Solution For Four Wheel Drum Brake Owners
Posted: Wed Sep 18, 2013 11:43 am
First, let it be clear that I understand that disc brakes are far superior to drum brakes and if you have a Toronado that came with factory disc brakes, then you are much better off. However, I disagree that the brake system conversions that are often discussed are necessary for the typical Toronado owner. I do not drive my 45 year old car at freeway speeds tailgating crowded traffic where multiple panic stops and the resultant brake fading would be an issue.
If you follow the process below, your car will stop as good as it did when delivered from the factory. But you have to do ALL the steps or you will be disappointed.
Replace all of the components with new (or rebuilt if new is not available). This includes power booster, master cylinder, all wheel cylinders, all wheel springs and fasteners, adjuster assemblies and the brake drums. All of the items are readily available from NAPA.
This is the most important part, that most restorers overlook: Do not get the brake shoes from any auto supply. I located a service (http://brakematerialsandparts.webs.com/) that will custom build the brake shoes. The material must be a “soft composite, non-metallic” material, bonded (not riveted) and arced to fit the brake drum. Arcing removes some material, so riveting will severely limit life.
Brake shoes sold by auto supplies use modern hard metallic material made to last longer. You do not want this. It needs to be soft and non-metallic so friction in maximized. They can be replaced easily for as often as one would drive a classic car. In addition, the surface must be arced to fit the curvature of the drum. Very few places will arc shoes anymore. If you are using new drums, then the service I mentioned above they will arc them to the 11” spec. If not, you have to send the original drums to them for fitting.
The primary factors that contribute to restored drum brake systems not working properly is old drums that have been turned mated to brake shoes that have not been arced to fit the drum and brake shoe material that is too hard. This results in a very small area of very hard material contacting the drum.
With the above work done, my 1969 stops as well as it did when it left the factory.
If you follow the process below, your car will stop as good as it did when delivered from the factory. But you have to do ALL the steps or you will be disappointed.
Replace all of the components with new (or rebuilt if new is not available). This includes power booster, master cylinder, all wheel cylinders, all wheel springs and fasteners, adjuster assemblies and the brake drums. All of the items are readily available from NAPA.
This is the most important part, that most restorers overlook: Do not get the brake shoes from any auto supply. I located a service (http://brakematerialsandparts.webs.com/) that will custom build the brake shoes. The material must be a “soft composite, non-metallic” material, bonded (not riveted) and arced to fit the brake drum. Arcing removes some material, so riveting will severely limit life.
Brake shoes sold by auto supplies use modern hard metallic material made to last longer. You do not want this. It needs to be soft and non-metallic so friction in maximized. They can be replaced easily for as often as one would drive a classic car. In addition, the surface must be arced to fit the curvature of the drum. Very few places will arc shoes anymore. If you are using new drums, then the service I mentioned above they will arc them to the 11” spec. If not, you have to send the original drums to them for fitting.
The primary factors that contribute to restored drum brake systems not working properly is old drums that have been turned mated to brake shoes that have not been arced to fit the drum and brake shoe material that is too hard. This results in a very small area of very hard material contacting the drum.
With the above work done, my 1969 stops as well as it did when it left the factory.