Technical Tips > Pre 84

Brake Pedal going to the floor

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76Vett:
Good morning All. I need the help of the brains trust once again.
Ok what I have done so far on my brakes:
Had the disc's machined
Replaced master cylinder (and yes primed/bled it on the bench first before installing)
Replaced brake lines and hoses
Replaced all four callipers and pads
Primed and bled all lines and callipers with a pressure bleeder
Bled air from calliper pistons by pumping the pedal
Have repeated the bleeding process four times thus far
The pedal is hard and feels good without the engine running
The problem is that the pedal still goes nearly all the way to the floor when the engine is started ie. vacuum applied to booster
There is some braking but minimal

I am now at a loss of what to do or what the problem is, any clues  :huh:

bfit:
Do you have the corect master cylinder for the model you have
Bfit

sirfixalot:
Around 76 they changed the length of push rod/piston recess depth also check that all pads are straight heard of a similar situation where a pad had a bow in it which straightened out when piston pushed against it. Also try jacking car up on each  corner you are bleeding Rrh 1st Rlh 2nd Frh 3rd Flh 4th also tap lines & caliper with a mallet to move air along pipes, calipers

77CVT:
 :yeahthat:

Also, if you want to determine which caliper may be a problem, clamp off all 4 lines and put your foot on the pedal.  Have someone release a clamp and feel how far the pedal travels (usually 10-20mm).  Foot off the pedal, reclamp and repeat process for the other corners.  If one is bad, you will feel a huge difference in travel compared to the others.

If it's the push rod, you won't need to adjust it by far.

 :cheers:

sirfixalot:
Is master cylinder 1' or 1 1/8should be 1 1/8"

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