Hydroboost on a 58 -59 3100

[1-ton of fun]

do you have any measurements on the bolt spacing of the mc and booster mounts for the silverado hydroboost unit?

thanks

[dwcsr]

do you mean spacing where it bolts to the firewall or the master to the boost unit or both?

[1-ton of fun]

both, if you don't mind

[dwcsr]

I'll measure it and let you know.

[dwcsr]

I don't know who did this picture but it does have the measurements on it.

I'll get the other as soon as I can

[1-ton of fun]

thanks

[shadow1967]

dwcsr,
I know this is an old thread , but info is good. Will that master and cap(Raybestos # MC390542) fit under the cab or will it rub the floor? I cant look under the truck right know.

[dwcsr]

Its tall so I would think it may hit the floor. There are shorter reservoirs you may have to do a little junkyard crawling to find out what vehicle will work best

[_Ogre]

nice write up dwcsr

shawdow: look in my build thread to see how i did an under floor hydroboost with remote reservoir.

[SARBlade]

Originally Posted by dwcsr

I decided to use a hydro-boost brake system after seeing one of the other posters here put one on a later model. I researched the parts and found a 2001 Chevy Silverado 1500 w/4 wheel disc had hydro-boot. This setup is from the 2001 Silverado with four wheel disc so if you are going to do this conversion with rear drums you need to get the master for rear drums.

The booster unit is an A1-Cardone # 52-7359 this comes with a diagram to connect the hoses correctly.
Brake Master Cylinder is Raybestos # MC390542 it’s new and comes complete with reservoir and cap Don’t get the MC390541 its for a vacuum booster. Don’t ask me the difference I didn’t see it but Raybestos says the 542 is the one.

You will need to get the push rod, pushrod spring and the spring retainer that goes between the master and the booster it does not come with a rebuilt unit. I did get a complete unit from a junk yard with master for $75.00.
The other items are Hose kit for the P/S lines going to the booster unit and P/S unit. Pump to booster hose you can use if you don't want the expense of AN type fittings and lines is an Edelman 92082 and some Russell P/S fittings -6 AN x M16x1.5 O ring fitting for the pressure out side of the booster to the rack. The M18x1.5 was for the pressure in side of the booster.

I ended up using some Aeroquip AN -6 to metric adapters M18x1.5 and 2 M16x1.5 with O rings which were made of steel rather than aluminum the Aeroquip fittings also had a taper on the end to help keep the O ring in place which the Russell ones didn't. This may not be a problem for some but the O ring on the Russell kept getting stuck in the bore or falling out completely when I was test fitting all this. The advantage to the Russell was half the cost of Aeroquip. I also use -6 AN fittings and hose to plumb the pressure side of the install.

We also need a Heidt’s adjustable P/S valve PS-114 so we can have full pressure to the booster but reduced pressure to the rack. The 86 TBird rack uses 600-800 psi. If we run full 1500 - 2000 psi from the GM pump to the Ford rack it will eventually blow out the seals and leak it would also be very touchy at higher speeds. So we put the Valve in the lines to reroute some of the pressure back to the return side of the pump.

Brake proportioning valve for 4 wheel discs or an adjustable. I used a Wilwood adjustable valve with an LBS (Lock Resistant Brake) valve from Larsen Racing it helps keep the fat tires on the back from locking up and spinning you around on wet or damp pavement. Metric nuts M10x1.5 to bolt on the master cylinder and some fender washers to bolt it to the firewall with.
You will need some lengths of brake line. I used copper/nickel line that is DOT approved and very easy to work with, you honestly can’t screw up a flare with this stuff unless you forget to put the nut on first. It flares very well, it bends nicely and you can give it a polish to a golden color. www.fedhillusa.com is the US supplier. It is a little more expensive but the advantages make up for it the cost

At the same time I’m doing the booster I am also fabing a brake pedal because I’m to cheap to buy the one at classic performance so I will include the How-to on that as well.

Here is the boost unit and as you can see the mounting plate is heavy enough to use without modifying it.

Hi, I know this is quite an old post, but our trucks are old and not getting any younger. I am doing this hydroboost conversion to my '56 Chev, and I have a question regarding the proportioning valve. I purchased a unit that has the built in proportioning valve on the side of the master cylinder. Its not the metering type for disc/drum, but rather just a straight through for disc/disc. Am I ok just using it? Or should I be taking this OP approach and buying a proportioning valve. I would assume that what was good in the donor 2001 Chev 4x4 with disc/disc, should be ok for my disc/disc setup. Anyone? Thanks

[Hcb3200]

go get one off of or for a panel van or 3/4 that has disc in front and drums in rear. it will handle it correctly then. Make sure you put in residual valves unless the master you bought has them built in. 10lb for drums 2lb disc up front if you your are frame mounted..

I did this setup in my 56

[SARBlade]

I have a setup from a 2001 Silverado, same part numbers as dwcsr in his write up. He also mentions in his write up something about master cylinders having different metering valves. I found a YouTube video speaking to this at 1:50 mark. Like I said, I have a disc/disc setup, so was wondering about this proportional valve on the side of the master cylinder. Not the metering one, but the one on the hydroboost setup as the video eludes to.

[Hcb3200]

Metering and residual valves are the same thing that’s your 2 pound and 10 pound valves to keep pressure on the brakes when the master is on the frame.
A proportioning valve is just that it does not have a different name

Some master cylinders have the residual valves built-in. You should see it just inside the port.

Some modern proportioning valves off of GM trucks and cars have a combination valve where it’s both are proportional, and a residual all built in together

[Hcb3200]

So if you have a combination valve that came with your set up and it’s a disk disk, and the residual pressures will be too light for the drum on the rear

[SARBlade]

I was watching a video on proportioning valves, now I'm in the know! They are really not proportional at all but a relief valve. Drum brakes are extremely efficient at applying stopping power on little pressure where as disc brake requires much more pressure to apply stopping power to its disc. The relief valve in a drum setup is used to release pressure at a set point as to not "lockup" the wheel by the person applying the pressure and potentially losing control of the vehicle. The disc setup requires more pressure, like 10 x the amount a drum requires for the same stopping power, so there is not really a requirement for a relief valve on disc setups. This is as I now understand it. Please correct me if I'm wrong. Thanks

I'm just adding to my post so its clear, the idea of the metering of pressure is so the rear brakes have pressure when stopping, if they don't and all the pressure is applied at the front, then there could be some ass passing ground looping happening.

[Hcb3200]

for some a metering valve in this definition just holds pressure to keep the fluid from flowing back to master when no brake pressure is applied. It does not “meter” or change pressure to the brakes when applying pressure. You don’t need them as much when mounted on fire wall as this is above the brakes and fluid flows down. This keeps air from entering system when brakes are not applied. They are also call residual valves for residual pressure.

Proportions valves do what you posted keeps different pressures
Proportioning valves are frequently used in cars and other road vehicles to reduce the brake fluid pressure to the rear brakes. Due to weight distribution during heavy braking, more pressure is needed for front brakes. A proportioning valve reduces the pressure in the hydraulic lines to the rear brakes relative to that supplied to the front brakes during this heavy braking.


A combination valve does both and what most modern cars have that need them and it looks like a funny shaped brass hunk of metal.

The problem is most YouTube. Guys call the combination valve a proportioning valve. When it may be doing both and not one function. They make modern ones that just do the proportions.
And most don’t know that metering and residual are one and the same.

[Hcb3200]

I will say metering is used to describe what the proportioning valve does as well. But so many have mixed and match metering combination proportioning and residual that finding a clear and concise answer is frustrating. But the three functions needed for brake systems are definitely needed not mater what you call them. I had same issue when i did my truck just making sure my combo valve as just that a true multi function valve. .

[SARBlade]

Thanks Hcb3200, you're right, a name by any other name is still a name, function matters. In my case, If I keep all components the same from the same donor, all should work. If I was piecemealing things, then I would need components that compensate for each other. The more I go down the rabbit hole the more I understand. A confusing time is through the 70's when brake components all went some kind of change, from brass blocks to separate portioning valves, to ABS, etc. Now everything is pretty much right at the master cylinder.