SonexBuilders.net

Hello All,

I am converting my Sonex brakes using Aero conversion Hydraulic wheel cylinders. I have installed Matco MC-4 master cylinders with toe brake actuation. I guess either the geometry may be wrong (Van's toe brake kit) or the master cylinder and wheel cylinder ratio is incorrect.

Is anyone else using this configuration?

I am also thinking about just switching to a stick mounted brake lever and am looking for input on proven systems using the Sonex (aero conversion) wheel cylinder brakes.

Any input related to this would be greatly appreciated.

Bob Carson
SNX-1033
Tail Wheel
Jab-3300
450 Hrs.

Hi Bob,

Sorry to hear you're having issues. What's the problem with your setup?

I used the Sonex brake kit and matched it to Hegar master cylinders I installed on brake pedals and while they've been smooth, they really don't have much stopping power. I figure I just used the wrong size of master cylinder but I'm too lazy to really mess with things. I'm toying with the idea of eventually switching back to a lever operated brake setup like the plans call for. Maybe someday...

I have the Sonex brake kit with the single lever per the plans and it works great. My second notch of parking brake holds at full run-up. You can see that there is a lot of leverage on the master cylinder with this setup. You would have to assure that you got the same amount of hydrolic pressure with the foot brake setup to match the single lever setup.

https://www.youtube.com/watch?v=RRZIaTf5G3c

Jim
Waiex 3300 TD

Hi Mike,
I am experiencing the same symptoms as you with what sounds like the same set-up. I may also go to the Sonex original master cylinder and lever set up.
Bob

Thanks for the feedback Jim. I have just ordered a pressure gauge so I can measure the the pressure exerted at the wheel cylinder by the toe brake master cylinder. Although Sonex wasn't able to tell me what pressure is typically required.
Bob

Hey Michaelfarley56.............

I was reading an old post of yours regarding poor braking power with the Sonex hydraulic brakes using toe brakes. I have the same setup (only with Matco cylinders) and my braking power is VERY poor. I am wondering if you have you resolved that issue by now and how?

You mentioned you might try switching to the hand lever brake cylinder to get more "purchase" and thus have stronger brakes. Maybe someone else has had the same problem and found a fix for it.......please chime in.

I am beginning to wonder if there may be some wheel bearing grease on the brake disc's.......?

Anybody else having poor brake performance with the Sonex hydraulic setup......?

Gordon......Hummel 2400.....Onex

Hi Gordon,

Over the summer I pulled off the toe brake portion of my setup and installed the standard hydraulic Sonex hand brake and master cylinder available from Sonex. I didn't do anything to the hydraulic system at the wheels (no need).

Anyway, the brakes now work just fine and I have plenty of stopping power out of the stock factory setup. I have no doubt that my self designed toe brake setup had the incorrect geometry at the master cylinders for sufficient leverage; I also didn't have a brake fluid reservoir so I had to crawl under the panel every few months to top off the master cylinders.

It was a cool idea in theory but I'm much happier with the factory hand brake setup. Just my experience of course; I know there are others who are much happier with their own toe brake setups than I was.

I use two standard Sonex master cyl’s and two handles for individual brakes.

Any body used this setup?

https://m.aircraftspruce.com/catalog/lg ... key=506927

I've installed the 06-01279 Hegar 1/2" bore w/7" T-lever single cylinder - right beside the seat pan on a bracket and removed the inter side of the "Tee" handle. I have the nose wheel setup.

Richard Stauffer