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Scott
07-27-2006, 10:38 AM
I just had the front flex brake hoses replaced on my 1962 Hawk (non-disc). There may still be a little air in the system. My question is, should the hydra-vac unit on the firewall always be bled whenever any kind of bleeding is done somewhere else in the system? I know the shop did not bleed the unit in this case. In fact, when I picked up the car, the mechanic was surprised when I told him it had power brakes!

kmul221
07-27-2006, 01:39 PM
If the brakes are bled properly at each wheel cylinder starting with the one furthest away from the master cylinder I blieve all the air in the lines should have been expelled.My presemt car does not have power brakes but I don't recall a bleeder screw on the power unit.

JDP
07-27-2006, 03:38 PM
You need to bleed the hydovac inlet first, then the outlet. (two bleed screws.)

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64 Daytona HT
63 R2 4 speed GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
62 Lark 2 door
62 GT(parts car)
60 Lark convert
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51 Commander

Scott
07-27-2006, 03:58 PM
I only remember seeing one bleeder screw in the diagrams in the manual, but there are so many parts, I'm not surprised if I did not notice another one.

So, are you saying, JDP, that the hydravac (hydro-vac?) booster should be bled in this case?

Update: I talked to Carl Thoms and he says it shouldn't be necessary to bleed the unit if they were only dealing with the other side of the system.

JDP
07-27-2006, 05:25 PM
I always do a full bleed whenever the system is opened.
http://stude.com/hydrovac.jpg

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Arnold Md.
64 Daytona HT
63 R2 4 speed GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
62 Lark 2 door
62 GT(parts car)
60 Lark convert
60 Hawk
56 Power Hawk/4 speed/289
51 Commander

Scott
07-27-2006, 09:20 PM
If there is some air in the booster unit, will it make the brakes seem more like manual brakes (in other words, will it reduce the level of brake boosting the booster gives)? My brakes seem fairly hard to apply for being power brakes. I don't trust these *&%*& hydravac boosters. This one was replaced twice already, the first rebuilt unit being defective!

I certainly wouldn't want to make a panic stop.

Dan White
07-27-2006, 09:26 PM
If they are as hard as you are saying it is not working properly. Mine will put you through the windshield with little effort. I would check the vacuum line and the inline check valve to make sure it is in the right way, and make sure you do the bleeding per the shop manual. I happen to like Hydrovacs, pretty neat device and it can be put anywhere!

Dan White
64 R1 GT
64 R2 GT

Scott
07-28-2006, 09:49 AM
OK, but does anyone know if any air in the booster will also result in hard braking?

I'll have to check those things, Dan.

prager
07-28-2006, 11:27 AM
Is there a good replacement for one of these? I have a 62 Lark that did not have power brakes, but I would like to add one to the system. Any advise on a cross over..Thanks!!

Dick Steinkamp
07-28-2006, 11:51 AM
quote:Originally posted by Scott

OK, but does anyone know if any air in the booster will also result in hard braking?



Air in the system results in a soft, squishy pedal. If it takes a lot of pedal pressure to stop the car, it sounds like the booster isn't working properly.


http://thenobot.org/images/s2d/s2d_01.jpg

Dick Steinkamp
07-28-2006, 12:00 PM
quote:Originally posted by prager

Is there a good replacement for one of these? I have a 62 Lark that did not have power brakes, but I would like to add one to the system. Any advise on a cross over..Thanks!!


The hydrovac is a remote booster (not attached to the master cylinder). A lot of hot rods use a remote booster made by Midland and other vendors. I'm sure one could be adapted to your Lark. The new ones are much smaller than the original hydrovacs and can be mounted almost anywhere.

OTOH, a '62 Lark has a suspended brake pedal and a firewall mounted master cylinder. I would think a '63 and up Lark or Avanti firewall mounted combination booster/master cylinder might be made to work.



http://thenobot.org/images/s2d/s2d_01.jpg

Scott
07-28-2006, 12:04 PM
I HATE Hydrovacs!!! What a waste of my money to take it out, put it in, take it out, put it in, get a rebuild, watch it fail, pay for freight, put new one in. Watch it fail, take it out....
:(:(:(:(:(:(:(

Dick Steinkamp
07-28-2006, 12:07 PM
quote:Originally posted by Scott

I HATE Hydrovacs!!!


You can remove it and/or plumb around it. If you do that, I believe you also need to put in the non power brake pedal assembly. Different geometery.



http://thenobot.org/images/s2d/s2d_01.jpg

abndad
07-28-2006, 12:19 PM
Ok going by the photo, which one is the inlet and outlet screw?[?] I have one of these units bleed all 4 wheels had great brakes. Let the car sit and the pedal will go through the floor [:0]. It is a new unit, new M/C and W/C's. Any thoughts?

Rodney
60 Black Hawk
"sometimes down"

Dan White
07-28-2006, 01:10 PM
Scott if you are having that much trouble with your hydrovac unit you may have someone that doesn't know what they are doing doing the rebuilds. I bought mine at a swap meet, had it rebuilt and installed and 8 years later it is still working great.

If the brake pedal is going to the floor you may have a bad piston seal in the MC. It may be NOS or "new" but it may still have bad seals! I would not necessarily blame the hydrovac yet.

Dan White
64 R1 GT
64 R2 GT

Scott
07-28-2006, 02:28 PM
Dan,

I got it through one of the major vendors (not Studebaker Intl.) I have talked to Karp's in Cal. They are the ONLY ones left making new parts like seals for these units. They rebuild for $195 (you have to send your unit in). They test them with fluid completely and warranty them for one year.

I also learned that even when everything's rebuilt these boosters will last 5 to 6 years MAX.

My main lesson is no more rebuilds from Studebaker vendors, since I have no idea what knuckle-head might have been hired to do the rebuilding. Brakes are too important to trust to an unknown third party.

Lesson 2 is never buy any car with hydrovac ever again.


No, the pedal is fine: right up there. It never gets near the floor. I just get about 10% boost if that, that's all.

Dwain G.
07-28-2006, 02:37 PM
Did you put any oil in the Hydrovac? It should have come back to you dry, but with instructions on how to oil it.

Dwain G.

Scott
07-28-2006, 02:48 PM
I did not install it. I had "professionals" do it. I have no idea what they did.

wagone
07-28-2006, 04:25 PM
I'm going to quote Scott: "I have no idea what they did". Many (read NOT all) rebuilders/vendors) use the attitude "I'm self employed, I can, therefore, do what I want. NOT true, the independent is working for his or her customer and SHOULD always keep that in mind. Anyone in business is working NOT FOR THEMSELVES but rather FOR THEIR CUSTOMER. But I strongly suspect that not many have that attitude. The attitude ought to be: take the time to learn what your customer wants and what he/she expects and then BE PREPARED TO DELIVER THAT LEVEL OF SERVICE or decline the job. A STUDE vendor is working for the customer not himself. YOU ARE WORKING FOR THE CUSTOMER NOT AT YOUR LEISURE AND NOT FOR YOURSELF. You are working for the guy paying the tab. The guy paying the tab has a right to expect a certain level of service for his money. "AMEN".

wagone

Guido
07-28-2006, 04:39 PM
quote:Originally posted by Dick Steinkamp
OTOH, a '62 Lark has a suspended brake pedal and a firewall mounted master cylinder.
Dick,

I have never owned a '62 Lark, but do currently own a '62 GT and a '62 Champ. I know the Hawks never went to the suspended pedals, but the trucks converted in '63 (I had 2 8E Champs). Are you saying the cars were converted in '62 but the trucks in '63?

Gary

Guido Salvage - "Where rust is beautiful"

1946 M-16 fire truck
1948 M-16 grain truck
1949 2R16A grain truck
1949 2R17A fire truck
1955 E-38 grain truck
1957 3E-40 flatbed
1961 6E-28 grain truck
1962 7E-13D 4x4 rack truck
1962 7E-7 Champ pickup
1962 GT Hawk 4 speed
1964 Avanti R2 4 speed
1964 Cruiser
And various other "treasures"
Hiding and preserving Studebakers in Richmond & Louisa, Va.

studee64
07-28-2006, 06:08 PM
Disc Brakes.??..

I just purchased a 64 GT with Hydrovac brakes...

Can they be converted to discs with Jim Turners kit, or is it a complete 'throw away' and start from scratch if you want disc stopping power..

Tks

Barry

StudeRich
07-28-2006, 06:30 PM
Barry; All '64 GT Hawks with Disc brakes have a Hydrovac! Have you looked at your front brakes for Drums/Rotors?? Very few have Hydrovac boosted drum brakes, although available. The answer is YES! They can go to Turner Disc. just a whole lot cheaper & easier if you now have Disc brakes, and you did not say!
Rich.


quote:Originally posted by studee64

Disc Brakes.??..
I just purchased a 64 GT with Hydrovac brakes...
Can they be converted to discs with Jim Turners kit, or is it a complete 'throw away' and start from scratch if you want disc stopping power..Tks Barry

StudeRich
Studebakers Northwest
Ferndale, WA

Dan White
07-28-2006, 06:42 PM
Although my R1 Hawk was originally a disk brake car, the previous owner had converted it to manual drums. I converted it to front disk w/ Hydrovac using a Steeltech kit (early version using Ford LTD rotors and large Chrysler/Kelsey Hayes calipers). It works great. I may have considered using the Stude setup but it was long gone. The Turner kit would also work as well, but if the Stude disk are already there I would leave them and just do a brake job if needed.

Dan White
64 R1 GT
64 R2 GT

ROADRACELARK
07-28-2006, 06:47 PM
Gary,
Larks had swinging pedals starting in 61', trucks, yes 63'.
Dan

Road Racers turn left AND right.

StudeRich
07-28-2006, 07:12 PM
Hey Guys, I've got a better way to do this, there are too many models of cars being discussed in this string to keep them straight![:0] I suggest that if:
abndad(Rodney)
Guido (Gary)
studee64(Barry)
prager
Have any MORE questions, that they post a new TOPIC for a new string! Then we will not be confused any more than usual ! :D LOL

bondobilly
07-28-2006, 07:36 PM
Quick question, since the "later" hawks did not have hanging pedals, but the Larks do, can you take a late model Lark Power Brake unit and install it in a Hawk?

I have heard that you should re-enforce the cowl, but, by looking at where the PB Unit goes, ie: where the battery is now in a Hawk, that corner of the fire wall is really stiff by the lip at the top and the brace on the side. Or am I wrong.

Thanks

http://bondobilly.com./1sdc.jpg Proud owner of the Hawk from Hell

Scott
07-28-2006, 08:23 PM
Bill I think I must have the other hawk from Hell. I have it parked next to the Cruiser from Hell.

prager
07-28-2006, 08:25 PM
Is there maybe a big 3 crossover booster that would work with a Lark or Hawk? I have a 70's Chrysler master cylinder on my 62 Lark now, but would love to find a booster to go with..Thanks!!

MikeW
07-28-2006, 09:27 PM
Make sure you do as the manual calls for and leave about 1/2 inch of air at the top of the MC. I know there are bleeder holes to eliminate lockup but they don't seem to work well enough. I found that if I don't have that 1/2 inch as the manual states then I get a hard pedal and brakes that don't release as they should. I only suggest that if you have not tried it as the factory stated then you might want to give it a try.

Mike
www.packardhawk.com

Scott
07-28-2006, 10:25 PM
Mike, that's VERY interesting. I'll definitely follow up on that. The brakes were so-so hard before the hoses were put on and the system bled. Now it is quite hard, so what you are suggesting makes sense.

If that solves my problem (probably a big IF), you get the Studebaker hero award.[8D]

Scott
07-29-2006, 10:07 AM
I checked the MC today and the fluid level was a little low. I added a bit and the level is about half inch from the top.

The feel is a little erratic. Sometimes I feel a reasonable amount of boost and the next time I push the pedal it seems pretty hard. I probably have about 1/2 inch of pedal travel.

I forgot to mention that before and after the new brake hoses were put on, the brake lights occasionally stay on and I have to jab the brake pedal a couple times to get them to go off. It could be a bad switch, but maybe there is a problem in the booster causing it?

Dick Steinkamp
07-29-2006, 10:13 AM
quote:Originally posted by Scott

I forgot to mention that before and after the new brake hoses were put on, the brake lights occasionally stay on and I have to jab the brake pedal a couple times to get them to go off. It could be a bad switch, but maybe there is a problem in the booster causing it?


Could be the rod from the pedal to the MC is adjusted incorrectly.



http://thenobot.org/images/s2d/s2d_01.jpg

JDP
07-29-2006, 06:09 PM
Bill, anything is possible, given enough time an money. At would be easier, but not easy, to start with a steet rod suspended pedal setup.

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Arnold Md.
64 Daytona HT
63 R2 4 speed GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
62 Lark 2 door
62 GT(parts car)
60 Lark convert
60 Hawk
56 Power Hawk/4 speed/289
51 Commander

JDP
07-29-2006, 06:52 PM
Make sure you have a few onces of Neat's foot oil in the rebuilt hydrovac or it won't work well.

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Arnold Md.
64 Daytona HT
63 R2 4 speed GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
62 Lark 2 door
62 GT(parts car)
60 Lark convert
60 Hawk
56 Power Hawk/4 speed/289
51 Commander

StudeRich
07-29-2006, 06:58 PM
This condition has previously been proven, in some cases to be swollen flex hoses at the power brake booster! I would just replace them, there are (2). Rich.


quote:[i]I forgot to mention that before and after the new brake hoses were put on, the brake lights occasionally stay on and I have to jab the brake pedal a couple times to get them to go off. It could be a bad switch, but maybe there is a problem in the booster causing it?

StudeRich
Studebakers Northwest
Ferndale, WA

Scott
07-29-2006, 09:56 PM
JDP, thanks for bringing that up. The manual says to inject an ounce of lubricant every year, but have yet to find any reference to where your supposed to inject it! Give us a clue!

Thanks Studerich for the flex hose idea. I honestly don't know if they were replaced since I've had the car (the last 3 years). I doubt it - they could be really old.

JDP
07-29-2006, 10:39 PM
There is a 1/4 inch pipe plug on the rear of the booster to add the Neats foot oil for the leather seal.

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Arnold Md.
64 Daytona HT
63 R2 4 speed GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
62 Lark 2 door
62 GT(parts car)
60 Lark convert
60 Hawk
56 Power Hawk/4 speed/289
51 Commander

hank63
07-30-2006, 11:04 AM
Another possible cause of soft brake pedal are the non-asbestos linings. I used to have a very hard pedal (non-power brakes). With these "environmentally friendly" new-age linings, one can bleed and bleed and bleed. The pedal is softer, and that's that.
/H

Scott
07-30-2006, 12:08 PM
I don't have a problem with soft pedal. I have a problem with hard pedal.

Scott
08-26-2006, 05:01 PM
After rebleeding the brakes we have found the part of the problem I was having was not air, but apparently leakage arounf the piston in th MC. If you push gently the peddle gets closer and closer to the floor. Then if you push again a little more suddenly it;s pretty hard and right at the top. I'm not sure if that affects how the booster works. So now I have inconsistent braking.

This is most annoying, since I replaced the MC with a rebuilt one about two years ago. I wonder of the rebuilders are letting units with pitted cylinders get through? Now if only I could find the original one so I can see if a kit will work in it...

ROADRACELARK
08-26-2006, 07:35 PM
Scott,
Save yourself a lot of headaches, go ahead and put a new M/C on it. Then there won't be any ?s if it was rebuilt correctly. Just make sure the push rod is adjusted correctly. Hope this helps.:)
Dan

Road Racers turn left AND right.

Laemmle
08-26-2006, 07:51 PM
Contact Brake Tech Solutions in "Race-City" North Carolina.

Speak to:

Anwar Karim
braketech@carolina.rr.com
OR
akinfo@adelphia.net

Anwar is making parts for all boosters.

Good Luck!

Scott
08-26-2006, 09:16 PM
Thanks guys. I could put another new MC in, but I am getting less and less secure about rebuilt brake parts. I had a bad rebuilt brake booster right out of the box, and this master cylinder was new (or rebuilt) when I put it in. I think it was rebuilt. I'll follow up on your suggestions.

JDP
08-26-2006, 09:40 PM
I sell brand new MC's for $55/$7.50 UPS

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Arnold Md.
64 Daytona HT
63 R2 4 speed GT Hawk
63 GT Hawk
63 Avanti R1/AC
63 Avanti R2/4 speed
63 Daytona HT
63 Lark 2 dr.
62 Lark 2 door
62 GT(parts car)
60 Lark convert
60 Hawk
52 Starliner
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Scott
08-27-2006, 01:35 PM
Thanks JDP. I'll probably get one from you. I'm not in a position to buy one right now and have pretty much decided to sell the hawk. I'll probably fix this, though, before it goes. :(

BrianC
02-17-2015, 09:29 AM
I'm a little confused about bleeding the Hydrovac??? My hydrovac type 'F' front disc/rear drum has only one bleeder and that's on the air cylinder? The slave or hydraulic cylinder doesn't have a bleeder, (Section II brake system page 41, 63 Hawk w/disc brakes) of the shop manual, so how do i bleed this? Just had it rebuilt and ready to go, but want to be extra carefull with the procedures. Hope someone can advise me on this?

bezhawk
02-17-2015, 10:13 AM
The bleeder valve is on the top of the inlet air filter housing. It is located behind the diaphragm that actuates the air valve. That is moved by the brake fluid pressure, so be assured that it is also the brake fluid bleeder valve. Since it is at the high point of the system, it should be bled first.

BrianC
02-17-2015, 12:57 PM
Thanks bezhawk for clearing that up for me, now i just have to find a plug for the end of the hydraulic sleeve to replace the brake light switch, i assembled it in-line. Not much luck finding a plug with the same thread so i may have to re-install the brake light switch.

64V-K7
02-17-2015, 08:18 PM
The plug is a 3/8 NPT

BrianC
02-17-2015, 08:53 PM
Thanks 64V-K7, burned enough time and gas with no luck so i put the brake switch back in its original spot, of coarse both crush washers leaked on the lines to the booster!!!

bezhawk
02-17-2015, 10:39 PM
You can sometimes reuse the crush washers if you re-anneal them to dead soft. You must heat them red hot, and let them cool naturally, that will soften the copper. so they will crush again.

BrianC
02-18-2015, 12:27 PM
Thanks, i did find new ones, while there however an old hand at hydraulics did tell me about the heating trick. Good to know. all assembled now with no leaks...Phew!

BrianC
08-09-2017, 02:25 PM
Before my hydrovac failed, i had amazing braking power, it could put you through the glass with little pedal effort. I had it rebuilt in Fla. was told it will never need oil again. Not at all happy with brakes, they wont lock up if you slam them, also have a hard time stopping in a panic stop though the pedal travel is correct. Any ideas? They seem to have been bleed properly????

T.J. lavallee
08-13-2017, 02:48 PM
I find the manual brakes on my 59' V8 Lark quite responsive with good feel and very little effort to apply. I do have the finned drums up front to relieve brake fade but I really see no need for power brakes on this car and I know it's got to be heavier than your 62' Hawk. I believe it was industry pressure to "up-scale" a vehicle with this accessory. I can understand them on a 62' Buick Invicta or similar large car but on a smaller compact it was overkill and in the case of your car rather complicated from some of the comments I've read on this subject. Sometimes simpler is simply better. It will take extra effort to keep it original but that's always the best way to go in my opinion. The best of luck.

BrianC
10-10-2017, 07:45 PM
Hey Scott: im with you on these cursed hydrovac brakes. I had mine rebuilt in Fla, i replaced the m/c for the rear with one from Turner brakes along with a proporting valve as suggested by them. When the hydrovac was returned i was told it would never need the neetsfoot oil again???? Ive had a hard pedal and cant find the problem, a panic stop isn't possible. Before the rebuild a hard panic stop would result in a face full of windshield, now i can't get the wheels to lock-up. Its a 63 Hawk w/disc.
Im about to store for winter and tempted to burn the f'n thing ive been so frustrated with endless hours working on this issue!!

tim333
10-11-2017, 01:52 AM
I had a problem with my 63 Hawk that drove me crazy. Everything in the system was new EXCEPT the hill holder. The fluid couldn't pass thru the clogged hill holder so I made a jumper brake line and bypassed it. Brakes were great afterwards.

bezhawk
10-11-2017, 11:50 AM
Hey Scott: im with you on these cursed hydrovac brakes. I had mine rebuilt in Fla, i replaced the m/c for the rear with one from Turner brakes along with a proporting valve as suggested by them. When the hydrovac was returned i was told it would never need the neetsfoot oil again???? Ive had a hard pedal and cant find the problem, a panic stop isn't possible. Before the rebuild a hard panic stop would result in a face full of windshield, now i can't get the wheels to lock-up. Its a 63 Hawk w/disc.
Im about to store for winter and tempted to burn the f'n thing ive been so frustrated with endless hours working on this issue!! The hydrovac for Disc brakes is very different from one with drum front brakes. If yours was replaced with a drum model, what you describe will happen. The line pressure is higher with disc brakes.

JoeHall
10-11-2017, 06:52 PM
Hey Scott: im with you on these cursed hydrovac brakes. I had mine rebuilt in Fla, i replaced the m/c for the rear with one from Turner brakes along with a proporting valve as suggested by them. When the hydrovac was returned i was told it would never need the neetsfoot oil again???? Ive had a hard pedal and cant find the problem, a panic stop isn't possible. Before the rebuild a hard panic stop would result in a face full of windshield, now i can't get the wheels to lock-up. Its a 63 Hawk w/disc.
Im about to store for winter and tempted to burn the f'n thing ive been so frustrated with endless hours working on this issue!!

I had a 63GT's hydrovac rebuilt by the guy in Florida 15 years ago; no more need for neetsfoot oil, due to a modern piston seal, instead of leather. It worked great. It sounds as if yours is not functioning. Even if it were for a drum brake setup, you'd still have most of the power assist available when you push the pedal. I'd suggest getting one of Si's repros, as I did about three years ago for another 63GT. It works as good as it should. A rock hard pedal suggests something other than air in the system. It suggest the HV is somehow stuck.

As for bleeding the system: start with the MC, then the HV, then right, then left rear wheel cylinders, followed by right and left front. Figure on about 1 quart of fluid through the system before the job is done. Be careful not to allow the MC to run dry during any of the above steps, or else you'll have to start again at square zero with the MC.

BrianC
10-12-2017, 02:03 PM
Looking for info: on my63 Hawk. There is a brake fluid splitter located below the hydrovac, it has one input and three outputs. I cant find any mention of it in any manual, i need to know 1) input from the reservoir on the firewall or the m/c under the floor? 2) the three outputs are for ??? Rear brakes and hydrovac??

64V-K7
10-12-2017, 07:00 PM
it has one input and three outputs.

Hydrovac to splitter / 1 for right front / 1 for left front / 1 for rear brakes

bezhawk
10-12-2017, 08:37 PM
Hydrovac to splitter / 1 for right front / 1 for left front / 1 for rear brakes Exactly. The master cylinder goes ONLY to the input of the Hydrovac booster. The output of the hydrovac to the brass junction/splitter. and from there to all of the brakes.

BrianC
02-06-2018, 01:36 PM
Thanks for that info, have a new distributor block ordered, planning to remove the dual Summitt m/c and go back to the original. Had the hydrovac rebuilt, new front calibers and pads, the pedal feels right but cannot get enough for a panic stop, it simply won’t lock up the brakes.

BrianC
02-27-2018, 04:13 PM
I have searched the web ,tech manualy and oddly I cannot find what the proper brake fluid should be used in my 63Hawk W/disk. DOT 3 or DOT4??? Synthetic or not? I know you should never mix them, i want to flush my system but cannot find the recommended fluid?...

64V-K7
02-27-2018, 05:22 PM
The hydrovac for Disc brakes is very different from one with drum front brakes. If yours was replaced with a drum model, what you describe will happen. The line pressure is higher with disc brakes.

Yes.... times 2 / the drum brake unit ( Type A) puts out only 6-700 PS brake line pressure / The owner complaints ( likeyours) were what generated the Hydrovac retro fit to make them Type F, which put out 1000PSI. You NEED 1000psi to squeeze a disk brake hard enough to panic stop, especially the little Dunlop square pucks.

BrianC
03-04-2018, 02:36 PM
Interesting, i had to ship the hydrovac to FLA for a re-build before the kits were made available. Hoe can i tell this unit is for disc btakes?

StudeRich
03-04-2018, 04:43 PM
I have searched the web ,tech manualy and oddly I cannot find what the proper brake fluid should be used in my 63Hawk W/disk. DOT 3 or DOT4??? Synthetic or not? I know you should never mix them, i want to flush my system but cannot find the recommended fluid?...

There isn't an American 1930's to 1980's or possibly beyond, Vehicle alive that will not work acceptably on Standard DOT 3 Fluid.

The DOT 4 is just a Higher Boiling Point Fluid compatible with DOT 3, but of course I would flush and bleed all old fluid and start with ONE type and keep a can for Top-offs or Bleeding.

DOT 5 Silicone is compatible with all Non-Hydovac Power Booster equipped Vehicles, if the System is thoroughly Flushed, and dried first, including ALL components.
It is by FAR the BEST Fluid to use in a Classic Car because of it's non-Hydroscopic, (non-moisture absorbing) Characteristics.

All Three WORK Unless you own a Stude. with a Power Brake, Hydovac System or a '63-'64 Hawk with Power Disc Brakes and Dual Hydovac as yours.

So, the best for YOUR car, would be the DOT 4 Standard Type.

bezhawk
03-04-2018, 07:31 PM
The disc brake hydrovac should have a tag that says it's a type "F"....unless it is missing. The type f has a much thinner slave cylinder, and it's also longer. The standard type is shorter. ....here is the type "F"70776 Here is a standard non disc booster70777Click on the first pick and enlarge it. The part with the visual clue to tell what type you have is pic # 1112-70

BrianC
03-05-2018, 05:36 PM
I had mine rebuilt in Fla, he assured me it would never need oil again???? How accurate is that?

BrianC
03-05-2018, 05:40 PM
Thanks Rich.

BrianC
03-15-2018, 11:13 AM
I installed a dual m/c from summitt racing. Should both outputs go to the booster? Right now I have it set up , the front going to the booster and rear directly to the rears. Which means there’s no line from the booster to the rear. The reason i ask is that I can’t get enough braking for a panic stop. The pedal is good, proper travel and feel.

StudeRich
03-15-2018, 07:09 PM
Sorry I am not the one to ask about that, I would NEVER put a Dual Master cylinder on a Car with an under the floor M/C that was not designed for it.

If you were to contact the Expert on Brake conversions: Jim Turner who has a Job and is sometimes hard to reach, I am pretty sure he would recommend connecting the Rear through the Booster but using a Proportioning Valve and a Rear Residual Valve to balance the system and allow residual pressure to the Rears only.

64V-K7
03-15-2018, 07:27 PM
Should both outputs go to the booster? Right now I have it set up , the front going to the booster and rear directly to the rears.

Well, you can't plumb both dual MC outputs to a Hydrovac, unless you have two Hydrovacs. The front brakes are the ones that do MOST of the stopping, so plumbing the (one) hydro, only to the front brakes, is not a"sin". Since the rear brakes do little more than keeping the car straight, the rear does NOT need any boost. As far as your ability to panic stop, this can be due to other issues, like air in the line, type fluid, etc.

Hallabutt
03-16-2018, 02:43 PM
I also learned that even when everything's rebuilt these boosters will last 5 to 6 years MAX.

That's funny my original HV has been on my 1955 Speedster for 63 years! I have a recent problem with the system, but it hasn't been touched since I restored the car in the 70's. At that time it was working okay, and I said what the heck and replaced the brake fluid with Dot 5 and left it alone. I have two rebuilt units here, one of which has been on the shelf for about fifty years, waiting.

BrianC
03-21-2018, 08:54 PM
64V-K7, on Bob Johnstones resource site he mentions that if using a dual M/C with a hydrovac, i should use a combination valve that both M/C outputs , then one side of that valve to the hydrovac and one to the rears. Question...what is a combination valve? Is it basically the distributor block that was stock? Why would that be necessary?

64V-K7
03-22-2018, 06:06 AM
.what is a combination valve? Is it basically the distributor block that was stock? Why would that be necessary?


The combo valve used was from Master Power Brakes. It acts as a proportioning valve but has no adjustments. When stopping, it actuates the rear brakes to a certain pressure point, maintaining straight line stopping and then the front and rears full on, to prevent nose-dive.

BrianC
03-22-2018, 07:00 AM
Thanks, researched the uses, i do have a proportioning valve in the rear line, so imagine that wouldn’t be necessary. I guess my struggle is air in the lines. Have bleed the hydrovac and lines and still having issue with one disk caliber not holding as firm as the other. Took it out , this one is new, and cleaned and made sure it was functionly properly. I put the proportioning valve midway and will start again. Using DOt 4 fluid. Before i start again im replacing those front hoses, one has hairline looking cracks, the other looks good, seeing they are originals, wouldnt hurt to change them.

BrianC
05-27-2018, 02:42 PM
I had mine rebuilt in Fla, was told it would “never” need oil???? Ive had no luck with these brakes since it initially failed.
I installed a Mitisbuchi dual m/c from Turned brake with the Hydrovac, hard pedal no braking power. I replaced every hose and line, still no luck. So , i figured id put the original m/c back and see what happens, now i have to pump twice every time? Im at at a loss to figure this out. Haven’t been able to use the car for the second summer ! ! Im so frustrated, spending dozens of hours at this. How do i know if this booster isnt working properly, vacuum is good, bleeds ok??

tim333
05-27-2018, 05:14 PM
Brian did you read my post #56?

TWChamp
05-27-2018, 05:15 PM
A soft pedal means air in the line, while pumping twice and getting a solid pedal usually means the brakes need to be adjusted.

BrianC
05-27-2018, 05:52 PM
Before my Hydrovac failed, the brakes were better than on new models. I have replaced every concievable brake part on my 63 Hawk. Hydrovac rebuilt, hydrovac hoses, calibers w/lines and hoses, pads, lines, distrubition block, m/c with turner unit, rebuilt original single m/c and even tried that. This is the most archaic design of a brake sysrem from hell! Two yrs now and i forgot how many endless hours, and $$$$ and still can’t drive the car. I think its time to part ways with nightmare. Im absolutely heartbroken over this crap.

BrianC
05-27-2018, 06:00 PM
TWChamp, whats there to adjust other than the rear shoes? No adjustments for pads, either the calipers work or they dont? Only other adjustment that i know of is the pedal travel?

tim333
05-27-2018, 06:41 PM
Brian, I did everything you did without fixing the problem until I bypassed the hill holder. Then the brakes worked great!

GTHawk
05-27-2018, 06:43 PM
After rebleeding the brakes we have found the part of the problem I was having was not air, but apparently leakage arounf the piston in th MC. If you push gently the peddle gets closer and closer to the floor. Then if you push again a little more suddenly it;s pretty hard and right at the top. I'm not sure if that affects how the booster works. So now I have inconsistent braking.

This is most annoying, since I replaced the MC with a rebuilt one about two years ago. I wonder of the rebuilders are letting units with pitted cylinders get through? Now if only I could find the original one so I can see if a kit will work in it...

Air in the lines will do exactly as you have described Slow push go to the floor next hard push comes right up. I have had to bleed brakes many times to remove all air. Sometimes people bleeding inadvertently let air back into the system while doing the job. One way is to use two men one pumps the pedal up tight the other opens the bleeder and while there is still some fluid gushing out tighten then repeat repeat repeat until no more air then to the next wheel etc. until you have full pedal. Just try again. Good Luck. One more thing, some times on an older vehicle you'll need the boost pressure in order to bleed properly. Thus the engine must be running. Try !!

JoeHall
05-27-2018, 09:18 PM
If it worked great before you fixed it, maybe put everything back exactly like it was before, including old hoses, rear shoes, etc.. Bypass the hydrovac for now, till you get pedal pressure restored as it was before.