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Metal brake lines

R

Rick RV-4

Well Known Member
Long time viewer first time poster . . .

I know the trend now is to not use the "plastic" Nylo-seal lines Vans provides, and go with the braided (Aeroquip?) hose between the brake pedal and the reservoir. And for that matter, using aluminum tubing between the master cylinder and the brakes.

Can anyone tell me what exact hardware to use here? I've been studying the Aircraft Spruce catalog and I don't see an easy way to convert from the fittings that come with the kit to something where I can use the braided Aeroquip style hoses. They seem like different fittings (AN versus NPT fittings).

Specific answers would be helpful . . .

Thanks
 
The "plastic" brake lines that Van supplies has been working perfectly for over 13 years on my -6.
 
Not in the heat...

Mel said:
The "plastic" brake lines that Van supplies has been working perfectly for over 13 years on my -6.
Click to expand...

Mel .. the "Bakersfield Bunch" worked out a long time ago that they don't work well in desert areas....

They went to metal and braided hose a long time ago - even before the RV-6s were invented... :)

They failed where the plastic line met the brake assembly.

Somewhat dependant on where you live....

gil in hot Tucson
 
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Thanks Mel . . .

I wasn't implying the Nylo-seal lines are bad. I'm just trying to make an educated decision on which way to go. I have a better "feeling" about the metal lines, but no hard evidence to say that's the better way to go.

One of the things that will help me make my decision is how difficult it is to go the metal route. If it is a real pain in the butt, I'll just stick with what the plans say to do.

Thanks,

Rick
 
Update

My early RV-6 plans call for nylo-seal tubing for the entire brake system, all the way to the brake assemblies.

The later copies I got (dated 1999) show soft alum. tubing down the gear leg, with nylo-seal only for the link between the dual pedals.

Rick.. if you are working from old RV-4 plans, you might want to update to the system Vans now calls for with alum. tubing down the gear leg.

Personally, I prefer a length of -3 teflon (from a race car supplier) hose down the gear leg , and that what I will do...

These guys are one supplier...

http://www.pegasusautoracing.com/productselection.asp?Product=3

gil in Tucson
 
Metal Brake line

Hi, I melted the plastic lines also, plus the brakes always felt spongy with them. I still have plastic from resovoir to master cylinders and back to the park brake valve, but changed to 'rigid' aluminium tube from the park brake valve to the wheel brakes. I used brass commercial compression fittings on the rigid tube at both ends, with no leaks ever. 200+ hrs like this, OK so far. I think an improvement would be to use a short flexible brake line between the brake caliper and the rigid tube somewhere near the bottom of gear leg, it would make removing the calipers easier, as I have just found when replacing my first set of pads!

RV-4 VH-PIO
250hrs
 
az_gila said:
.. if you are working from old RV-4 plans, you might want to update to the system Vans now calls for with alum. tubing down the gear leg.
Click to expand...
Gil _ I have plans for the -4 which shipped in 2005 and they still show NSR44 all the way from top to bottom. That is the current and considered spec for the -4 from VANS.

I did speak to Gus at VANS earlier this year and his view was many people had good experience with the nylo-seal though long taxis in hot climates was not so good. He suggested replacing the nylo-seal every 5 years. I will go with that. I have pasted my key exchange with Gus below.

On 6 Nov 05, at 10:48, Steve Sampson wrote:
>
>> Gus - I am just puzzling a little about the 44-NSR tube used on the
>> pressure side of the RV4 brakes. Is this still how you recommend to do
>> it?
>
> Yes, that's what's in the kit.
>
> I have had negative comments / rumours about the fittings coming
>> off the lines under pressure and note the later VANS aircraft have
>> gone to aluminium.
>
> The only known failure is usually lack of maintenance. The nylon
> lines need to be replaced every five years or so (more if you brake
> hard a lot) as the heat affects them.
>
>>
>> Is there any reason not to substitute the soft aluminium tube as used
>> on the RV9A and associated AN fittings?
>>
> One issue is that there isn't much room for braided hoses and the
> firewall fittings in the cockpit. People have made it work, so you
> could do it, but I'd take a view when you have the fuse assembled to
> see where you can put things.
>
> Gus
Click to expand...
 
Not hot...

Steve... since you won't have to often taxi in 100 F (38 C for those of in the US that are C-challenged, including me) conditions... it should be fine... :)

I believe the Bakersfield folks got way less than 5 years life out of their nylon tubing..... average Bakersfield high for 4 Aug. = 96F

gil in hot Tucson .... but born in mild (cold?) Liverpool
 
I suggest using the solid aluminum or braided steel lines down near the brakes. You can use nylo-seal except for the last 6" or so, but a couple of local RV-4 guys have discovered <the hard way> that the nylo-seal can and will fail if the brakes get too hot during a long taxi or aggressive braking.

Losing a brake is a real pain. Losing a brake away from home is even worse, because you probably won't have the tools you need to fix the problem.

One of my buddies discovered the failure mode while in a long line of aircraft at SnF. Not a good place to lose one brake *right now* and the other one a couple of brake pumps later when the master cylinder emptied.
 
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Sorry,
I didn't mean to imply to use the "plastic" down to the calipers. I use the plastic from the reservoir to the master cylinders and then to the firewall. Then use aluminum from the firewall to the calipers.
 
just changed to aluminum coupled halfway up firewall to plastic. 400 hrs on my 4 and if i was building it metal all the way for me. remember on tri gear plastic may be fine but on taildragger theres either more pressure on right brake or right side of tailwheel. and yes i changed my lines because they failed. also i live in canada where its not nearly as hot.
 
Metal braka line failure

My RV-3 had metal break lines from the firwall down the legs. They chaffed at the front of the firwall and failed (no damage, just a missed flight opertunity). Nylon would have done the same if it had been routed through the same bad place. Just a heads-up, dont run the brake lines between the gear mount and the firewall, along the bottom of the gear is prefered.

-Bruce
 
i just encountered that chaffing problem on inspection last week[oil change]. have applied lots of anti chaff hopefully that solves the problem.ill keep an eye on it. i too experienced plastic brake line failure on landing in a crosswind.
 
Give me a brake...

My RV4 originally had teflon/plastic brake lines and an RV "old timer" told me they would be leaking in 5 years. Well after exactly five years and 1000 hours they were leaking from every connection. It was especially frustrating to have a hot girl along on a fly-out and after returning to the airplane in the AM finding a red puddle under the wheels. I completely removed all the plastic and replaced them with Parker braided steel teflon line bought at an auto parts store with steel fittings. I replaced all my lines from the resevoirs to the calipers...no more red puddles...
No offense Mel, plastic lines are sub-standard...time and temperature dry them out, shrink the fittings and cause leaks. If they were good, the F16 would use them, and they don't...

RR
 
I guess this has turned into more of a debate about IF you should use metal versus plastic.

What I really want to know is . . .

What fittings do you use to convert from the connection at the master cylinders to allow you to use Aeroquip style hoses? I'm assuming you go with something like an AN822 4D, as shown in the Aircraft Spruce catalog page 112. Then any type of -4 hose that works with hydraulic fluid? I claim ignorance, as this is the first time I have had to mess with hoses and the RV-4 plans leave you hanging on this one.

Thanks in advance . . .

Rick
 
The port on the master cylinders and calipers should be a female NPT, probaly 1/8", maybe 1/4" (I have no clue.) You use an adaptor to get it to the AN fitting. AN816, AN823, or AN822 depending on the angle you want. Then, any -4 hose end, or -4 flared tube (with sleeve and nut) will fit.


Us
Rick RV-4 said:
I guess this has turned into more of a debate about IF you should use metal versus plastic.

What I really want to know is . . .

What fittings do you use to convert from the connection at the master cylinders to allow you to use Aeroquip style hoses? I'm assuming you go with something like an AN822 4D, as shown in the Aircraft Spruce catalog page 112. Then any type of -4 hose that works with hydraulic fluid? I claim ignorance, as this is the first time I have had to mess with hoses and the RV-4 plans leave you hanging on this one.

Thanks in advance . . .

Rick
Click to expand...
 
Use -3 hose....

G-force (?), Rick.....

Why use the bulkier -4 hose? Use -3 teflon, the smaller diameter will make them easier to route, and cheaper that the Aircraft $pruce ones.

My previous link gave one good source...

http://www.pegasusautoracing.com/productselection.asp?Product=3

In this case the AN 822-3D fitting should work (assuming a 90 degree angle is required), answering your specific question - 1/8 NPT to AN-3 tubing.

gil in Tucson
 
Thanks guys!

That is the info I needed! I looked at length at the Pegasus site, and now the only question I have is this . . . are their "AN" fittings flared at 37 degrees like the rest of our stuff? In other words, if I order a hose from Pegasus and a fitting from Aircraft Spruce, will they match up? If so I'm good to go. If not I'll just order the fittings from Pegasus as well and I'm sure they'll probably fit.

I'll call Pegasus tomorrow to check on this, but if someone knows the answer now I'll save them the hassle . . .

Gracias!
 
All AN fitting are the 37 degree aircraft standard. The only other flare you might come across is an SAE or 45 deg which is common most automotive brake lines, you probaly wont find any aviation supply that carrys anything in 45 deg so its pretty much a moot point. I agree with the other poster, -3 teflon lines are industry standard for brake systems in most racing applications. Goodridge will make you custom length lines with whatever ends you want, and even in a varity of colors.
 
Stainless Brake Hose

Try Baker Precision. Don't have the link here but i believe if you "google" that you will come to their web site. They are in the LA area.

Wally H
Rockford, IL
 
Went to Baker Precision the other day and they made my braided brake lines while I waited. Took about 10 minutes and they were real nice too.
 
Kyle Boatright said:
I suggest using the solid aluminum or braided steel lines down near the brakes. You can use nylo-seal except for the last 6" or so, but a couple of local RV-4 guys have discovered <the hard way> that the nylo-seal can and will fail if the brakes get too hot during a long taxi or aggressive braking.

Losing a brake is a real pain. Losing a brake away from home is even worse, because you probably won't have the tools you need to fix the problem.

One of my buddies discovered the failure mode while in a long line of aircraft at SnF. Not a good place to lose one brake *right now* and the other one a couple of brake pumps later when the master cylinder emptied.
Click to expand...

I concur. At the very least, convert your nylon brake lines to aluminum about halfway down your gear leg. I had a similar experience to Kyle's friend. I had just landed at my very first Oshkosh and as I was rolling out my right brake pedal suddenly went soft. I managed to taxi to parking but they guys got really worked up when I did a 270 to the left when they motioned for a hard right turn. :) Apparently my brake line was just touching my wheel pant bracket which was just touching my brake rotor. This heated the nylon enough to cause the line to develop an pinhole leak. After spending $30 dollars at the Aircraft Spruce booth to have them overnight me a coupling so I could cut out the failed portion of tubing and finding out it was the wrong fitting.... Cy Galley drove me to Napa where I bought a 30 cent fitting that worked perfectly. Cy even installed it for me.

The rest of the story is that I still have the nylon brake lines and Cy's splice is still there and working perfectly.

But... if I had to do over again, it would be aluminum brake lines.
 
cutting braided hose

Wrap the area you're going to cut tightly with masking tape, put the hose in a vise and clamp it lightly, lengthwise. Use a thin blade 3" air powered cutoff wheel to cut the hose squarely and smoothly. Be careful for wickets from the braided steel when taking the tape off and inserting your fittings. I clean the inside of the hose with a q-tip lightly wetted with isopropyl alcohol before I insert my hose ends. Use eye protection with the cutoff wheel and pay attention to where it's throwing material...ask me how I know.

Bob
 
az_gila said:
G-force (?), Rick.....

Why use the bulkier -4 hose? Use -3 teflon, the smaller diameter will make them easier to route, and cheaper that the Aircraft $pruce ones.

My previous link gave one good source...

http://www.pegasusautoracing.com/productselection.asp?Product=3

In this case the AN 822-3D fitting should work (assuming a 90 degree angle is required), answering your specific question - 1/8 NPT to AN-3 tubing.

gil in Tucson
Click to expand...

Rick,
I'll second Gil's recommendations of using AN3 Teflon hoses. I used AN822-3 fittings (steel) rather than the AN822-3D (aluminum) that Gil suggests. I'm willing to take the 5 gram weight penalty for using steel fittings. I have size 12E feet. I don't want to break a hose (if you used the stock plastic) or a fitting if I got my feet tangled up in the hoses on my 8A.
If you are using a Matco Parking Brake Valve, you need AN816-3 or AN816-3D fittings at that end. Another benifit of the size 3 hoses is that they make installation of the hose to the AN816 fittings much easier when used with the Matco Parking Brake Valve.
For an 8 or 8A, you want to use the 21" long hoses with straight fittings on both ends. I can supply photos of my installation, off list, if you want to see them.
I bought my hoses from RV-9A builder/owner Chris Heitman's company, Pegasus Auto Racing Parts, as did Gil. Great stuff at a great price. :D Use of AN3 or AN4 hoses is your choice. If you go with AN4 hoses, the fittings needed are AN822-4 and AN816-4. Pegasus, ACS or Wicks can supply the fittings.
Charlie Kuss
 
Brake hose

Six or seven years ago, someone put hose down the gear leg to the brakes on an RV-6. When you hit the brakes, the hose would stiffen and create movement of the caliper. This would cause a LOUD brake SQUEAL[font=&quot][/font].

The builder had to remove the hose and install aluminum line down the gear leg to get rid of the noise.

If someone does a search of the Matronics.com RV-List archive, you should find the problem created when changing the aluminum line to hose.
 
RV6_flyer said:
Six or seven years ago, someone put hose down the gear leg to the brakes on an RV-6. When you hit the brakes, the hose would stiffen and create movement of the caliper. This would cause a LOUD brake SQUEAL[font=&quot][/font].

The builder had to remove the hose and install aluminum line down the gear leg to get rid of the noise.

If someone does a search of the Matronics.com RV-List archive, you should find the problem created when changing the aluminum line to hose.
Click to expand...

Gary... it would seem to me this would be a function of the rotation angle of the 90 degree fitting on the brake caliper....
Instinct says that a fore-aft direction would be best..... was this done?

This is also the same method (flex hose at the caliper) that lots of certified planes use... it's not a bad method....

gil in Tucson
 
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