I had been meaning to post this to the forum and Area-51’s email jogged my memory. I recently replaced the original mono master cylinder with a unit that has a built in reservoir. See photo. I never liked the idea of continuously bringing DOT3 brake fluid into the cabin to top off the master cylinder due to brake pad wear. The new unit has more than enough brake fluid capacity in the reservoir such that it shouldn’t require refilling even with completely worn down brake pads. Since the new unit mounts forward of the original, I fabricated a rail in order to utilize the original mounting holes in the tunnel. This left room for the installation of a hydraulic line-lock parking brake. The plunger of the line-lock uses the existing filler hole on the top of the tunnel. The side of the classic cockpit module tunnel is approximate 15 degrees off vertical. To allow the plunger to be perpendicular to the top of the tunnel I canted the line-lock by the same amount on the mounting rail. See photos. The new master has a smaller piston which really improves brake performance. It’s really quite remarkable. I am finally able to hold the plane without undue effort during the run up when cycling the CS prop at 4300 rpm. In fact, the parking brake holds up to 5000 rpm. So happy to be rid of the wedge I use to stuff into the slot as a makeshift parking brake. The operation of the line-lock is so simple; pull back on the brake lever and simultaneously depress the plunger, then release brake lever. To undo the parking brake simply pull back on the brake lever. That’s it. And the beauty of the design is such that you can’t inadvertently set the parking brake. I did have to replace the spring, which serves to push the plunger back up, with a softer one as the original one wouldn’t allow the plunger to remain depressed when I released the brake lever. Additionally, I replaced the original bulky rubber knob on the plunger with a low profile one (just a screw actually). Came out nice IMHO. I purchased the unit from AliExpress for less than $10 US. The Jamar parking brake was a bit more expensive at $60, although knockoff are out there for much less. Erich Trombley N28ET Classic Mono 914 E-Props CS
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