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FlyingMonkey

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I went to make my first flight today following the tail reinstall. Got the airplane out, started, warmed up...

 

And when I took off the parking brake to taxi, the left brake was locked onto the disc and would not budge. I shut down, pulled the brake off the wheel, and used a clamp to get the piston pushed back in. Reinstalled, taxied around, and it did it again.

 

Has anybody seen this with Matco brakes? It seems like the piston is binding in the caliper housing, and not being able to release. I opened the drain valve a bit and confirmed the brake was not pressurized when the brakes were released.

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I went to make my first flight today following the tail reinstall. Got the airplane out, started, warmed up...

 

And when I took off the parking brake to taxi, the left brake was locked onto the disc and would not budge. I shut down, pulled the brake off the wheel, and used a clamp to get the piston pushed back in. Reinstalled, taxied around, and it did it again.

 

Has anybody seen this with Matco brakes? It seems like the piston is binding in the caliper housing, and not being able to release. I opened the drain valve a bit and confirmed the brake was not pressurized when the brakes were released.

 

Check the thickness of the shoe, if too thin it could happen.

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I agree with 100 Hamburger. If the pads get too thin the caliper piston comes out a little too far and will not retract as it gets cocked a tad sideways at times. new pads usually take care of this. The other thing that can also cause this is water that may have intruded into your caliper area and caused some minor corrosion. The Matco brake pad has a notch cut into it. You can see it without pulling the wheel on the top edge of the pads. If that is gone time for new pads.

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Andy, the pins that the pads slide on are alignment pins. I had this problem when one of the nuts loosened, about drove me crazy. It was a call to Matco that the topic accidentally came up. I loosened the nuts, trial and errored the fit and have not had an issue since. PM me if you need more info.

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That is a different problem I think, Ian. The pins I am referring to are the pins that the floating side uses to align with the piston side. They are eccentric and if they are lose our get moved they will jam in the holes. Then they need to be realigned before they are tightened.

I am surprised the bolts you mention came loose. Did someone replace the nordlock washers? They seem to be extremely effective in this application. I have never had a hint of looseness in those bolts.

Worth checking though, Andy.

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Matco brake pads on FD CTs are compatible with all RA066-10600 (rapco part #) or 066-10600 (Cleveland part #). Six 4-4 and Six 4-6 brass brake lining rivets are also needed. Matco part number is WHLM66-106 for the liners, MSC4-4 and MSC4-6 for the rivets. It's easier to just buy this as it comes with everything: http://www.matcomfg.com/BRAKERELINEKIT-idv-3485-12.html

 

You will also need a brake liner tool. Instructions here: http://www.rapcoinc.com/pdf/Informational%20Tips/Rivet%20Tool%20Instructions.pdf . NOTE: as an amendment, I find it much easier to remove the pins without damaging the pads by using a drill press and appropriately sized bit to "shave" off the shop head of the rivet before punching. Availableon aircraft spruce from here: http://www.aircraftspruce.com/catalog/topages/RapcoBrake.php?clickkey=10764

 

As always, I recommend cross referencing in case your brake system is different.

 

Finally, please pay attention to the brake pad notches! Those are wear indicators! Look below at these photos. The U shaped notches on the left and right of the pad are what I am talking about. When any of them are gone, it's time to replace!

 

brake_preview.jpg

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The wear indicators were just barely at the end when this problem started, so I thought I had a few hours left on them.

 

I made a drive over to Aircraft Spruce today and picked up two sets of pads and rivets, and the rivet setting/removal tool.  I will put the new pads on tomorrow.

 

I probably won't get to fly tomorrow due to forecast high winds, but I should at least be able to taxi around a bit and test the brakes.

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The wear indicators were just barely at the end when this problem started, so I thought I had a few hours left on them.

 

I made a drive over to Aircraft Spruce today and picked up two sets of pads and rivets, and the rivet setting/removal tool.  I will put the new pads on tomorrow.

 

I probably won't get to fly tomorrow due to forecast high winds, but I should at least be able to taxi around a bit and test the brakes.

 

Morden,  the life expectancy for the shoes is about a year.  The reason has to do with the high RPM of the Rotax that requires using the brakes during taxi...they wear out fast.

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I installed my Matco brakes on 9/7/09 at 171.4 hours. I just completed an annual a few days ago and had to replace the brake pads for the first time at 405.3 hours. 

 

So, I went 233.9 hours and 459 landings on one set of pads. Seems pretty good considering, as Hamburger says, the CT requires frequent brake application when taxiing at 1900-2000 rpm, which I do. I am also pretty heavy on the brakes as I like to make the 800 ft turnoff - stupid, I know, considering our home plate runway is 3000 Ft. 

 

When you see the pad wear indicators are about to disappear, don't wait to change them. In my limited experience with these pads, one set, when the indicators are gone, you will be right at the rivet head. 

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I installed my Matco brakes on 9/7/09 at 171.4 hours. I just completed an annual a few days ago and had to replace the brake pads for the first time at 405.3 hours. 

 

So, I went 233.9 hours and 459 landings on one set of pads. Seems pretty good considering, as Hamburger says, the CT requires frequent brake application when taxiing at 1900-2000 rpm, which I do. I am also pretty heavy on the brakes as I like to make the 800 ft turnoff - stupid, I know, considering our home plate runway is 3000 Ft. 

 

When you see the pad wear indicators are about to disappear, don't wait to change them. In my limited experience with these pads, one set, when the indicators are gone, you will be right at the rivet head. 

 

Let me frame the comment better.  My new CTLSi wore down the factory installed brake pads in 25 hrs.  They were replaced at factory expense, but done here in the USA at a shop in Carson City, NV.  Since those pads were placed on the plane, I have put another 225 hrs.  so far so good.

 

I was told by FD that the brake pads wear out quicker due to the fast idle and taxi of the Rotax engine.  Possibly that statement only applies to the factory pads?

 

I can't say...just relaying what I was told...

 

I am also intrigued by Morden's comment that he wears out tires quickly.  So far my factory tundra tires look new after 250 hrs.

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The brakes and tires are different issues. My original Matco pads have 80 hours on them. That's about a year of flying. As I said, I'm not shy on the brakes -- they are wear items.

 

The tire wear issue is better than it was, but still bad. I wore out a set of the stiff 8 ply tires in the same time period as the brake pads, 80 hours. That is probably 250-300 landings how I fly. I am going to revisit the tire issue, probably after the summer flying season. I will probably get some lasers and a machinist friend of mine involved.

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Rotax doesn't have a fast idle, that comes from the mechanic or pilot during taxi.

If you have to hold constant pressure on the brakes at idle taxi then your idle rpm is too high or you are just trying to taxi too slow and just ride your brakes or resting your hand on the brake lever. Brake pads should last a few hundred hours under normal use. If you need them use them, they are cheap to replace compared to many things. I'm not easy on mine and they tend to last approximately 400+ hundred hours. I have only put on 1 replacement set of pads on my SW. Most of my clients put on hundreds of hours too.

 

FD uses jigs to quick drill many items. There have been many cases where the toe in & out have not been correct and people have worn out tires in 25-50 hours and especially the smaller 4.00-6 tires. They have many with too much camber too so the outside half wears much faster than the whole tire.

 

When I put Matco's on I correct all CTSW's for the camber to make the tires sit flatter and wear even across the whole tread. The SW's are worse than the LS's.

 

The nice thing about our brake pads is you don't have to mess with removing anything other than a couple of bolts and It doesn't take very long to swap pads.

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Rotax doesn't have a fast idle, that comes from the mechanic or pilot during taxi.

If you have to hold constant pressure on the brakes at idle taxi then your idle rpm is too high or you are just trying to taxi too slow and just ride your brakes or resting your hand on the brake lever. Brake pads should last a few hundred hours under normal use. If you need them use them, they are cheap to replace compared to many things. I'm not easy on mine and they tend to last approximately 400+ hundred hours. I have only put on 1 replacement set of pads on my SW. Most of my clients put on hundreds of hours too.

 

FD uses jigs to quick drill many items. There have been many cases where the toe in & out have not been correct and people have worn out tires in 25-50 hours and especially the smaller 4.00-6 tires. They have many with too much camber too so the outside half wears much faster than the whole tire.

 

When I put Matco's on I correct all CTSW's for the camber to make the tires sit flatter and wear even across the whole tread. The SW's are worse than the LS's.

 

The nice thing about our brake pads is you don't have to mess with removing anything other than a couple of bolts and It doesn't take very long to swap pads.

That's exactly my situation...excess toe in and excess negative camber. The tires wear 80% on the outsides. I shimmed the wheels to the allowable limits, and still have issues. As I said, I will put some lasers on it and try to figure out what would be needed to engineer a solution. Will probably require a machined shim plate instead of washers, longer axle bolts, and a blessing from Matco and FD.

 

I do have the small tires.

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Data point:

 

Sky Arrow with the supposedly inferior Marc Ingegnos.

 

About 405 hours over 7+ years and still have life on the original pads. Same ROTAX, same idle, no need to routinely drag the brakes when taxiing.

 

Replacement pads are very expensive, with bonded linings. When the time comes I'm considering drilling the backing plate and riveting on replacement linings - I found a set with near identical shape.

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My idle is about 1500 RPM but I keep it above 1800 during tax, and all other times. A 1900-2000 RPM will give me a taxi above 12K if I let it. To keep it in the 10-12K range I don't ride the brakes but I give it continue short applications as required. I suspect much of my brake wear is due to my desire to make the 800 ft turn off.

 

But, I don't care. They are wear items and relatively cheap.

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Roger,

 

By fast idle I mean the Rotax engine idles much faster than a Continental or Lycoming engine.  The POH says idle range is 1500-1800rpm.  Mine is around 1700rpm and need to run around 1900rpm for taxi.  Taxiing is a challenge because the plane wants to gain speed and roll too fast even on flats and the brakes have to be feathered to keep the plane taxiing at a safe speed.

 

FD said the phenom is known to them and that they expect the brakes to be worn down at a faster rate than other planes.  I don't know what 'normal' is for the Matco brake pads, but the factory supplied pads wore out quickly, after about three months of regular flying.  The current set has lasted over 15 months so far.

 

My tires on the other hand show no wear at all after nearly two years and 250 hours and over a thousand landings.  So Morden's tire issue seems troublesome to me and I will be interested to see what the problems turns out to be...

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Prop rpm, which is what matters, is not that different from a typical Continental or Lycoming.

 

One needs to divide engine rpm by 2.43 to get an apples to apples comparison.

 

So 1,700 engine rpm = about 700 rpm at the prop. Maybe even less than a Continental or Lycoming direct-drive engine at idle.

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Data point:

 

Sky Arrow with the supposedly inferior Marc Ingegnos.

 

About 405 hours over 7+ years and still have life on the original pads. Same ROTAX, same idle, no need to routinely drag the brakes when taxiing.

 

Replacement pads are very expensive, with bonded linings. When the time comes I'm considering drilling the backing plate and riveting on replacement linings - I found a set with near identical shape.

 

Matco pads are so cheap, that I'm not worried about them wearing fast.  I got two sets of pads (one set covers both wheels) with the rivets to attach today for $60.  While others might be getting a lot of time out of their pads, I'm happy with replacing them annually.  In fact, I just did my annual, so I will probably add "replace brake pads" to my check list and avoid this issue forever more.

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