Brake issue

[LarryEWaiex121]

I have had the Aeroconversions hydraulic brakes almost since they came out. They have probably been in use about 550 flying hours.
I've been loosing brake pressure slowly the last few flights that required a couple extra pumps to get brakes to hold.
Checked for leaks and nothing. It was possible though to see air in the brake tube lines. This has always been an ongoing problem that forces me to bleed the lines a couple times a year.
Back to the story. Sunday I pulled the brakes apart after coming back from a morning breakfast flight. Changed engine oil and filter and then got into the brakes.
The pilot side caliper is badly worn on the back hole. The damage is a fairly deep gouge on the front (axle) side of the rear hole.
It would seem if the piston is moving in relation to the puck and rotor interaction the gouging would be on the rear of the caliper, but that is not the case. It's on the front.
I've never spoken with any other Sonex owners about their brake experiences. I'm not impressed with the overall durability of the package. I change pucks and rotors at virtually every condition inspection. The steel rotors are very high wear in my experience with them. I fly about 100-120 hrs a year and that's about all they seem to be good for.
I run them till the rotors are just about flush with the shoulder bolt heads. Never into the bolts.
Like to hear from anyone that's had similar issues and what they did to correct it, or did the caliper just get replaced and start over?

Larry

[DCASonex]

Larry, I do not have the Sonex hydraulic disk brakes, but before those were made available, (and when Sonex was telling all that better brakes would tip a tail dragger on its nose) I installed Great Plains (now O'Keefe) Full floating caliper disk brakes. They have one very small puck on each side of the disk, that squeeze the disks, not try to push them off the end of the axle, that looked like they would have the life expectancy of a snowball in h**l, but after 9 years and 450 hours, I still have the original pucks in place and the disks look great, Must be something about the Sonex design that accelerates wear.

David A.

[builderflyer]

Hi Larry,

I'm really not understanding what damage you are referring to.........a photo would be helpful. But your wear experience is totally different than mine. There are well over 400 hours on my Aeroconversions hydraulic brakes and the pucks are still in decent shape. No need to replace them as of yet. The stainless steel rotors have worn to where the bolt heads have worn somewhat as well, but not to where I would worry about it. At some point in the future I can see needing to replace both the rotors and the bolts but that's still a ways off.

I've never been able to bleed all the air out of the system but there aren't any air bubbles noticeable in the lines. There is a bit of sponginess in the application of the brakes and they will pump up a bit with a couple of pulls of the lever.

Overall all, I really like this hydraulic system compared to the original mechanical brakes. I did have one scary incident, however, when one of the brake lines popped of of the master cylinder when the mechanic (me) failed to have the line fully inserted into the fitting. This, of course, resulted in a total brake failure at the worst time as I had landed long and hot with little runway left. Fortunately, I was able to make a rapid u-turn to the parallel taxiway without hitting anything. It was very impressive as to how quickly one can turn a Sonex without catching a wingtip on the pavement, or groundlooping it for that matter. It felt very much like driving a go-cart at the track.

Do you have a photo you can share?

Art,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,Jabiru 3300 #261

[gcm52]

I have the Sonex hydraulic disk brakes in my Onex and they cannot hold the plane to do a proper runup with the Rotax engine I have installed. I am looking to upgrade the brakes. Has anyone upgraded to something they are happy with? I looked into Beringer brakes but they are expensive (maybe $2000) and they would not adapt easily to the Onex axle setup. I have a trigear and am not worried about too much braking power.

[WaiexN143NM]

hi george,
take a look at matco, see what they have to offer.
www.matcomfg.com

WaiexN143NM
Michael

[sonex892.]

I have the Sonex hydraulic disk brakes in my Onex and they cannot hold the plane to do a proper runup with the Rotax engine I have installed. I am looking to upgrade the brakes. Has anyone upgraded to something they are happy with? I looked into Beringer brakes but they are expensive (maybe $2000) and they would not adapt easily to the Onex axle setup. I have a trigear and am not worried about too much braking power.

I have had great plains brakes on both my present sonex and previous sonerai. They hold the 3300 jab at full power. As for them fitting the Onex it looks to have the same landing gear setup as the Sonerai, so should be an easy fit.
Steve
Sonex 892

[DCASonex]

You may not really want stronger brakes. My Great Plains (now O'keefe) disk brakes will hold my Sonex TD with a CAMit 3300-- But: One day while doing so at end of our hill top runway, freak gust picked up tail while applying full WOT, and I found myself looking down at runway in front of me. Did somehow get tail back down before prop hit, but bent tail spring in doing so. Now I only do Full throttle run-ups with tail tied down. Rotax in an Onex might produce similar results.

David A.

[ldmill]

I have the Sonex hydraulic disk brakes in my Onex and they cannot hold the plane to do a proper runup with the Rotax engine I have installed. I am looking to upgrade the brakes. Has anyone upgraded to something they are happy with? I looked into Beringer brakes but they are expensive (maybe $2000) and they would not adapt easily to the Onex axle setup. I have a trigear and am not worried about too much braking power.

I've had Matco's on my Jab3300 Waiex since 2012. Have 350 hours on them and have relined the pads once - and I'm not shy about using brakes at all... I can do a WOT run with no creep. I just transitioned last year from a single Matco hand brake for both wheels to individual toe brakes and really like the differential ability. I still have the Matco hand brake however and will sell it and the parking brake for it for $100 if you are considering a Matco solution.

Lorin

[builderflyer]

Doing a full power runup in a 3300 powered taildragger Sonex with any type brake system is a risky idea and one that I wouldn't attempt without the tail being tied down. David A. said he almost dumped his Sonex on its nose and an early builder, Marty S., actually did take out his propeller doing a full power runup in his Sonex. Its less expensive to learn from the experiences of others.

Art,,,,,,,,,,,,,,,,..Sonex taildragger #95,,,,,,,,,,,,,,,,Jabiru 3300 #261

[ldmill]

Doing a full power runup in a 3300 powered taildragger Sonex with any type brake system is a risky idea and one that I wouldn't attempt without the tail being tied down. David A. said he almost dumped his Sonex on its nose and an early builder, Marty S., actually did take out his propeller doing a full power runup in his Sonex. Its less expensive to learn from the experiences of others.

Art,,,,,,,,,,,,,,,,..Sonex taildragger #95,,,,,,,,,,,,,,,,Jabiru 3300 #261

Agree, and I only did it to see where the plane would start creeping after initial installation. It would be silly to do a full power run up each time or even repeatedly.
Lorin