When I was working on the brakes on my -71 Camaro, I replaced the seal between the master cylinder and the booster. The parts guy didn't even know what I was asking for, until I took one out from my friend's Camaro, and got the part number off it. The parts store had it on the shelf, the guy just didn't know where to look for it (seems to have fallen in between the booster and the M/C in the books, and is not listed with any of them)

Now I'm in the process of putting the M/C on my -69 Chevelle, and have asked the Chevy dealership, Auto Zone, NAPA, NPD and MP brakes for the seal. None of them are aware of this seals existence.

The only one I have heard saying that this seal exists and is crucial to the function of the booster and the engine is Powerbrake Bob (in another thread here). Haven't been able to get hold of him yet, so I would really like to know if any of you guys have got this seal installed, and where you found it.

I guess what I really want to hear though is if anyone left it out, without having any problems.

News to me. :confused: There's no seal on mine. Has worked great so far.

I put in a seal when I installed power brakes on my '69 pickup. I didn't try to run it without the seal but if a seal was in there to begin with it must serve a purpose. The parts store could never locate one so I made my own.

There is vacuum right behind the master cylinder so I would imagine without a seal you are looking at a potentially large vacuum leak if you run without one. I eventually found a good used seal as my homemade one never worked very well. Then I had to find a better pushrod as the one I had was pitted and also allowed for a vacuum leak. The power brakes would work but when I found a good push rod (that was quite a search!) and used it with a good seal things sure worked better than ever.

Install a new check valve and check valve grommet too while you are at it.

It's discontinued by GM but they called it a body seal. 73-74 Bendix # 2510508 GM discon.#335077 graemlins/beers.gif

I know when I purchsed my reman booster and new master, I believe the booster came with a felt like washer that went behind the master. I later had to remove it cause it was spacing my master out enough to not get full stroke on the piston. Other then that, there is a rubber diaphragm type seal in the booster that the pushrod goes through. Couldnt say I've seen one in the aftermarket. If thats what your looking for, it should have come with your booster if you bought a reman one.

Wonderful! So I'm not insane, there's supposed to be a seal :D I'm surprised that a GM shop and some people in the brake business don't know about this, but I guess the reason could be that a leak between the master cylinder and the booster won't be very big if the mating surfaces are ok.

Could obviously be ok to omit it, but I'm of the same opinion as Rich: GM didn't waste money on that seal if it didn't serve a purpose. I'll get on the phone tomorrow, now even armed with a part number! Thanks guys!

Give Powerbrake Bob a call...I tried the e-mail route in my initial thread and couldn't connect. I called his company in CA, spoke to an assistant and then a day later to Bob....they sent one out to me...nice guy and group.

Originally posted by drielly:
Give Powerbrake Bob a call...I tried the e-mail route in my initial thread and couldn't connect. I called his company in CA, spoke to an assistant and then a day later to Bob....they sent one out to me...nice guy and group. Ok, that might be the problem. Haven't had an opportunity to call, just e-mailed and PM'd him but haven't heard anything back. I'll see if I can give him a call, if he has the seal I'll order it right away... or maybe a few of them so I don't have to mess with it next time ;)

So, is this seal only for Bendix boosters, or is it universal so it's needed on Delco boosters too? From the preceeding postings, it sounds like it's needed on a '71 Camaro and a '69 Chevelle and '69 pickup.