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HybridZ

Too much pedal effort


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I've been fighting brake pedal effort problems for some time. My 73 sat for 8 years or so until I bought her. $800 for a SBC Z seemed like a dream come true, but that was many wrench turnings ago.

I have replaced the MC (twice), the booster (with a used one, though the original tested good for vacuum function, the front calipers/rotors. I still have to stand on the pedal to stop. I have bled till I feel like a medieval physician; get pretty good squirts judging by the sound and splashes (one-man operation).

One thing I have noticed is that the drivers-side rear adjuster is not turning the wheel on the cylinder. I replaced the cylinder (it seemed stiff in turning action, but still no luck.

I theorize that under-adjusted rear brake will affect all wheels' braking as the master cylinder will bottom out and pressure will be low. Is this the case? Also, the lever is moving on the adjuster, but not turning the cylinder wheel; any ideas? Thanks.

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I'm assumining he's using a one-man brake bleed like I've got, that has a check valve (ball and spring) that keeps the fluid from backing up through the discharge tube attached to the bleed screw.

 

I had a similar problem in that my rear brakes were not adjusting (turbo ZX calipers) resulting in a mushy pedal. This was because all the braking was being done by the front brakes and none by the rear.

 

I wish I could offer some advice here, but I've just about forgotten all I knew about drum brakes.

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Not terribly important, but here's an easy way to do a one man bleed:

 

Just use a vacuum hose on the bleeder into a plastic bottle with a little brake fluid in the bottom. The bottle end of the vacuum hose needs to be submerged in the brake fluid. 20 oz Coke bottle or similar works good, if you bleed a lot go a little bigger with a small Gatorade bottle or similar. Then bend a wire hanger to grab the top of the bottle and make a hook on the other end and you can hang it on the suspension.

 

Open the bleeder and pump all the way up and down 5 or 6 times and get out and close the bleeder, then move to the next one.

 

As far as your problem goes,

 

Manually adjust the rears so that there is a little drag on the drum when the wheel turns, if necessary get a new adjuster. If you still have a soft pedal, do the master test. Push soft and slow, see how it feels. Then stab pedal hard. If you get a firm pedal with the stab but not with the soft and slow then replace the master. If your wheel cylinders are way out of adjustment, then the pedal will go down farther because you're using the stroke just to get the shoes to contact the drums, not to actually apply the brakes.

 

Jon

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