[Jammin' James]

I recently did a front to rear brake rebuild on a 1971 El Camino 454 SS, including all front brake lines. I've been over and over the system and multiple bleeds but I still get a hard pedal and can not lock the brakes up. It feels like no boost from the (new) booster but it passes the pedal tests and holds vacuum (15") after the engine is shut down. I used the 'H' shaped gauge to check the MC push rod, the booster push rod is in the right hole. The one change I did make was move the Prop valve from the frame rail to under the MC. It is a 2 V for the F disc and D back as is the MC. I'm at my wits end. It does feel like the booster even though it checked out (and it is new).

 

[greywolf]

How did you break in the front disk brake pads?

 

[Jammin' James]

How did you break in the front disk brake pads?

Just a few minutes driving around slowly and easily braking. The pedal stayed stiff and I could not fully lock the brakes.

 

[Karadjgne]

Is the zerk on the brakes up or down pointing?

 

[Jammin' James]

The zerk is up, on top, the hoses on the bottom. The system has been bled twice and the new MC bench bled 2.

 

[Karadjgne]

Hmm. Then my only other guess would be the proportion valve being moved and all the subsequent bleeding etc has tripped it, if only partially, it could be sticking partially closed.

 

[Jammin' James]

It

Hmm. Then my only other guess would be the proportion valve being moved and all the subsequent bleeding etc has tripped it, if only partially, it could be sticking partially closed.

It is brand new and a 2V prop valve. I put the bleeder tool into the switch slot while bleeding the brakes. I think greywolf may have solved it (about breaking the rotors and pads in). I'm going to drive it some more and try to get some of the pad material built up on the rotor.

 

[ECFAN]

What brand of brake linings and type of material? Organic?, semi-metallic, etc.

 

[Karadjgne]

Bedding the brakes just means an even layer abrasive friction, so it doesn't feel like you've warped the roters after you get them hot. Never heard of it actually making any difference to stopping power or being able to 'lock the brakes up'.

Locking up brakes depends on several things, such as mass of the vehicle, momentum, gripping power of the tires, pad friction/pressure, pad material etc. If you are trying to lock the brakes doing 60mph and have fat tires with good grip on rough dry blacktop, it's doubtful gonna happen. If using 'Red' pads at slow speeds on cold rotors, not gonna happen either.

About the only thing you actually need the front brakes to do is hold at a stop, with a moderate amount of gas pedal. If they'll do that, they'll stop you in the required distance, without locking up. If they won't hold you still at a stop with a moderate amount of pedal, they aren't getting required pressure.

Holding 15lbs just means there's no vac leaks, doesn't mean the booster is actually putting enough pressure to the calipers.

Was this originally a front drum car converted to discs? I ask because disc/drum requires a different proportioning valve to a drum/drum or disc/disc, discs and drums have different pressure/release requirements

 

[87ls5.3]

I recently did a front to rear brake rebuild on a 1971 El Camino 454 SS, including all front brake lines. I've been over and over the system and multiple bleeds but I still get a hard pedal and can not lock the brakes up. It feels like no boost from the (new) booster but it passes the pedal tests and holds vacuum (15") after the engine is shut down. I used the 'H' shaped gauge to check the MC push rod, the booster push rod is in the right hole. The one change I did make was move the Prop valve from the frame rail to under the MC. It is a 2 V for the F disc and D back as is the MC. I'm at my wits end. It does feel like the booster even though it checked out (and it is new).

New master cylinder?

Joe

 

[Jammin' James]

What brand of brake linings and type of material? Organic?, semi-metallic, etc.

They are ceramic, made or distributed by BrakeEasy, bought them at O'Reillys. I took the tire off and after 100 miles of on and off braking with cool down every half hour, the rotor is still shiny as a mirror. I'm thinking of roughing them up with a sander then going with semi metallic pads.

 

[Jammin' James]

New master cylinder?

Joe

Yes, everything new on all 4 wheels, master cylinder, prop valve and the power booster.

 

[Jammin' James]

Bedding the brakes just means an even layer abrasive friction, so it doesn't feel like you've warped the roters after you get them hot. Never heard of it actually making any difference to stopping power or being able to 'lock the brakes up'.

Locking up brakes depends on several things, such as mass of the vehicle, momentum, gripping power of the tires, pad friction/pressure, pad material etc. If you are trying to lock the brakes doing 60mph and have fat tires with good grip on rough dry blacktop, it's doubtful gonna happen. If using 'Red' pads at slow speeds on cold rotors, not gonna happen either.

About the only thing you actually need the front brakes to do is hold at a stop, with a moderate amount of gas pedal. If they'll do that, they'll stop you in the required distance, without locking up. If they won't hold you still at a stop with a moderate amount of pedal, they aren't getting required pressure.

Holding 15lbs just means there's no vac leaks, doesn't mean the booster is actually putting enough pressure to the calipers.

Was this originally a front drum car converted to discs? I ask because disc/drum requires a different proportioning valve to a drum/drum or disc/disc, discs and drums have different pressure/release requirements

No paper work to even prove it's an SS car but everything looked original and I do believe the front disks were factory installed. What other test can be done on a booster? I've pad and rotor change outs on other vehicles in the past and never had run in problems and I could indeed lock up the brakes (pre ABS)

 

[Karadjgne]

Avoiding Common Mistakes: How To Make Your Street Rod Stop

It goes without saying that quality brake system components like those available from Wilwood are a wise addition to any street rod.

www.motortrend.com

According to this article, it's possible that even with no other hardware issues, you may not be getting enough pressure to the pads. Going with a larger bore mc, with a shorter pedal travel = disaster. Drums require about half the pressure disks do, so if the MC is for drum front and rear, not disk/drum, you are definitely not getting correct pressure.

Carbon Deposits: Cleaning Up What's Left Behind | MOTOR

When upgrading a performance vehicle’s original drum/drum or disc/drum braking system to disc/drum or four-wheel-disc brakes, several variables must be considered when determining correct master cylinder size. These variables include vehicle weight, the weight bias of the vehicle, the tire and...

www.motor.com

 

[Bill chippi]

I recently did a front to rear brake rebuild on a 1971 El Camino 454 SS, including all front brake lines. I've been over and over the system and multiple bleeds but I still get a hard pedal and can not lock the brakes up. It feels like no boost from the (new) booster but it passes the pedal tests and holds vacuum (15") after the engine is shut down. I used the 'H' shaped gauge to check the MC push rod, the booster push rod is in the right hole. The one change I did make was move the Prop valve from the frame rail to under the MC. It is a 2 V for the F disc and D back as is the MC. I'm at my wits end. It does feel like the booster even though it checked out (and it is new).

I

 

[Jammin' James]

Avoiding Common Mistakes: How To Make Your Street Rod Stop

It goes without saying that quality brake system components like those available from Wilwood are a wise addition to any street rod.

www.motortrend.com

According to this article, it's possible that even with no other hardware issues, you may not be getting enough pressure to the pads. Going with a larger bore mc, with a shorter pedal travel = disaster. Drums require about half the pressure disks do, so if the MC is for drum front and rear, not disk/drum, you are definitely not getting correct pressure.

Carbon Deposits: Cleaning Up What's Left Behind | MOTOR

When upgrading a performance vehicle’s original drum/drum or disc/drum braking system to disc/drum or four-wheel-disc brakes, several variables must be considered when determining correct master cylinder size. These variables include vehicle weight, the weight bias of the vehicle, the tire and...

www.motor.com

I replaced the MC in kind (stock size and bore). It has 2 different size chambers, a large one for the front disks and smaller one for the back drum.

 

[Jammin' James]

I recently did a front to rear brake rebuild on a 1971 El Camino 454 SS, including all front brake lines. I've been over and over the system and multiple bleeds but I still get a hard pedal and can not lock the brakes up. It feels like no boost from the (new) booster but it passes the pedal tests and holds vacuum (15") after the engine is shut down. I used the 'H' shaped gauge to check the MC push rod, the booster push rod is in the right hole. The one change I did make was move the Prop valve from the frame rail to under the MC. It is a 2 V for the F disc and D back as is the MC. I'm at my wits end. It does feel like the booster even though it checked out (and it is new).

I want to thank everybody for their suggestions and opinions. I think greywolf has put me on the right path. The brakes are getting better with more driving but not near fast enough in my opinion and still not able to lock them up. They are ceramic and reading up on them, they are not made for older cars with weight and horsepower. I have decided to replace the pads with semi metallic ones. Thanks again for the conversations.

 

[Bill chippi]

I

F you didn’t get answer yet , might want to check proportioning vavle if you installed disc on rear brakes. Went threw same **** as you

I want to thank everybody for their suggestions and opinions. I think greywolf has put me on the right path. The brakes are getting better with more driving but not near fast enough in my opinion and still not able to lock them up. They are ceramic and reading up on them, they are not made for older cars with weight and horsepower. I have decided to replace the pads with semi metallic ones. Thanks again for the conversations.

Just a few minutes driving around slowly and easily braking. The pedal stayed stiff and I could not fully lock the brakes.

 

[ghbanksonit]

How did you break in the front disk brake pads?

I had an issue when i put all new disk breaks on my 1960 El Camino.
I found out that I had a preload going on with the booster. If the small
acorn like nut on the booster is out to far it would not let me get any peddle

 

[Jammin' James]

I had an issue when i put all new disk breaks on my 1960 El Camino.
I found out that I had a preload going on with the booster. If the small
acorn like nut on the booster is out to far it would not let me get any peddle

I have the gage to measure that and I'm on the money, no preload.