8KCAB Brake Master Cylinder overhaul

Bob Turner

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Surprisingly, I found Cleveland instructions for overhauling my 10-54 master cylinders over on the Shortwing Piper forum.

I bet every single toe brake Champ and Decathlon uses this cylinder, so accepting tips from knowledgable mechanics, and I will share what I learn when done.

First, getting these things out of the aircraft is easy with floorboards removed, and probably impossible for normal humans otherwise.

The "spring collar" at the bottom of the piston rod is probably threaded on. I say that because assembly instructions say to use Loctite 262, and they seem to indicate that you let it dry for 24 hours before assembly. I seriously doubt that. I will check the Loctite site.

Meantime, if anybody here has done this task, let me know if there are any tricks or "gotchas" involved. Most of my hydraulic experience is with Grove parts. Easy to repair. Similar to Cleveland except for the check valve.
 

Bob Turner

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Well, done! Just in case any of you are mechanically challenged like me, here is the plan:
Floorboards first. Not terribly difficult, but takes some time. Removing them is trivial with floorboards out, and marginally possible with them in.
I got kits from Plane Parts Inc, with a Stat-O-Seal, three O rings, and a lock nut and snap ring. Under $13, and reasonable postage. I know that we are looking at five bucks worth of stuff, but I was pleased.
You need a good pair of lock ring pliers, and a short hunk of rope for reassembly.
 

Bartman

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I think my new project has Gerdes cylinders. Would you mind posting a photo of yours?
 
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Bob Turner

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Sure. Have to do that tomorrow - almost installed #2 today, but flew instead. My intent is to post a bit more on how-to and O ring part #s.
 

Bob Turner

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Look the same to me. Mine are cleaner; have a Cleveland tag pasted on them. Cleveland probably bought Gerdes.

image.jpeg
 

Bartman

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Thanks for the photo. I found two others in my stash but the two in the photo are the two best so they'll get cleaned up, rebuilt, and put back into use. My IA recommended I buy all new brake parts but when I told him the prices he said it'll be ok to use the old parts!!!
 

Paragriz

1978 Bellanca 7ECA
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I rebuilt the master cylinders and calipers about 4 months ago on my ‘78 7ECA. All were leaking to one degree or another. Ordered rebuilt kits from Plane Parts and pads from Groves. I found the project to be a straight forward with minimal tools or experience required. Cleaned everything well with solvent. Checked for scoring on the cylinder walls. Mine were good, but I’ve heard others having to hone their’s. Removed nicks or burs on the piston shaft with a fine Scotchbrite pad, otherwise the bur will shred your brand new seal as it slides over it. Used a light lube during assembly. Be sure the snap ring in the master cylinder seats into its grove properly or you’ll find pretty red streaks down the belly of your aircraft. Took me a little bit to clean up that mess...... 🤨
 

Bartman

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I rebuilt the master cylinders and calipers about 4 months ago on my ‘78 7ECA. All were leaking to one degree or another. Ordered rebuilt kits from Plane Parts and pads from Groves. I found the project to be a straight forward with minimal tools or experience required. Cleaned everything well with solvent. Checked for scoring on the cylinder walls. Mine were good, but I’ve heard others having to hone their’s. Removed nicks or burs on the piston shaft with a fine Scotchbrite pad, otherwise the bur will shred your brand new seal as it slides over it. Used a light lube during assembly. Be sure the snap ring in the master cylinder seats into its grove properly or you’ll find pretty red streaks down the belly of your aircraft. Took me a little bit to clean up that mess...... 🤨
might be a good subject for a quick how-to video when the time comes to do mine. thanks for sharing the details of it.
 

Bruce

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I just did mine kit # 199-516 Aircraft spruce # 08-00353 only comments are pay attention to small end of spring And which way it faces. next I used 5606 only for assembly I would not recommend mixing oils in the brake system, in automotive world If you use Petroleum Based product it will swell all the seals. Last item I placed The cylinder the snap ring facing up On bench and used a tool box drawer to compress the shaft wile removing snap ring and re installing it. Good luck with the end results.
 

Bob Turner

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Oh, ouch! I did not notice any difference in spring diameter or end contour. We’ll see, I guess; mine are installed.

I concur - use 5606 to lubricate during assembly. Just takes a drop or two.

Plane Parts uses MS parts with date codes - $12.95 with extra snap ring and jam nut. Not sure how the jam nut wears out. Spruce; just the O rings and Stat seal - $29.95.

Necessary parts
MS28775-111, 112, and 012 - under a buck each. Stat O Seal 095-26200 - don’t know where you buy this part separately; probably under $4. Easier to buy the Plane Parts kit.

You need a very small flat blade screwdriver or an O-ring pick, a snap ring pliers, a short hunk of cord, and a few drops of 5606. Also need a small pair of regular pliers, a piece of cardstock to avoid scarring the little collar, and Loctite 262.

Disassembly is straightforward, but use the cord to compress the spring. A loop, wrapped around the fork and the outlet fitting, will do it. Snap ring removal is the hardest part - use the small screwdriver once you have the snap ring compressed. See photo for a version of snap ring pliers. Ignore my nails; couldn’t find the proper points.

Put the jam nut and fork in a vise, and gently undo the threaded on collar. Use the card stock and small pliers.

The whole thing comes apart - the Stat O Seal takes some coaxing, because it has an indent on the piston rod. Replacing the O rings is easier than it looks; that internal ring just jumps into place. Re-assemble with a drop of 5606 on each rubber part and a coat on the piston rod.

Clean the threads with alcohol or something, then a drop of Loctite and the collar. Almost done - 24 hrs later, assemble into housing, put the cord back on to compress the spring, and insert the snap ring. Nice to have new ones. They just go right in.2E649F3A-34B0-43A5-B978-10C12E9A4FD6.jpeg
 

Bob Turner

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One of my rebuilds failed. It does fine until I sort of need it, then it will go "to the floor" - no resistance. I suspect the lock-o-seal. It fails on roughly every fourth or fifth push. No external leak.

The 30 minute video doesn't seem to cover our cylinders - my impression is that the 10-54, the Gerdes, and the Grove are all interchangeable. I do know that the Grove does not use "Lock-o-Seals."

I will re-do it next week, with great care on spring orientation.
 

Bob Turner

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Springs look the same, both ends. The problem is what I was calling a “lock-o-seal.” It is a “Stat-O-Seal.” It had come apart - the rubber part had come loose from the metal part.

The fun thing is - I can get a cylinder out in 30 minutes now, instead of two weeks. Easy - take the cowl off, undo the firewall belly pan, and then the cylinder is easy to get at. Glad I did not know that before, since it forced me to re-do the floorboards.
 

AKpilot

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I just ordered kits from Plane Parts Inc. Beware there are a few companies with the name Plane Parts, make sure it has "Inc" attached: https://www.planepartsinc.com, I didn't get any results when searching for specific o-rings or for the kit part number. Just put in the part number of your master cylinder and it will pull up the kit you need, or call, they are very knowledgeable and helpful.
 

Bradc16

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The second cylinder in the video above is the Gerdes A110-10 that are in my Decathlon. Couple tips from my mechanic. Very thin tape over the shaft threads can protect the inner seal on the plunger when pressing it back in. Also polish the shaft prior to reassembly.
Thanks for posting the video!
 

Big Ed

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My left brake pedal gets spongy after a couple of weeks. I keep pumping brake fluid into it. It must be going somewhere over time, but I'll be damned if I can find any physical evidence of a leak.

Chad at ACA slipped me a rebuild kit with a few hard-to-find o rings when I visited the factory during Oshkosh. It's on my to-do list for this winter, when I pull off the boot cowl.
 

Bartman

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need to get mine done too so the new floorboards can go in. glad you posted to this thread Ed! forgot it was here
 
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Bartman

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I ordered two rebuild kits from PlanePartsInc.com but it ends up they're not correct for the Gerdes A110-10 master cylinders. The website showed the Cleveland 10-54 and the Gerdes A110-10 as using the same kit but now that I've received them it appears they are different. The main difference is that the Cleveland uses a Lock-o-seal where it appears the Gerdes just uses an o-ring and that o-ring (Part number MS28775-008 I think) isn't in the kit.

The part numbers for the four o-rings appear to be
MS28775-008
MS28775-111
MS28775-014
MS28775-011

PlanePartsInc.com has already revised their website page to show the kit is only good for the Cleveland 10-54 and not the Gerdes A110-10 also. The current Cleveland parts catalog shows the Cleveland 10-54 was originally manufactured as the Gerdes A110-10 but that isn't correct which has contributed to the parts kits being incorrect. Page 8, Note 1 on the left in the link below.

Also wanted to add that the interior bore of the Gerdes cylinder is a steel sleeve so it'll need a coating of hydraulic oil during reassembly if the cylinder isn't going back into service right away. I'd guess the Cleveland cylinders are also steel lined so take a look and lube it up during reassembly if the parts are going to be sitting for any length of time.
 
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