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Overheated brakes

BJohnson

Well Known Member
I just replaced the brake pads with a set from Vans on my Cleveland brakes about a month ago. I have about 8 landings on them. The other day I landed a bit fast and used moderate braking to stop. The right brake faded and the plane drifted left but was still under control. Taxiing back to the hanger I could smell a strong hot brake odor entering the cockpit that persisted during the short taxi to the hanger. Upon exit, the smell was more apparent. The next day I removed the pads and found a buildup on the pads as shown in the two photos linked here.

https://photos.app.goo.gl/HVYqPlmHss3Bl2KB2
https://photos.app.goo.gl/N7uy5PPp1ccu43m72

The buildup was easily removed with light sanding. The pins also required cleaning. There was no evidence of any fluid leak. But the was more discoloring of the primer on the wheel pants bracket than I remember from the condition inspection. Things did get hot pretty quickly.

After installing the new pads, when tightening the two bolts on the caliper, something happened that caused a momentary fluid leak. I removed the bolts, and reinstalled them taking care that everything was aligned right. The leak has not occurred again.

What could have caused this brake to overheat and what is the buildup on the pad? I have applied much harder braking on the previous pads without this occurring.
 
What could have caused this brake to overheat and what is the buildup on the pad?
Maybe the pads got contaminated with brake fluid? Also, in my plane with the tiny little tires, I have to stay off the brakes until below 45 Kts lest I smoke the tires.
 
Let?s talk brakes

I haven?t put too much thought into brakes as I?m not that far into my build yet. However I will soon be running brake lines.
It?s been my assumption that at our low landing speeds, that I would not have to worry much about what brakes I use. Are upgrading the brakes worth it. And if I do, what advantages do they bring me. I have heard good words about both Grove and Beringer. So real world experience from those who have used both standard brakes and upgraded ones would be beneficial for those of us who are about to make a decision on which brakes to purchase.
 
If the brakes got that hot, it would be prudent to replace the caliper o-ring. It?s talking to you anyway by trying to leak upon assembly.
 
Agreed.

If the brakes got that hot, it would be prudent to replace the caliper o-ring. It’s talking to you anyway by trying to leak upon assembly.

And try and get some Viton "O" rings to replace them with. You will be a lot happier in the long run. It is common for the old standard "O" rings used in the calipers to bake and get a flat spot on the sealing area. The Viton rings will stand up to a lot more heat and stress. Just two cents, Yours, R.E.A. III # 80888
 
Maintaining good brakes.

Yes, replace o-rings now and when installing new linings, condition
them this way:
NONASBESTOS ORGANIC LININGS METALLIC LININGS
1. Taxi aircraft for 1500 feet with engine at
1700 rpm applying brake pedal force as
needed to develop a 5-10 mph taxi speed.
1. Perform two (2) consecutive full stop braking
applications from 30 to 35 knots. Do not allow
the brake discs to cool substantially between the
stops.
2. Allow the brakes to cool for 10 to 15
minutes.
2. Allow the brakes to cool for 10-15 minutes.
3. Apply brakes and check for restraint at high
static throttle. If brakes hold, conditioning
is complete.
3. Apply brakes and check for restraint at high static
throttle. If brakes hold, conditioning is complete.
4. If brakes cannot hold aircraft during static
run up, allow brakes to completely cool,
and repeat steps 1 through 3.
 
DANGER!

1: Taxi aircraft for 1500 feet with engine at
1700 rpm applying brake pedal force as
needed to develop a 5-10 mph taxi speed.
2: Perform two (2) consecutive full stop braking
applications from 30 to 35 knots. Do not allow
the brake discs to cool substantially between the
stops.
3: Allow the brakes to cool for 10 to 15 min.

Please do this procedure (If you decide to do it) without the wheelpants installed!

Personally, I don't do this anymore.
 
I had the same issiue after the testing of TO and LDG distance. 3 to 5 landings at MTOW ...
After this I needed to replace my linings. There was too much heat involved. Dont do this like one landing by another ... go 5-10min flying inbetween to let the brake and wheel cool down. It was interesting, how much heat goes into the wheel!

After this I changed the o-rings and the linings. I put RAPCO linings on. What a difference! They improoved my braking quit a lot and can handle the heat much better!

Like to upgrade for a thicker brake-disc which can take more energy. Mentioned once here in this forum, try a search.
 
This might be a factor

Maybe the pads got contaminated with brake fluid? Also, in my plane with the tiny little tires, I have to stay off the brakes until below 45 Kts lest I smoke the tires.

I did not fully disassemble the brake calipers when I noticed the leaks. I loosened the two bolts and adjusted the outer plate, which appeared to have bound on the pins. It is possible that fluid got on the pads. I did follow the break in period, without wheel pants, and everything seemed normal afterward except for a little squeal on the right side. So I thought all was well. The other puzzle is that I have flown several times afterwards. In the absence of problems I put on the wheel pants and flew it. Not until the last flight did I get this issue, although it was heavier braking than on any other previous flights.

I will be picking up O rings tomorrow and replacing those.

Any good tips on disconnecting the assembly from the brake line and reconnecting in a way that minimizes trapped air to simplify the bleeding process? Can I bleed from the bottom fitting after reconnecting to fill the brakes, and then go through the standard bleed, pushing fluid up from the fitting?
 
Drain the system ...

Any good tips on disconnecting the assembly from the brake line and reconnecting in a way that minimizes trapped air to simplify the bleeding process? Can I bleed from the bottom fitting after reconnecting to fill the brakes, and then go through the standard bleed, pushing fluid up from the fitting?

If you change the o-ring, you have to take the piston out. So before doing this, I put a jar under the drain-valve, open it and drain the system.
Change the o-ring and the other things, then put all back together and fill the system from bottom to top.

Even if you can do it without draining, you must get the air out, then you have also to bleed the system from bottom to the top, which is the same work than refilling it.

I hope it helps!
 
I haven?t put too much thought into brakes as I?m not that far into my build yet. However I will soon be running brake lines.
It?s been my assumption that at our low landing speeds, that I would not have to worry much about what brakes I use. Are upgrading the brakes worth it. And if I do, what advantages do they bring me. I have heard good words about both Grove and Beringer. So real world experience from those who have used both standard brakes and upgraded ones would be beneficial for those of us who are about to make a decision on which brakes to purchase.

I tend to believe most problems with brakes are simply pilot induced. The stock brakes and wheels are more than adequate for most. Those I know who have had brake fade or lost seal issues;

Mind your feet when you taxi so you are not inadvertently applying them, especially long taxi's, and during roll out on landing.
You don't need to make that turn off if it means heavy sustained braking unless you have run out of runway.
If you run out of runway, you probably have landed way too fast, which is pretty common in RV's, especially those pilots who wheel land at high rates of speed as they have not learned how to wheel land at lower, slightly tail low, speeds.

Still, at that, moderate braking, for short duration should not be an issue. I do not understand why this occurred with the OP's brakes. Although I was trained in antiques that had little to no brakes, I have never had an issue when I needed to use them in my RV. I try to stay off of them, per my early training, and tend to apply them when needed in short even strokes rather than hard sustained stomps.

My brake pads last 300-400 hours. I routinely land at our home field which is 2100' and I easily have slowed without much if any braking within 1200 feet or less. I also fuel at a field and make the second turn off easily with moderate braking which is less than 1000'.

This is just my experience. All RV's are different and there are other factors to consider. Hope that helps.
 
Improper break in?

I have been reading many of the other posts on brakes - lots of great information.

This is the third set of pads, and the first time I have used Matco pads on my Cleveland brakes. Every two years I have replaced pads even though it hasn't worn to the limit.

I conditioned these pads like the last set, by dragging the brakes at 1800 rpm for a distance. That allowed me to hold position at high throttle. But the Matco instructions say to apply firm braking at 30 to 40 mph 2 or 3 times.

Is it possible the brake fading was from incorrect conditioning?

Or maybe the last landing wore off the glazing on the one pad?

Lastly, do the Matco pads smell worse than the Raptco pads when hot?
 
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