Brake issue
Posted: Tue Jun 08, 2021 5:43 pm
by 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
Re: Brake issue
Posted: Wed Jun 09, 2021 8:47 am
by 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.
Re: Brake issue
Posted: Wed Jun 09, 2021 10:09 am
by 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
Re: Brake issue
Posted: Fri Jun 11, 2021 3:26 pm
by 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.
Re: Brake issue
Posted: Sat Jun 12, 2021 12:56 am
by WaiexN143NM
hi george,
take a look at matco, see what they have to offer.
www.matcomfg.com
WaiexN143NM
Michael
Re: Brake issue
Posted: Sat Jun 12, 2021 8:28 am
by sonex892.
gcm52 wrote: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
Re: Brake issue
Posted: Sat Jun 12, 2021 9:19 am
by 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.
Re: Brake issue
Posted: Sat Jun 12, 2021 7:16 pm
by ldmill
gcm52 wrote: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
Re: Brake issue
Posted: Mon Jun 14, 2021 9:35 am
by 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
Re: Brake issue
Posted: Mon Jun 14, 2021 1:31 pm
by ldmill
builderflyer wrote: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
Re: Brake issue
Posted: Tue Jun 15, 2021 3:14 pm
by Kai
Sorry,
I’m not that far down your path yet.
Although I’ve had the Aeroconversion hydraulic brake setup in my Sonex for the last three years, I can’t make them work as I would like. They won’t hold the plane during runup, and braking action during rollout is hardly any better than the old mechanical ones.
As far as I can understand the issue is getting the air out of the system. I religiously follow the procedure recommended by Sonex. But after a short while I again have to ‘pump’ the handle in order to have any braking action at all- and lo and behold: the air bubbles are back.
I can’t find any leaks. The discs are nice and dry. No spill anywhere. Hardly any loss of fluid in the master reservoir. All fittings dry as a desert. The bores in the calipers are prestine. Piston o-rings replaced 2-3 times every season. Anywhere else I should look?
What the blazes do you guys do to make these things work?
Thanks
Kai
Re: Brake issue
Posted: Tue Jun 15, 2021 3:27 pm
by WaiexN143NM
Hi all,
It may be how you are bleeding them? are you a one man or two person operation?
i’ve posted before on check valve brake bleeders. you can find these at your local auto parts store. run a tube into a clean cup. crack open the bleeder valve, get some fresh brake fluid handy, sit in plane and pump the handle. add more fluid as needed. tighten valve replace master cap. should be good to go.
WaiexN143NM
Michael.
Re: Brake issue
Posted: Tue Jun 15, 2021 4:16 pm
by Area 51%
The reservoir capacity of the master cylinder my be your issue. The wheel pistons will use-up the small amount of reservoir fluid in short order as the brake linings wear. These master cylinders are not vented, and when the system would like to draw fluid from the master cylinder to take up space, a vacuum forms making it possible for air to get sucked in past the wheel piston seal.
I added an external reservoir from a motorcycle brake system and have never had any air get introduced into the system.
I can send you a picture of my setup if you PM me your email.
Re: Brake issue
Posted: Wed Jun 16, 2021 1:09 am
by Kai
Hi,
Great- a photo of your setup would be very welcome.
PM with email address sent.
Thanks
Kai
Re: Brake issue
Posted: Wed Jun 16, 2021 9:14 am
by builderflyer
Area 51% wrote:The reservoir capacity of the master cylinder my be your issue..
The capacity of the master cylinder is very limited but a simple way to get additional capacity is to screw a 3" tall, 1/2" o.d., standpipe into the threaded hole that the filler plug occupies. I found such a brass tube that came threaded at both ends along with a brass cap at the local hardware store. This tube adds enough capacity such that the brake fluid level can drop a little without the possibility of getting air in the attached brake lines.
Art,Sonex taildragger #95,..Jabiru 3300 #261
Re: Brake issue
Posted: Wed Jun 16, 2021 4:58 pm
by racaldwell
A cheap way to add the reservoir is with tubing. This way you can see the level and know when to add fluid. I did this with my One Design and used a syringe to add fluid by inserting a small tube connected to the syringe. I used teflon tubing 5/16" OD x 1/4" ID. On my Xenos, I have a large access panel on the glasreshield to access these for refilling. Surprisingly, the volume in the tubing is greater than the volume of the Grove brake reservoirs he sells.
Rick Caldwell
Xenos 0057