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Brake piston O-Ring size ?

Ironflight

VAF Moderator / Line Boy
Mentor
OK, quick question for all the experts sitting inside with their reference libraries becasue it's too cold to be outside.....

I have found several confilcting sources for the size of the standard Cleveland Brake piston O-ring size, and want to know what others have found. I dont want to taint the results by giving you my numbers, but I can tell youthat if you order from the Aircraft Spruce online catalog, you'll get one that is way too big.

Anyone? Gil? ;)

Paul
 
You might check with Prof. Horton-------seems as I remember him posting an "O" ring chart awhile back------good ones like magic silicon or viton or some such.
 
Paul,

2-218 for the Cleveland's on the 2-place RV's...

2-222 for the Matcos...

Go to Aceseal.com and buy a dozen. I would also recommend the viton material...
 
Thanks Joe. I've got 2-218's that just seem a little small, and for the second time in a year, I walked out and found a puddle underneath one of the Val's wheels - the leak coming from the piston. I think I'll try a new supplier and see if they have better tolerances.
 
Thanks Joe. I've got 2-218's that just seem a little small, and for the second time in a year, I walked out and found a puddle underneath one of the Val's wheels - the leak coming from the piston. I think I'll try a new supplier and see if they have better tolerances.

Buy the part specified by Cleveland which is a MS28775-218 9 (or Cleveland's number 101-02300).

Spruce and the other suppliers sell them.

Perhaps you are seeing the difference between commercial and Mil-Spec part numbers?

Above assumes the Cleveland brake assy is a 30-9.
 
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Thanks Joe. I've got 2-218's that just seem a little small, and for the second time in a year, I walked out and found a puddle underneath one of the Val's wheels - the leak coming from the piston. I think I'll try a new supplier and see if they have better tolerances.

What was the failure mode, Paul? Did you measure the removed o-ring, was it small in ID or in cross section?

What I am wondering is if it got hard, shrank, chipped from excessive clearance or something else. This just seems odd, and recalling some previous investigations, the piston/bore clearance seemed to be excessive for a "precision" aircraft part, and resulted in a circumferential split due to extrusion from braking pressure. In that case a Viton material would improve the situation. Your part is unlikely a repeat, but just asking.

Maybe a new supplier will have better materials.
 
for the second time in a year, I walked out and found a puddle underneath one of the Val's wheels - the leak coming from the piston. I think I'll try a new supplier and see if they have better tolerances.

I hope your leak is just an bad O-ring, I don't think Val is old enough to have the other issue that can cause that leak. Which is pitting in the caliper bore where the O-ring seals. Older brakes that have had moisture in the system tend to develop that problem.
 
What was the failure mode, Paul? Did you measure the removed o-ring, was it small in ID or in cross section?

What I am wondering is if it got hard, shrank, chipped from excessive clearance or something else. This just seems odd, and recalling some previous investigations, the piston/bore clearance seemed to be excessive for a "precision" aircraft part, and resulted in a circumferential split due to extrusion from braking pressure. In that case a Viton material would improve the situation. Your part is unlikely a repeat, but just asking.

Maybe a new supplier will have better materials.

I took things apart carefully, and the leak was definitely from the piston, but the bore and piston are in good shape. It is hard to caliper an O-ring down to the thousandth without compressing it, but it appears that the ones in there were slightly undersized in cross-section, based on the 218's that I just picked up at NAPA (and the specs for the 218's). Looking at my maintenance notes, the one that was in there came from ACS, and looks to be in good shape - just not quite as fat as the new one. Subjectively, the fit of the piston in the bore (with O-ring) seems a tad more snug with the new ring, and it pumped up just fine.

That should last until I get a nice set of Vitons for all the airplanes, now that we live in a place definitely colder than Houston....
 
O ring

ive had the same problem ..Twice one on the left once on the right. The part number is AN6227B-23 and / or MS28775-218
 
That should last until I get a nice set of Vitons for all the airplanes, now that we live in a place definitely colder than Houston....

Actually the caution with Viton is increased hardness at low temperatures, in return for much higher heat resistance. A Parker engineer told me that's why they don't just go ahead and install Viton as the stock component; customers in the polar regions.

It never gets to -40 in Alabama. If it gets to -40 in Carson City, I submit that your migratory patterns are greatly confused ;)
 
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Yep - steer away from Viton if you fly in the cold.

Actually the caution with Viton is increased hardness at low temperatures, in return for much higher heat resistance. A Parker engineer told me that's why they don't just go ahead and install Viton as the stock component; customers in the polar regions.

It never gets to -40 in Alabama. If it gets to -40 in Carson City, I submit that your migratory patterns are greatly confused ;)

Dan, you've nailed it.

My recent data point: you don't have to be in a "polar region" to see the side effects of Viton hardness! I replaced my original O-rings with Viton <2 months ago since my originals were leaking (and they worked fine). Saturday morning my plane was quite cold-soaked in an uninsulated hangar; the low at Hartford-Brainard overnight was 10F. When I stepped on the brakes prior to startup, I was surprised one pedal went to the floor with no resistance; I hopped out to see the puddle and cancelled plans. :( I flew a few weeks ago when the low temp was 21, things were fine.

I dug out my old o-rings (and the 23 other new Viton rings I now own) which were sitting in the cold hangar; it was a night and day difference between the two as far as hardness.

Luckily I was at home base, but I can't imagine how things would've played out if this had happened after a cold night flight (or a landing on the ice at Alton Bay!).

The first ones lasted 790hrs & 820 Landings. I'm switching back to the original Nitrile.

-AO
 
Joe, how about the 10??

Got those numbers handy?

Here is what I've got for the RV-10 in my notes:

Grove: 2? piston 36-2M (Grove 60-269)
Cleveland: 199-104A

Van's is also selling the Royco 782 (Higher Temp Flash Point) brake fluid in quarts, and has discontinued the gallon size MIL 5606.
 
Just to update, a search on the Ace sight for MS28775-218 returns 0 results now.

I also notice that a search on the Van's site returns:

"MS28775-218 is no longer available. Order USE U-00015 instead."

I'm curious what the specs are on U-00015?

Aircraft Spruce still sells MS28775-218. The price is about a third of what Van's is charging for the U-00015.
 
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Cleveland Brake O-ring: RV-6. 5:00x5 wheel.

AN6227B-23 O-RING
FOR:
Cleveland 30-9 Brake Assembly
It's been 10-21 degrees in Oregon and these O-Rings were installed 2 years ago; and no leaks.
Remove brake calipers from axel and remove piston carefully using low pressure compressed air. Put a rag and a pad over piston and protect it from damage when it pops out.
Remove O-Ring from piston by squeezing the sides between fingers & using a non-metallic device to slide under O-Ring & remove from piston.
Inspect piston and inside caliper for corrosion or pits. If significant corrosion; replace them.
If corrosion is minor then;
Lightly sand inside piston housing using 400 then 600 grit; using solvent as a lubricant. Wash out & clean throughly using solvent. You can carefully do this with piston groove where O-Ring sits.
Clean & dry the parts and lubricate with 5606 Hydraulic Fluid (or brake fluid you are using).
Lube piston groove and O-Ring with hydraulic fluid; and press piston into brake housing using the palm of your hand. **Make sure the O-Ring end of piston goes into housing first** Press piston into housing until flush with brake housing.
Service brake fluid reservoirs and bleed brakes to remove any air trapped in system.
Test brakes and if not solid; repeat brake bleeding procedure.
 
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I replaced O-rings twice before figuring out it was worn brake pads.. they don't have to be down to the rivets before they allow the piston to come out too far, cant (as in angle coming out of piston), and leak. Simple fix = its time to change the Pads. THEN... careful about brake "break-in" I overdid that by a 1/4 mile and boiled the brake fluid... had to rebleed.

Somewhere along the way I also replaced marginal discs with new, which reduced pad to disc clearance (ie: piston extension).

I am using the Viton 2-218s from ACE. Haven't had any leaks in WI/MO winter, but keep a/c in 40f hangar.
 
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