R

riobison

Well Known Member
Blew a hole in my plastic brake line.

I was just getting my landings down to where I?m more comfortable with my new to me RV4 and I blew a pin hole in the right plastic line down on the gear leg just above where it joins the steel/aluminum tubing. Good thing that happened during my run up and not on a landing.

What pressure is that clear plastic brake line rated for?

What kind of pressure are we capable of putting on the lines with our master cylinders and a pair of Size 10's??

To me this appears to be marginal at best and should be upgraded to something heavier as I don?t want to have this happen again.

My RV4 was built in 1998 and has 570 hrs TT on it.

Thanks

Tim
 
I am sure someone with lots more experience in the early RV days will come along and say that they all used plastic lines back then....but today's design uses aluminum tube or flexible stainless-jacketed lines for the pressure side of the brake system. Nylon tubing is used for the reservoir lines. I personally would replace anything on the pressure side with something other than plastic.

Paul
 
I had to replace the plastic on my old 4 for the same reasons. I would upgrade as Paul suggests for good reason and don't look back.
Ryan
 
Bonaco

Tim,

Do a quick search for "Bonaco" on this forum. He makes custom brake lines for a reasonable price. There is no "standard" size for RV-4's; so you can either use your old lines or a string as a reference. Recommend you run a relief loop at the wheel in accordance with Van's drawing. If you have any questions, feel free to drop me a PM--I did the same modification to my "new to me -4" a couple of years ago.

Cheers,

Mike
 
Van's has a replacement kit for RV-4's with the plastic line to convert them to the aluminum and flex lines like the rest of the models. I agree with Paul also on this one... Call or E-mail me at Vans and we'll get you set up.
 
I have no problem with anyone wanting to upgrade their brake lines, but just as a point of reference, my plastic lines have been working great and continue to do so after more than 19 years in service.
My plastic lines are all inside the cockpit, but are on the "pressure" side.
 
Mel said:
I have no problem with anyone wanting to upgrade their brake lines, but just as a point of reference, my plastic lines have been working great and continue to do so after more than 19 years in service.
My plastic lines are all inside the cockpit, but are on the "pressure" side.
Click to expand...

Are you sure about that?
 
gasman said:
Are you sure about that?
Click to expand...

YEP! What part are you questioning?

I have plastic from the reservoir to the pilot side master cylinders, from pilot side master cylinders to copilot side master cylinders and from the copilot side master cylinders to the firewall.
 
failure

Hello Joe

I will drop you a note on this to upgrade.

For me brake lines, oil lines, fuels lines etc are not not expensive items nor do they add much weight. Cutting corners here and having failures over something so simple can be costly. Needless to say the down time fixing this would be better spent flying.

Reading here on the forum I?m not the only one that has experienced this
problem.

Thanks

Tim
 
Mel said:
YEP! What part are you questioning?

I have plastic from the reservoir to the pilot side master cylinders, from pilot side master cylinders to copilot side master cylinders and from the copilot side master cylinders to the firewall.
Click to expand...

And also on the low pressure side. The "but" is what threw me off. I see no problem in that location. But going down the leg and right to the cyl, with the heat and vibration and scuffing etc etc, is not good.

With the flow as described above, it would look like you have placed the copilot side master cylinders failure in the way of your brake control. If the copilot was applying not enough brake, and you wanted to apply more (like in a training situation) your efforts would be blocked by the closed port.

Piper went to the copilot side first to eliminate any of the issues because that makes it just the supply side and far less connections from the high pressure master to the wheel cyl.
 
Anything on the pressure side should be upgraded. As for pressures at the calipers, you might see 500 psi max, depending on the master cylinders you are using.
Tom
 
gasman said:
I see no problem in that location. But going down the leg and right to the cyl, with the heat and vibration and scuffing etc etc, is not good.

With the flow as described above, it would look like you have placed the copilot side master cylinders failure in the way of your brake control. If the copilot was applying not enough brake, and you wanted to apply more (like in a training situation) your efforts would be blocked by the closed port.

Piper went to the copilot side first to eliminate any of the issues because that makes it just the supply side and far less connections from the high pressure master to the wheel cyl.
Click to expand...
OK, I over simplified my answer. Actually that's not exactly the way it runs. It would take too long here to explain my precise set-up. Just suffice to say that I am using "plastic" lines between the master cylinders and the firewall.

Forward of the firewall and to the calipers, I have aluminum tubing.
 
My RV-6 (completed 2003) has plastic lines from the reservoir to the co-pilot side master cylinders and plastic from the outlet of the co-pilot side master cylinders to the inlets of the pilot's side master cylinders. The outlets of the pilot side master cylinders have "normal" Aeroquip-type brake flex lines to bulkhead fittings on the firewall and aluminum lines from there to the disc brake calipers

Since the co-pilot side brakes rarely ever get used, I'm not too worried about any ruptures in the copilot-to-pilot plastic lines. The worst part thus far is that every one of the B-nuts on the plastic line fittings oozes a tiny bit of red 5606 fluid over time and must be periodically wiped off with a rag. The leakage is not bad enough yet to warrant re-plumbing everything, and I really don't yet wish to drain the system and try any sealant inside the fittings since that will require re-filling and re-bleeding the whole system between the reservoir to the pilot side master cylinders, and it's working well enough the way it is now.
 
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1987

My RV-4 was built in 1987 with plastic lines to the brake calipers. Still working good, but might upgrade them next winter.
 
Ironflight said:
I am sure someone with lots more experience in the early RV days will come along and say that they all used plastic lines back then....but today's design uses aluminum tube or flexible stainless-jacketed lines for the pressure side of the brake system. Nylon tubing is used for the reservoir lines. I personally would replace anything on the pressure side with something other than plastic.

Paul
Click to expand...

How about these steel braided Teflon hoses I purchased from the UK:
http://stores.ebay.co.uk/Torques-U-...909910012&_sid=81447352&_trksid=p4634.c0.m322

Hans
 
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