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Parking Brake Replacement
The parking brake on the Alfa Spider is unique and interesting. It uses a cable and pin system that operates brake shoes inside the rear brake-rotor assemblies. When the parking brake lever is pulled, a cam device is elongated so that it pushes out against brake shoes which, in turn, push out against the inside of the brake rotor. In this sense, the inside of the brake rotor essentially functions like a brake drum.
This shoe-and-drum braking system -- used in conjunction with the four-wheel disc-brake system -- is part of a mechanical emergency and parking-brake system. The mechanical brake system could be used to stop the car in the event of a failure in the hydraulic (disc) brakes.
This set-up essentially provided the vehicle with three separate braking systems: the front servo-supplied disc brakes, the rear servo-supplied system and a separate mechanical brake system. In the event of a complete failure in the hydraulic braking system, the stand-alone mechanical brake could be used to bring the Alfa to a controlled stop.
Replacement of the parking/emergency brake
- Steps:
- With the car on a lift, the first step is to remove the cotter pin and remove the parking brake cables where they meet under the car.
- Next, remove the nuts from the rear of the backing plate where it connects to the housing, and remove the axle assembly, which includes the backing plate and parking-brake assembly.
- Carefully slide out and remove the assembly from the car.
- Take note of the bearing and locking rings as they are removed from the assembly. The bearings on this vehicle will be replaced, but the axle will be re-used since it's in good condition.
- Disassemble the backing plate, noting the position of each piece as it's removed. Keep the backing plate from the other side of the vehicle assembled to serve as a guide until the first one is complete.
- Use locking pliers to remove the springs one at a time.
- Note::
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Always wear safety glasses or goggles when removing these springs, as they can fly loose when released.
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With the backing plate disassembled, the parts can all be cleaned up using a parts washer.
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With the parts cleaned up, the re-assembly consists of reversing the disassembly procedure. Begin by installing the rubber grommet on the backing plate. The grommet serves as a weather seal to prevent moisture from contaminating the brake assembly.
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Re-assemble the cam device that attaches to the parking brake cable. The cam device is the part responsible for pressing the brake shoes outward against the inside of the rotor when the parking-brake handle is pulled.
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Continue the re-assembly by re-installing the brake shoes on the backing plate.
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Line up the hold-down springs so that they can be inserted into their corresponding holes in the backing plate, and lock them into position.
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Assemble the adjuster and install it into the assembly. Make certain that it spins freely once installed.
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Carefully re-connect the springs, making certain to wear eye protection during the procedure. Use the intact assembly from the other side of the vehicle to identify the locations of individual springs if you're uncertain.
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Continue installing the springs until the assembly is complete.
- Repeat these steps for the other brake assembly.
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With the parking brake assembled, it can be re-installed onto the backing plate. Push the axle through the backing plate, and press the bearing into place taking note of the notched spanner nut.
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One of the notches contains a lock tab that holds the spanner nut secure. It's very important that this be secured properly to prevent the brake assembly from loosening during use.
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The dust shield has been cleaned of dirt and corrosion, and repainted using heat-resistant paint.
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Slide the dust-shield over the axle assembly, and re-install the axle assembly onto the vehicle. You may need to lube the axle housing with some grease to make the re-installation of the axle assembly easier.
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Re-install the retaining nuts at the back of the assembly. Some thread-lock on the nuts will help ensure that the nuts stay in place. Tighten the backing plate to mate to the axle flange.
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The next step is to bolt on the new parking brake cables by lining them up and fastening them onto their mounting blocks. The brackets attach with through-pins held in place by cotter pins.
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The main cable hooks into the trailing arm. It is held in place by supporting clips, and attached at its front to an adjuster device.
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The adjoining cable attaches to the bottom of the lever that extends up into the passenger compartment and is controlled by the driver when applying the parking brake.
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A clevis pin secures the cable that leads from the backing plate, and is fastened by a cotter pin.
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