Citabria 7ECA Heel Brake Master Cylinders, Cleveland 10-5

[Bartman]

Decided to try to finally get these to stop leaking while we're doing the annual this week. These are the Cleveland 10-5 master cylinders with integral reservoirs and parking brake valves. There's not much out there about these valves so I took some photos and tried to explain how the rebuild went.

Here's the master cylinder installed under the floorboards. You can see the heel brake pedal sticking up through the floorboard on the right.


Start by opening up the hydraulic line in the back left of the photo. Then unscrew the blue AN fitting and pry out the little spring and plunger that are being held in by the AN fitting. That block like appendage hanging off the side of the cylinder is the parking brake valve, unscrew the nut and twist/push the pivot shaft out the top. You might have to turn the parking brake pivot shaft to get it out, I'm not sure what the trick is but it didn't just pop out. If the plunger is stuck in the there then there will be interference, turn, push, turn, push some more, it will eventually pop out.

Brake line disconnected


View of the top of the master cylinder, that return spring for the parking brake has to be disconnected too at some point.


That's the pivot shaft of the parking brake dangling in place after being pushed out the top. It acts a lot like the cam shaft in the more common Gerdes parking brake valves that are bolted to the floorboards of later Citabrias and Decathlons.


The green tube is an extension that allows the aft end of the master cylinder to be attached to a frame member and the forward end of the tube to be attached to the bottom of the brake pedals. It has to be removed from the brake cylinder shaft so the packing nut can be slid off the plunger shaft. Chances are, the holes for the pin are pretty out of round. Use an awl or something through the plunger shaft and unscrew the nut and threaded end that were attached to the extension tube.


Unscrew the packing nut and slide the plunger assembly out. The packing nut has an o-ring on the inside.


At the other end of the shaft is the actual brake plunger. There's an o-ring on the outside and a plastic washer buried under the plunger. There's a really fragile snap ring of some sort holding this end together, if you decide to go looking for the plastic washer be really really careful removing the little snap ring keeping that end of the assembly together. The photos should explain it.


There is an o-ring on the shaft for the parking brake valve and another inside where the parking brake shaft goes into the housing. I'm pretty sure that those two parking brake o-rings weren't changed when my cylinders were supposedly rebuilt which is probably why they continued to leak.

Here it is all back together, cleaned up and ready to go back in.


Part tag from Planepartsinc.com and the assembly lube I used. The rebuild kits I used were about $30 each.


Hope that helps!
Bart

 

[Bartman]

For what it's worth, if you don't have a crimped sleeve on the end of your parking brake cables or if the end isn't frayed like mine, you can try to pull the brake cable out and then do all of the disassembly on the bench. I had a crimped sleeve on one side and the other side was frayed so I had to leave the parking brake cables in place on both sides which explains why I did some disassembly of the unit in place before taking it out.

 

[Bartman]

Was in my Citabria parts manual looking for an air filter part number and saw there is actually a parts diagram for the Cleveland 10-5 master cylinders.

 

[Bill Vickland]

Your photos are a live saver, but Im still in need of life support. I have two issues.
1. In your #1 and #7 photo it is evident that there is a threaded attachment (paart # 18 in your ACA diagram.) coming out of the push rod that is treaded into the master cylinder shaft. Mine had only a washer and cotter pin that attached the push rod and shaft. Looks shaky by comparison. Is that part 18 available separately somewhere or can I make my own. Can I duplicate it with a 1/4 - 28 bolt. It would also need a 3/8 x 1/4 bushing to stabilize the bolt in the 3/8 bore of the push rod. The 1/2-inch extension seems to make a big difference in the brake pedal, making it tilt to the rear significantly. If that's normal, Ill go for it.
2. I overhauled the cylinders with the Cleveland kit and attempted to bench test them. Wierd results. Moving the piston shaft does not send fluid out the exit port and when it retracts under spring pressure hydraulic fluid comes out of the vent port in the filler plug with enough force to spray the ceiling. I am careful to ensure that the parking brake lever is open. I have disassembled and check the installation of the seals and dont see a problem.

Any suggestions.
This forum site is absolutely essential to any 7ECA Owner.
Many thanks for doing it. The pics are great
Bill Vickland

 

[Bartman]

there is a better picture of that clevis end in this used parts listing but the part has been sold already.

Cleveland Brake Master Cylinder

Cleveland Brake Master Cylinder

aircraftpartsandsalvage.com

i would search ebay for a master cylinder assembly or call Ron at Rainbow Flying Service, he has a pretty rich assortment of used parts. if you have to make a new part just make sure your IA will sign it off.

as for the fluid flow, i can't imagine how that would happen. it wasn't really obvious to me when it was apart how the fluid flows down from the reservoir and into the cavity ahead of the piston without it being blown out the top like you experienced either in the braking or the return stroke. there are a few o-rings that look similar but are slightly thicker or slightly larger in diameter. Maybe you swapped out two that were close but now there's blockage keeping the fluid from moving around in the master cylinder assembly?

glad to hear the site is helping you with your plane Bill!

 

[Bartman]

Bill,

The 10-5 master cylinder is still in the Parker/Cleveland catalog. The page from the catalog is attached to this post below. There is a part number for that clevis, 143-00400, and Aircraft Spruce lists it but it's $500!!

Cleveland Clevises | Aircraft Spruce ®

Cleveland Clevises Cleveland Clevises.

www.aircraftspruce.com

Maybe now that you have a part number you can scrounge one up from somewhere?

 

[Bob Turner]

Get one from Grove and get a field approval. I think the Grove part is a bolt-in replacement -an expert would not know except for the data tag.

 

[Bill Vickland]

New set of problems. In attempting to bleed the brakes, I cannon push the 5606 into to cylinder. The parking brake mechanism appears to be installed correctly. Shouldn't this be easy, the brake pressure in the line would have to relieve in order for the wheels to roll. I can't image that the pressure from my little 5606 oil can would not fill the reservoir.

 

[Bartman]

Bill, you're trying to pump the fluid up from the caliper nipple? make sure you're loosening the nipple and not the adapter it's screwed into. i made that mistake initially and couldn't get the fluid to drain out. the nipple needs a 1/4" wrench.

 

[Bill Vickland]

Yes, I bleed it up to the cylinder with the AN nut and tubing off at the cylinder. Then I pulled the cylinder and tried to do it on the bench. But now I wonder the little # valve is assembled correctly. Is the #3 o ring supposed to be a shaft seal for the valve or is it a valve seat that seals fluid pressure against the end of the AN elbow fitting?

 

[Bill Vickland]

What is the function of the parts marked 6,7,8,9. Can they be the source of my problem. I may not have serviced them when I installed the repair kit.

 

[Bartman]

the only thing to change out in those pieces is the plastic washer although part #9 does have an o-ring on the outside. i'm not sure what the consequences are if you're missing the plastic washer or if it's cracked/worn.

 

[Bartman]

Bill,

look at the diagram in this post

Citabria - 7ECA Heel Brake Master Cylinders, Cleveland 10-5

Decided to try to finally get these to stop leaking while we're doing the annual this week. These are the Cleveland 10-5 master cylinders with integral reservoirs and parking brake valves. There's not much out there about these valves so I took some photos and tried to explain how the rebuild...

champcitabriadecathlonforums.com

it shows parts 24, 25, 26, and 28, they are the parts for the parking brake valve you're asking about. the o-ring goes in first and seals the check valve plunger #24.

 

[Fong]

when it retracts under spring pressure hydraulic fluid comes out of the vent port in the filler plug with enough force to spray the ceiling.

Resurrecting this because I am having this same problem on the right brake. Is it possible that the self-bleeding function is contained in the fill plug and has failed somehow? That is, it should let air pressure in but not out, but it is acting as a diaphragm and pushing the fluid out? I refill a teaspoon every couple of flights and it all seems to spit out the top even when I am gentle with the right brake. Is it possible I just need a new one of these? https://www.univair.com/ercoupe/parts/415-33447-ercoupe-plug/

 

[Bob Turner]

Possible. I am going to guess trapped air.

Drain every scrap of fluid out, then refill from the bottom.

I have done a couple Grove conversions to mechanical brake Champs - I always add a bleeder screw at the master cylinder, even though I have not had to use them. On the Cubs the bleeder screw is so essential that I drill the master at its highest point, tap 1/8 NPT, and install a bleeder screw. I use those almost every time I add fluid (once a year or so) because I let the fluid get low and air gets in the main cylinder. Once the air is out, if you keep the reservoir almost full, you won't have that problem.

 

[Bob Turner]

By the way, you can rebuild these things with an $11 kit from Plane Parts. The tricky part is the Stat-O-Seal (and the snap ring - I bought special Snap-On snap ring pliers).

 

[Fong]

That's awesome, thanks for the advice--I tried normal bleeding since it was easy with the door off on the right brake and that seems to have done the trick. It seems to have stopped spitting out the top, too. I'll try your bleed-from-below technique if it doesn't hold for some reason.

 

[RichXP]

Overhauled the right master cylinder on my 1970 7KCAB today, no issues other than I can't seem to reinstall the parking brake valve into the cylinder body on the master cylinder. There seems to be a spring loaded plunger internal to the cylinder that is preventing the valve from sliding in. I tried twisting the valve while pushing but no luck. Is there a technique to this that I'm missing?

 

[November67]

I can remember having to push it in a bit until it won't go further and twist it to get it into position.
You have an example on the left, pay attention while taking it apart....

 

[RichXP]

I figured it out, you have to remove the AN fitting that goes to the wheel brake, under the fitting is a spring and plunger that must be removed to re-install the parking brake valve. Once the valve is in place you can reinstall the spring, plunger, and AN fitting.