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  #1  
Old 09-15-2017, 03:24 PM
Fred.Stucklen's Avatar
Fred.Stucklen Fred.Stucklen is offline
 
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Default RV-7A Brake Master Cylinder

I've got a leaky pilots left side brake cylinder. The leak results in draining the fluid out of the upper line going to the co-pilots left brake (which results in a failed co-pilot left braking action).

I'm not sure what repair kit to order from Van's as I'm not sure of the master cylinder type. Cleveland (P/N M/C REPAIR KIT) or Matco (P/N /M/C RBD4 REPAIR).

The master brake cylinders have a gold colored finish... Anybody got any idea which is correct?

(NOTE: I'd post a picture of what's currently in the aircraft, but PhotoBucket has shut me off....)
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  #2  
Old 09-15-2017, 03:39 PM
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Quote:
Originally Posted by Fred.Stucklen View Post
I've got a leaky pilots left side brake cylinder. The leak results in draining the fluid out of the upper line going to the co-pilots left brake (which results in a failed co-pilot left braking action).

I'm not sure what repair kit to order from Van's as I'm not sure of the master cylinder type. Cleveland (P/N M/C REPAIR KIT) or Matco (P/N /M/C RBD4 REPAIR).

The master brake cylinders have a gold colored finish... Anybody got any idea which is correct?

(NOTE: I'd post a picture of what's currently in the aircraft, but PhotoBucket has shut me off....)
Something like this? We seem to have the same thing. Pilot's side LH cylinder. Pilots side RH cyl is dry. Fluid appears to be coming out where the piston exits the cyl. Also a tiny leak in the manifold on the firewall.

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Last edited by LouFly : 09-15-2017 at 03:44 PM. Reason: fix pic
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  #3  
Old 09-15-2017, 05:48 PM
bdserv bdserv is offline
 
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Default

Quote:
Originally Posted by Fred.Stucklen View Post
I've got a leaky pilots left side brake cylinder. The leak results in draining the fluid out of the upper line going to the co-pilots left brake (which results in a failed co-pilot left braking action).

I'm not sure what repair kit to order from Van's as I'm not sure of the master cylinder type. Cleveland (P/N M/C REPAIR KIT) or Matco (P/N /M/C RBD4 REPAIR).

The master brake cylinders have a gold colored finish... Anybody got any idea which is correct?

(NOTE: I'd post a picture of what's currently in the aircraft, but PhotoBucket has shut me off....)
Those sound like Matco cylinders to me - mine have that gold iridite finish and they are Matco.

Bruce
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  #4  
Old 09-15-2017, 06:24 PM
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Fred.Stucklen Fred.Stucklen is offline
 
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Default Master Brake Cylinders

Quote:
Originally Posted by LouFly View Post
Something like this? We seem to have the same thing. Pilot's side LH cylinder. Pilots side RH cyl is dry. Fluid appears to be coming out where the piston exits the cyl. Also a tiny leak in the manifold on the firewall.

Bob, Those are definately Cleveland, and silver colored. Mine do not have the lables, and are gold colored, so probaly the Matcos....

Thanks for the feedback...
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  #5  
Old 09-15-2017, 06:25 PM
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Fred.Stucklen Fred.Stucklen is offline
 
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Default Master Brake Cylinders

Quote:
Originally Posted by bdserv View Post
Those sound like Matco cylinders to me - mine have that gold iridite finish and they are Matco.

Bruce
Bruce, I tend to agree with you as the previous post showed the Cleveland units, which are not like mine.....

Thanks,
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  #6  
Old 09-15-2017, 11:05 PM
gasman gasman is offline
 
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[quote=Fred.Stucklen;1204301]I've got a leaky pilots left side brake cylinder. The leak results in draining the fluid out of the upper line going to the co-pilots left brake (which results in a failed co-pilot left braking action)./QUOTE]

I think you mean coming from the co-pilot side. Your lines should go from the fluid res. to the co-pilot then to the pilot side. If it went to the pilot side first, then the pilots brake pedals would not work if the passenger were pressing on the brakes.
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  #7  
Old 09-16-2017, 08:23 AM
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Yes, the lines need to go from the reservoir to the co-pilot top of master cylinders, then co-pilot bottom to pilot top and then pilot bottom to brakes.

Roberta
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  #8  
Old 09-16-2017, 08:55 AM
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AndyRV7 AndyRV7 is offline
 
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That doesn't sound like a small leak.

My Matco masters are gold and they have the white, aluminum (??) label on them. Fluid will take the labels off though so yours may be gone. I had a LOT of gremlins in my set-up when I bought the plane. Weeping fluid and a drop or two on the floor every once in a while. But the masters were always wet. It didn't effect my braking and was a very steady-state problem from the day I flew the plane home.

I had someone help me rebuild all the cylinders and they were dry for about a week after that. Then, more dripping. So I bought more repair kits and did it again myself. There are going to be a million suggestions for why they leak. In the end, mine seems to have been then simplest of all, loose line fittings into the cylinders. The guy that helped me initially didn't have a good answer for how tight the fittings should be, so I would get them to where they felt snug and try to turn them further until they were in the correct orientation for the lines to attach. They didn't feel particularly tight at that point but I was afraid to turn them past vertical for fear they would not be able to be brought another 360 degrees back to where I needed them to point. In the end and at the end of my rope, I finally went past "tight" and found that I had another 360 degrees of tightening left in them. That seems to have done the trick for me. All this time spent and trial and error certainly made me comfortable working on the brake system.

I was chasing my tail for so long with these that I finally decided to clean the fluid off and tape some clean white paper towel over every junction in the system, inside the cockpit (don't forget the end of the cylinder where the rod exits!). I figured this way I could identify where the leaks were and I might learn something from that information. They never leaked again though. Clean all your fittings and the threads inside the fitting holes in the cylinders with a wire brush and a solvent. I can't remember what solvent I used but it wasn't a difficult job. Just a little tedious. I originally had one of the sticky, black, sealants on my set-up. I can't remember what it was (fuel lube or one of the other common sealants), I have them all!! Matco and some people in here recommended Loctite 567. It is white and much easier to see a weeping leak on than the black gunk I had in there earlier.

At the end of the day, I tried the scatter-gun approach to fixing the problem in the beginning. I would suggest doing the rebuild and cleaning all the fittings and threads and then put it all back together. You will be back at square one now. I would also try the paper towel trick so you can see exactly where your fluid is leaking. If the rebuild doesn't help, at least you will know exactly where the leak is and you can use a more directed attempt to fix it from there.

Good luck!! Andy

PS. Maybe you knew all this already and really just needed to know which kit to buy...

Last edited by AndyRV7 : 09-16-2017 at 09:04 AM.
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  #9  
Old 09-16-2017, 02:38 PM
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Fred.Stucklen Fred.Stucklen is offline
 
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Default Brake line routing

[quote=gasman;1204368]
Quote:
Originally Posted by Fred.Stucklen View Post
I've got a leaky pilots left side brake cylinder. The leak results in draining the fluid out of the upper line going to the co-pilots left brake (which results in a failed co-pilot left braking action)./QUOTE]

I think you mean coming from the co-pilot side. Your lines should go from the fluid res. to the co-pilot then to the pilot side. If it went to the pilot side first, then the pilots brake pedals would not work if the passenger were pressing on the brakes.
Yep, you're correct. My description was wrong. My brakes are plumbed as you have described.
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  #10  
Old 09-17-2017, 07:21 AM
TS Flightlines TS Flightlines is offline
 
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Hey Fred---
Resealing the cylinder will fix the problem 98% of the time. IF the piston has worn the cylinder bore in a slight taper, then it may not. Depending on the hours on the cylinders, it might be a good idea to check them all.

Tom
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