  On the back side of the end plate, is a pressed in seal. Extract the pressed in seal however you want. I took a screw driver and started prying my way around it, bending the old outer ring up. Then grabbed the newly bent edges with some needle nose pliers and twisted it apart until I got the old metal ring out, and rawhide seal out. Be careful not to go to deep, as there is a plastic washer under this seal, and you do not want to damage it. Once out, I pulled the white plastic washer out, regreased it with white lithium grease, greased the rubber side of the seal, pushed it down rubber side first, and carefully and lightly hammered the new seal in place until it seated the same place the old one did.

Now, you can flip the plate over, and put it up against the large spring in the bellows and slide it down, making sure the shaft carefully goes through the new plate seal you just installed. The spring will be giving you a lot of resistance at this point.  But get the plate down into the bellows, prying the outer lip of the bellows over the end of the plate.

  You can now push the bellows down, exposing the end of the shaft. Put the new rubber washer over the shaft, followed by the metal washer, followed by the snap ring. Make sure the snap ring completely goes into the groove at the end of the shaft.  Now put the old old metal cone shaped air filter into the open end of the shaft and slide the retainer clip on from the side.



Now you can bolt the end plate bracket back on by sliding the bracket over the three exposed studs coming out of the end belows plate. Thread the 3  nuts down and tighten.

Check the booster by collapsing the bellows assembly by squeezing the assembly together with your hands. You should hear  and feel air swooshing through the end piston of the booster. Then, find the small white button coming out of the end pivot joint. Push and hold the button down while collapsing the booster. You should feel air pushing through the outlet tube.  the last piece from the kit was a large foam shaft cushion that slides over the end mount shaft housing. It slides on easily.

You have now successfully rebuilt the Kelsey Hayes 1957 – 1958 Brake Booster!!

I have chosen not to clean or repaint the rear mount bracket at this time. I will at a later date. Then it will look brand new!


I have acquired a factory 1958 Ford Power Brake pedal assembly for cars with an Automatic Transmission.  Someone I knew purchased the unit for the Brake Booster, and gave me the Pedal assembly. I needed an Automatic pedal assembly anyway, so finding one for a Power brake car was a big plus. All I need to do now is find a Kelsey Hayes Brake booster for it.