| Home | Articles | CP reprints |

HEAVY DUTY BRAKES
From CP52, Page 4 (July, 1987)

     If you elect to install the larger brakes as strongly recommended in CP51, there is a possible problem to watch out for. If you have not installed the wheel pants, the easiest way to take care of the problem is to order two special steel spacers from Brock . The part number is A484-187. These new spacers will be installed on the axles first, then the main wheels will be installed normally. This will space the wheels 3/16" outboard.
     If you already have wheel pants installed, watch for an interference between the wheel/tire and wheelpant. The amount of interference will depend on how tightly fitted your wheelpant is. The only alternative to this fix, which will not affect the wheel-to-wheelpant fit, is to make new, longer locator pins and install them in the brake calipers. This requires some machining capability as well as lathe and thread cutting capability . We did go this route and we simply removed the locator pins by removing the nuts and pressing the pins out. We carefully measured these pins and machined up four new ones, but made them 1/4" longer. This will cure the potential problem without causing any wheel-to-wheelpant interference, but is much more difficult to accomplish than the first option of using the two Brock spacer rings.
     The reason for the above change is the possibility of the brake caliper locator pins pulling out of the fixed brake plate, thus allowing the brake caliper to rotate. This has already occurred in one case and it caused considerable damage to the wheelpant and the gear strut. Look carefully at the brake caliper and disc and you will see that as the brake linings wear down, the brake caliper will move inboard, away from the wheel and disc, If the brake linings are allowed to wear all the way down to the rivets, the locator pins may pull out of the steel bushings in the fixed brake plate - This is a real GOTCHA so don't ignore it if you have the heavy duty brakes.
     NOTE: This will not occur if you are still using the standard 500x5 Cleveland brakes. However, we feel very strongly that any Long-EZ should use the heavy duty brakes (part #199-152, see CP51) and even some of the heavier VariEzes probably should be using them.

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.
wpe1B.gif (15000 bytes)(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.