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JoeHall
08-20-2013, 04:32 PM
It began a few days ago. With the 63GT's motor running, sometimes when pushing the pedal, it would push back against my foot, and wind up an inch or so taller than when I first pushed it. With the engine off, the pedal would go very low.

This morning I drove a few miles, then parked and shut the motor off; I then pushed the pedal, and it went straight to the floor. Upon restart of the motor, the pedal came right back up.

Driving again later, the pedal was low & hard, but still stopped the car very smoothly without any wheel-grab. After motor shut down, I again pushed the pedal, and again it went straight to the floor. I pumped it a half dozen times to see if it would pump up, and it did not. But it did come up again quickly upon restart of the motor. However, this time the left tail pipe put out a thick cloud of blue/white steam for about 5 minutes. When revved up, it sprayed some black droplets on the pavement, that were thin like brake fluid, but did not smell.

With no wheel grab and smooth stopping, I am guessing the problem is not a wheel cylinder. The exhaust crossover valve is disabled, so I am guessing the hydrovac pushed brake fluid into an intake runner for the left bank.

QUESTION: Is the problem in the hydrovac? The master cylinder? Both? Neither?

Thanks

41 Frank
08-20-2013, 04:44 PM
I have seen this problem of the pedal pushing back many times, mostly in the trucking field where I worked for many years. Hydrovacs were/are prevalent in trucks. When the pedal pushes back it indicates the hydrovac is defective and needs replacement.

JoeHall
08-20-2013, 06:33 PM
Thanks Frank,
I have been reading the archives, and it looks like I will either call SI in the morning for one of their new ones, or pull this one and send it to Rebuilders Enterprises, per JimJim's suggestion in another thread from a year ago.
If I pull this one, I can always bypass it for now, till it comes back from the rebuilder. http://forum.studebakerdriversclub.com/showthread.php?63536-Power-brake-booster-conversion This thread from the archives was helpful, and it looks like it would be wise to check the banjo fitting threads before sending it off for rebuild though.
Thanks Again

UPDATE: The banjo threads look OK, from what I can see. There was no check valve in the vacuum hose. Won't need the two hoses many folks suggest replacing, since they have been converted to metal lines.

Think I will at least call the Rebuilders, since $200 is a lot less painful than $375.

SN-60
08-20-2013, 08:04 PM
I liked the way My old '56J was set up Joe.....Stick O/D, P/S, and NON-Power Brakes. That's 'Where It's At'!!

studebaker-R2-4-me
08-20-2013, 08:39 PM
Joe, the hydrovac is shot. Pull the vacuum line and I will bet that there is brake fluid in the line. Be careful removing the line so that you don't get brake fluid on your paint. This same thing happened to me while I was in South Bend a few years ago for the spring swap meet. It took up my entire weekend chasing down a new hydrovac and associated parts needed to repair my Hawk. Thank goodness Dave "Barnlark" Arnold was there to drive me around. This is the exact reason I DO NOT use modern brake fluid with silicon. Can you image the damage to your engine with silicon burning through it? It took my Hawk about 15 minutes to burn off the brake fluid after I finished replacing the hydrovac

It is simple to blow a hydrovac without a check valve in the vacuum line. Yours it either not there or it is shot as well. A simple engine backfire is enough to blow an aging hydrovac.

I opted to purchase the NEW hydrovac from SI which has a built in check valve. BTW the inline check valves are made of unobtainium and have not been available for many many years. Make sure you get the two sizes of copper seals for the installation on the banjo fittings, you are going to need two #10 Metric nuts as well to attach it to the bracket. Some assorted brass fittings are required as well for the vacuum line as well.

Good luck and consider yourself lucky that your were not driving when it let go. Someone was looking after me when my went without warning.

Allen

JoeHall
08-20-2013, 09:07 PM
Joe, the hydrovac is shot. Pull the vacuum line and I will bet that there is brake fluid in the line. Be careful removing the line so that you don't get brake fluid on your paint. This same thing happened to me while I was in South Bend a few years ago for the spring swap meet. It took up my entire weekend chasing down a new hydrovac and associated parts needed to repair my Hawk. Thank goodness Dave "Barnlark" Arnold was there to drive me around. This is the exact reason I DO NOT use modern brake fluid with silicon. Can you image the damage to your engine with silicon burning through it? It took my Hawk about 15 minutes to burn off the brake fluid after I finished replacing the hydrovac

It is simple to blow a hydrovac without a check valve in the vacuum line. Yours it either not there or it is shot as well. A simple engine backfire is enough to blow an aging hydrovac.

I opted to purchase the NEW hydrovac from SI which has a built in check valve. BTW the inline check valves are made of unobtainium and have not been available for many many years. Make sure you get the two sizes of copper seals for the installation on the banjo fittings, you are going to need two #10 Metric nuts as well to attach it to the bracket. Some assorted brass fittings are required as well for the vacuum line as well.

Good luck and consider yourself lucky that your were not driving when it let go. Someone was looking after me when my went without warning.

Allen
Thanks Allen,
What's really scary is that my wife has drove the car about 85 miles since Sunday. I watcher her pull away from the driveway once and noted some blue/white smoke, but just figured it was condensation.

jimmijim8
08-20-2013, 09:19 PM
The banjo fitting copper washer area on the remanufactured booster may needs buttered up a little with some of that copper type head gasket dressing{perhaps something else may do} for a good seal between the washer like looking copper ring, and booster because when the unit is sandblasted, the mating surface between the copper washer and booster output sometimes gets abrated a bit enough to eliminate what seems to be a series of scribed circles within one another on the shoulder of the banjo gasketed booster output port. Maybe a bit of the same sealer might be applied to that bolt wouldn't hurt. Lil' dab 'l do ya. 6 years and I'm still a happy booster. I got a complete check valve assembly from SI. Not over the phone or catalogue. 4 yrs. ago. in person. cheers jimmijim

StudeRich
08-21-2013, 01:15 AM
I believe that the rebuilders do not need all of that mounting hardware and Brackets hanging on it, and may lose some of it. You should ask.

swvalcon
08-21-2013, 07:39 AM
Joe Had the same problem with my hawk just before I stopped driving it for restore. I unhooked the hydrovac and you couldn't even tell. Thinking about going with a powerbrake booster under the floor from speedway and either remove the hydrovac or just let it sit there for show.

JoeHall
08-21-2013, 08:14 AM
Steve,
I too, had thought of just installing a pedal for standard brakes (more leverage), and disconnecting the booster. If it weren't the wife's car, I'd do that in a heartbeat. Both of our other Studes have that setup, but with the huge, 12" brakes and high quality pads. Someone has installed a Turner kit on this car, and I have heard his kits, if not boosted, sometimes result in a harder pedal, and that would not work for the wife. In choosing to boost or not to boost, one must also choose between single or tandem MC, since the booster will only accommodate a single MC. So its a trade-off.

JimJim, your guy in IL has had a price reduction; I just got off the phone with "Bill" there, and a rebuild is $189 plus shipping. They include a lifetime piston seal that will never need neetsfoot oil. That sounded familiar with the place in FL who rebuilt the one on the wife's other GT, around 10 years ago. They said don't bother oiling it, ever.

Looks like I will get this one ready to ship tomorrow on the way to work.

PackardV8
08-21-2013, 10:09 AM
I unhooked the hydrovac and you couldn't even tell.

If so, that's because the Hydrovac wasn't working correctly. When they're right, there's a noticeable reduction in the pedal pressure required.

jack vines

JoeHall
08-21-2013, 10:12 AM
If so, that's because the Hydrovac wasn't working correctly. When they're right, there's a noticeable reduction in the pedal pressure required.

jack vines
My thoughts exactly.

swvalcon
08-21-2013, 11:33 AM
Joe I'll have to keep in touch and see how your rebuilt works out. I could rebuild the hydrovac and just change out the master for a double unit. That way if one fails I still have brakes.

JoeHall
08-21-2013, 08:54 PM
I removed the hydrovac this eve after work, and re-connected the lines, using a brass junction block. Didn't bother to bleed it, but got plenty enough pedal to test drive it and get a feel for Turner brakes without a booster. I could definitely live with it as is, if I were going to be the primary driver, would simply install a Turner dual MC kit, then ease on down the road.

Alas, I am not to be the primary driver. I let the wife test drive it tonight also, and she said the pedal is too hard. So the hydrovac goes in the mail Friday to "Rebuilders Enterprises", on my day off work. The trade-off is, will have to stick with the single MC. But with power brakes, the MC does not get as much of a hydraulic work out anyway.

jimmijim8
08-22-2013, 05:18 AM
Great news. I hope yours works as well as mine. Stuff is supposed to get more xpensive as years go by. What's up wiff dat. cheers jimmijim

Dan White
08-22-2013, 06:51 AM
This needs to be a sticky or put somewhere since it comes up fairly often. YOU CANNOT (safely) run a dual master cylinder and a Hydrovac power booster, UNLESS you use one of the double Hydrovacs, which I think are still available, but expensive, and must be mounted in the trunk (not a great way to go in my opinion). The Hydrovac powers all four lines at once when you push down on the brake pedal and does not go back through the master cylinder, i.e. the master cylinder activates the Hydrovac and the Hydrovac puts pressure to the brakes. Also the idea of running dual master cylinder and plumbing the booster only through the front brakes is not a safe idea.

JoeHall
08-22-2013, 08:36 AM
This needs to be a sticky or put somewhere since it comes up fairly often. YOU CANNOT (safely) run a dual master cylinder and a Hydrovac power booster, UNLESS you use one of the double Hydrovacs, which I think are still available, but expensive, and must be mounted in the trunk (not a great way to go in my opinion). The Hydrovac powers all four lines at once when you push down on the brake pedal and does not go back through the master cylinder, i.e. the master cylinder activates the Hydrovac and the Hydrovac puts pressure to the brakes. Also the idea of running dual master cylinder and plumbing the booster only through the front brakes is not a safe idea.

"Sticky" for who? I thought I said above, what you just said here. Isn't this common knowledge? Does anyone not know this? Who said anything different in this thread? Did you read any of the above, or just scan it?

Dan White
08-22-2013, 02:29 PM
Joe you said it but I don't think it was clear enough. Swavlcon made a comment "Joe I'll have to keep in touch and see how your rebuilt works out. I could rebuild the hydrovac and just change out the master for a double unit. That way if one fails I still have brake This appeared to me to mean that he was going to use a hydrovac and dual MC. No this is apparently not common knowledge and at least once or twice a year someone asks how to put a Turner dual master cylinder kit on a car with a Hydrovac! It should be well known but apparently not enough. Your comment was enough for those of us that understand the system but not for those that don't.

JoeHall
08-22-2013, 03:17 PM
Joe you said it but I don't think it was clear enough. Swavlcon made a comment "Joe I'll have to keep in touch and see how your rebuilt works out. I could rebuild the hydrovac and just change out the master for a double unit. That way if one fails I still have brake This appeared to me to mean that he was going to use a hydrovac and dual MC. No this is apparently not common knowledge and at least once or twice a year someone asks how to put a Turner dual master cylinder kit on a car with a Hydrovac! It should be well known but apparently not enough. Your comment was enough for those of us that understand the system but not for those that don't.
Got it Dan,
Apparently, I "scanned" right past Swavlcon's post which indicates a (now obvious) misunderstanding :o

Dan White
08-23-2013, 11:43 AM
No problem. It is just kind of a pet peeve of mine over the years. For some reason the fact that Hydrovacs and dual master cylinders don't go together never seems to be understood. I can understand how it happens, but those that sell brake parts, kits, etc. should highlight this fact so there are less confused customers. Frankly, I like the hydrovacs in my two Hawks, and also the one in the wagon, although that one needs to be rebuilt. They stop when they are supposed to, but shoot if you have an original it is long past time to rebuild them. There seems to be some mystique about these beast, but they were used by many car manufacturers over the years, including Mercedes Benz. I believe they were in use in large and medium duty trucks into the early 80s. These last units were the double Hydrovac that worked both front and rear brakes.

Here are some interesting sites about Hydrovacs (and other boosters)
http://www.cardone.com/tech-help/brakes/faqs/top-hydro-vac-questions

blackhawk
08-24-2013, 02:42 PM
Dan, thank you for pointing out that one should not install a dual master cylinder on a car with a functioning Hydrovac power booster. I don't understand why someone would assume this is common knowledge. Some of us do not read every post on this forum or have a SDC Chapter where we can get together with other Studebaker owners to swap stories and share information. I have a '63 Hawk with front disc brakes and the Hydrovac booster. I purchased the Turner dual master cylinder kit to get the added safety provided by the dual cylinders. I haven't installed the kit yet. I just set it on the shelf for the day that I get time to work on the car. I did not even read the instructions that came with it, so I do not know if Mr. Turner included this warning in the write-up. I suspect that I would have realized that something was wrong when I went to hook up the brake lines when installing the kit. It seems like at that point it would become obvious that the Hydrovac boost would only be applied to the front brakes. I am enough of a mechanic to know that would not be a good idea.

Dale Haggstrom
Fairbanks, AK

swvalcon
08-24-2013, 07:04 PM
I thought there had been many post including a write up in Bob Johnson's site that you could hook the front to the Hydrovac an the rear right off the master with no boost.

blackhawk
08-24-2013, 09:24 PM
I thought there had been many post including a write up in Bob Johnson's site that you could hook the front to the Hydrovac an the rear right off the master with no boost.

I guess I am going to have to search for those earlier posts and read the write up on Bob Johnson's site. As I understand it, the front disc brake/rear drum brake setup on a '63 equipped with this option uses the older style brakes on the rear with small wheel cylinders to maintain the desired ratio of braking between the front and rear brakes. Studebaker did not incorporate a pressure proportioning valve in the lines. So, how do you prevent the front brakes from prematurely locking up if the Hydrovac only boosts the front brakes?

Dale

swvalcon
08-25-2013, 08:36 AM
Maybe they are hooking in a adjustable proportioning valve. I don't remember as I was not that deep into it.

rusty nut garage
08-25-2013, 09:09 AM
If you want the proper pedal feel(not too hard) then you will need to replace the power brake pedal with a manual brake pedal. The ratio of pedal or brake pedal leverage is considerably different on a power brake vs manual brake car

I removed the hydrovac this eve after work, and re-connected the lines, using a brass junction block. Didn't bother to bleed it, but got plenty enough pedal to test drive it and get a feel for Turner brakes without a booster. I could definitely live with it as is, if I were going to be the primary driver, would simply install a Turner dual MC kit, then ease on down the road.

Alas, I am not to be the primary driver. I let the wife test drive it tonight also, and she said the pedal is too hard. So the hydrovac goes in the mail Friday to "Rebuilders Enterprises", on my day off work. The trade-off is, will have to stick with the single MC. But with power brakes, the MC does not get as much of a hydraulic work out anyway.

JoeHall
08-25-2013, 04:04 PM
If you want the proper pedal feel(not too hard) then you will need to replace the power brake pedal with a manual brake pedal. The ratio of pedal or brake pedal leverage is considerably different on a power brake vs manual brake car
Did that already. It is still too hard for her. I think the "hard pedal" many say Turner brakes produce, is due to the steel braided front lines. At least that's what are on mine.

blackhawk
08-25-2013, 05:30 PM
Maybe they are hooking in a adjustable proportioning valve. I don't remember as I was not that deep into it.

I think that would do it, but probably would require a lot of trial and error adjusting to get it right. I do have an adjustable proportioning valve on the shelf. It is not an immediate concern for me, since I am not using the car or working on it. I will have plenty of time to research the question this winter. Right now, summer is fading fast and I need to be doing other things. I just enjoy the exchange of ideas over a cup of coffee in the morning or any other time I take a break.

Dale

rodnutrandy
08-25-2013, 08:49 PM
I learned on this post. I have never ran a hydrovac , so did not know you can not upgrade to a dual master cylinder. Thanks for the lesson, its one I will remember!

BrianC
03-09-2015, 09:07 PM
Dan, help me out here..when my hydrovac failed i used a dual m/c under the floor(63 GT front disc). Not happy with the stopping power (no booster), i had the booster rebuilt. Since i already had the dual m/c in i plumbed the outputs from the m/c to the booster and then from the booster to all four. A residual check valve and a proportioning valve for the rears. You're saying this won't work or is unsafe...Why??? Other than the fact if the booster fails i'd have no rear braking power. Having said that, why not just plumb the front of the m/c to the front and the rear to the rear? The m/c is activating the hydrovac and the hydrovac puts pressure to the brakes... as you said. Originally, the Hawk has dual braking system, booster for the disc and m/c for the rear drums, only now, this way the booster supplies all four.
I've spoken to a number of car builders(hot rods) an it seems logical to them. Do you think that there would be to much output pressure from the m/c for the booster?
Right now i'm ready to bleed the system, having a fading pedal issue(air probably). I'd like more input and opinions on this before go ahead with it. Thanks.

karterfred88
03-09-2015, 09:57 PM
One, your dual/split system master cylinder has 2 pistons inside, they are not matched exactly for volume and capacity. Depending on the one you used there can be, and probably is, a differential in the output volume at each port on the master. Then you put different residual valves, further complicating the volume at the hydrovac input. As such the one with the highest pop off, actually doing all the work and the residual with the least pop off is getting all the fluid back to the M/C, overpowering one chamber and depleting the other. The hydrocvac can only have one source for intake, and one output. Either get rid of the hydrovac or get rid of the split M/C, all your trouble will go away.

BrianC
03-10-2015, 09:08 AM
Thanks Karterfred, that being said, back to my original thoughts...Why can't i run the hydrovav from the the one supply(front) from the m/c and the rears from the other supply? This way the hydrovac has is own supply and in turn supplying only the front. Wouldn't that theoretically do the same as the original set-up?

karterfred88
03-10-2015, 01:20 PM
Thanks Karterfred, that being said, back to my original thoughts...Why can't i run the hydrovav from the the one supply(front) from the m/c and the rears from the other supply? This way the hydrovac has is own supply and in turn supplying only the front. Wouldn't that theoretically do the same as the original set-up?
Yes and no. Depending on the master cylinder design, the front and rear pistons inside it could be designed to put out different volumes. Remember they are not really "separate" chambers. There is usually a spring on one piston that pushes the second piston, that's why it is necessary to attach the disc brake portion to the right chamber, and the drum brake to the right chamber. To illustrate this, pull the rear line and plug the outlet. Then try to move the piston in the M/C-- won't move. Allow the brake fluid to flow back without resistance as if you were bleeding the M/C and it will work fine for the fronts, but when you add the rear line back in the pressure differences start to come into play. Theoretically you can "re-optimize it" with an adjustable proportioning valve on the rears only, adjusting it till you get it just right. But you still need to play with residual valves to insure "flow back" to the separate chambers is correct ( needed due to the M/C being the lowest point in the system). Can it be done-yes, do you want to spend your life getting it right--no. Easy way- want a split system, put in a hot rod aftermarket vaccum booster designed to fit below the floor, between the pedal linkage and the M/C and get rid of the hydrovac. Or, put it back the way it was with a single M/C and it will work without any further effort. Keeping an eye on hose conditions and watching for leaks is all you need to do to keep it "safe". Remember, even with a split system, if you "pop" a front disk brake hose you won't have enough braking from the rears to panic stop the car. Good luck, hope you make one of the easy choices.

BrianC
03-10-2015, 04:31 PM
Thanks Karterfred for your explanation. The m/c i'm using is from Turner brake (mitsubshi). They're not big on details, the packing slip in scribble writing says "67 Hawk 4 wheel drum"???? Great attention to detail!!! Other than that there was no literature at all come with it. Before that, i purchased a complete booster conversion from Summit racing, assured me this was the conversion for the 63 Hawk...under the floor! if i remove the drivers seat maybe!! It was the size of a four cylinder motor! So frustrated at this point, between the exchange on the American dollar, freight, customs and return freight' and rebuild on the hydrovac i'm into this for more than a $1000 and still no brakes!!!
I'm going to have to replace the m/c with original equipment and certainly won't be from Turner brake or Summit! So i'm stuck with a $400 paper weight.

BrianC
04-18-2015, 08:23 PM
Thanks again Karterfred. Special thanks to 64V-K7 for his patience and advise. As it turns out, the hydrovac and the dual Turner M/C work just fine, despite all the negative opinions on the matter. Since i just finished the install, i've only drove it a couple of times to adjust the rear proportioning valve and minimize the nose dive at panic stops, the car stops quite well. The pedal has a very good feel and panic stops are good. So if it's not supposed to work, i'm guessing i should keep my fingers crossed and carry an anchor?? I hope i'm not in for any surprises?

StudeRich
04-18-2015, 09:49 PM
It sounds to me like Jim Turner knew what he was saying when he said: "Hawk 4 Wheel DRUM Brakes"!
He might have gotten the Car year wrong because of being in a hurry maybe, but if you had followed that advice and returned it you would be better off in my opinion.

BrianC
04-19-2015, 09:16 AM
No doubt you're right on that Rich. Never assume that what you order is what you get..or what you actually need? With the m/c installed since last summer, i thought it was worth a try. Certainly i'll always be conscious of the possibility of something going awry? This has been quite a learning curve, but as i said earlier "it's better to ask the stupid questions than to make the stupid mistakes"...
I will say that if someone is having their hydrovac rebuilt, if the housing is in good condition, never let them sandblast it!! It hadn't dawned me to tell them not to. Mine was like new, i had a high polish on it and it looked great. The sandblasting damaged the bleeder threads, and the rings on the casting where the bango seals go. I re-grooved as best i could on the bench, annonized the washers, used copper seal. Small 'sweat' type leaking, noticeable on the finger if you wipe it after a few days, imagine next winter i'll take it apart and re-mill both. I'm trying to keep the Hawk as original as i can, so i may just put the original m/c back in as well now that i've re-built it. For now, the hawk is on the road for this summer and i'm thrilled!