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Old 07-10-2020, 01:24 PM
72lmsconv 72lmsconv is offline
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Default Soft Brake Pedal

I have a 4 drum bake car and years ago had them all redone and started driving the car
more often and the brake pedal is soft and took it to a mechanic to have the
brakes bled and everything checked and the car stops but they engage like half or more
before stop the car. he says its normal on a drum brake
When you push the brake pedal a few times fast the brake engage a lot better but
I was wondering if there is an adjustment by the brake pedal or if the power booster
is failing and I need to replace it. He said it was working properly

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Old 07-10-2020, 02:37 PM
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north north is offline
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The shoes (pads) need to be periodically adjusted for wear, in theory they self adjust when backing up but I find that they still need to be manually adjusted from time to time. The adjustment is with a thumb wheel which you access with a flat scewdriver behind each drum .

A failing booster will lead to more effort but won't change when the brakes engage. A failing master cylinder will create a situation where once you apply enough pressure to hold the car firmly in place in drive the pedal gradually sinks further with constant pressure applied.

Other possible causes of soft feeling pedal are deteriorating flexlines (especially chinese junk) that swell under pressure or small fluid leaks at the wheel cylinders or on the lines from rustout.

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Old 07-10-2020, 03:33 PM
72lmsconv 72lmsconv is offline
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Quote:
Originally Posted by north View Post
The shoes (pads) need to be periodically adjusted for wear, in theory they self adjust when backing up but I find that they still need to be manually adjusted from time to time. The adjustment is with a thumb wheel which you access with a flat scewdriver behind each drum .

A failing booster will lead to more effort but won't change when the brakes engage. A failing master cylinder will create a situation where once you apply enough pressure to hold the car firmly in place in drive the pedal gradually sinks further with constant pressure applied.

Other possible causes of soft feeling pedal are deteriorating flexlines (especially chinese junk) that swell under pressure or small fluid leaks at the wheel cylinders or on the lines from rustout.
Thanks for the info
I put the car in drive and applied the brakes the brakes are on the bottom basically and holding
the car in place If you apply the brake a few times quickly they go up maybe an inch back
so it sounds like he never adjusted the brakes -Air and shoes properly and I need a new brake booster?

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Old 07-10-2020, 04:43 PM
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could be shoes way out of adjustment but could also be a failing master. When a master is leaking a bit internally you can sometimes get a little more clamping action by pumping the pedal and moving the air bubbles in the line around. Sounds like you need a better mechanic. I'd start by having a look at the fluid level in the master cylinder bowls. Also look at the backing plates of each drum for any sign of leakage at the bottom of the drums as well as anywhere else along the brakelines for dripping or even wet spots indicating tiny leaks especially at fitting locations.

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My Break Away Squad
1969 Fbird (Base, 350 & Sprint Cvt’s - 400HO & TA Hardtops)
1969 LeMans (2dr & 4dr Hardtop and a Cvt)
1969 LeMans Safari 2 seat Wagon
1969 GTO (2 Cvt, 2 Hardtops & Judge Hardtop)
1969 Catalina (3 Cvt’s & a 2dr hardtop)
1969 Ventura 2 Seat Wagon
1969 Executive 4dr Sedan
1969 Bonnie Cvt
1969 Bonnie 3 Seat Wagon (2 of them)
1969 Bonnie Brougham (4dr Hardtop & Cvt)
1969 Grand Prix SJ (2 of them)
1969 2+2 2dr Hardtop (Canadian model)
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