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| Fig. 1. Pedal box hardware |
A pair of phone calls concerning unresponsive clutch pedals prompts a review of Alfa Romeo's suspended clutch and brake pedal engineering. Since 1969/ 1970 the late 105 and 115 series cars (Berlinas, GTVs, and Spiders) have shared the same firewall mounted pedestal arrangement. These cars have the clutch master cylinder mounted on a bracket integral to the power brake booster assembly. The power brake booster is mounted on an alloy pedestal and the clutch master cylinder is mounted on the outboard side of the power brake booster. The brake and clutch pedals are suspended from a shaft mounted inside the alloy pedestal. The shaft then has an arm welded to the outboard end to actuate the clutch master cylinder.
The brake pedal is simply suspended from the shaft, however, the clutch pedal is cinched to the shaft with a taper pin and keeper nut. Depressing the clutch pedal rotates the shaft in the pedestal thus actuating the clutch.
The steel shaft is notched through approximately half its diameter to accept the taper pin. This notch is the weak point in the pedestal set up. Eventually the shaft begins to bind causing it to twist and shear. There are various causes for this problem, mileage, number of shifts, and corrosion enter into the equation, but the other culprits are the springs in the clutch pressure plate. They become rusty and it takes more force at the pedal to engage the clutch hence the shaft eventually fatigues and shears at its weakest point.
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| Fig. 2. Pedal securing bolts |
There are a couple of hints at the impending failure of the shaft. First, the clutch pedal appears lower than the brake pedal. The clutch pedal should be level with if not slightly higher than the brake pedal. Second, engaging 1st and reverse gears seem a tad bit more challenging than usual. When the shaft does shear, the clutch pedal goes to the floor and will not return to its normal height. Shifting becomes a grinding affair. You decide to "help" and when you pull up on the clutch pedal it becomes slack. Now, moving the clutch pedal by hand, you will see no corresponding movement of the clutch master cylinder lever under the hood.
You must remove the entire assembly to include clutch master cylinder, brake master cylinder, power booster and pedestal to effect the repair. Once the entire assembly is removed, the shaft can be welded and put back into the car. The alternative is to let your friendly neighborhood Alfa Repair Shop pull the shaft and recondition it for you.
[For a second article describing clutch pedal shaft replacement, see Replacing the Alfa Clutch Pedal Shaft, RHH.]