Brake Lines

November 27, 2011

The brake line routing is going to be kept very simple and very light.  No rear brakes and no parking brakes. I used 3003-0 1/4" Versatube aluminum.  I also used some 1/4" Nylaflow tubing and fittings.

We'll start at the reservoir and trace it all the way to wheel brakes.  I used the Aircraft Spruce A315 aluminum reservoir and mounted it out on the engine side of the firewall for easy access. The little individual reservoirs that mount on the master cylinders were tempting but in the end,  I decided that this old man is just too darned lazy to be crawling up under the panel to check the brake fluid.  Here it is mounted for easy access from the left engine cowling door.:

The reservoir has a 1/8" pipe threaded opening at it's bottom. I used a straight AN816 nipple and 1/4" aluminum tubing to a 90 degree elbow (AN822) near the center of the firewall but just a little higher than the top fittings on the master cylinders.

Here is the penetration through the firewall:

On the other side of the firewall (see next picture) is a pipe threaded Tee fitting (AN917) so I needed this elbow to have pipe threads.  I couldn't find a bulkhead fitting like this with pipe threads so I just made my own.  I found a nut that was threaded the same as the fitting and cut it in half to make it thin.  Once the Tee fitting was tightened down on the other side of the firewall, the jam nut was tightened against the firewall, pinching the firewall between the nut and the tee fitting.

Here is the pilot's side of the firewall.

The firewall had some oil canning here at this point, so I fashioned a stiffener plate out of some .032 aluminum and riveted it in place with stainless steel pull rivets.

Here is an overall picture showing the hookups to the brake master on each rudder pedal. I used 4 Brass Male connectors (P/N 268P-04X02). Two of them went into the tee connector and one each at the top of each master cylinder.  The Nylaflow tubing was cut to be long enough that it will allow full rudder pedal travel. The hoses coming out of the bottom of each master cylinder is Aeroquip 303-4  hose and fittings.  Enough slack was left for full rudder pedal travel.  The 303 hose is held off the tunnel by a couple of adel clamps as shown below:

The bottom hoses from the brake master cylinders attach to bulkhead fittings at the bottom fuselage former at the aft end of the tunnel.

Aluminum brake lines are then used from the bulkhead fittings back to the top of each landing gear where again there is a bulkhead fitting.  Due to a small amount of flexing of the landing gear at this point the aluminum brake lines are run using a couple of nice looping 90 degree bends to give the tubing plenty of flex ability.  Note that the bulkhead fitting on the top of each landing gear is mounted at the aft end of the gear to allow for the maximum length of tubing run. This allows you to get the  larger looping bends needed to allow for some flexing of the gear leg.  The gear leg doesn't really move very far at this point anyway since it is right on the pivot point of the gear leg, where it attaches to the fuselage..

From the bulkhead fitting at the top of the landing gear, aluminum tubing runs down the inside between the gear legs and is secured with adel clamps to a couple of tabs welded to the aft gear leg tube   It then makes a small looping turn and goes into a 90 degree fitting on top of the wheel cylinder:

Addendum:  After some discussion with Bob, it was determined that the location of my main reservoir would cause some interference issues with the left magneto on the engine. Therefore I relocated the reservoir as shown in the picture below.  This will also allow easier access to it:

That's the whole braking system - pretty simple and lightweight.

Click here to go to the Fuselage index page

Click here to go to the Home page