Bob's Resource Website (2007)
Studebaker Disk Brakes
Bob's Resource Website (2007)
The rebuild info is below
The first section is an information dump of Studebaker Disk Brakes.
Technically, the original Bendix disk brake system is of a superior design, to the Turner and Steel-Tech systems. It has a massive, rigid caliper bridge, fixed to the spindle and straddles the rotor and allows a piston to apply brake pressure to each side. Each piston rides on a steel pin, fixed in the caliper housing. The base of the piston has the guide, which is a small spring that binds on the pin. The spring extends slightly when you apply the brakes and retracts the pad, the same amount, when the pressure is released. This action of pulling the pad away from the rotor, contributes to less pad wear, less rolling resistance and cooler rotors, as well as a self-adjuster mechanism. Another feature is, that the pads/pistons will only extend a fixed amount, preventing a pad from wearing down to the steel. A worn pad can never contact and gall the rotor. When the limit is reached, the braking effect diminishes. So, if the original Avanti disk brakes start to pull, they may be telling you to change the pads.|
The very same brake system was being used on Ferrari, Aston-Martin and Jaguar, of the period. They are still manufactured, today, in stainless steel, to the exact same specifications. The company is named Hye-dra-cyl, in St. Charles, MO.
(*) 1) It is very important, that when rebuilding the Bendix calipers, you remove the piston, with air pressure, applied to the fluid line recess. Prying the piston out of the cylinder will inevitably, bend the guide pin and render it useless.
An item of equal importance, you should be aware of, prior to removing your piston assemblies
I have seen two or three instances, where all of the 3/4" bolts were equal length and the ones that fasten to the spindle hole which overlays the rotor, will bind on the rotor, unless an additional washer was installed under it.
The original Dunlop-Bendix caliper pistons are 2.125" diameter and have the
number 2780516 on the piston housing. There's also the size, in numerics,
near the pipe outlet, but it's too small to really be legible.
| In the late 60's, it became known that there was a larger size piston that
could fit the calipers, which was used on the Toyota Crown. Toyota Part# 47740-30011/ kit # 04479-30012|
This piston was 2.25" in diameter, bolted right up to the bridge and used the same pads.
Using the larger diameter piston on an Avanti can be beneficial,due to the higher hydraulic pressure, exerted on the pads. You can upgrade the master cylinder easily to larger than stock. The down side is if these are used on a Hawk, the 1" bore, master cylinder, isn't large enough to supply the caliper pistons without excessive pedal travel and there's not much out there, with a larger bore, to replace it with.
dip in light acid solution to derust
neutralize with a (base) baking soda/water solution
rinse in clean water
rinse again with alcohol to absorb excess water, trapped internally
Fill piston spring recess with brake fluid. This is very important, as even though there are vent holes, the piston sits sideways and air can get trapped inside, if you only fill and bleed the system. If air gets trapped in here, you'll never get a solid pedal
Lubricate and install the piston seal
Wet the inside of the bore with some brake fluid.
Place piston over pin and press lightly until you can pick up the entire assemble with your fingers. This indicates the pin has started into the piston recess.
Use a rubber mallot and piece of wood between your mallot and the piston. Protect the external pad retainer from damage.
Tap the piston toward the bore until the seal is slightly pinched between the two. The bore has a bevel to make it easier for the seal to enter, but it still needs help.
Use a blunt tool to press the seal into the bore hile pushing down on the piston.
Press the piston halfway into the bore, as you have to install the boot now. Some boots have a steel retainer ring to hold it onto the circumference of the cylinder , some do not.
Once the boot is in place, press the piston all the way into the bore. It's ready for installation in the bridge.
These can be installed in the up or down position, usually up so you can read the embossed stampings.
The crossover line goes from the lower port on the outside piston, across the rotor and up to the top of the inside piston. The brake line goes to the bottom of the inside piston.
(Click images for larger size)
Questions? Email Me
Some technical opinions are my own from experience, other informational data is from online sources with credits when available and while care has been taken to be as accurate as possible, it is offered only as a guide and caution should be exercised in the application of it.