1970 Toronado brake overhaul....please help!
September 23rd, 2012, 06:02 PM
#1
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Join Date: Jan 2012
Posts: 44
1970 Toronado brake overhaul....please help!
Hi all,
I'm rebuilding a 1970 Toronado and I decided before I put my rebuilt 455 rocket into it I would make sure I can subdue the power with all new brakes! I have cleaned out all steel hoses and installed new front rubber hoses as well as the rear intermediate hose. New rear cylinders, new rear hardware, new shoes, had drums cut, new front rotors, slotted and drilled of course to disperse heat, rebuilt calipers, but only cleaned the master cylinder. Then bench bleed and installed master cylinder. Then proceeded to bleed all the lines starting with passenger rear and worked my way forward . After all the air was removed the pedal still goes all the way to the floor and when I pressed the pedal I assumed it would at least engage the calipers and the cylinders in the rear, but nothing! Does the power booster have to be engaged with vacuum to complete some hydraulic circuit? Shouldn't it even somewhat engage the brakes? Thanks if you read all this... And even more if you can help, I'm new to the car world and any suggestions would be helpful....
Marc
I'm rebuilding a 1970 Toronado and I decided before I put my rebuilt 455 rocket into it I would make sure I can subdue the power with all new brakes! I have cleaned out all steel hoses and installed new front rubber hoses as well as the rear intermediate hose. New rear cylinders, new rear hardware, new shoes, had drums cut, new front rotors, slotted and drilled of course to disperse heat, rebuilt calipers, but only cleaned the master cylinder. Then bench bleed and installed master cylinder. Then proceeded to bleed all the lines starting with passenger rear and worked my way forward . After all the air was removed the pedal still goes all the way to the floor and when I pressed the pedal I assumed it would at least engage the calipers and the cylinders in the rear, but nothing! Does the power booster have to be engaged with vacuum to complete some hydraulic circuit? Shouldn't it even somewhat engage the brakes? Thanks if you read all this... And even more if you can help, I'm new to the car world and any suggestions would be helpful....
Marc
September 23rd, 2012, 06:15 PM
#2
Registered User
Join Date: Feb 2012
Posts: 18
barring any obvious external leak, your master cylinder has an internal leak. When you push the master past its normal travel, your pushing the O rings into the un-used portion of the bore which may be rusted or have a rough surface. It tears up the O rings and the master cant develop any pressure. Put a new master in and you should be fine
September 23rd, 2012, 08:32 PM
#4
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Join Date: Feb 2008
Location: Plano, TX
Posts: 11,798
Like other have said, replace the master. If over ten years old it was ready for it anyway. A thorough brake job like you just did should have a fresh MC to top it off (no pun intended!)
BTW, welcome to the forum!
BTW, welcome to the forum!
September 23rd, 2012, 08:43 PM
#5
Just an Olds Guy
Join Date: Jul 2008
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
Then proceeded to bleed all the lines starting with passenger rear and worked my way forward . After all the air was removed the pedal still goes all the way to the floor and when I pressed the pedal I assumed it would at least engage the calipers and the cylinders in the rear, but nothing!
Toronado is a classy car - great to see you chose a beauty to restore.
Before you replace the master cylinder -
* are you SURE you've bled all the air? It doesn't sound like it
* check to see if any of the bleeder valves and brake hoses aren't done up and may be still leaking fluid.
The brake pedal should feel soft, but it doesn't need vacuum boost to bleed brakes, and the pedal shouldn't bottom out. If you've already checked both of those ^^^, by all means proceed to replace the MC.
September 24th, 2012, 07:52 PM
#8
Just an Olds Guy
Join Date: Jul 2008
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
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