Hydraulic Brake Help

[DCASonex]

This won't help much, but my toe brakes use the basic Hegar cylinders but are operating Great Plains brakes, and works great. The Great Plains brakes, (Now sold buy a new company) are full floating caliber, not all on one side trying to push the wheel off the axle. but both those and Sonex use two cylinders per wheel and have similar surface area.

David A.

[builderflyer]

I have the standard Aero Brake hydraulic set up (single brake lever) and the stopping power is more than adequate. My observations, however, in utilizing the system since it came out are the following:

1. For whatever reasons, I have found it near impossible to get and keep all the air out of the system
2. The amount of wear showing on the stainless steel discs is surprising. At some point they will need to be replaced.
3. The amount of dust produced by the pucks is annoying in that it travels up the gear leg fairing into the engine compartment where it settles on everything.

Despite the above annoyances, I wouldn't go back to the mechanical set up as the stopping power and smoothness of operation of the hydraulic system are overriding benefits.

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

[Gordon]

Thanks Michael Farley and the other folks who chimed in on the Sonex brake issue.

I agree with Michael that the geometry he had (and I assume I have) for the toe brakes was incorrect. I have the very same Matco cylinders I had on my RV-7 but the geometry is different on the RV.

I REALLY hate to mess with installing the "hand brake" system however my brakes are unacceptable at this point and I need to do something about it.

Michael.....I already have a brake fluid reservoir up on the firewall for my Matco's........can I plumb that fluid line into my Sonex hand brake cylinder? Some brake cylinders (like Hegar) do not allow that.

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

[ldmill]

Doug Boyd used the Matco bicycle style handbrake master cylinder and the Sonex brakes on his Waiex and also had issues. There appears to be a size/ratio mismatch - he had to pump the Matco hand brake multiple times to get enough pressure on the Sonex brake cylinders to get them to work. He ended up using the standard Sonex handle/master cylinder and Sonex brakes and they work just fine.

I also have the Matco bicycle style handbrake master cylinder but went with the Matco conversion for Sonex wheels/brakes and have plenty of braking power in reserve. I can do a full run-up with my Jab3300 in my Waiex and get no creep. I absolutely love the Matco brakes and would use them again. Putting the Matco wheels/brakes on is not difficult, getting the wheel pants on them takes a little more work. If you've already got the toe brakes installed - I would seriously consider installing the Matco wheels/brakes. That's actually my next step - a Matco based toe brake setup.
Lorin

[Gordon]

I got a message from Mike Turrel www.onexmike.org whose toe brakes I copied..... he says his brakes work fine.

I think before I start changing too many things I need to pull the wheels and check for wheel bearing grease on the discs.

I hope I find some and then that would explain the poor braking power.

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

[LarryEWaiex121]

Art,

I completely second your assessment of the operational observations. I replaced my "disks" upon condition inspection after 160 hrs of use.
I was surprised with the level of erosion. It was too the point that the heads of the wheel bolts were polished smooth.
I would suspect that the material hardness isn't too much? I replaced both the pucks and the disks.
I've bled my brakes now 3 times. Each time I get great response on the handle. Good firm brake pressure. Go out and fly for 10 hrs and I'm back to what I effectionately refer to as the "double pump" to get a solid pressure. I don't even think about it now. When you want to do a runup or stop, you simply double pump and all is well. It is irritating though. In a nut shell its inexpensive, easy to install and moderately effective. But not perfect.

Larry
Waiex121YX, Camit 3300, Skyview, 650 hrs.

[builderflyer]

Art,

I completely second your assessment of the operational observations.

Larry
Waiex121YX, Camit 3300, Skyview, 650 hrs.

Thanks, Larry. It's always good to read that others have the same experience. And I'll second your comment regarding the "double pump". The double pump is especially important when setting the parking brake on my Sonex.

One other comment on another responders comment about his brakes holding on a full throttle runup, if I understood him correctly. Another Sonex pilot tipped his 3300 powered Sonex on its nose while attempting the same thing. Personally, I won't do a full throttle runup without having the tail tied down. Something to consider.

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

[Area 51%]

Just a thought.....but what you may be experiencing is the puck moving back into the caliper slightly, necessitating the extra pump to get it back out on the job, not necessarily air introducing itself into the system.


In the automotive world, there are residual brake pressure valves that can be installed at the caliper/wheel cylinder to keep the fluid from returning to the master cylinder that allows the retraction of the pucks. There can be (of course) a slight drag on the brakes. But it matters not to a "67" Camaro with a 396.


Reminiscing about my high-school car here @Area 51%

[GordonTurner]

When you do a full power run up in a taildragger it is prudent to hold full aft stick.

Gordon

[LarryEWaiex121]

Full power run ups are the perfect way to ensure a quick recycling of your propeller and probably an engine tear down, if you have conventional gear and don't tie it down.
I doubt an Aero Vee would tip one over but a Jab 3300 or Corvair certainly can.

Larry