Braking Points: Updated equipment improves the stopping and going

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Chuck Jostad writes: I have a ’65 Pontiac Bonneville convertible with a stock 389. Several months ago, it died on the street. After a couple of minutes, I turned the key and it fired right up. It died and restarted twice more in the next five minutes, then didn’t start after the third time. I replaced the coil to no avail. I opened the distributor cap to check the points but instead found an odd metal plate with two crescent-shaped slings. No one can tell me what it is or how to deal with the problem, other than to replace the whole mechanism with Pertronix. Some have suggested I have a factory attempt at electronic ignition.

In most distributors, the points and condenser are under the cap, and the advance mechanism is hidden in the body. But in the distributor used in many ’50s and ’60s GM cars, that’s reversed: The advance mechanism is directly under the cap, and the points are normally beneath that. You don’t see points because you have Option K66, GM’s transistorized (electronic) ignition, also called the TI System. Though mostly used on C2/C3 Corvettes, the TI System was an option on full-size Pontiacs beginning in 1963. Note that the system includes the distributor, amplifier module, and a special low-resistance coil, so if you replaced the latter with a conventional coil, the spark will likely be weak. You certainly could replace the distributor with a conventional one with points, or with a modern breakerless system without the fragile 55-year-old amplifier module. But if, after checking for bad connections and traditional crank-spark testing, you haven’t found the problem and want to keep the original system, I’d recommend you talk to Dave Fiedler at tispecialty.com.

Transistorized Ignition
Transistorized ignition, RPO K66, was a $75 option on some GM cars of the mid-1960s, including Pontiacs and Corvettes. Courtesy Corvette Forum

Edwin Hyatt writes: My ’39 Dodge has Lockheed brakes, which I would like to replace with Bendix drum brakes. I have been told that disc brake conversions will not fit with the original wheels and would make my new tire and hubcap purchase unusable. I also have a ’72 Cuda parts car with drum brakes available. Will those fit?

Check out Scarebird Classic Brakes LLC. They offer a disc brake package that they claim “will clear most stock wheels.” If you tell them the details of your car, they should be able to give you a definitive answer on what will work and what won’t.

Tom Anderson writes: I have a custom-built hot rod that has front disc brakes, though I can’t find a brand name on them. I was told they have three pistons in each caliper that work progressively as you push the brake pedal. Right now, there is too much pedal travel to use the brakes. I think the pistons in each caliper require so much fluid to operate that the piston in the master cylinder just isn’t large enough to push it. Do you know if there are master cylinders out there that have a larger piston that will move more fluid with a short stroke?

If your rod has drums in the back, I would first make sure the shoes are properly adjusted, as that will affect pedal travel. But yes, all other factors being equal, increasing master cylinder bore size will result in a shorter pedal stroke. However, it will also decrease the line pressure, making it so that you have to press harder on the pedal to generate the same braking force. Master cylinders are widely available in 7/8-inch, 15/16-inch, 1-inch, and 1 1/8-inch diameters, but the configuration of the mounting flange, pushrod, and fittings all need to match your application.

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Rob Siegel has been writing the column The Hack Mechanic™ for BMW CCA Roundel magazine for 34 years and is the author of six automotive books. His most recent book, Just Needs a Recharge: The Hack Mechanic™ Guide to Vintage Air Conditioning, is available on Amazon (as are his other books), or you can order personally-inscribed copies here. His new book, The Lotus Chronicles, will be released in the fall.

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