Hydroboost brakes.. Thanks CaptainFab

[crakarjax]

You mean that hydro was just bolted to the firewall?

[Dene Risden]

Hey Captain Fab,
Can you provide the pricing and how to purchase info for your Hydro Boost brackets? I'm putting it on my 1963 GMC 1/2T short bed.
Much appreciated, Dene

[Captainfab]

PM sent.......

Originally Posted by Dene Risden

Hey Captain Fab,
Can you provide the pricing and how to purchase info for your Hydro Boost brackets? I'm putting it on my 1963 GMC 1/2T short bed.
Much appreciated, Dene

[bubba327]

Originally Posted by bubba327

Update on my hydro boost changeover--
I installed a hydro boost from a Astro van back in October and all is great. Brakes are really responsive and stop fast on dry roads .
Problem is that on the ice they are too touchy and lock up pretty easily.

I found a pressure reducer for use in a GM power steering pump when using a Ford rack and pinion that reduces the pressure and flow rate.
http://www.summitracing.com/parts/BRG-899001/

Has anybody used a either the Borgeson or the March pressure reducers on a GM power steering pump with the stock 71-72 GM gearbox AND a hydroboost??
I would like to take some of the" touchiness" out and fine tune this hydro boost as it works really nicely...Attachment 858032

Update --I found this article and started here first.
I went back and rechecked my pedal geometry. I had moved the linkage to the upper Hole when I was having vacuum booster problems . when I swapped over to the hydro I forgot and re-installed the new linkage back in the upper hole...
I drilled a new hole lower on the arm and went from a 7:1 ratio to a 4:88 ratio.
It is much better now and requires more leg pressure to apply the brakes now . The travel of the pedal is about the same ,but applying the brakes is more consistent and more reliable.
Is not locking up as before if you panic stop. I will try it out on the ice maybe tomorrow.

Dean Oshiro wrote a great article!!!
http://www.hotrodheaven.com/tech/brakes/
Pedal ratio is talked about towards the last part of the article

Quoted from the article.
A = height of pedal
B = center to center measurement of the lower arm
C = pedal ratio
A divided by B equals C
Or example 9" divided by 1.5" equal 6 to 1 ratio

Factory cars generally have two (2) pedal ratios, one for manual brakes and one for power brakes. You will find manual pedals with ratios from 5:1 to 6.5:1 and power pedals 4:1 to 5:1. A good example of this would be the 68 Mustang uses a longer brake pedal with a power booster. This pedal mounts about 2.5” above the manual pedal setup. The longer pedal reduces the pedal ratio.
If you did not change the pedal, your brakes would be too sensitive, because there would be too much pressure applied too quickly.
GM cars have two holes on the pedal, when a power booster is used the brackets are at an angle so the rod will point to the lower hole. Installing the rod in the wrong hole will cause damage to the booster.

[66farmer]

Originally Posted by bubba327

Update --I found this article and started here first.
I went back and rechecked my pedal geometry. I had moved the linkage to the upper Hole when I was having vacuum booster problems . when I swapped over to the hydro I forgot and re-installed the new linkage back in the upper hole...
I drilled a new hole lower on the arm and went from a 7:1 ratio to a 4:88 ratio.
It is much better now and requires more leg pressure to apply the brakes now . The travel of the pedal is about the same ,but applying the brakes is more consistent and more reliable.
Is not locking up as before if you panic stop. I will try it out on the ice maybe tomorrow.

Dean Oshiro wrote a great article!!!
http://www.hotrodheaven.com/tech/brakes/
Pedal ratio is talked about towards the last part of the article

Quoted from the article.
A = height of pedal
B = center to center measurement of the lower arm
C = pedal ratio
A divided by B equals C
Or example 9" divided by 1.5" equal 6 to 1 ratio

Factory cars generally have two (2) pedal ratios, one for manual brakes and one for power brakes. You will find manual pedals with ratios from 5:1 to 6.5:1 and power pedals 4:1 to 5:1. A good example of this would be the 68 Mustang uses a longer brake pedal with a power booster. This pedal mounts about 2.5” above the manual pedal setup. The longer pedal reduces the pedal ratio.
If you did not change the pedal, your brakes would be too sensitive, because there would be too much pressure applied too quickly.
GM cars have two holes on the pedal, when a power booster is used the brackets are at an angle so the rod will point to the lower hole. Installing the rod in the wrong hole will cause damage to the booster.

Thanks for the info. I'm trying to get things ready to install my hydro system.
I have a few questions I hope you could help me with.

1. How much lower on the brake pedal arm is your new hole.
2. Can you tell me how you hooked up the lines (from port to port)
3. What rig did you get your hydraulic lines off of. They look like they fit well.
4. What proportioning valve are you useing. Do you think it's a good match.

Thanks for your help

[bubba327]

Originally Posted by 66farmer

Thanks for the info. I'm trying to get things ready to install my hydro system.
I have a few questions I hope you could help me with.

1. How much lower on the brake pedal arm is your new hole.
2. Can you tell me how you hooked up the lines (from port to port)
3. What rig did you get your hydraulic lines off of. They look like they fit well.
4. What proportioning valve are you useing. Do you think it's a good match.

Thanks for your help

Glad to help.. we are all learning about this hydro boost.
This is the original brake pedal- but it was a 3 speed truck. I heated the arm and straightened things out and welded a wide pedal on so the placement felt right while driving. I felt it it was hanging just too high and was too close to the gas pedal.
The pedal length is now 16.5" from the bottom of the foot pedal to center of the top attachment hole.
The brake linkage from the stock hole was 2.25" from center line.( 16.5/2.25 = 7.33)
The new lower hole I drilled is 3.375" from center line ( 16.5/3.375= 4.88)

[bubba327]

Originally Posted by 66farmer

Thanks for the info. I'm trying to get things ready to install my hydro system.
I have a few questions I hope you could help me with.

1. How much lower on the brake pedal arm is your new hole.
2. Can you tell me how you hooked up the lines (from port to port)
3. What rig did you get your hydraulic lines off of. They look like they fit well.
4. What proportioning valve are you useing. Do you think it's a good match.

Thanks for your help

#2 http://67-72chevytrucks.com/vboard/s...365170&page=17 my build thread has a few pictures of the swap in post 409 Page 17.
The hydraulic lines were the 94 Astro hoses I grabbed from the junkyard. The hoses were cut off and new hose was purchased at NAPA. They have a crimp fitting to press on the hose that is a 3/8 compression to attach to the stock metal ends. So I have the metric ends on the hydro and the flare ends at the pump and gearbox. I had one side pressed together, took it home and marked things , took it back the next day to be shortened to length and the second end pressed on
There are quite a few threads that have the piping layout shown in detail, so I wont re-post unless you cannot find any.
edit ---(http://67-72chevytrucks.com/vboard/s...d.php?t=393108 Post #3)
The pressure hose runs from the pump to the hydro boost, then to the gearbox and then returns to the pump. The hydro also has a third line that Tees into the return line.
The prop valve was from the 71 C-10 that donated the front crossmember. the bracket is from a S-10 that I straightened to fit better

[66farmer]

Thanks for your time and info. I was thinking of using a adjustable proportioning valve. Do you think your valve has the proper pressure from front to rear.

[bubba327]

Originally Posted by 66farmer

Thanks for your time and info. I was thinking of using a adjustable proportioning valve. Do you think your valve has the proper pressure from front to rear.

This site is all about sharing information and Ideas!!
I started with the 71 prop valve that I had, but an adjustable valve or a inline valve would be a great idea as it is not a expensive or difficult thing to install.
My truck stops straight and fast . It will not lock the tires on dry clean pavement , and the 235 radial tires provide a lot of grip.

I do recommend having 3 point shoulder harness seat belts cuz it will STOP!. The old lap belts with any power brake set-up is just asking to get hurt.
It does not nose dive and I am satisfied and very happy with it now.

Icy roads are a problem for anything even with anti lock brakes,and also having no weight in the bed of a 1 wheel drive means spinning and usually stuck .
We just use the 4X4's for the bad winter days and be careful.
Good luck with your project- And pass along your information to others..

[HEI451]

It is all in the geometry, which IS "leverage ratio".

[bubba327]

Originally Posted by HEI451

It is all in the geometry, which IS "leverage ratio".

Another thought -This truck still has the inline six- I wonder if the stopping will be affected by weight ratio from front to rear if and when I swap things over to a small block.
I may find out soon...

[LostMy65]

Right now I'm completely manual steering and brakes.
Drums all around.
This winter I want to do discs up front, hydroboost, and power steering.
I'd rather not do these upgrades with pieces and parts from different vehicles and years.
I'd like to find a GM year that had disc brakes, power steering, and hydroboost that I can go down to my local parts store and get everything by just saying one year vehicle.
Should I go with pre 80's, or mid to late 80's?

[Captainfab]

If you go with a '73-'79, the hose fittings will be SAE. If you go with '80-'87, the hose fittings will be Metric with an O-ring. Typically the hydroboost was a C30 thing. The only C10's that I know of that had hydroboost were the ones with diesel engines. I do know that those were available in '79. They were more than likely available in the early '80's as well.

Originally Posted by LostMy65

Right now I'm completely manual steering and brakes.
Drums all around.
This winter I want to do discs up front, hydroboost, and power steering.
I'd rather not do these upgrades with pieces and parts from different vehicles and years.
I'd like to find a GM year that had disc brakes, power steering, and hydroboost that I can go down to my local parts store and get everything by just saying one year vehicle.
Should I go with pre 80's, or mid to late 80's?