Brakes: Update: Hydrovac Failure & Smoky Exhaust

[JoeHall]

It's been awhile since I had to fool with a hydrovac, so hopefully someone here can refresh my memory. Today, while out exercising the wife's 63GT, the brakes decided to act up. While sitting a light, with foot resting on the brake pedal, it began to drop, and stopped about an inch off the floor. I knew there was a problem, so gingerly returned home. ON the way home, the brakes would feel fine when initially pushed, but then the pedal would drop an inch or two. In the driveway, I pressed hard on the pedal several times, and eventually it went to the floor. Then I looked in the rear view mirror, and blue smoke was billowing out the exhaust. I am thinking the booster was shooting brake fluid into the intake. If so, where is the malfunction in the system? The booster? The check valve? Appreciate any input.

This is a new repro booster from SI, installed a few years ago. Up till now, it has worked perfectly.

Thanks

[StudeRich]

The Hydraulic portion of the Hydrovac is leaking fluid and being sucked into the Intake Manifold Cyl. #7 & ? runner.

[Dan White]

To make sure pull the vacuum hose off the hydrovac and see if it has brake fluid in it.

[JoeHall]

The Hydraulic portion of the Hydrovac is leaking fluid and being sucked into the Intake Manifold Cyl. #7 & ? runner.

Thanks Rich, I was afraid it was something seriously wrong with the hydrovac. Not gonna fool with rebuilt, and not sure what the repros are going for nowadays, but I may just bypass it this time around.
Thanks Again

[rkapteyn]

Since the repop failed already do you really want to spend more money in China?
Find a good rebuilder for your old booster..
The repos look nice but we do not know if the correct seal material was used.
I believe that Stephan Allen in Florida has these rebuild by a good rebuilder.

https://mystudebaker.com

[r1lark]

This is a new repro booster from SI, installed a few years ago. Up till now, it has worked perfectly.

Oh oh, doesn't bode well for the new SI booster that I purchased a couple of years ago but have not installed on the '62 GT yet. (A bad booster is what took this car out of service 30+ years ago - the engine locked up after sucking brake fluid into it. Number 7 piston was a bear to get out.)

[JoeHall]

Since the repop failed already do you really want to spend more money in China?
Find a good rebuilder for your old booster..
The repos look nice but we do not know if the correct seal material was used.
I believe that Stephan Allen in Florida has these rebuild by a good rebuilder.
https://mystudebaker.com

I followed that link and, unfortunately they do not list boosters for 63-64 Hawk with DB. They do list a, "Power Brake Modification Kit" for 63-64 Hawks with DB. It is part number 1565515, and cost $125. Not sure what that is. I will call them tomorrow. Definitely done with the repros. I have the old, OEM hydrovac around here somewhere to send them as a core. Will see what they say on the phone tomorrow.

[mbstude]

Joe, we (S.A.) don’t stock rebuilt Hydrovacs for Disc Brake Hawks because the new ones are readily available, though we don’t stock those either. That said, we do have an excellent rebuilder here in Florida. I’ll shoot you a message.

[JoeHall]

Joe, we (S.A.) don’t stock rebuilt Hydrovacs for Disc Brake Hawks because the new ones are readily available, though we don’t stock those either. That said, we do have an excellent rebuilder here in Florida. I’ll shoot you a message.

Thanks much Matt. I appreciate it

[Bob Andrews]

These guys are really good. Never had a problem with them

http://boosterdeweyexchange.com/

[Jeffry Cassel]

Packard did same thing several years ago. All jumped in to go to the drive-in , backed out of the garage and stepped on brake. Pedal went to the floor and a big cloud of white smoke came out the exhaust. I do not think they are very effective or safe, and they they are expensive to rebuild.

[bezhawk]

The originals had a leather seal on the main shaft from the vacuum chamber to the brake portion. The new ones are rubber. If the shaft gets any type of rust on it the seal is destroyed. If the new ones use a plain steel shaft, that is the problem Originals were chromed to keep the rust off the shaft. When the brake is at rest, the main spring on the vacuum piston retracts the piston, and it's shaft to the back of the vacuum chamber, the shaft is exposed to a non oil environment, and can rust. When you apply the brake the shaft (now rusted) goes through the seal. I rebuilt our on our Packard Hawk around l985 and we never had trouble. The trouble comes with cars that are not driven for long periods of time. Things rust when they don't get oil. That's why with hydrovacs you need to use a good silicone grease on the vacuum chamber walls and keep the leather oiled with neatsfoot oil. The shaft should be stainless or chromed, and it should be run and used every couple of months. Without starting the engine and applying the brakes, the vacuum portion wont move and spread the lubrication to the vacuum chamber.

[JoeHall]

I installed the repro HV in April 2014, and 24,000 miles ago. I see boosterdewey guarantees his for 2 years. If rechromed shaft is key to longevity, I doubt the Chinese repro is chrome. In any case, they're too expensive to replace every few years. I plan to call around today, but hopefully will find place to rebuild my OEM core and send it back to me. I did that with another 63GT in the late 1990s and it was still ok when the car was destroyed by fire, at least 15 years later. Just hoping I didn't toss the OEM core. Will look for it today. If so, will probably just convert to huge 12" DB setup, as the other 2 Studes have. That way I can just toss and forget about the HV. Thanks for all the input.

[JoeHall]

Well it appears I screwed the pooch on the HV core. After searching for it today, I vaguely recall tossing it away the last time I cleaned the garage, a couple of years ago. I am a hoarder, when it comes to Stude parts, but in a moment of insanity, tossed that HV. So no point in calling the rebuilders, I don't have one to be rebuilt. Maybe I should call anyway, but I believe the core charge is about as much as the rebuild. So plan 'A' may not be feasible at this point, unless I can pick up a core somewhere reasonable.

Mean while, I have a couple of alternate plans. Plan 'B' is to bypass the HV and see just how much harder the pedal becomes. I have heard it is significant, but won't know till I try. If it increases pedal pressure much at all, it will be a deal breaker for the wife.

Plan 'C' will be to swap the 12" DB setup from the other GT, out with the Turner DBs on the wife's GT.

[tsenecal]

There is one on flea bay from a 57 President, but looks a little rough, $150. A few others, some for GM, and some rebuilt. You might check it out. The Stude one is in PA, and may be rebuildable, or you could possibly use the chrome shaft out of it in yours. Good Luck!