brakes Brake Questions

[Mark92131]

I have been struggling with the Brakes on my 1975 after completing a suspension upgrade.  I ended up going with the Volvo brakes and 320i vented disks because my stock calipers were pretty much shot.  After getting everything installed, I built my own brake bleeder using a 1 gallon sprayer and the GM replacement cap.  I decided to just pressurize the brake system instead of filling the sprayer with brake fluid and pumping it through the cap.  I bled the entire system from front to back in the proper order and everything seems clear with no bubbles in the system.  I expected the calipers (used) to expand and snug the pads to the disk, this seems to be the case on the drivers side, but the passenger side turns freely, like the pistons are stuck.  More concerning is the brake pedal, that will push down to the floor with little or no resistance.  I can see the brake fluid level drop when I press the pedal, but it still goes to the floor.  Is the master shot?  How can I test the function of the master, should I try bleeding the old fashion pump method?  The brakes were marginal at best before I started this upgrade.

 

Thanks in advance for your comments,

 

 

Mark92131

[Conway]

I used a pressure bleeder when I did the same upgrade. I had to bleed 3 Times before the pedal got to where I wanted it. Try bleeding a couple more times before you worry about the master. Bleed the clutch while you're at it.

Edited February 10, 2014 by Conway

[M3M3]

yup.  more bleeding needed.  and push the brake pedal several times per corner while bleeding. 

 

did you not rebuild the used calipers before you put them on?  

 

did you replace all the soft brake lines in the process?

 

does the pass side turn when the brake pedal is down?

 

did you bleed all three valves on each front caliper in the right order?

Edited February 11, 2014 by mlytle

[Mark92131]

Marshall:

 

I'll try the pedal push technique this round of bleeding.  I didn't rebuild the calipers. the PO purchased them new, drove them for a while and pulled them off after a wreck.  I did replace the soft lines with new soft lines.  I did not not try turning the passenger side rotor when the pedal was down, i'll try that after this next round of bleeding.  I bled the Volvo calipers outside to inside, (Outer top, Inner side, Inner top), is that the right order?

 

Thanks for the tips...

 

 

Mark

[Mark92131]

Tried the brake push technique this time through.  Opened the bleeder valve and while it was filling my fill bottle pumped the pedal 3-5 times.  Passenger side rear, driver side rear, passenger caliper (Outer top, Inner side, Inner top), driver caliper (Outer top, Inner side, Inner top), pumping the brake at each bleeder valve.  This procedure used an entire 12oz bottle of brake fluid to complete.  Buttoned everything up, jumped in the car, pedal goes to the floor.  The calipers did seem to clamp up on the rotors this time through, providing a slight drag when turning the hub.  More bleeding?  It doesn't seem like air in the system should be the problem with that much fluid being pushed through the system under pressure.

 

Any ideas of what to check next?

 

 

Mark

[M3M3]

are the rear brakes properly adjusted?

 

how old is the master cyl?

 

if you do a bunch of quick half-pumps of the brake pedal can you build any pressure?

 

is the car level while you are bleeding brakes?

 

ps - those don't look like any volvo calipers i have seen, and the rotors are not vented.  the ones i had had bleed valves on upper inside and middle on both sides.  is your pic of the stock brakes?

Edited February 12, 2014 by mlytle

[Mark92131]

Rear brakes are properly adjusted, I am guessing that the MC is original by the amount of gunk where it mounts to the booster.  It doesn't seem to build any pressure with quick half pumps.  The car is mostly level during the bleed procedure, I jack up each corner just enough to remove the tire, so I have better access to the bleed screws.  You are correct, the picture is my original OEM brakes before starting this "easy and quick" upgrade.  Here's what I am working with now...

 

The car's original brakes were pretty sketchy, (soft pedal, no grab).  I used a lot of downshifting to get the car home because the brakes were weak.  I have a near new MC I salvaged from a wreck I parted out.  My next option might be to swap out the MC, although that doesn't look like a fun job at all.  Any tips for that procedure or anything I should try before the swap to ID the MC as the cause of my brake problem?

 

Thanks for your help,

 

 

Mark

[Hans]

Can you clarify your bleeding procedure? The idea is to have a helper pump the pedal a few times and then hold it down, at which point you open the bleed nipple. When flow slows, close nipple and helper releases pedal. Repeat. With old master, advice is to avoid pushing it right to the end. Put something under pedal to keep it off the floor.

[jireland2002]

If the MC is old then it is probably the problem.  I have seen lots of MC that sort of work ok until you start to bleed and use the full stroke.  That is when the gunk, rust or what ever that has collected ruins the seals. 

Just put the new MC on.  You were going to do it later anyway.

 

Jeff

[M3M3]

Can you clarify your bleeding procedure? The idea is to have a helper pump the pedal a few times and then hold it down, at which point you open the bleed nipple. When flow slows, close nipple and helper releases pedal. Repeat. With old master, advice is to avoid pushing it right to the end. Put something under pedal to keep it off the floor.

 

this process does not apply in this case.  he is using a pressure bleeder.

 

If the MC is old then it is probably the problem.  I have seen lots of MC that sort of work ok until you start to bleed and use the full stroke.  That is when the gunk, rust or what ever that has collected ruins the seals. 

Just put the new MC on.  You were going to do it later anyway.

 

Jeff

agree with Jeff.   replace the MC.  it is not that hard.

 

btw...your rotors are on the wrong sides of car...

[Hans]

I misread the part about pushing the pedal. And yes, a new master is a good idea if adding new items on the corners.