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digidocs
Joined: 04 Dec 2013
Posts: 59
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 Posted: Sun Apr 28, 2019 7:38 pm Post subject: Brakes have me stumped |
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Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco brakes) and found that they were showing checking/cracking as shown the attached photos. In speaking with Matco, I learned that this is caused by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by hand and cause them to retract (makes sense). Unfortunately, this was very difficult to do with mine, indicating there is some sort of restriction. To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the pistons in. I'm starting to wonder if it's possible that a) my -3 Bonaco brake lines are restrictive, b) there's another problem I haven't thought of, or c) that is is all a wild goose chase and it's always hard to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
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Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
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| Posted: Sun Apr 28, 2019 8:25 pm Post subject: Brakes have me stumped |
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I can't comment on the Matco brakes, as I have the Clevelands. I do
however have the Bonaco lines. I have never been able to push the piston
back in on any Cleveland brake that was hooked up to a system, only if
there was no line connected. I always used a cushioned C clamp to push
the piston back in if I was replacing pads.
I have found the MS O-rings that Clevelands come with do not tolerate
the heat generated by the -10 brakes. So I have the Viton O-rings and
the synthetic equivalent to 5606 brake fluid (Royco 782?). I was able to
get the O-rings from Spruce.
The minute variation in the brake disc pushes the piston back just
enough so they don't drag. If you can push your plane by hand without a
lot of effort, on a flat surface, your brakes are not dragging. If they
drag, it is both hard to push and you generally can hear the dragging.
On 4/28/2019 8:36 PM, David Carr wrote:
| Quote: | Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco
brakes) and found that they were showing checking/cracking as shown the
attached photos. In speaking with Matco, I learned that this is caused
by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by
hand and cause them to retract (makes sense). Unfortunately, this was
very difficult to do with mine, indicating there is some sort of
restriction. To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure
they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the
pistons in. I'm starting to wonder if it's possible that a) my -3
Bonaco brake lines are restrictive, b) there's another problem I haven't
thought of, or c) that is is all a wild goose chase and it's always hard
to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
|
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Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
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Kelly McMullen
Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ
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| Posted: Sun Apr 28, 2019 8:38 pm Post subject: Brakes have me stumped |
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Looking at your photos, yes, it is possible they got a bit hot. However, it is also possible the rivets were squeezed a little too tight. That will cause cracking around the rivets.
They only need to be tight enough that you can't move the pad on the backing plate by hand.
| Quote: | | Sent from my TRS-80 Model 100 |
On Sun, Apr 28, 2019 at 8:42 PM David Carr <junk(at)dcarr.org (junk(at)dcarr.org)> wrote:
| Quote: | Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco brakes) and found that they were showing checking/cracking as shown the attached photos. In speaking with Matco, I learned that this is caused by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by hand and cause them to retract (makes sense). Unfortunately, this was very difficult to do with mine, indicating there is some sort of restriction. To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the pistons in. I'm starting to wonder if it's possible that a) my -3 Bonaco brake lines are restrictive, b) there's another problem I haven't thought of, or c) that is is all a wild goose chase and it's always hard to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
|
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD |
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rleffler
Joined: 05 Nov 2006
Posts: 680
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| Posted: Sun Apr 28, 2019 8:46 pm Post subject: Brakes have me stumped |
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I went through this a couple years ago.
1. I installed return springs on the cylinders to ensure they were wide open when not depressed.
2. I had an incident in which I had to taxi back to the hangar with higher than normal rpm. This got everything extremely hot. I was having all kinds of problems getting decent life out the pads afterwards. I had to replace the rotors and the spacers because they became deformed due to the heat. The spacers can also flare at the ends if they are over torqued and hit up. What I found was the the various parts were hanging up and not moving freely.
If the inner shoe pad doesnt move freely, you may want to examine the spacer they ride on. Similarly there is another set of spacers the calipers ride on. Can you move either of these freely with you hands?
Have you checked your rotors to ensure they arent warped? The same goes for the plate that the pads are riveted. They can warp if over heated to.
It wasnt until I replaced all of these that brakes started functioning properly. I cant say these are your issues, but it does give you other things to check.
Get Outlook for iOS
From: owner-rv10-list-server(at)matronics.com on behalf of David Carr <junk(at)dcarr.org>
Sent: Sunday, April 28, 2019 11:50 PM
To: rv10-list(at)matronics.com
Subject: Brakes have me stumped
Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco brakes) and found that they were showing checking/cracking as shown the attached photos. In speaking with Matco, I learned that this is caused by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by hand and cause them to retract (makes sense). Unfortunately, this was very difficult to do with mine, indicating there is some sort of restriction. To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the pistons in. I'm starting to wonder if it's possible that a) my -3 Bonaco brake lines are restrictive, b) there's another problem I haven't thought of, or c) that is is all a wild goose chase and it's always hard to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV10-List |
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_________________
Bob Leffler
N410BL - Phase I
http://mykitlog.com/rleffler |
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peter(at)peteraringer.de
Guest
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| Posted: Sun Apr 28, 2019 9:36 pm Post subject: Brakes have me stumped |
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Hi guys,
do you have metal or bakelite brake pistons?
We found, that bakelite pistons tend to „grow“ on the hot side (brake pad side). We see this on our Chrysler, Jeep & Doge models in our workshop, when driven more than 60.000 miles  )
They normaly are zylindrical. This plus normal little debris from the piston o-ring will make the pistons to block when hot. Sometimes even after cool down. With a lathe I finally turn them zylindrical, replace o-ring and dust boot and everything is fine. When from metal, you may see some rust inside on the piston. Same problem with growing in diameter. Then the only way is to replace them. The pads on the photos are definetly overheated ( see cracks in the middle where there is no rivet). When you can scratch material out from the pad material with a screw driver, you know they are burnt out.
With RV-10 greetings from Germany
Peter
Am 29.04.2019 um 05:47 schrieb David Carr <junk(at)dcarr.org (junk(at)dcarr.org)>:
| Quote: | Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco brakes) and found that they were showing checking/cracking as shown the attached photos. In speaking with Matco, I learned that this is caused by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by hand and cause them to retract (makes sense). Unfortunately, this was very difficult to do with mine, indicating there is some sort of restriction. To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the pistons in. I'm starting to wonder if it's possible that a) my -3 Bonaco brake lines are restrictive, b) there's another problem I haven't thought of, or c) that is is all a wild goose chase and it's always hard to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
<IMG_0423.JPG>
<IMG_0422.JPG>
<IMG_0421.JPG>
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carl.froehlich(at)verizon
Guest
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| Posted: Mon Apr 29, 2019 5:41 am Post subject: Brakes have me stumped |
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I had the left brake drag on the RV-10 at about the 100 hour point. It was so bad the left tire lost most of its inside tread.
The problem was a rolled O ring on the brake caliper piston. I replaced the O ring with a standard one from Van’s and it has been trouble free for 500 hours.
I agree that it looks like the brake pad rivets were squeezed too tight.
Carl
On Apr 29, 2019, at 12:28 AM, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:
| Quote: | Looking at your photos, yes, it is possible they got a bit hot. However, it is also possible the rivets were squeezed a little too tight. That will cause cracking around the rivets.
They only need to be tight enough that you can't move the pad on the backing plate by hand.
| Quote: | | Sent from my TRS-80 Model 100 |
On Sun, Apr 28, 2019 at 8:42 PM David Carr <junk(at)dcarr.org (junk(at)dcarr.org)> wrote:
| Quote: | Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco brakes) and found that they were showing checking/cracking as shown the attached photos. In speaking with Matco, I learned that this is caused by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by hand and cause them to retract (makes sense). Unfortunately, this was very difficult to do with mine, indicating there is some sort of restriction To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the pistons in. I'm starting to wonder if it's possible that a) my -3 Bonaco brake lines are restrictive, b) there's another problem I haven't thought of, or c) that is is all a wild goose chase and it's always hard to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
|
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http://www.matronics.com/Navigator?RV10-List |
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Lenny Iszak
Joined: 23 Mar 2008
Posts: 270
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| Posted: Mon Apr 29, 2019 7:05 am Post subject: Re: Brakes have me stumped |
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Mine has been doing that for a while and I think i just now fixed it.
The discs were warped and that was overheating the calipers/pads even when not using the brakes.
Replacing the discs only didn't help. Adding return springs on the master cylinders didn't help.
The pads crack just as well with Matco's SwiftLine pad/shoe that they rivet together themselves. So I doubt it's an oversqueezed rivet problem. Plus the whole pad looks charred by the time it cracks around the rivet holes.
This time around I replaced the shoes, pads, the pins, everything. Also put thermocouples on both calipers. AFS has two TIT thermocouples inputs so my caliper temps are showing on the screen.
The one thing I learned from that exercise is that when I hold onto the brakes after landing i can see the temps zoom up above 200F in seconds, otherwise they stay below 130F.
Just tap them and let go and the heat from the disc won't have time to transfer over to the pads.
Lenny
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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_________________
Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 500 hrs |
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digidocs
Joined: 04 Dec 2013
Posts: 59
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| Posted: Mon Apr 29, 2019 10:12 am Post subject: Brakes have me stumped |
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Lots of good stuff here.
Bob - The inner pads did seem tight on the spacers so I am replacing those along with the pads. I'm pretty sure the pedals are not sticking. I have a single long pivot bolt to reduce friction and they don't seem to move when I pull them "back" to release further.
Peter - The Matco brakes have aluminum pistons. I had no idea that you could make brake pistons out of bakelite, very interesting.
David
On Sun, Apr 28, 2019 at 11:49 PM Bob Leffler <bob(at)thelefflers.com (bob(at)thelefflers.com)> wrote:
| Quote: | I went through this a couple years ago.
1. I installed return springs on the cylinders to ensure they were wide open when not depressed.
2. I had an incident in which I had to taxi back to the hangar with higher than normal rpm. This got everything extremely hot. I was having all kinds of problems getting decent life out the pads afterwards. I had to replace the rotors and the spacers because they became deformed due to the heat. The spacers can also flare at the ends if they are over torqued and hit up. What I found was the the various parts were hanging up and not moving freely.
If the inner shoe pad doesn’t move freely, you may want to examine the spacer they ride on. Similarly there is another set of spacers the calipers ride on. Can you move either of these freely with you hands?
Have you checked your rotors to ensure they aren’t warped? The same goes for the plate that the pads are riveted. They can warp if over heated to.
It wasn’t until I replaced all of these that brakes started functioning properly. I can’t say these are your issues, but it does give you other things to check.
Get Outlook for iOS
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) on behalf of David Carr <junk(at)dcarr.org (junk(at)dcarr.org)>
Sent: Sunday, April 28, 2019 11:50 PM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Brakes have me stumped
Hi list,
The brakes have me stumped. I recently removed my brake linings (Matco brakes) and found that they were showing checking/cracking as shown the attached photos. In speaking with Matco, I learned that this is caused by excessive heat which is likely caused by the brakes dragging.
Matco suggested that I should be able to squeeze the brake pistons by hand and cause them to retract (makes sense). Unfortunately, this was very difficult to do with mine, indicating there is some sort of restriction. To narrow this down I sequentially:
- Bypassed the notorious parking brake valve
- Disconnected the master cylinder pushrods from the pedals to ensure they're fully extended
- Removed the reservoir cap (why not)
Despite these changes I still find it very difficult to squeeze the pistons in. I'm starting to wonder if it's possible that a) my -3 Bonaco brake lines are restrictive, b) there's another problem I haven't thought of, or c) that is is all a wild goose chase and it's always hard to squeeze the pistons in.
Any ideas out there? I'd appreciate the help.
David
|
| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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digidocs
Joined: 04 Dec 2013
Posts: 59
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| Posted: Mon Apr 29, 2019 10:15 am Post subject: Brakes have me stumped |
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Lenny,
This is very interesting. How did you determine that the discs were warped or was it obvious? Hopefully you've found the issue now!
David
On Mon, Apr 29, 2019 at 10:10 AM Lenny Iszak <lenard(at)rapiddecision.com (lenard(at)rapiddecision.com)> wrote:
| Quote: | --> RV10-List message posted by: "Lenny Iszak" <lenard(at)rapiddecision.com (lenard(at)rapiddecision.com)>
Mine has been doing that for a while and I think i just now fixed it.
The discs were warped and that was overheating the calipers/pads even when not using the brakes.
Replacing the discs only didn't help. Adding return springs on the master cylinders didn't help.
The pads crack just as well with Matco's SwiftLine pad/shoe that they rivet together themselves. So I doubt it's an oversqueezed rivet problem. Plus the whole pad looks charred by the time it cracks around the rivet holes.
This time around I replaced the shoes, pads, the pins, everything. Also put thermocouples on both calipers. AFS has two TIT thermocouples inputs so my caliper temps are showing on the screen.
The one thing I learned from that exercise is that when I hold onto the brakes after landing i can see the temps zoom up above 200F in seconds, otherwise they stay below 130F.
Just tap them and let go and the heat from the disc won't have time to transfer over to the pads.
Lenny
--------
Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 500 hrs
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=489001#489001
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Lenny Iszak
Joined: 23 Mar 2008
Posts: 270
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| Posted: Mon Apr 29, 2019 11:36 am Post subject: Re: Brakes have me stumped |
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Clearly visible. Attached some pictures.
Lenny
| digidocs wrote: | Lenny,
This is very interesting. How did you determine that the discs were warped or was it obvious? Hopefully you've found the issue now!
David
On Mon, Apr 29, 2019 at 10:10 AM Lenny Iszak <lenard> wrote:
| Quote: | --> RV10-List message posted by: "Lenny Iszak" <lenard>
Mine has been doing that for a while and I think i just now fixed it.
The discs were warped and that was overheating the calipers/pads even when not using the brakes.
Replacing the discs only didn't help. Adding return springs on the master cylinders didn't help.
The pads crack just as well with Matco's SwiftLine pad/shoe that they rivet together themselves. So I doubt it's an oversqueezed rivet problem. Plus the whole pad looks charred by the time it cracks around the rivet holes.
This time around I replaced the shoes, pads, the pins, everything. Also put thermocouples on both calipers. AFS has two TIT thermocouples inputs so my caliper temps are showing on the screen.
The one thing I learned from that exercise is that when I hold onto the brakes after landing i can see the temps zoom up above 200F in seconds, otherwise they stay below 130F.
Just tap them and let go and the heat from the disc won't have time to transfer over to the pads.
Lenny
--------
Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 500 hrs
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=489001#489001
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FORUMS -
eferrer" target="_blank">http://forums.matronics.com
===========
WIKI -
errer" target="_blank">http://wiki.matronics.com
===========
b Site -
-Matt Dralle, List Admin.
rel="noreferrer" target="_blank">http://www.matronics.com/contribution
===========
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Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 500 hrs |
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gengrumpy
Joined: 07 May 2013
Posts: 131
Location: Tullahoma, TN
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| Posted: Mon Apr 29, 2019 6:42 pm Post subject: Brakes have me stumped |
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At the risk of being tar’d and feathered by the crowd, let me offer a thought on using brakes in GA aircraft, especially RVs.
Biggest problem with brakes is usually related to the pilot.
Back a long time ago when military brakes were not what they are today, pilots were taught to “never ride the brakes” …. when you need them, step on them and then “get your feet off the brakes”. Reason was the brakes (and they were disc brakes then) would overheat quickly, which was not a good thing. The pilot risked one of the following: brakes would “fade” and give no stopping power; brakes would lock up; brake pucks would spring a leak due to heat and start a fire; etc, etc. Mil 6606 brake will burn very hot and fast….
Fast forward to today. As a CFI, I am constantly battling pilots who like to “ride the brakes” ….. whether they realize it or not. It is easier to “ride the brakes” in an RV than in other GA planes just because of the way the pedals are made and how they are installed. It is far too easy to “ride the brakes” when merely thinking you are only applying rudder when in fact you are inadvertantly applying some brake pressure as well.
And how about those long taxi routes to the runway or ramp? Do you ride the brakes to keep your speed constant on a long taxiway? (the wrong way)
Or do you let the bird coast (with increasing speed) and then apply brakes quickly to slow down, then immediately get off the brakes and start the coast process again? (the right way)
Same thing with slowing down after landing on the runway ,,,,, do you ride the brakes to slow down gradually and then keep your feet on the brakes to turnoff?
Or do you apply moderate, constant pressure to start slowing down …. and then get off the brakes totally and coast a bit, then reapply brakes again?
Remember ….. if you get on the brakes (moderate pressure) to use them, and then immediately get off of them, you won’t generate near as much head on the disc's as if you use a constant pressure on them……I am 12 years on the same MATCO discs and have change pads once.
Just saying. Much of the brake problems in the RV's are not who makes the pads or the disc’s…..it is how you use them.
Oh, don’t forget to let her roll to the far end of the runway to turn off rather than stepping on the brakes to make the closer turnoff whenever you have the option.
grumpy
N184JM
| Quote: | On Apr 29, 2019, at 2:36 PM, Lenny Iszak <lenard(at)rapiddecision.com> wrote:
Clearly visible. Attached some pictures.
Lenny
digidocs wrote:
> Lenny,
>
> This is very interesting. How did you determine that the discs were warped or was it obvious? Hopefully you've found the issue now!
>
>
> David
>
>
> On Mon, Apr 29, 2019 at 10:10 AM Lenny Iszak wrote:
>
>
>>
>>
>> Mine has been doing that for a while and I think i just now fixed it.
>> The discs were warped and that was overheating the calipers/pads even when not using the brakes.
>>
>> Replacing the discs only didn't help. Adding return springs on the master cylinders didn't help.
>>
>> The pads crack just as well with Matco's SwiftLine pad/shoe that they rivet together themselves. So I doubt it's an oversqueezed rivet problem. Plus the whole pad looks charred by the time it cracks around the rivet holes.
>>
>> This time around I replaced the shoes, pads, the pins, everything. Also put thermocouples on both calipers. AFS has two TIT thermocouples inputs so my caliper temps are showing on the screen.
>>
>> The one thing I learned from that exercise is that when I hold onto the brakes after landing i can see the temps zoom up above 200F in seconds, otherwise they stay below 130F.
>> Just tap them and let go and the heat from the disc won't have time to transfer over to the pads.
>>
>> Lenny
>>
>> --------
>> Lenny Iszak
>> Palm City, FL
>> 2014 RV-10, N311LZ - 500 hrs
>>
>>
>>
>>
>> Read this topic online here:
>>
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Lenny Iszak
Palm City, FL
2014 RV-10, N311LZ - 500 hrs
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peter(at)peteraringer.de
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| Posted: Mon Apr 29, 2019 9:13 pm Post subject: Brakes have me stumped |
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John,
this is what I expierienced too in my flight club in Bielefeld - Germany.
One reason is for sure, that the engine idle speed is often too high. Before I read about Mike Bush, I run the engines on the Cessnas, Pipers and Cirrus at 1.200rpm while taxiing, because the self made checklists from the club said this to prevent spark plug fouling at lower rpm. Since I lean the engines to max. rpm/best power on the ground, I rearely use the brakes on taxiing....
Like you said: Human factor )
David,
the bakelite pistons are great while preventing corrosion to the brake calipers, but have their downsides...
On my Dodge Charger SRT-8 I had to change all the metal pistons (six per side at front axle)at about 100.000 KM for corrosion problems...
Von meinem iPad gesendet
| Quote: | Am 30.04.2019 um 04:52 schrieb JOHN MILLER <gengrumpy(at)aol.com>:
At the risk of being tar’d and feathered by the crowd, let me offer a thought on using brakes in GA aircraft, especially RVs.
Biggest problem with brakes is usually related to the pilot.
Back a long time ago when military brakes were not what they are today, pilots were taught to “never ride the brakes” …. when you need them, step on them and then “get your feet off the brakes”. Reason was the brakes (and they were disc brakes then) would overheat quickly, which was not a good thing. The pilot risked one of the following: brakes would “fade” and give no stopping power; brakes would lock up; brake pucks would spring a leak due to heat and start a fire; etc, etc. Mil 6606 brake will burn very hot and fast….
Fast forward to today. As a CFI, I am constantly battling pilots who like to “ride the brakes” ….. whether they realize it or not. It is easier to “ride the brakes” in an RV than in other GA planes just because of the way the pedals are made and how they are installed. It is far too easy to “ride the brakes” when merely thinking you are only applying rudder when in fact you are inadvertantly applying some brake pressure as well.
And how about those long taxi routes to the runway or ramp? Do you ride the brakes to keep your speed constant on a long taxiway? (the wrong way)
Or do you let the bird coast (with increasing speed) and then apply brakes quickly to slow down, then immediately get off the brakes and start the coast process again? (the right way)
Same thing with slowing down after landing on the runway ,,,,, do you ride the brakes to slow down gradually and then keep your feet on the brakes to turnoff?
Or do you apply moderate, constant pressure to start slowing down …. and then get off the brakes totally and coast a bit, then reapply brakes again?
Remember ….. if you get on the brakes (moderate pressure) to use them, and then immediately get off of them, you won’t generate near as much head on the disc's as if you use a constant pressure on them……I am 12 years on the same MATCO discs and have change pads once.
Just saying. Much of the brake problems in the RV's are not who makes the pads or the disc’s…..it is how you use them.
Oh, don’t forget to let her roll to the far end of the runway to turn off rather than stepping on the brakes to make the closer turnoff whenever you have the option.
grumpy
N184JM
> On Apr 29, 2019, at 2:36 PM, Lenny Iszak <lenard(at)rapiddecision.com> wrote:
>
>
>
> Clearly visible. Attached some pictures.
>
> Lenny
>
>
>
> digidocs wrote:
>> Lenny,
>>
>> This is very interesting. How did you determine that the discs were warped or was it obvious? Hopefully you've found the issue now!
>>
>>
>> David
>>
>>
>> On Mon, Apr 29, 2019 at 10:10 AM Lenny Iszak wrote:
>>
>>
>>>
>>>
>>> Mine has been doing that for a while and I think i just now fixed it.
>>> The discs were warped and that was overheating the calipers/pads even when not using the brakes.
>>>
>>> Replacing the discs only didn't help. Adding return springs on the master cylinders didn't help.
>>>
>>> The pads crack just as well with Matco's SwiftLine pad/shoe that they rivet together themselves. So I doubt it's an oversqueezed rivet problem. Plus the whole pad looks charred by the time it cracks around the rivet holes.
>>>
>>> This time around I replaced the shoes, pads, the pins, everything. Also put thermocouples on both calipers. AFS has two TIT thermocouples inputs so my caliper temps are showing on the screen.
>>>
>>> The one thing I learned from that exercise is that when I hold onto the brakes after landing i can see the temps zoom up above 200F in seconds, otherwise they stay below 130F.
>>> Just tap them and let go and the heat from the disc won't have time to transfer over to the pads.
>>>
>>> Lenny
>>>
>>> --------
>>> Lenny Iszak
>>> Palm City, FL
>>> 2014 RV-10, N311LZ - 500 hrs
>>>
>>>
>>>
>>>
>>> Read this topic online here:
>>>
>>> http://forums.matronics.com/viewtopic.php?p=489001#489001 (http://forums.matronics.com/viewtopic.php?p=489001#489001)
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> Lenny Iszak
> Palm City, FL
> 2014 RV-10, N311LZ - 500 hrs
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pietflyer
Joined: 19 Jun 2017
Posts: 45
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| Posted: Tue Apr 30, 2019 3:33 am Post subject: Brakes have me stumped |
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Well said, General! As a Seaplane CFI teaching in a Cessna on amphibious floats (which have castering nosewheels steered by braking, just like an RV-10), I spend the first 15 minutes teaching a student just how to taxi the floatplane, and invariably they want to ride the brakes, even on takeoff. On landing, they want to stop quickly and then turn around to back taxi to the ramp (we don't have a taxiway on our runway, so back-taxiing is the norm). I always point out that "runway is cheaper than brakes", and have them gradually slow down, without using the brakes any more than necessary.
Part of the problem with the RV-10 brakes is the efficient, fully enclosed wheel pants that don't allow a lot of cooling air to reach the brakes, compared to older designs that usually did not enclose the brakes. Keep that in mind when using your brakes.
Jack Phillips
Smith Mountain Lake, Virginia
RV-10 #40610 - In the Paint Shop. Should fly for the first time in early June
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trigo(at)mail.telepac.pt
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| Posted: Tue Apr 30, 2019 4:14 am Post subject: Brakes have me stumped |
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Hello Jack
and all
On the subject of your last paragraph, the wheel pants not letting the brakes to cool as good as they would if no pants were used, why not think in a solution for the brakes cooling with the wheel pants, like for example put some shark grills in the pants, forcing air to cool the brakes?
Would this cause any extra drag?
Just food for thaught
Carlos
Enviado do meu iPhone
No dia 30/04/2019, às 12:30, Jack Philips <jack(at)bedfordlandings.com> escreveu:
[quote]
Well said, General! As a Seaplane CFI teaching in a Cessna on amphibious floats (which have castering nosewheels steered by braking, just like an RV-10), I spend the first 15 minutes teaching a student just how to taxi the floatplane, and invariably they want to ride the brakes, even on takeoff. On landing, they want to stop quickly and then turn around to back taxi to the ramp (we don't have a taxiway on our runway, so back-taxiing is the norm). I always point out that "runway is cheaper than brakes", and have them gradually slow down, without using the brakes any more than necessary.
Part of the problem with the RV-10 brakes is the efficient, fully enclosed wheel pants that don't allow a lot of cooling air to reach the brakes, compared to older designs that usually did not enclose the brakes. Keep that in mind when using your brakes.
Jack Phillips
Smith Mountain Lake, Virginia
RV-10 #40610 - In the Paint Shop. Should fly for the first time in early June
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pietflyer
Joined: 19 Jun 2017
Posts: 45
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| Posted: Tue Apr 30, 2019 10:34 am Post subject: Brakes have me stumped |
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Carlos,
Having just gone through all the filling and sanding to get the wheel pants ready to paint, I can't imagine working around cooling vents when doing that! I think General Grumpy put his finger on it - just stay off the brakes as much as possible, and NEVER ride them.
Jack Phillips
Just finished the Condition Inspection on my other airplane - a Pietenpol Air Camper
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woxofswa
Joined: 12 Aug 2008
Posts: 349
Location: AZ
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| Posted: Tue Apr 30, 2019 3:36 pm Post subject: Re: Brakes have me stumped |
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Interesting thread. I have the original Cleveland brakes. Everything g ok through 600 hours but I am about to install my third set of pads.
One thing I have found very interesting involves buying pads. I always try and buy from Van’s just to keep the home fires burning plus they usually have fair prices.
Shopping for the 66-112 pads for the Cleveland’s however, Van’s has jacked their prices through the roof. More than twice what they sell other pads for and more than twice what the pads (rapco version) sell for from Spruce.
Just thought that was curious.
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Myron Nelson
Mesa, AZ
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Tue Apr 30, 2019 5:08 pm Post subject: Re: Brakes have me stumped |
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The simple truth is, brakes generate a lot of heat. Sure, you could make them much larger and heavier, but who wants to do that. Even without fairings, air cooling is pretty ineffective (unless you can make a rotor with lots of fins, like on your cylinders!). Large jet aircraft have no fairings (since they're retractable) and it's pretty common to have the brakes sized for just one maximum effort stop, after which the plane has to be parked until the brakes cool down.
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