1964-1974 [Subscribe to Daily Digest] |
Anders is right, if your brake warning light is flickering on and off even when you don't touch the brakes, the problem with THAT has gotta be in the switch. This isn't a very complicated system! The switch is just a little plunger thing that has a wire on it and screws into a fitting on the firewall. When brake pedal travel gets long enough to push in the plunger, the wire gets grounded to the firewall and bingo, the light comes on. Once the brakes are fixed, the system is reset "digitally," i.e., the mechanic grabs the plunger with his digits and pulls it back out. Take out the carpet and the driver's side footboard (slanted metal plate behind the pedals) and you'll be able to see the whole system. My guess is that you'll find either that the plunger-switch is broken so it shorts out sometimes, or that the insulation has worn off the wire and it grounds itself sometimes on the surrounding metal.
Now (you ask) why would brake pedal travel become excessive in the first place? Simple: unlike probably any other car you've ever owned, the Sonett has *manually adjusted* rear brakes. That's right, every oil change or so you need to adjust these to compensate for brake shoe wear. There's a little square-headed adjuster sticking out of the top of each brake backing plate for this purpose, and it's easy to do the adjustment yourself once you've got the proper square socket. Just jack up the car (removing wheels is optional but makes it easier to reach the adjuster), pump the pedal a few times to center the shoes, then tighten the adjuster until the drum locks; then back it off a couple of clicks until the drum spins freely. This adjustment also automagically adjusts your parking brake (since it acts on the same shoes.) In fact, a good tip-off that it's time to adjust the rears is if you have to pull up the parking brake more than 5 clicks or so to make it take hold.
If your brake system is in good shape generally, this adjustment is all you should ever need to prevent excessive pedal travel from making the brake light come on. In fact, if you adjust the rears regularly, the light will NEVER come on.
Now, since you asked, is there any separate adjustment for brake-pedal travel itself? Yes, there is, but you don't want to mess with it to solve problems with the brake light; it's only for adjusting the "free play" at the pedal. If you take off the footboard as described above, you'll be able to. see this. There's a rod that runs forward from the brake pedal into the firewall (the master cylinder is on the other side) and when you step on the pedal this rod gets pushed forward to activate the master cylinder. You'll notice that there's a locknut and a threaded section on this rod. By releasing the locknut and turning the rod, you can increase or decrease its clearance at the master cylinder.
You do need a certain amount of free play at the pedal (about a half-inch measured at the tip of the pedal, I think, but check your manual) to make sure that there's enough space for the master cylinder to return all the way, and THAT's the purpose of this adjustment.
(PS -- While you're in there, you'll also notice a bent-metal tab attached to the side of this rod gizmo, and this tab is what pushes the brake-pedal-travel switch described above. If you do adjust the pedal free play, this tab may slip out of position, so check it before you put everything back together.)
posted by 204.76.1...
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