HEAVY DUTY BRAKES
Installing and Bleeding Brakes
We had assumed that everyone would know how to install and
plumb the brakes on an EZ, and that everyone would know how to bleed the brakes. This has
not been an area of great problems but has been an ongoing support requirement. Recently
we saw a brake installation on a new Long-EZ that was done so as to make it extremely
difficult, if not impossible, to successfully bleed the brakes.
First of all, when you receive a new set of Cleveland brakes, the brake bleeder fittings will almost certainly be installed into both brake calipers the same way. In other words, you may assume you have two left hand or two right hand brakes. Not so 1 The bleeder fitting must be installed so it is on the bottom, or lowest point, on each brake caliper. You should never have a brake bleeder valve on the top of a brake caliper. So remove the one that will end up on top of the caliper and install it on the bottom, using teflon thread paste or tape. The 90° elbows should be similarly installed on the top of each caliper.
The brake plate, or brake caliper locator, a steel plate with a large hole in the center and 8 smaller holes punched a round the large hole and with two steel bushings in it, should be slipped over the axle and should seat snugly against the axle flange. If it does not, which is quite common, use a file or a Dremel tool and radius the large hole in the steel plate until it will fit tightly against the axle flange. Choose the appropriate 4-hole bolt pattern (you have two choices) and bolt the axles onto your main gear strut. See CP34, page 11 for a clear photo of the left main wheel and brake on a Long-EZ installed correctly. Also see the sketch below.
(Click to enlarge)
Now, when you are ready to bleed the brakes, a really handy gadget is a Cleveland brake line bleeder tool (part #87-5) currently $21.30 in the Aircraft Spruce catalog. Install an 18" long flexible rubber or tygothane hose on this tool and connect the other end of the rubber hose to the nozzle of a large oil can with a trigger-type pump. Fill the oil can with Dot 5 automotive 100% silicone brake fluid, usually purple in color and made by most brake fluid manufacturers including GE which is the one we used. Now, remove the rubber bleeder cap and install the 87-5 tool onto the brake bleeder valve. Using a 1/4" wrench, loosen the bleeder valve 1 to 2 turns. Pump the silicon brake fluid until the master cylinder reservoir is 3/4 full and tighten the bleeder valve (be gentle, this is a tiny little valve!). Remove the 87-5 tool and your brake is ready to fly. Since the whole system goes continuously uphill, there will not be any air in the system. Due to the small size and throw of an aircraft-type master cylinder, it is almost impossible to fill the brake master cylinder and line from the top as you would in an from automobile. Using an 87-5 tool and filling the bottom mounted brake bleeder valve, bleeding your EZ brakes is quite literally a 5 minute or less job. It helps to have an assistant watching the level in the master cylinder reservoir so you can quit before you pump fluid all over the place.
We highly recommend the 100% silicone brake fluid (must be Dot 5). Since it is completely inert, compatible with any type "O" rings and seals. It is not flammable and it does not destroy your paint as normal aircraft brake fluid does. We bought it at a Hot Rod-type auto parts store locally.