ZS-UDT again hydraulic brakes etc.

[jantar]

Hi all you helpful folks. Am now in UK for a while but before I left SA I am pleased to say that I gave UDT some taxi trials on the dirt runway. So far so good but now is the start of serious bureaucracy. For interested parties I fitted cycle hyd. disc brakes---Haynes--calipers & lever.There are some problems.The volume of a single lever master is marginally adequate to drive 2 calipers, especially as the pads retract after braking(unlike automotive ones). First taxi trial ended with no brakes and a desire to have a hooter!! Modified by substituting a motor cycle front brake master & lever, but this has to be mounted horizontally,so is actuated by a bowden cable between the lever on the stick and the horizontal M/C lever. Copied from Carat M/G. Definitely better but not yet fine tuned & no park facility yet. As have no help for prop swinging use chocs & devised a method of withdrawing same from cockpit---really heath but it works safely. Some photos soon--I promise. Jantar

[RobW]

Hi Jantar - thanks for your post. I look forward to seeing your pictures.
I had a nice hydraulic system on my previous aircraft (a skyranger microlight). It used a single master cylinder and a plastic hose to each caliper. Worked very well, was simple and lightweight. Parts etc can be obtained from flylight. (www.flylight.co.uk). I haven't had to give it too much thought but I think it would transfer across to the Nipper fairly easily if required.
Regards,
Rob

[Neil Spooner]

Your pistons retracting back into the calipers will be caused by excess "wobble" of the disc, maybe down to disc runnout of the disc or wheel bearing play. Pumping the brake lever should get the pistons back out, but it depends on the amount of runnout. Automotive pistons do retract themselves, this is done by the square O ring that deforms as the piston is pushed out, the O ring grips the piston and retracts it slightly......at least it should do if the piston is not partially seized!

Neil