How to Bleed Your Fox Body Mustang’s Brakes
Bleeding your brakes is essential to properly maintaining your Fox Body
The brakes are a critical component of any motor vehicle and as such, it is important to keep then in good running order. This warning should go double for any owner of a Foxbody Mustang, as, while the factory brake system does work, many find the factory disc/drum combination to be underpowered. Rotors, pads, drums and shoes (the springs as well!) should be periodically checked and replaced when worn below their minimum thickness. All of the maintenance above, however, is pretty simple and doesn’t require bleeding the brakes afterward.
When should I bleed my Mustang's Brakes?
However, anytime a caliper, wheel cylinder or the brake line itself needs to be replaced, upon reassembly, all the brakes will need to be bled. Basically, any time a brake line is exposed to open air, it will need to be bled afterward. A second scenario requiring the lines to be bled is if the fluid in the master cylinder and reservoir gets below the minimum level (either by boiling off under hard braking, or leaking somewhere). Air trapped in the lines leads to a spongy brake pedal and ultimately less braking power, as air can be compressed whereas brake fluid cannot.
So, this leads to the question, how do we bleed the brakes on our Foxbody Mustangs? Well, it’s actually not too difficult. However, an assistant will be required!
Required Materials to Bleed Fox Body Brakes
* Fresh brake fluid (unopened) 1L or more, DOT 3 or 4
* Catch jar or aluminum can (I like jam jars the best)
* Clear plastic tubing
* 3/8” wrench and socket
* An assistant (willing or unwilling… doesn’t matter)
* Penetrating oil (WD40, Jigaloo, Super Wrench, etc.)
The Brake Bleeding Procedure
The easiest way to do this is to have all wheels off at the same time and the car resting on jackstands (4 jackstands). If this is not possible, no worries, you’ll just have to lift one corner (or one half of the car) at a time.
When bleeding Foxbody brakes, you always start with the brake that is the farthest away from the master cylinder and end with the brake that is the closest. In this case, the order for Fox Mustangs is to start with the passenger side rear brake, then the driver side rear brake, passenger side front brake and finally finishing with the driver side front brake.
The job of the assistant is to sit in the car and pump the brake pedal when called to.
1. Open the new jug of brake fluid and top off the reservoir in the engine bay. Leave the cap off the reservoir. Also pour some into the empty catch jar. Just pour enough that one end of the plastic tubing can be submerged.
2. With the vehicle properly resting on jackstands, look for the brass bleed nipple on the back of the wheel cylinder. As always, lefty-loosey and righty-tighty. Quite often, the bleed nipple becomes gummed up and difficult to turn. Spray it with penetrating oil and let it sit. I find to initially loosen the bleed nipple it is easier to use a socket, and has a less chance of stripping it. It is very important that we don’t strip the nipple (which is easy to do as it is brass and thus very soft). Another trick if it is being stubborn is to actually try tightening it first before loosening.
3. With the bleed nipple loose, snug it back up with the wrench.
4. Slip one end of the clear plastic tube over the bleed nipple and drop the other end into the catch jar. Make sure the end in the jar is submerged in fresh brake fluid.
5. Now, have the assistant (who is in the car) pump the brake pedal a few times and then hold it to the floor.
6. With your assistant holding the pedal to the floor, loosen the bleed nipple just enough that fluid travels out and through the tube. You should be able to spot air bubbles in the tube.
7. Tighten the bleed nipple back up and have your assistant release the pedal. Repeat this procedure several times, pumping out the old fluid. However, keep a vigilant eye on the fluid reservoir up front. Top it up as needed. (every 3 pumps of the assistant I go and check the reservoir).
8. When there are no longer air bubbles coming out of the bleed nipple, tighten the nipple. That line is bled. The safest best however is to wait until the fresh fluid starts coming out. This way you know all the old fluid in the line has been replaced with new fluid.
9. Move on to the next wheel, as described at the beginning of the section.
Again, I want to stress how important it is to make sure the reservoir never gets too low. If it does, you will have to start over, as air will have entered the system again.