Heinkel Brake System Part 5- Adjustments

Adjustments are the final step in having better brakes. We’ll start with bleeding the brakes and wrap up with adjustments.

If you've installed a new master cylinder or wheel cylinders you’ll have to bleed out the air that is now in the system. As I mentioned in a previous post, air in the system leads to bad performance, as air compresses much more than liquid brake fluid.

One way to get rid of air is to vacuum it out using a Mighty Vac or similar product. To do this you attach the Mighty Vac to a bleeder port while the port is still closed, pump the Mighty Vac about 30 times to build a up good vacuum pressure, and then crack the bleeder valve open. This will immediately start to suck fluid and air out of the system. The problem with this method is that it can suck the reservoir dry and reintroduce air back into the braking circuit. If you have a friend helping you can keep the master cylinder topped up and you might have a chance of successfully completing the process. I’ve tried it by myself and found it very difficult. As appealing as it sounds I would pass on this method.

Another option is to use the Mighty Vac as a pump and pump fluid into the system to replace whatever air is there. The drawback of this approach is that it spews corrosive brake fluid into the car through the vent hole in the master cylinder (this is because you have the reservoir fill cap off and fluid pops up through the hole). Once again you might be able to get it to work with a friend, but I’d be wary about damaging your paint.

This leads us to the third method, which is described in the original Workshop Manual. Let’s call it the “Jelly Jar Method” for now. In this system you take a jelly jar and add about ¾ inch (15cm) of brake fluid. Then, take a clear plastic hose (I use 3/16” inside diameter tubing from the hardware store) and insert it into the jar with the end covered by the fluid. Attach the other end of the tubing to the bleeder port.  You’ll pump the brakes until bubbles cease coming out of the hose end in the jar. 

The Heinkel Brake "Jelly Jar" Method of Bleeding Brakes

You know I love step by step instructions, so here’s how this works:

1.     Fill the reservoir with fluid up the bottom of the cap threads;

2.     With one hand get under the car and crack the bleeder with an 8mm wrench

3.     Slowly and deliberately pump the brake pedal with your other hand. Yes, you can actually  do both of these things at the same time by yourself as a one person operation (although your 
  back may object)!

4.     Close the bleeder valve

5.     Repeat the Open-Pump-Close-Release cycle twice

6.     Refill the reservoir with fluid (you can only get three full pumps before you risk emptying    the reservoir)

7.     Once you are only pumping fluid, pump a couple of cycles to be certain that there is no air  left in the system.

Add Fluid to Bottom of Screw Threads

You can verify that there is no air in the system by giving the brakes a good pump and holding he pedal down. If the pedal continues to sink you either have air in the system or a fluid leak.

With the brakes bled you can start on the wheel adjustment. The goal here is to have both front wheel brakes engage at the same time.

With the car still raised turn one of the wheels. You should not hear any rubbing sound. Now use a flat bladed screwdriver to expand the adjusters on the wheel cylinder until the pads start to scrape against the drums. You do this by sticking a screwdriver in one of the access holes and turning it either up or down. Use every bit of spatial knowledge you have to figure this out. Since it always confuses me I’ve supplied a cheat sheet below on which way to turn them:

From under the car:

Left wheel:

• Top hole: Push the adjuster up (or to the right) to back off the adjuster.
• Bottom hole: Push the adjuster to the left to back it off

 Right wheel:

• Top hole: Push the adjuster towards the back of the car to back off the adjuster
• Bottom Hole: Push the adjuster towards the front of the car to back off the adjuster

Slots in brass adjusters can be seen through holes

The instruction manual says to start with the “leading” shoe, I have no idea what that means nor has anyone been able to tell me, so I adjust the bottom ones first. 

Turn the adjusters until the brake shoes make a noise, then back them off just enough so they are silent when you turn the wheel. This is why absolute cleanliness and easy operation of  the adjusters is key; it will be impossible to turn the adjusters if they don’t already move easily when you install them in the car.

Do this on both wheels, now go out for a drive. As you drive pick a spot where you can press hard on the brakes. The car should not pull to one side. If it does, that means the side that is pulling is overadjusted, You may have to fiddle with it a bit, but that’s the essence of brake adjustments.