AeroBrakes (Hydraulic Brakes) Important Notes/Corrections

[NWade]

Hi All,

I recently assembled my AeroConversions AeroBrakes onto my Sonex axles, and noticed issues with my installation. Others have posted messages about the AeroBrakes in the past, but I wanted to consolidate their learnings and incorporate the info I've recently received from Sonex/AeroConversions - making it easier for folks to find this info in the future.

As several people have commented, the AeroBrakes are clever, compact, and a good design; but the instructions leave something to be desired. :roll: And as I found out, parts changes in the Sonex lineup over the years can have an effect on how your AeroBrakes go together onto your Sonex aircraft. Hopefully the list below provides a series of answers and items to check when assembling your wheels & brakes...

1. The clevis pins called out in the plans are incorrect. They should be "-3C39" length pins for standard Sonex/Waiex axles.
   [Source: My emails with Sonex/AeroConversions Tech Support]
   
   
2. Clevis pins are preferred over the bolts listed in some plans/instructions sheets because bolt-heads can stick out further and possibly contact wheel components.
   [Source: Sonex plans revisions, see SNX-L07 revision posted on 4-1-13]
   
   
3. The Brake Pistons are installed with the narrow part of the piston facing down into the brake housing, and the O-Ring nearest the top of the piston.
   [Source: Shown on SNX-L07 Detail B but it is very hard to see. You can download the PDF from Sonex and zoom in to view this much better than is shown on the printed version.]
   
   
4. Check your bearings when you assemble the brakes and wheels onto the axle! The axle nut should be turned until the brake pucks are lightly dragging on the brake disc. Then be sure to examine both sides of the wheel, paying attention to the wheel bearing area. On the outside of the wheel, the nut should be contacting the bearing washer. On the inside of the wheel the raised lip of the brake housing (where the axle slides through) should be contacting the bearing washer. NOTE that Sonex changed the Azusa tapered roller bearings over the years. Both wheel bearings will work, but the older (unsealed) wheel bearings are not as wide. This may leave a gap between your brake housing and the wheel bearing, and might allow the bearing to move and the wheel to be improperly supported as the brake pucks wear down. Here is a photo of this issue. Sonex support suggested two solutions to my particular issue: You can stack up washers between the wheel bearing and the brake housing, or you can order the newer sealed Azusa bearings, which are thicker and will take up this space. To order the bearings, Log In to the Sonex Web Store and then do a search for "Azusa-8229" (and yes, you must log in first). They are sold as individual items not pairs, so you'll want to order 2 or 4 of these.
   [Source: Emails with AeroConversions/Sonex Tech Support]

I hope this information is helpful, and everyone gets good use and long life out of their AeroBrakes!

--Noel

[WaiexN143NM]

Hi all,
You may also want to consider welding the tracy obrien ss backing plate onto your axles as well, as the greater stopping force of the aerobrakes have broken off a few of the tabs on some axles. You will need to slightly chamfer the plate on one side for the radius on the axle bolt,an slightly ream one or more holes for the caliper bolts or pins. You will be able to pick up 3 holes. Most welding shops charge $25 per axle. And yes if you change the bearnings to the new dust shield , you may have to change the cotter pin hole on the axle. After the brakes are installed on the axles you have a multitude of design choices for the hyd brakes. Toe brakes, hand brakes, heel brakes , differential brakes . We also have a matco parking brake on firewall, works well. And like many homebuilts they are never finished. Constantly we are modifying to make them better. Enjoy!

WaiexN143NM
Michael

[Waiex 49]

Having just completed my installation of the Sonex hydraulic disc brakes, I would agree with what Noel and Mike have said, and would like to add a few more things I have learned through accomplishing this modification.

The Sonex "instructions" are totally stupid, the drawing isn't much better. If you choose to do this mod you are own your own to figure out how to do it.

The backing plates absolutely do not work with a tailwheel configured aircraft. I had to modify mine extensively to get them to work.

Yes, do get the TOB backing plates and have them welded onto the axles. I don't care what they say in Wisconsin, use bolts instead of the specified clevis pin to secure the brake housings to the axles.

Throw away the elbow hydraulic fittings that Sonex supplies. I got much better fittings from Spruce. Use a 3400 x 2 Weatherhead "street" elbow and a 269P-03x02 elbow fitting. Not only are they much better quality fittings, but this setup allows a much smoother installation of the nylaflow tubing.

The landing gear fairings and the wheel pants have to be modified to work with the new brake housings. What they show on the "drawings" is totally wrong. If you make the specified cutout on your wheel pants per drawing you will never get your wheel pants on or off the plane. The cutout must allow the wheel pant to move backwards to clear the hydraulic fittings.

Don't get me wrong. I like the Sonex hydraulic brakes. I did modify my setup to use toe brake pedals and dual master cylinders for differential braking. Sonex could do everyone a favor and do a "reality check" on this kit. I am convinced whoever put this kit together and wrote the instructions did so from the comfort of his or her desk, and did not check any of it out by actually doing the installation. This reminds me very much of the lame instructions that came with the "ooops" fittings for the fuel tank.


Don Bowen
Viking Waiex N49YX

[WaiexN143NM]

Hi all,
Just to clarify, and don can post back on this, is the backing plates he was refering to are the flat alum rect. Plates to mount the wheel pants. Use caution for left /right, front/back , and top or bottom. Predrilled holes to mount the wheel pants, and holes for the red calipers. You will want to order the $25 mounting kit along with the brakes. It has the plansheet and some hardware. It will get you started. The other backing plates are the tracy obrien square ss plates to mount/ weld onto the axles. We have our red calipers slightly tipped up in the front. Also the check valve bleeder fittings ive mentioned before make bleeding the brakes a one man job.,also as don mentioned you will have to cut the inner face of the pant bigger than whats shown to get them on and off. . We like our set up. Been maint. Free. We have 2 sonex master cyl. Mounted on angles riveted to floorboard and center sq. tube. Two flat handles and knobs facing inward. Scott thanks for posting the pics. And dont forget about electric flaps. Have a safe and fun weekend, cheers,

WaiexN143NM
Michael

[ffdavis]

I installed the Sonex hydraulic brakes on my Xenos, and I agree with most of the comments about the installation. For me they work better than the mechanical brakes with machined drums, I would offer a suggestion to replace the plastic filler plug on the master cylinder with a brass pipe plug (think Home Depot). I tightened the plastic one too much and broke the square top off leaving a ring of threads in the cylinder, Fortunately a large easy-out removed it.

Frank

[mike.smith]

I would offer a suggestion to replace the plastic filler plug on the master cylinder with a brass pipe plug (think Home Depot). I tightened the plastic one too much and broke the square top off leaving a ring of threads in the cylinder, Fortunately a large easy-out removed it.

I agree. The same thing happened to me. I was able to get it out simply by using a fat flat bladed screwdriver. The flare on the screwdriver wedged in and the piece backed out easily.

[racaldwell]

Thank you Noel, Don, & all others for the heads up about the hydraulic brakes. I am starting on the front fuselage and starting to get a plan together for it. I got the Aerobrake option with my kit and I see now why the welded tab has broken where the clevis pin is anchored to on some others planes. Not much meat there. So I went ahead and ordered the TOB axle assembly to mount on the titanium leg. That welded four hole plate looks much more robust. I can see when I get my arframe done and have a hangar sale that I am going to have a lot of Sonex parts for sale that I didn't use.

Rick Caldwell
Xenos 0057

[Waiex 49]

Hi Rick,

If you are interested, I posted step-by-step descriptions and photos of my installation of the Sonex disc brakes (AeroBrakes) to my web page:

http://www.mykitlog.com/donbowen

Click the link on the right side titled "DISC BRAKES".

Good luck with your project!

Don Bowen
Outlaw Viking Waiex N49YX

[WaiexN143NM]

hi all,
the additional cut out on the wheel pant i was refering to is aft of the axle and about a 45 degree angle. it makes getting the pant on/off easy reference the ground. just the fiberglas. the alum mount plate will fill up this opening.
i recently added some steel L brackets on the bottom axle two bolts facing inward, for a jacking pad , just under the gear leg fairings. , and using a jacking handle similiar to peter ansons . if u use the tracy obrien axles then you will have a small ammount of your the axle sticking inwards to use as a jacking point.
wheel bearings. i recently ordered a $80 wheel bearing race puller kit. azusa sells new races, about $2. if it works i’ll put the tool out for use. new bearings can be ordered from sonex or azusa.

fly safe!

michael

[racaldwell]

Good info in your kitlog, Don. Thanks again for helping those of us coming downstream. That reinforced my decision of using the TOB axle assemblies.

Did you ever get the swingback canopy installed? I also have one of those kits but I haven't even opened the box yet. But that will be soon. Somebody else has the swingback posted on their kitlog (Ryan maybe?) and if you are reading this, did you ever figure out an external latch for it?

Rick Caldwell
Xenos 0057
starting forward fuselage