The hissing means that either you have had a snake curl up under your dash,
and he is upset by the fact that your socks don't match (he can only see
them when you step on the brake pedal), or that you have an internal vacuum
leak in the power brake booster. Try putting your foot on the floor
alongside the brake pedal. If there is no hiss now, you can bet it's the
second option (be sure to do this before you change your socks).
The pedal going to the floor means that you have to displace an inordinate
amount of fluid from the master cylinder before the pads or linings move all
the way to the friction surface. This means that either your self adjusters
are not working (probably not put together right last time the rear brakes
were serviced) or that the system has trapped air bubbles in it. Another
possibility is that you habitually don't use the parking brake - this will
keep your brake adjusters from doing their job as well as they should.
The warning light lighting when you step on the pedal means that the
pressure is building up in one half of the system but not in the other
half - which also indicates that one half of the system is working sort of
right, and the other half isn't. In the bad self adjuster scenario, the
rears would be the ones that are not developing pressure while the fronts
are sort of OK.
How to fix it in 3 steps:
1. Replace the power brake booster.
2. Bleed the system with a power bleeder - if you don't have access to one,
take it to a real actual brake person to do it for you.
3. Inspect the rear brakes, paying special attention to the brake adjusters.
One common error is to put the right side adjuster on the left side of the
car, and vice versa - this makes them into brake misadjusters, at no extra
cost.
Dick Benjamin
----- Original Message -----
From: "Greg Graham" <gregtx@xxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Thursday, April 03, 2003 11:35 AM
Subject: IML: 67 Braking problems again
>
> Oh great powers that make things stop, I need your wisdom now. Here are
the
> symptoms with my '67 (naturally, front disks and rear drums). I press on
> the stop button and there's quite a bit of pedal travel and a noticable
hiss
> from the pedal area when I do so. The pedal will go to the floor with
> little effort and the brakes will finally grab, but at a minimal amount.
> The pedal is not "hard", it simply goes to the floor. No amount of
pumping
> the brakes makes any difference at all. The hiss stops as soon as I reach
> the floor (only hisses while the pedal is in motion). The "brake system"
> light comes on. Once to the floor and the car has stopped, the brakes
will
> hold it stopped indefinitely as long as I keep my foot on the pedal (no
> gradual slip like a bad Master cylinder). What on earth is wrong with my
> brakes now?
>
> Here are the things that have been done: The following items have been
> replaced: Master Cylinder, all metal brake lines, rear wheel cylinders,
> rubber lines up front from the metal line to the brake itself. No leaks
> anywhere under the hood and no drips at any of the wheels. No loss of
brake
> fluid; Master Cylinder stays full. I recently had the brake lines bled
when
> I purchased new tires, but I am not exactly confident in the quality of
> their work. Still air in the lines? Bad Power brake booster? Bad "new"
> master cylinder? Can pads or disks or drums be the culprit? What sort of
> thing would result in so much pedal travel with so little result in
braking?
> The Convertible starts every time and rides like a dream... but that
> won't do me any good if I can't stop!
>
> Thanks, Greg
>
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