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At 10:27 PM 1/29/02 -0500, Alan Fairclough wrote: >Lately I have noticed a problem with my brakes. The 'lately' is a clue. I'm assuming that the Cleveland conversion was done right. That is, the hard-line leading to the brake-block has been removed and replaced with a hose (originally there was a hose only at the knuckle joint). Cleveland brake blocks 'float' so require hose all the way between the brake block and the fitting that comes out of the wing. Otherwise, they'll drag. And eventually bust the aluminum line. Another clue is that the problem is implied to be symmetrical. That means it's somewhere before the tee under your butt, which kind of eliminates the calipers. Outside chance, I guess, of brake fluid that has been contaminated, and has turned into a sticky, gloppy mess. Or the wrong kind of brake fluid. You DID use the right kind, right? >They work great and hold just fine but when I try to back the plane into the >hangar they do not release completely and it takes all my pushing to get the >plane to move. When I pull the planer out next day they are OK. >I am thinking maybe an air bubble in the system that is keeping pressure in >the lines. Maybe it is the master cyliinder check valve that is sticking... An air bubble keeps the brakes from working (i.e., sponginess). It doesn't stop them from releasing. One thing to try. Hook your toe under the pedal, and see if you can lift it up. If you can, something is amiss. The problem might be physical. The most frequent failure mode for the master cylinder is right at the shaft. If it's seeping a bit there, the sticky brake fluid could easily keep the master cylinder from returning properly. What about a weak return spring in the master cylinder? Or maybe something has compromise the parking brake, and is causing it to stick. Do you have the more common cable arrangement (which can be interfered with by a loose bit of interior), or a parking brake check-valve (which could get obstructed). Now, if the brake line between the master cylinder and the tee under your butt is obstructed or kinked, the brakes might work (stomping on the brake makes a LOT of pressure) fine, but the flow of fluid back to the master cylinder might be slower than it should be. Take up the floorboard on the pilot's side and see if something went bad there. Maybe blow that line out with compressed air. >Any suggestions which I try first? Alan, if you're going to dig into that area, you may as well call Lee at Skyport and get the new master cylinder STC. Chances are 2 in 3 that it has to do with that component anyway. Damned thing is 56 years old! And even checking out the state of the lines (beyond physical damage) involves doing 80% of the work of installing the STC. 80% of the work is lifting the floor, reassembling it, and bleeding the system. Be smarter than I was: get the improved brake reservoir STC at the same time, to eliminate the stupid PET milk container. Again, once you are pulling things apart and bleeding the brakes, might as well set them up first-class while doing that 80% overhead. Oh, you'll likely need the hose that runs from the master cylinder to the hard-line. Yours will be cracked and rotten, and you won't want to re-use it. Besides it will have to bend into a different shape for the new cylinder anyway, and after all these years, it has taken a 'set' that will fail it when you try to install. So order up that hose. The length is a little different. If your A&P is set up to make up custom hoses, so much the better. Get the bits from Aircraft Spruce and sort it out in the field. Let me tell you, you WILL love the way the brakes feel with the STC. Nice, smooth, progressive feel that allows for lots more shades of grey between 'off' and 'locked.' Every bit as good as a 'modern' plane. Just do it, because it's winter and not great flying now. Believe me, it's better than spending a good flying weekend doing the STC after your ancient master cylinder explodes during the summer. And you're going to be doing a recto-cranial inversion to get under there anyway. Trust me, it's not so much fun in July! Greg ==^================================================================ This email was sent to: [EMAIL PROTECTED] EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiLm.aVzvvT Or send an email to: [EMAIL PROTECTED] T O P I C A -- Register now to manage your mail! http://www.topica.com/partner/tag02/register ==^================================================================
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