Classic Mustangs List Archive

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Mail From: (email redacted) (email redacted)

I'm having the same problem with my 73 Ranchero. The pressure stays on the
brakes when I take my foot off the brake pedal. I have to pull it up with from
underneath with my foot. I was told it is the power brake booster causing the
problem. Any ideas before I buy this expensive item? Thanks.

Sharon

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This read-only message was archived from a public mail list.
Mail From: Myjak (email redacted)


> I'm having the same problem with my 73 Ranchero. The pressure stays
> on the brakes when I take my foot off the brake pedal. I have to
> pull it up with from underneath with my foot. I was told it is the
> power brake booster causing the problem. Any ideas before I buy this
> expensive item? Thanks.

Sharon,

Probably is, but it could also be a sticking caliper or proportioning
valve, a master cylinder going bad (or the power break booster!) or
leaking wheel cylinder. I do find it odd that you have to "pull up" on
the pedal... its also unlikely to be the booster check valve, but you
should check it anyway since your there.

Take the booster and master cylinder off the car. Check the rear
master cylinder seal for signs of a leak. If its wet, and/or the
inside of the booster is filled with break fluid, replace the both MC
AND the booster. Rebuild the proportioning valve, and flush and bleed
the system. (I prefer DOT 5 in my vehicles, YMMV)

If its dry, check the booster's action. Chuck up a vacuum source to
the check valve and see if it will hold vacuum (if not... replace it,
the diaphram's shot). With the vacuum source connected, see if it
operates correctly when you apply <synthetic> pedal pressure to it.
If not, replace it.

If the booster and MC appear to be OK, then its either the
proportioning valve and/or a sticking brake caliper (or leaking wheel
cylinder). For the calipers, check for uneven ware between inside and
outside pads. Check both left and right sides... they should all be
equal (give or take 1/32". Check inside the wheel cylinder rubber
boots for fluid. Chances are you'll find your answer somewhere along
this path.

thats my $.02 worth...

--
Net@You.Later,

- Michael D. Myjak
Senior Research Scientist
Institute for Simulation and Training
The University of Central Florida
email: <(email redacted).>
Voice: 407.658.5043 FAX: 407.658.5059 LAB: 407.658.5078

Off the keyboard, over the bridge, through the router..... Nothin' but Net!








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This read-only message was archived from a public mail list.
Mail From: Chuck Pazdzioch (email redacted)

I had a 66 Buick with the same problem. I had to bring the pedal back
up by pulling on it. It was a leaking break line. I'm not saying that
it's a break line, but it does sound like a leak somewhere.

-Chuck

70 Mach1

----Original Message Follows----
Date: Fri, 30 Jan 1998 15:40:03 -0400
Reply-To: (email redacted)
From: Myjak <(email redacted)>
To: Multiple recipients of list
<(email redacted)>
Subject: [CM:8963] Re: Proportioning Valve or Booster?


> I'm having the same problem with my 73 Ranchero. The pressure stays
> on the brakes when I take my foot off the brake pedal. I have to
> pull it up with from underneath with my foot. I was told it is the
> power brake booster causing the problem. Any ideas before I buy this
> expensive item? Thanks.

Sharon,

Probably is, but it could also be a sticking caliper or proportioning
valve, a master cylinder going bad (or the power break booster!) or
leaking wheel cylinder. I do find it odd that you have to "pull up" on
the pedal... its also unlikely to be the booster check valve, but you
should check it anyway since your there.

Take the booster and master cylinder off the car. Check the rear
master cylinder seal for signs of a leak. If its wet, and/or the
inside of the booster is filled with break fluid, replace the both MC
AND the booster. Rebuild the proportioning valve, and flush and bleed
the system. (I prefer DOT 5 in my vehicles, YMMV)

If its dry, check the booster's action. Chuck up a vacuum source to
the check valve and see if it will hold vacuum (if not... replace it,
the diaphram's shot). With the vacuum source connected, see if it
operates correctly when you apply <synthetic> pedal pressure to it.
If not, replace it.

If the booster and MC appear to be OK, then its either the
proportioning valve and/or a sticking brake caliper (or leaking wheel
cylinder). For the calipers, check for uneven ware between inside and
outside pads. Check both left and right sides... they should all be
equal (give or take 1/32". Check inside the wheel cylinder rubber
boots for fluid. Chances are you'll find your answer somewhere along
this path.

thats my $.02 worth...

--
Net@You.Later,

- Michael D. Myjak
Senior Research Scientist
Institute for Simulation and Training
The University of Central Florida
email: <(email redacted).>
Voice: 407.658.5043 FAX: 407.658.5059 LAB: 407.658.5078

Off the keyboard, over the bridge, through the router..... Nothin' but
Net!








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