Hydraulic brake issues , again !!!

[Sonex541]

Sonex brake issues , well after a few months of using the Sonex brakes , I had no brake pressure and noticed fluid running down the tire , I pulled it all apart and noticed it was leaking from the o ring I pulled the brake pucks out and noticed both cylinders were gauged and scored and caused the o ring to fail , I pulled the other side apart and same thing ,but not bad enuff to start leaking , I contacted Sonex and they said to use a caliper hone and hone all four cylinders and replace the o rings , well it happened again today , 20 hours later , it seems as tho the brake pucks are rubbing or hitting the inside of the sleeve when the brakes are applied , once the pucks wear out and the piston comes out farther is when it reaches the score or gauge and leakes , one cylinder looks as it was wet sanded thats how smooth it is and the other is a gauge that is deep ,
Calling Sonex ASAP
Has anyone else had this issue , , the calipers are pretty much junk now ,I'm sure they couldn't stand another honing , ,
Adam Simmons
Sonex541

[hickej]

Mine have been working fine for over 80 hours.
Jim W0162 3300 TD

[mike.smith]

Maybe as a group we can find the problem. I have only just installed mine, so have not used them yet. I'll simply add some food for thought.

If the pucks (the pads that contact the rotors) are going far enough into the calipers to score the sides, then it seems like they are traveling too far into the caliper holes. They should only be traveling a fraction of an inch in and out.

I added a fat washer between the caliper body and the inside wheel dust cover.
http://www.mykitlog.com/users/display_l ... 8167&row=7
Sonex does not mention this, but as others have found, if you don't do this then the rotor (the friction plate on the inside of the wheel hub) will make extreme contact with the pucks/pads right from the start, and in fact (in my case anyway) the brake caliper body will also make contact with the outside edge of the wheel. But that washer/spacer is only about 1/16" to 3/32" thick.

Even with this washer, my pads are lightly touching the rotor. I know this is the way automobile brakes work, but I asked Sonex if this was OK, and they said yes, that is normal, as long as the contact is not excessive and does not provide braking when the brake isn't being applied. In this configuration the pucks should only move a fraction of an inch outward when the brake is activated. Therefore the pucks should never be pulled back far enough into the caliper body to cause scoring that would reach the area of the plunger and O-ring, which are well inside the holes.

So I will simply venture a guess that perhaps your pucks are set up so they are inside the caliper body with an air gap between the pucks and the rotor, and that excessive travel is what is scoring the sides to the point that they affect the O-rings.

Just a hypothesis...

Mike Smith
Sonex N439M

[Sonex541]

Hi mike I'm goin to send you a few pics from my phone so you can see , the brake puck sits inside the caliper a bit. , and that's what is causing the groove and wear , wait till you see the pics , your going to. Be shocked ,

Also are you keepin the Sonex at minute man cause I flew a navy n3n into minute man for lunch today , and someone said there is a Sonex based there ,
Thanks Adam Simmons

Also can you post the pics I'm sending you so other people can see it , I can't post pics from iPad
Thanks again

[Sonex541]

Also I have few hundred landings on these and when the puck get worn the piston is goin to have to travel farther out , but in my case the pucks are not even worn down at all , I was one of the first few people who installed the brakes and I contacted them about the issue of them not fitting right unless a washer was installed and they said it was fine , and I was the first one to have a issue , but now every one had issues unless a washer was added , let me know what you think of the pics , the pic I sent you is the left caliper so it's the forward part that is worn and the rear cylinder has a groove worn in it ,

[hickej]

I did not need the spacing washer. When I put my wheels on I was able to push the brake pads down and there was clearance enough for the wheel to spin freely. Of course when I bled the lines, the pads now touch the disk but the wheel is free to rotate. I looked at your pictures (Mike Smith) and saw where you put the washer. There must be some variation in the setup though I can't think of what that would be. Could the brake pads themselves be a different thickness causing the puck with O ring to bottom out? I will keep an eye out for the issue and take my brakes apart at my next annual. Sorry that you're experiencing trouble but mine went right on without a hitch. Please post pictures of the groove so we can see what to watch out for.
https://m.youtube.com/watch?v=RRZIaTf5G3c
Jim

[mike.smith]

Hi mike I'm goin to send you a few pics from my phone so you can see , the brake puck sits inside the caliper a bit. , and that's what is causing the groove and wear , wait till you see the pics , your going to. Be shocked ,

Also are you keepin the Sonex at minute man cause I flew a navy n3n into minute man for lunch today , and someone said there is a Sonex based there ,
Thanks Adam Simmons

Also can you post the pics I'm sending you so other people can see it , I can't post pics from iPad
Thanks again

I got the photos. The wear pattern seems totally lopsided to one area. I wonder if that has anything to do with it, and what might cause that? I also wonder if the pistons (with the O-rings) should have the O-ring installed way near the bottom of the piston body instead of near the top, to keep the O-ring away from the wearing surfaces. That would be a design change.

Mike

[Sonex541]

Hi mike glad you saw the pics , isn't it weird and both sides are worn in the same spots ,the anodized is worn same forward piston wear and rear groove wear , it's from the brake puck rubbings against the inside , and everytime you brake the force of the rotor spinning is putting force toward the front of the plane and when you apply the brakes it's wearing the inside of the caliper out ,, I'm curios has any one else pulled there's apart to see , I do have a few landings on them but jeez to wear out in that amount of time , also I think as the puck wears out its going to get worse cause the piston is goin to move more to compensate for the wear on the puck ,, I dunno , I'm not a happy camper with this setup ,
Adam Simmons

[Sonex541]

Mike can You post the pics please for me cause I can't post them thru my I pad
Thanks mike

[mike.smith]

Hi mike I'm goin to send you a few pics from my phone so you can see , the brake puck sits inside the caliper a bit. , and that's what is causing the groove and wear , wait till you see the pics , your going to. Be shocked ,

Also are you keepin the Sonex at minute man cause I flew a navy n3n into minute man for lunch today , and someone said there is a Sonex based there ,
Thanks Adam Simmons

Also can you post the pics I'm sending you so other people can see it , I can't post pics from iPad
Thanks again

OMG! That was you! I walked right past you on the way to the hangar to get some things to take home! I stopped and took two pics of your N3N! Small world!

Mike