Over the years, I've experimented with all sorts of methods to bleed air from the brake lines. Even the slightest bit of air in the lines can lead to a soft pedal and poor brake operation, so proper bleeding is critical. None of the one-man gadgets or methods have impressed me in the past. I've used a WillysPoints
, some method is needed to pressure bleed the brake system without a helper.
This is where Speed Bleeders
come to the rescue. They automatically function the same as manually opening and closing the bleeders but without the hassle. I've always been skeptical of such gadgets, but they worked flawlessly. Speed Bleeders replace the original bleeder screws at each wheel cylinder with absolutely no modifications needed. I picked up a set at my local parts store (NAPA #675-1567, 2 per package). They can also be ordered online
from the manufacturer. My CJ-2A's wheel cylinders have bleeders with 1/4"-28 threads (Speed Bleeder #SB1428). Do other year or model Jeeps have the same threads? The answer is a firm, definite maybe. My '51 wagon also has the same size, but doublecheck your existing application due to potential changes over the years or non-stock parts.
Here's a close-up of a Speed Bleeder. There is a spring-loaded check valve inside, but it is important to understand it is only active during the bleeding process. When the brakes have been bled and the Speed Bleeder is tightened with a wrench, just like a normal bleeder screw, the tapered tip on the end mates with a matching seat in the wheel cylinder. This metal to metal contact at the tip forms the seal for normal brake operation. The check valve portion is just going along for the ride except when bleeding is performed. When the Speed Bleeder is loosened for bleeding, brake fluid and/or air escapes around the tapered seat and to the bleed hole on the side. Pressure at the bleed hole forces open the internal check valve so that brake fluid and/or air can travel to the opposite end where a drain tube is connected. Note the sealer on the threads. This prevents air from leaking back into the system when the brake pedal is released and the check valve closes:
No special equipment is needed when purging air from the lines with Speed Bleeders. At the front brakes, there isn't a lot of room to attach the drain hose. While not mandatory, a 90 degree fitting makes the job much easier. While I no longer bleed brakes with a vacuum pump, Mityvac includes this handy part with their kit
. You will also need some means to depress the brake pedal. This does NOT mean to inflict tales of woe upon it, but rather to physically push the brake pedal, for which a normal human foot works exceedingly well:
Installation of Speed Bleeders is a piece of cake. Remove the old bleeder screws and thread the Speed Bleeders in place. A few drops of brake fluid may spill, but this is not a big deal. Here you can see the drain hose attached to the newly installed Speed Bleeder. Loosen the Speed Bleeder approximately 1/4 turn and slowly depress the brake pedal. Applied fluid pressure will force open the check valve and fluid will drain. I'm using an empty container to catch the old brake fluid for disposal. When the brake pedal is released, line pressure drops and the check valve closes. Repeat the process until all air is purged and then tighten the Speed Bleeder. Move on to the next wheel and repeat. This mimics The Man & A Boy Method of manually opening and closing each bleeder, but is fully automatic and doesn't involve any inappropriate language:
A few precautions are in order during the bleeding process, whether or not Speed Bleeders are used. Follow the service manual to adjust the freeplay in the linkage to the master cylinder. If the freeplay is excessive, the pedal will travel too far before the piston starts to move. This limits the effective travel of the piston. If freeplay is too tight, the piston won't fully retract when not in use. This will limit the amount of fluid from the reservoir entering the piston bore for the next brake application. Once again, brake effectiveness will be reduced. Freeplay is measured at the pedal and is adjusted by changing the length of the pushrod entering the back of the master cylinder:
Adjust the brake shoes
to compensate for normal wear. Remember, these brakes are not self-adjusting like on newer vehicles. Adjustment of the brake shoes won't have any effect on the air in the lines, of course, but it will reduce the amount of pedal travel before the shoes contact the drums. The net result is a firmer pedal and better braking action. As a last note, don't let the reservoir run dry during the bleeding process, or entire procedure will have to be repeated. This picture shows the handy remote master cylinder reservoir
being replenished. Note the old blanket on the fender to protect against any spills: