Tracy O'Brien brakes not braking

[JohnF]

I have a flying Sonex (277 hrs TT) that I purchased to facilitate transition training while I build mine. I just started flying it after a fair amount of maintenance, including new pads for the Tracy O'Brien brakes. I've only done three flights (including a few touch and go's) on the new brake pads, but the brakes have faded into non-existence. At this point the brakes only generate heat and stinky-ness. They are so bad that I will not fly it until this is resolved. It has the stick mounted brake handle and it feels solid with no mush, so it seems I'm into major glazing.

I will be calling Tracy O'Brien to discuss the situation, but I would appreciate any insight that any of you may have.

Thanks,
John

[daleandee]

I've only done three flights (including a few touch and go's) on the new brake pads, but the brakes have faded into non-existence. At this point the brakes only generate heat and stinky-ness. They are so bad that I will not fly it until this is resolved. It has the stick mounted brake handle and it feels solid with no mush, so it seems I'm into major glazing.
John

Hi John,

I have the exact same set-up as you report. When I first installed mine I thought I had done a fair job of getting the brakes bled but after having to refill them after adding the wheel pants (braked had to be removed to mount the backing plates) I realized that although the handle felt solid I did have air in the system. It was in the stick mounted master cylinder as I have the translucent lines and can see any air bubbles. Inverting the master cylinder while bleeding helped tremendously.

Many have noted that the TOB's fade pretty quickly under hard braking with a heavy aircraft. My aircraft is probably a bit heavier than most (Corvair power) but at 70 hours I find the TOB's to be adequate. The secret for me was learning to slow the airplane down on landing and not use so much braking. In this landing video you can see I'm in the mid 50's for airspeed over the numbers, and the tire chirp happens at an indicated speed of 36 MPH:

http://www.youtube.com/watch?v=WjA7JDJVKeQ

Admittedly I use the LRI (lift Reserve Indicator) more than the ASI but my point is that perhaps, being fairly new to the airplane, you are landing too fast and working the brakes a bit too hard. Still I will concede that the Tracy O'Brien brakes leave a bit to be desired but I have managed to learn to live with them. Mine work quite well after bleeding them ... so much so that they now hold when I do a run-up to 2800 RPM. During a recent landing with the CG very near the forward limit (full tank, solo,no luggage) as I was braking hard to make the first turn off I heard a tire grab and felt the tail get light. They had not happened before. Needless to say I had the stick all the way back but got off the brakes rather quickly. :oops:

Dunno if this helps,

Dale
N319WF

[sonex293]

I'll concur with Dale about the TO brakes. The have really good holding power and I learned to pulse them to extend their braking capability. But they would fade if used too much. Like Dale, I learned to slow the Sonex down on final and relied more on gravity than brakes.

==
Michael
ex N293SX

[JohnF]

There is no doubt that I am coming in hotter than I should be, and I will refine my landings with practice, but the brakes still seem to be marginal. Should I have followed a procedure for bedding the pads after replacement? And if I got them glazed over from my over-zealous landings, is there any way to get them back in shape?

As to the bleeding issue, what is the recommended procedure and what kind is the fitting is on the brakes so that i can procure the mating fitting?

Thanks,
John

[fastj22]

I also have TOB brakes. I switched from Great Plains disc brakes when I converted to a tail dragger. The GP brakes were so strong, I had to be careful not to lock up a tire on landing. I went with the TOBs because I also bought the TOB gear legs. They mate nicely. I also didn't like the squeaking I was getting from the GPs while taxiing.

The TOBs barely hold during runup at full throttle. They work fine during taxiing and light braking on landing and are smooth and quiet. I'd like more holding power, but they seem to be fine for me right now. The GPs sit in a box waiting for the coach to give them a second chance.

[sonex293]

I had no problem with holding power of the TO brakes with my Jab3300. I could do a full power run-up and it wouldn't move an inch... I was able to latch the brake handle on my flaps motor for a nice parking brake.

==
Michael

I also have TOB brakes. I switched from Great Plains disc brakes when I converted to a tail dragger. The GP brakes were so strong, I had to be careful not to lock up a tire on landing. I went with the TOBs because I also bought the TOB gear legs. They mate nicely. I also didn't like the squeaking I was getting from the GPs while taxiing.

The TOBs barely hold during runup at full throttle. They work fine during taxiing and light braking on landing and are smooth and quiet. I'd like more holding power, but they seem to be fine for me right now. The GPs sit in a box waiting for the coach to give them a second chance.

[fastj22]

What master cylinders did you have? I have Hagars.

[Bruce593SX]

I'm in the process of installing mine, the instructions talk about making sure the bleed valve on the master cylinder is in the up position when bleeding while pumping fluid in from the brake.... Warns that air can become trapped in the master if not, especially using the stick mounted MC.

Bruce

Sonex 593
plans building since 2006... Maybe fly this spring......

[rbarber]

I have TO brakes and matco master cylinders. After 637 hours, here is what I have learned about them: shortly after installing new pads, you will have to remove a spacer washer to keep the gap between the disc and pads correct. Otherwise you will have to pump them quite a bit to get full function. Also, they will get hot quick and take a while to cool off. If the gap between the pads and rotor is at the minimum, they will stick a bit when hot, and have diminished maximum braking power. They still work, just not as well as when cold. I have met several folks who have them, but didn't know how to adjust the gap. If you don't adjust the gap, you will get poor performance.

[sonex1284]

I had a similar issue. Turns out that I had mounted the TOB brakes with the 2 vent ports at the 3 and 9 o'clock positions. I think a big air bubble was present between 2 and 10 o'clock. I took the brakes apart, got an additional fitting from Tracy, tapped and installed it at the 12 o'clock position. It helped a lot.