Master Cylinder

[Powerguy480]

We have a 1960 cadillac deville. All wheel drum. I'm trying to convert single resevoir master to dual. Any suggestions on possibility. Can I get the after market universal and bolt it direct to booster? Do I need a master with booster. It's my wife's daily driver. I would like a secondary for her. 

[joe_padavano]

8 hours ago, misterc9 said:

You will also need a combination valve.

 

Four wheel drum cars do not need or want a combination valve.

[joe_padavano]

2 hours ago, misterc9 said:

Drum brake cars need and have a combination valve. Look at any 67 or newer car with all drum brakes. It also contains the switch that makes the low brake warning light come on.

 

You might want to educate yourself about braking systems.

 

The item you are describing is used on the drum brake cars and is called a distribution block. The primary purpose it serves is to house the differential pressure switch that turns on the BRAKE warning light if you lose pressure in half of the system. There is no "valve" part to it - there is only the internal piston that will slide one way or the other if pressure is lost and activate the switch contact. The drum brakes will work just fine without it.  This is a distribution block. Note there are NO valves in it.

 

 

The combination valve is only used with disc brakes. It COMBINES (get it...) the functions of the distribution block, differential pressure switch, metering valve, and proportioning valve all in one housing. It is NOT EVER used with drum brakes.  This is a combination valve.

 

 

 

[Powerguy480]

Thank you so much for the help. I'm going to research from everyone's info. 

[Powerguy480]

Will I need a new booster or will my existing work

[m-mman]

If I remember correctly those Moraine master/booster set up had the piston attached to the rod in the booster and they needed to be repaired as one unit.  (if you unbolted the master and pulled, it would pop the piston out of the master)  

 

Since you are changing the master then, yeah the booster will need changing too. Or as suggested above using the booster/master combo from the later Cad. 

[trini]

The booster is bolted to the firewall with the master in front. The master has 2 sections for the brake fluid. The proportioning valve has 2 lines, one for the front section and one line to the rear. The diagram is quite clear. You will have to find a hot wire for the proportioning valve. Do not forget you may  have to replace the carburetor , to one which has a pipe to source vacuum with a one way valve if there was none before. The booster needs vacuum to operate. Manifold vacuum .To get the brake light to go out you will need help. Get the helper to pump the brakes and hold the pedal  down while you try to bleed one or the other lines  at the valve slowly until the light goes away. At that point the front and rear brakes are balanced. To know if the vacuum system is working pump the brake and hold the pedal down. Start the engine. The pedal will go down a little.

[Frank DuVal]

???????

[Frank DuVal]

Hot wire to proportioning valve? For what? And what proportioning valve?  It is just a switch that grounds a wire to light the BRAKE warning light. 

 

Power brake vacuum typically comes off the intake manifold, sometimes off a spacer under the carburetor, I do not know what the 60 Cadillac vacuum setup is, but the original poster's car already has a power booster, so the vacuum plumbing exists.

[joe_padavano]

16 hours ago, trini said:

The booster is bolted to the firewall with the master in front. The master has 2 sections for the brake fluid. The proportioning valve has 2 lines, one for the front section and one line to the rear. The diagram is quite clear. You will have to find a hot wire for the proportioning valve. Do not forget you may  have to replace the carburetor , to one which has a pipe to source vacuum with a one way valve if there was none before. The booster needs vacuum to operate. Manifold vacuum .To get the brake light to go out you will need help. Get the helper to pump the brakes and hold the pedal  down while you try to bleed one or the other lines  at the valve slowly until the light goes away. At that point the front and rear brakes are balanced. To know if the vacuum system is working pump the brake and hold the pedal down. Start the engine. The pedal will go down a little.

 

Sorry, but that is completely incorrect.

[Frank DuVal]

On 8/2/2020 at 12:07 PM, joe_padavano said:

To know if the vacuum system is working pump the brake and hold the pedal down. Start the engine. The pedal will go down a little.

 

Well, Joe, I thought, this part was correct, then I noticed the "pump" part of the statement.  Yep, not needed. Just apply the brakes normally, start the engine, and the pedal should  go down a little.

[PFitz]

And on some with the pressure differential brake light switch, no need to play with slowly bleeding the lines again to get the brake light to go out.

 

Just unscrew the brake switch/plunger from the housing and gently press the brake pedal a couple of times. With the plunger removed and brake fluid pressure applied evenly to both ends the piston will re-center itself. Then just screw the switch/plunger back in and reconnect the brake light wire.  

 

Paul

[joe_padavano]

1 hour ago, PFitz said:

And on some with the pressure differential brake light switch, no need to play with slowly bleeding the lines again to get the brake light to go out.

 

Just unscrew the brake switch/plunger from the housing and gently press the brake pedal a couple of times. With the plunger removed and brake fluid pressure applied evenly to both ends the piston will re-center itself. Then just screw the switch/plunger back in and reconnect the brake light wire.  

 

Paul

 

On the GM differential pressure switches, you shouldn't even need to unscrew the plunger - though it won't hurt anything to do so. It isn't actually a "plunger", it's simply a fixed metal contact - as shown in the first cross section drawing I posted above in Post #3. The piston slides one way or the other and makes contact with it to close the circuit. The light springs on either side of the piston provide the path to ground, since the piston itself is insulated from the bore by o-rings. One thing I have found is that sometimes crud in the body of the distribution block can cause the piston to stick when it gets pushed to the end of travel due to either a leak or during bleeding. This is more prevalent with the cast iron combination valves GM used in the early 1970s, as moisture in the brake fluid causes the bore to rust.

 

[PFitz]

14 minutes ago, joe_padavano said:

 

On the GM differential pressure switches, you shouldn't even need to unscrew the plunger - though it won't hurt anything to do so. It isn't actually a "plunger", it's simply a fixed metal contact - as shown in the first cross section drawing I posted above in Post #3. The piston slides one way or the other and makes contact with it to close the circuit. The light springs on either side of the piston provide the path to ground, since the piston itself is insulated from the bore by o-rings. One thing I have found is that sometimes crud in the body of the distribution block can cause the piston to stick when it gets pushed to the end of travel due to either a leak or during bleeding. This is more prevalent with the cast iron combination valves GM used in the early 1970s, as moisture in the brake fluid causes the bore to rust.

 

With the ones in my early 70's AMC's, both the four drum  and the disc/drum system's differential switches have a spring-loaded plunger in the switch like in your second picture. The AMC shop manual says to use the method I mentioned because the piston won't always move back to center easily if the spring-loaded plunger is still pressing on the piston.

 

Paul 

[joe_padavano]

2 hours ago, PFitz said:

With the ones in my early 70's AMC's, both the four drum  and the disc/drum system's differential switches have a spring-loaded plunger in the switch like in your second picture. The AMC shop manual says to use the method I mentioned because the piston won't always move back to center easily if the spring-loaded plunger is still pressing on the piston.

 

Paul 

 

Fair enough. My experience is only with GM, which is why I included that caveat.

[m-mman]

Lots of information about how a factory installed pressure differential switch works, however the OP is ADDING all this stuff to a 1960 Cad. 

The only 'brake light' that a 1960 auto would have is something to remind you to release the parking brake. 

 

It does bring up an interesting point however. In all the times where people add or discuss adding a dual master cylinder to a single master cylinder car, I have never heard anyone ask the best method to add a light that would warn of a (pressure differential) failure.

 

In most original installations (1967+) the factory wired the brake failure light to illuminate when the key was turned to the start position to test the bulb. Then the car might have a second red light to warn if the parking brake was left on.  If the same bulb was wired and used for both the brake failure and the parking brake; it would glow when you turned the key, stay glowing when you left the brake on and come on again if there was s failure. Quite confusing I would think.

This is probably why the  modifiers dont hassle adding any pressure differential light when they change their brake system in the guise of making it safer. 

[joe_padavano]

4 hours ago, m-mman said:

Lots of information about how a factory installed pressure differential switch works, however the OP is ADDING all this stuff to a 1960 Cad. 

The only 'brake light' that a 1960 auto would have is something to remind you to release the parking brake. 

 

It does bring up an interesting point however. In all the times where people add or discuss adding a dual master cylinder to a single master cylinder car, I have never heard anyone ask the best method to add a light that would warn of a (pressure differential) failure.

 

In most original installations (1967+) the factory wired the brake failure light to illuminate when the key was turned to the start position to test the bulb. Then the car might have a second red light to warn if the parking brake was left on.  If the same bulb was wired and used for both the brake failure and the parking brake; it would glow when you turned the key, stay glowing when you left the brake on and come on again if there was s failure. Quite confusing I would think.

This is probably why the  modifiers dont hassle adding any pressure differential light when they change their brake system in the guise of making it safer. 

 

In my experience, the differential pressure switch turns on the BRAKE light right after the pedal goes all the way to the floor and you finish saying "OH $**T". I believe it was designed by Captain Hindsight.

[Frank DuVal]

1 hour ago, joe_padavano said:

In my experience, the differential pressure switch turns on the BRAKE light right after the pedal goes all the way to the floor and you finish saying "OH $**T". I believe it was designed by Captain Hindsight.

 

My experience also! Living in the rusty east, one gets to experience this not great experience!

 

Late model Corvairs (67 to 69) are the same dash panel light for both parking brake and differential pressure problem. Of course, as they never had a parking brake warning lamp as standard equipment on the 60 to 66 models. The optional parking brake on lamp hung on a bracket  under the dash.

Edited August 6, 2020 by Frank DuVal (see edit history)

[joe_padavano]

9 hours ago, Frank DuVal said:

 

My experience also! Living in the rusty east, one gets to experience this not great experience!

 

Late model Corvairs (67 to 69) are the same dash panel light for both parking brake and differential pressure problem. Of course, as they never had a parking brake warning lamp as standard equipment on the 60 to 66 models. The optional parking brake on lamp hung on a bracket  under the dash.

 

The differential pressure switch and associated warning light were federally mandated in NHTSA FMVSS 105 for the 1967 model year when the dual circuit brakes were also mandated.

[m-mman]

16 hours ago, joe_padavano said:

In my experience, the differential pressure switch turns on the BRAKE light right after the pedal goes all the way to the floor and you finish saying "OH $**T". I believe it was designed by Captain Hindsight.

 

4 hours ago, joe_padavano said:

The differential pressure switch and associated warning light were federally mandated in NHTSA FMVSS 105 for the 1967 model year when the dual circuit brakes were also mandated.

 

Whenever a modification is made essentially you then need to train every driver on the road about the new procedures. 

 

An old single circuit driver would know a failure when the pedal went all the way to the floor and the car kept going. Put that driver in a new dual circuit car and they might say "The pedal is a little softer but since it doesn't go to the floor, and it still stops, then everything must be fine. . . . " 

I think the light was the government's attempt to tell the older drivers that things were not fine.  Now a days its an "ABS light" that glows and needs a code reader to find the problem and reset. 

[joe_padavano]

53 minutes ago, m-mman said:

I think the light was the government's attempt to tell the older drivers that things were not fine.  Now a days its an "ABS light" that glows and needs a code reader to find the problem and reset. 

 

The light is the government's need to demonstrate that it is doing SOMETHING, whether that action adds value or not. The tire pressure monitoring systems mandated after the Ford Explorer/Firestone fiasco is another such example. Now you can't even rotate your tires without a TPMS tool to re-initialize the sensors.

 

I'll add that I'm well aware of what's going on when I drive my vehicles. I've probably had 4 or 5 instances of having the brake lines blow out on me. There was never any warning from the idiot light before the line blew, since the failure usually happened during a harder-than-normal application of the brake pedal. I knew the line had blown before the light came on.

Edited August 6, 2020 by joe_padavano (see edit history)

[Frank DuVal]

8 hours ago, joe_padavano said:

Now you can't even rotate your tires without a TPMS tool to re-initialize the sensors.

 

Most GM cars/trucks can be done without a scan tool or a TPMS tool. Built in to dash data screen system. Check out Youtube videos.

 

FYI, State of Virginia state safety inspections can NOT fail a vehicle for an amber ABS light on or the TPMS system indicating a fault! They are just informational lights/displays and not mandatory equipment. They also can NOT fail for Check Engine light! Now, if that light is on, it will not pass emissions inspection, however, in those areas with that inspection.

 

Ask me how I know!😁

[joe_padavano]

8 hours ago, Frank DuVal said:

 

Most GM cars/trucks can be done without a scan tool or a TPMS tool. Built in to dash data screen system. Check out Youtube videos.

 

 

Given that I'll never own a vehicle with a touch screen or TPMS, I'll take your word for it. 😉

[Frank DuVal]

Not a touch screen system. My 2011 Sierra with hardly any accessories (an actual WT, work truck) it is the odometer reset button that runs through the TPMS recalibration with engine on, in Park. Once you shift to Drive, you only get odometer, trip odometer and transmission temperature. Truck does NOT have an ENTER button.😁

 

Of course, I have a bad RR sensor, so the system doesn't work..... I got the truck that way. Real cremepuff, only 187K miles.... 🤔  Maybe I'll buy four when I buy tires. Before that, it is labor charge to replace them. With tires, labor is included!😉  So maybe in 6 years.....

 

If you are young enough, you might get a vehicle with TPMS in 25 years.... 😉

Edited August 8, 2020 by Frank DuVal (see edit history)