How bad is the 71 early 72 brake booster?

[Big Red Mach 1]

Apparently these underwent an upgrade in mid-72 that was supposed to help with reliability. Were that many of the 71-72 Bendix boosters failing? What did they change in them to make them more reliable? Thanks!

 

[Stanglover]

Apparently these underwent an upgrade in mid-72 that was supposed to help with reliability. Were that many of the 71-72 Bendix boosters failing? What did they change in them to make them more reliable? Thanks!

 Good question. Next question is; what are rebuilt boosters upgraded to or are they?

I have a Cardone (Car Done as Don C says) and although it tests and hold vacuum as it should, it is not THAT much better than when I ran the front 4 piston disc brakes without a booster.

 

[droptop73]

I put a ton of miles on my car and have not had any (known) issues with the booster.  But then again, mine is a 73. 

 

[Hemikiller]

Never had a booster issue with any of the 71-73s I've had, including three 71s. Since I wasn't the original owner, can't guarantee that they weren't replaced over the years. 

 

[Big Red Mach 1]

 Good question. Next question is; what are rebuilt boosters upgraded to or are they?

I have a Cardone (Car Done as Don C says) and although it tests and hold vacuum as it should, it is not THAT much better than when I ran the front 4 piston disc brakes without a booster.

Classic Cougar says on their website that they rebuild all to the better 73 specs. But it does not say what that actually means. 

 

[timachone]

All I can say that my '73 Bendix Booster is original to the car, was unmolested and still holding vacuum after 48 years. So they have something in there that really is longlasting... 

 

[jscott]

My '72 (Sept '71 build date) has the original booster still going strong

 

[Big Red Mach 1]

So the reason I'm asking is because my master cylinder is leaking terribly, and has been since I've owned the car. I was under the assumption that the fluid will get inside the booster and kill it. Inevitably most of these 48+ year old cars have had to have had the master cylinders leak in this manner at some point in their lives. Yet no one in this thread has had a known issue, and my 73 booster also still holds vacuum. I was going to have the booster rebuilt or replaced when swapping the master cylinder. But now I'm wondering if I shouldn't just spare the expense and clean it up really well and re-paint it and run it. 

 

[jscott]

while mine is working fine if I was to replace the master I would just do it all.  In fact when my car goes into a shop in a few months I am having all the brake lines replaced and I very well might go for a new mc and booster as well.  Mine are working but look 49 years old and you can't take your money with you!!

 

[Don C]

while mine is working fine if I was to replace the master I would just do it all.  In fact when my car goes into a shop in a few months I am having all the brake lines replaced and I very well might go for a new mc and booster as well.  Mine are working but look 49 years old and you can't take your money with you!!

And, having bad brakes could mean you won't get to spend it all before you depart.

 

[Big Red Mach 1]

If I do send it off, it's going here, but it will suck to be without it for 4-6 weeks. https://harmonclassicbrakes.com/contact/

https://www.parts123.com/parts123/yb.dll?parta~dyndetail~Z5Z5Z50001029z~Z5Z5Z5AADKP~P255.95~~~~S62C0Q8AHM68107116580g~Z5Z5Z5~Z5Z5Z50001029z

 

[Stanglover]

If I do send it off, it's going here, but it will suck to be without it for 4-6 weeks. https://harmonclassicbrakes.com/contact/

https://www.parts123.com/parts123/yb.dll?parta~dyndetail~Z5Z5Z50001029z~Z5Z5Z5AADKP~P255.95~~~~S62C0Q8AHM68107116580g~Z5Z5Z5~Z5Z5Z50001029z

That's a useful link. Cardone never seem to have any these days.

 

[Don C]

David (Carolina Mountain Mustangs) was trying to put together the tools and parts necessary to repair them, you might check with him. I know that he rebuilt his own. 

 

[72HCODE]

So the reason I'm asking is because my master cylinder is leaking terribly, and has been since I've owned the car. I was under the assumption that the fluid will get inside the booster and kill it. Inevitably most of these 48+ year old cars have had to have had the master cylinders leak in this manner at some point in their lives. Yet no one in this thread has had a known issue, and my 73 booster also still holds vacuum. I was going to have the booster rebuilt or replaced when swapping the master cylinder. But now I'm wondering if I shouldn't just spare the expense and clean it up really well and re-paint it and run it. 

it can. but if your booster is still holding vacuum then it is fine.

I've had to replace my original booster 2 times. first was it was original to the car and the diaphragm was dead inside.

the second blew up when i had a massive lean Carb backfire through the intake that blew up all my vacuum accessories.

the worst case that can happen when your booster blows is pushing the brake pedal requires some effort the brakes will still work and stop the car it will be harder.

then the engine will have a vacuum leak and start stalling.

 

[timachone]

I am with 72HCODE! 

I replaced all of my suspension and brake system parts including soft and hard lines, clips, master cylinder, brake cylinders, calipers, bolts and so on BUT the brake booster. If that fails, your brake will go harder but will brake anyway. And you will eventually have a vacuum leak. But all other parts should be done right. That's the reason why I bench tested my original booster with a vaccum device - you can read the procedure on page 10 and 11 on my resto thread ('Tim's 1973 Mach 1 rebuild thread'). As I then knew my booster was holding vacumm steadily at the minimum of 10 minutes I chose to use it as is and give it some cosmetic resto. That included an order of a kit from harmonicclassicbrakes.com and a paint strip wih new nice semi gloss black. With this kit I renewed the front seal, front vaccum line seal and check valve, the rear bellow and felts and was done. For 25 bucks. So I would first recommend to test you booster before sending your original unit elsewhere... 

 

[Big Red Mach 1]

That's the reason why I bench tested my original booster with a vaccum device - you can read the procedure on page 10 and 11 on my resto thread ('Tim's 1973 Mach 1 rebuild thread'). As I then knew my booster was holding vacumm steadily at the minimum of 10 minutes I chose to use it as is and give it some cosmetic resto. That included an order of a kit from harmonicclassicbrakes.com and a paint strip wih new nice semi gloss black. With this kit I renewed the front seal, front vaccum line seal and check valve, the rear bellow and felts and was done. For 25 bucks. So I would first recommend to test you booster before sending your original unit elsewhere... 

Great advice. Thanks!!

 

[Carolina_Mountain_Mustangs]

The housings are all the same. The materials inside were changed slightly but nothing major. They are really all the same. I rebuild my own. Took me years to track down the components.

 

[Idaho Chris]

Chris-

The leaking master cylinder did mine in.

I used these guys for my rebuild:  http://boosterdeweyexchange.com/

Long time business and willing to chat on the phone.  Lifetime guarantee on the work.  They put their sticker inside the rebuild and if they ever get it back they repair it free no matter the owner.

 

[NOT A T5]

+1 on Booster Dewey!

 

[GERMYS_72]

How can you test if the Power booster is working while everything is on the car ? H

Here is my situation

The car was not stopping when I bought it.
The hydraulics are tight, no leaks at the calipers/rear cylinders, or the master cylinder.
I changed the brake pads in front, and it started stopping a little better.
I sanded the rust off the front side of the front rotors, and it started stopping a little better, but still having to press the pedal fairly hard.
I'm going to change the rotors and put on new rear brake shoes soon, but I'm wondering if the booster is working.

I bled the rear brakes, when the bleeder valve is open and the fluid is released, the brake pedal goes to the floor and stays down, so I'm assuming that the vacuum is working fine, but I still feel like there might be something wrong.