Brake Line Routing at the Caliper

[jaredyates]

I'm getting ready to reconfigure my brake line routing, and while I'm there, I was thinking about changing the way the line comes into the caliper. The caliper is mounted vertically, on what I would call the front of the wheel. The brake line attaches at the top of the caliper, and the bleeder is at the bottom. I was visiting another builder recently who did it the other way around, with the line entering the caliper on the bottom, and the bleeder on top. In either case, the line attaches to the caliper with a 90-degree AN fitting pointed aft. Having the bleeder on top seems to make sense for two reasons- a more clean line routing, and easier bleeding. It seems like any air bubbles trapped in the caliper would travel up to the fitting instead of traveling up into the lines. Has anyone tried it this way? Is there an obvious (to everyone else) reason why this would not be a good idea?

[DRLPatrol]

Airplanes are usually set up to bleed from the caliper TO the master cyl, while cars are the other way around. To bleed the system you pump fluid from the bleeder(lowest point in system) up though master to reservoir. If you change the route at the caliper now your master is going to be backwards, as far as bleeding is concerned. Check the lines on your master. The pressure line should come off the bottom, supply from reservoir to top. A friend of mine built an RV and mounted the masters upside down because they fit better, PITA to keep those brakes working right.

Doug

[Zzz]

I'm getting ready to reconfigure my brake line routing, and while I'm there, I was thinking about changing the way the line comes into the caliper. The caliper is mounted vertically, on what I would call the front of the wheel. The brake line attaches at the top of the caliper, and the bleeder is at the bottom. I was visiting another builder recently who did it the other way around, with the line entering the caliper on the bottom, and the bleeder on top. In either case, the line attaches to the caliper with a 90-degree AN fitting pointed aft. Having the bleeder on top seems to make sense for two reasons- a more clean line routing, and easier bleeding. It seems like any air bubbles trapped in the caliper would travel up to the fitting instead of traveling up into the lines. Has anyone tried it this way? Is there an obvious (to everyone else) reason why this would not be a good idea?

I wouldn't want my brake line underneath unless it was really low profile. The 90 degree fitting might help with that, but the way I've plumbed mine at this point in time, it would present a lasso for catching sticks or rocks, or be easily sheared off if it does come close to debris. This is obviously only a consideration if you are planning on operating on nasty surfaces.

[stinger]

Jared. There are several methods. My biggest concern is ground clearance for the break line given the conditions in the back country bush. Stinger

[tailwind]

I have plastic lines on mine. The line is mounted on the top of the brake cylinder. When bleeding the lines you can watch the air moving up the lines to the master cylinders.

[jaredyates]

Here's what it looked like. Damage vulnerability did not seem like a concern.

[DRLPatrol]

What is on the rotor, paint? Looks odd, I take it the airplane is not flying.

Doug

[jaredyates]

The plane in the picture is not yet flying. I can't remember if it had paint on the rotor or if it just looks odd from the picture. I decided to route the line as before, with the bleeder on the bottom, in part because I was able to still come up with a fairly clean installation by adding a tab or two. I'll post a picture in the coming days when my progress is more clearly visible.

[N942VT]

Put the line on top Jared and keep it tight, better for landing in the weeds and pressure bleeding.

[Battson]

When you fill the brake system by pumping up from the bottom the way I got taught to do it, having the bleeder at the top would make life harder.

I like the method of pumping the system full from the bottom upwards, because there is basically no way air bubbles can get trapped in the system.