Hi,
In my 69 Toronado, the master cylinder has a leak coming out of a hole at the bottom. I don't know what the hole is for, if it's missing something, or just cast that way. I read various posts on replace vs restore. If this seems in ok enough shape, I'm up for restoring it. It was all crusty rusty, so I think they're original. If replacing, I'm having trouble figuring out model/part numbers. It's a Bendix from the stamp on the gasket. Drum brakes on all 4 wheels. If restoring, there were a few recommendations that look good.
I'm also up for replacing or restoring the booster - plenty of posts say to do it while I'm at it.
Any advice or opinions?
Thanks!


MC and Booster.

Leaks out mystery hole

Hole viewed from the driver side

 

Restore it. Talk to White Post Restoration in VA or Karp’s in CA.

Good luck!!!

 

I think you are going to be hard-pressed to find a replacement power booster. If you want a new one, sending your off to be rebuilt is probably your only option. From what I can find, no one even sells the correct master cylinder anymore. You might want to contact Craig at Mobileparts.

 

The leak isn't likely coming from "that hole". That's just where the fluid is migrating to and settling/puddling as it leaks...gravity sends the leaking fluid to that spot. Could be coming from the piston/bore/seals - the open end of the bore is right above that cast-in hole that you show.

Talk to Mike @brakeboosters.com.....he's in San Luis Obispo and rebuilds/restores a large number of power brake boosters (he also offers sleeving for the master cylinders but you may be able to get a better price on that part by going direct to Apple Hydraulics, Whitepost or Karp's).

 

......also....there is another hole at the top of the horizontal/side-to-side hole you show at the bottom of your MC. The hole I mention ends up in the machined face around the cylinder bore. Possibly put there for the very reason of indicating a leak in the bore (like a water pump with hole that leaks when the seals are bad).....the fluid leaks past the worn piston seals, makes it's way out the back of the bore and runs down to this hole/passage to the exterior of the master cylinder.

 

Thanks - I like the idea of it being a seal, and not something cracked. And all the good references - BrakeBoosters does seem to focus on the booster, and I do like White Post for the one-stop shopping on the MC - and they want all the parts, just stick it in a box.

 

I believe you need both the master cylinder and brake booster. Brake booster diaphragm is likely ripped putting vacuum to the back of the master. The master seal under vacuum has failed. So you need both. Get them both rebuilt. For the brake booster I had a good experience with Booster Dewey also know as Power Brake Booster Exchange out of Oregon.

 

Just a progress update. MC and booster are out, and did distribution block while I was at it. Going with White Post as a one-stop shop - they didn't even want them separated. Thanks for all the recommendations.

Any guesses for master cylinder color? Cast gray or black, up to me. Posts here say it varied. Looks like cover is usually cadmium plated, and White Post says booster will be O.E. spec (whatever that was)



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Also, the top half of the booster had the black almost-solid gunk sealing it to the firewall. Was that original? Or a fume/water leak someone did later? It was a pain to remove.

 

The sealer is factory to stop water and air leaks into the passenger compartment.

 

While waiting for the restoration, the battery died. I was looking for a fancy high tech reason. Here's my solution (well, this and disconnect the battery)

 

I have a hunch the drum master you need may be no different than the drum master for A body cars.
The Master you took off has been changed.
Is the car a front drum brake car?

 

Yes, it's drums on all 4 wheels. Does that seem off? The brake lines, etc. all look cruddy enough to be original.

 

Parts are back from White Post - they did a nice job. Can even read the stamping on the cylinder cover, I thought that would have to be scoured off.