SonexBuilders.net

I have the mechanical Azusa breaks.

I understand sonex makes higher quality machined drums, and I know that sonex offers hydraulic disk breaks. However, I intend to use the stock breaks, because the costs are rapidly adding up and i have a very long runway to use. Also because i WANT to believe that sonex did not send a useless or inferior product as part of their kit.

The wheels are bolted to the stock break drums.
The breaks are assembled in accordance with the plans, with the exception of the machine screws called out for the pant plate to break backing plate ( bolt callout to long. used shorter bolt).

Issue is the wheel bolts are too long and they hit the cam causing the wheel to lock instantly.

I have attempted to grind the wheel bolts shorter, but i am approaching 1.5 threads exposed from the locknut and i do not want to go any shorter. I have verified the cam is properly seated.

I left the workshop before verifying the dimensions of the axle spacer. And will do so tomorrow. Think i can change the orientation of the bolts (swap head and nut location) but this does not seem in keeping with the drawings. I also question how much clearance this may afford me ( not eliminating the root of the problem, possible unplanned wheel lock on landing with any side force). In addition, flipped bolts are not as the sonex 2 page instructions would indicate.

My current thoughts are that this feels like an immense design flaw in the wheel design by Azusa and the wheel choice by sonex.

Has anyone seen this issue? Have i failed to assemble the unit correctly or is the equipment provided faulty? I want to believe i failed somewhere, but after 2 days working on it, i am having trouble seeing what the issue may be. Any feedback would be greatly appreciated.

Very Respectfully,
Matthew
Onex kit #037, TD, Revmaster R-2300 (on order), prince carbon fiber p tip (on order)

I had the standard Azusa (without the Sonex machined drums) and was never happy with them, i bought a set of brake pedals from John Gillis intending to use them and switch to hydraulic brakes.
However, my home runway is long enough so I didn’t care that much so I never bothered upgrading.

One day, taxying to the runway (in a hurry) one of the brakes jammed.
As a result the little tab welded on the axle that holds the brake back plate to the axle with an AN3 bolt broke. The wheel pant is attached to that back plate so once that was rotating with the wheel, you can imagine the mess.

Anyway, that was enough incentive to finally upgrade to hydraulic brakes, now that I have, I don’t understand how I ever considered those mechanical brakes to be acceptable.

Michael,

Thank you for your response. The mounting system for the Onex sounds a little different then for the sonex, but i worry of a similar issue occuring (especially during landing). It is satisfying to hear that there exists a satisfactory upgrade.

However, it is disheartening to hear from you, and on other forms, that the stock sonex supplied product is so poor.

Very Respectully,
Matthew
Onex kit #037

Are the stock Sonex brakes really "poor"? Yes, they aren't as strong as hydraulic brakes, but I found them to be adequate for how I operated. Most of my flying was from grass fields (1700 feet and longer) and there was never any issues with braking. When flying from paved runways I was always careful to keep my taxi speed low and to avoid overheating the brakes so that they wouldn't fade too much.

Are you saying the side of the bolt with the nut is hitting the cam? I'm pretty sure mine are installed so the heads of the bolts are inside the drum. It's been a long time, and I haven't found where the orientation of the bolts are described in the plans. I'm also not sure how the installation differs between the Sonex and Onex.

I, like you, chose to go with the stock brakes and haven't felt a need to upgrade.

I did have a problem with the little tab. It stretched out, ovaling the hole. I think I decided it was because I had too much play in the joint. I had to cut it off and weld on a new one.

matthait wrote:However, it is disheartening to hear from you, and on other forms, that the stock sonex supplied product is so poor.

Matt,

The stock brakes are functional and inexpensive, but they certainly are not as good as the more deluxe options. Each person can decide for themselves how much the upgrades are worth. Probably the biggest thing about the stock brakes is that they have much more variation in how they fit up and thus how they perform. Some builders seem to get them setup well, while others have problems, and I don’t think we really understand how or why this happens.

The upgraded machined drums are a step up (better heat shedding, rounder so less chattering, and these together make them more effective with better stopping power). The hydraulic brakes are even better yet.

I think brakes are one of those things that will enhance your experience in the plane. You’ll enjoy having good brakes on every flight, even if you don’t really need the added performance. My recommendation is to install the hydraulic brakes right from the start. They’re pretty straight forward to install (with a few caveats), they work really well, and are relatively inexpensive to install.

Jeff

I plan on converting to the Sonex hydraulic brakes and use a stick mounted master cylinder hand lever. What hand lever master cylinder works best with the Sonex system, especially on the ONEX, and the source.

David W

onex28 wrote:I plan on converting to the Sonex hydraulic brakes and use a stick mounted master cylinder hand lever. What hand lever master cylinder works best with the Sonex system, especially on the ONEX, and the source.

David W

I used the hand lever from this vendor: http://www.okeefeaero.com/-hydraulic-brakes.html
Hand lever master cylinder $139.95

You can see it being used at the end of this video: https://www.youtube.com/watch?v=rh2DvA6RkTc

Thanks Mike, I’ll go with it.

David W