Kokemiller

Kokemiller

Well Known Member
Just had my first maintenance issue on my yet to fly 9a. noticed brake fluid building up in the area where the piston goes into the master cylinder, cleaned it up a few times and in a few days it would pool up again. Vans sent a rebuild kit free of charge and I installed it last night, bled the lines, and so far so good. Just wandering if these Matco master cylinders have cronic leak issues or if it was just bad luck.
 
Bad luck

Personally never heard of another one leaking. Mine are fine at 350 hours ish.

Frank
 
Yep, me too.

Both of my cylinders leaked from the beginning as you describe. I went by Van's Sun-N Fun booth to ask the question to see if this has been an issue. I spoke with Gus and he said I had probablely let some shavings get into the master cylinder. I could not imangine this happening to both master cylinders. He suggested I order their rebuild kit.
I contacted Matco. They said that if the master cylinders had set on the shelf for a while, the fluid they use in assymbley could dry and cause a leak.
I ordered two kits from Matco at about the same price as one from Van's. It did lack an aluminum piston that I did not need.
Now I have one that does not leak and one that does.
I know of one Yak 52TW that has the same issue and will be watching this thread to find the answer.
 
Me as well

I just hooked up my master cylinders in my -8 and the left started to leak immediately at the same location. I havn't flown yet. I'll contact Vans and shoot for a replacement.

Robert Grigson
RV-8
 
Matco tent at OSH

I found the Matco tent this morning and am planning to visit with them tomorrow.
I will try and post there coments.
 
Try Grove

I just rebuilt my brake system, and added right-side brakes. I used Grove cylinders, and they are top-of-the-line! Adjustable, also, so it is easy to get the right "tilt" on the brake pedals.

Very happy with Grove!!! :)
 
I showed Matco my master cylinders.

I just returned from OSH. While there I spoke to a Matco rep about my ongoing problem. After answering a few questions he wanted to walk to RV parking for a look at my installation. Examining the master cylinders he felt the shafts could possibly have an imperfect finish. He took my address and said they would try and ship a new set same day.
It is a blood running to my head pain to remove and replace the cylinders, but I am very pleased with their attention and support.
 
Matco Master Cylinder Leak - Which Shaft?

I have the same thing, on the left, after 8 years, about 600 hours. Rebuilt the cylinder but still leaks. The shaft has wear (a groove) and I believe that is where the leak is. I want to replace the shaft. Matco Site shows several shafts.
http://www.matcomfg.com/MasterCylinderParts-tp2-46.html?Pos=54
I believe it is the MC-4G but it could be but it could be the MC-4A. I don't have this apart or even where I can see it now. Anybody know for sure?
 
Leaking at the Fitting

I have a leak on the lower brake line fitting on mine, which is due to hole being oval. Someone had a loose fixture when they were machining. I called them and they said I have to buy a new one and then send in the old and they will credit me if it is oval as I say. I have seen a few others with the oval hole as well. I don't really want to buy another, possibly defective, master cylinder from them, and the leak is slow, so I am in a holding pattern on it for now.

Hans
 
another leaking Matco Master Cylinder

I am also having a leak on my left mc. Exactly on top where the pin inserts. the leak occurred immediately when I charged the system. Its a brand new system. I'll call vans tomorrow to get their input. perhaps they'll send me a repair kit. Anybody know if the kit comes with how to on replacing the o ring?
 
Mike, google matco brake and you may find a diagram showing the parts. I did that a year or so ago and it was easy to take it apart and replace the O-rings.

Refilling the fluid was not a pretty thing to watch.
 
follow up

Vans sent me a rebuild kit and I installed it. It has been about 4 months and looks to be sealed well (not flying yet).

I have had a very slow leak on the bottom fitting, about 1 drop per month. Just recently tightened it 1 revolution. I hope that fixes it because it is heading to the paint shop in a month.

Bleeding the system is really easy if you push the fluid up from the bottom such as described in other posts.
 
van's response

I wanted to post for those interested that van's stated Matco will cover issues if you have them less than 1 year. for those of us who had your fuse kit longer than 1 year.. your out of luck. I'm buying the replacement o rings for 13.00.. hopefully they'll work:eek:
 
Mike Stansbury said:
I wanted to post for those interested that van's stated Matco will cover issues if you have them less than 1 year. for those of us who had your fuse kit longer than 1 year.. your out of luck. I'm buying the replacement o rings for 13.00.. hopefully they'll work:eek:
Click to expand...

That is pretty pricey for o-rings. I have replaced serverl over the years using harware store o-rings, with no leaks.

Make sure you debur the hole in the shaft for the clevis pin. When you pull the replacement o-ring over it a sharo edge can cut the o-ring. This was some of the problems Maco was having.
 
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Matco leak again

I posted earlier when my Matco leaked as soon as it was installed. Vans replaced the master cylinder, so that was cool. However here I am again with the same leak again in the replacement master cylinder. I have flown 70 hours. I'll order the refurb kit and try that.

Robert Grigson
RV-8 Fastback
 
still leaking

I wanted to provide an update to this issue. iv'e replaced my left o ring. yep... still leaking with all new componets:mad:

Matco stated that I could purchase a replacement and ship my original back to them for "inspection" to see if they'd warrenty it. brand new carpet I'm ready to put in but not going to b/c of this leak. real shame. anybody else had any luck with a diagnosis?
 
MATCO leak

Hi Mike

Yes, I had some success with the refurb kit. Basically the shaft was scored in and around the area that contacts with the top inner seal. I cleaned up the scoring (on the deburring wheel) and then modified the brake pedal to get rid of the applied end moment.

Matco (George at Matco) was very pro-active and keen to see the master cylinders mounted in a manner that minimizes the any applied end moments. Basically I believe the Vans method of mounting these cylinders inevitably results in some bending moment on the end of the master cylinder (RV-8 ground adjustable rudder pedals). This may lead to a problem and it may not. It did with me.

I have some pictures but have not worked out how to post them. Sent me a PM and I'll send the picture of the modified pedals.

Robert Grigson
Mill Creek, WA
RV-8 IO-375M1B 200RV
 
Mine have leaked from the beginning and still leak about the same at 450 hours. Just about a drop every week or two-not enough to make me change masters but is messy and aggrivating. I add a squirt of brake fluid when I have the cowl off and keep flying.
 
I see a trend here

This is an old story for Matco. When I installed my master cylinders in 2005, one of the two leaked. I bought the rebuild kit and the unit still leaked just more slowly. It would hold pressure for a short while and then go flat sort of like a bad master cylinder on a car brake system. When I was flying off my test hours the situation got so bad that during one landing I had no left brake (it was good on takeoff) and I had an excursion off the runway barely missing a runway landing light. For those who have not flown yet, trust me when I say, you need good brakes on an RV.

To their credit, Van's sent a free replacement master cylinder so I could make my trip to the paint shop two days later. The replacement was better but not leak free.

These master cylinders also exhibited the related 'weak spring' problem and I could often feel the brakes dragging when taxing. I went through a pair of brake pads in 50 hours. So I replaced the Matco with Grove units and haven't had a problem of any sort since (300+ hours on the Groves now). I bleed them once a year during the condition inspection.

If your troubles persist, I recommend the Grove units.

Chris
 
I need to check mine but I believe that they are Cleveland units. I did change out the O-rings as a pre-emptive measure. No leaks ever to my knowledge.
 
Stat-O-Seal

I had a failure on my left brake. It was the master cylinder and it wasn't the o-rings. It was a funny little washer with a seal in the hole that goes on the end of the piston. After tearing down, you could see the breakdown of it.

The leak was internal with no visable leaking brake fluid. Prior to replacing the seals, brakes were flushed and no air seen in lines.

Initial compression of the cylinder gave very little pressure on the brakes. After a 3 or 4 pumps, had the left brake again.

Have been noticing on the last few flights that the left brake just didn't seem 100%. Then it went all at one time.

Part directly from Matco cost $1.38. The three other seals were common #7,9,10 o-rings. I will be adding a set of these to my travel kit.
 
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