Can you replace rear drum brakes with disk brakes?

Answer 1

AnswerAnything is possible. However, you may or may not have a great deal of difficulty in doing a proper conversion, and here's why...

First off, the Knuckles need replacing. For Drum brakes, you have knuckles that accommodate the installation of the Wheel Cylinder, Backing Plate and brake Hardware, whereas for Disc brakes, the knuckles only have the mounting through-holes for the Caliper. Also, the Wheel Cylinder will most likely be fed by a hard steel brake line which would have to be cut down and a flexible Brake Hose (Rubber or Braided-Steel is fine) installed on the end.

Second, you will most likely need to replace your Parking Brake (sometimes inappropriately referred to as "E-Brake") cable, especially if you are installing an integral caliper. This, however, is usually an easy fix that can be remedied at your local junkyard.

Third, Drum brake Wheel Cylinders take considerably less force to operate than Disc brake Calipers do (ie., Drums at 40psi to stop from 50kph in 5 sec. -vs- Discs at 90psi). To accommodate this on your vehicle, you have a Proportioning Valve which directs more or less pressure toward the front or rear of your vehicle, depending on the amount of pressure applied as well as how quickly you depress the brake pedal. On the Ford Contour/Mystique the rear brake lines utilize a Pressure Reducer which reduce brake pressure, so the Proportioning Valve in the Rear Drum and Rear Disc model vehicles are the same. Most vehicles are not like this, however, and if you replace all of the appropriate rear hardware without taking this valve into account, you will be replacing your rear pads and rotors quite often.

Lastly, if you have ABS, then that could be a whole other animal. But the best way to find out what you need to do about converting your Rear Drum brake system with a Disc brake setup is to consult others who have successfully done the same. Try to find an Enthusiast website like a *.org or a local group where others with your model vehicle discuss similar transitions.

Be absolutely sure that you have acquired everything that you will need before taking your vehicle apart. The brake system is one of the most under-rated systems on your vehicle as to its importance and must not be compromised or assembled in a shoddy manner, especially when altering brake lines.