scard

scard

Well Known Member
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I'm interested in hearing from people with more than about 100hrs flying their projects on the suitability of the plastic brake lines in the cockpit with respect to annoying leaks. I understand that some feel it is much easier to just put in braided lines to start with. (Note: I'm just talking about on the master cylinders and reservoir, not down to the gear.) I'm currently trying to decide whether to use what came with the kit or have some braided lines made. Would you do it differently next time?
 
Heres some info on the parts needed.

http://www.jeffsrv-7a.com/FUSELAGE/04-12-08.htm

FUSELAGE%20254.jpg


and Scott, gimmie a call sometime. I hear your canoe is about ready for a stand... ;)


FUSEJIG%20056.jpg


-Jeff
512-699-8505
 
The lines feeding fluid to the master cylinders in my RV-6 are plastic and have not leaked a drop of fluid in the nearly two years I've owned this airplane. At this years condition inspection, the fluid level was where I'd put it a year before.

Bob Severns
 
It's my understanding that the lines in question are low/no pressure lines and that the plastic lines are more than adequate.

A question I have, however, concerns the fittings for them. My kit came with plastic elbow fittings, the same style as that for the connection to the reservoir. Anyone else use these fittings?? I have them installed and am about to fill'er up with brake fluid. I'll report back with my findings.



Regards,
 
In my 7A kit Van's provided brass elbows with brass inserts for the plastic tubing. The only plastic fittings for the brake lines are the ones off the reservoir. Here is a shot of my brake line installation. I used plastic tubing from the reservoir to the top of the pilot master cylinders. The rest was braided hose and AL tubing. I have had no leaks in two years.

Roberta

soundproof24gl.jpg
 
follow-up question

I have the plastic lines, no leaks. However, I have had some trouble getting the air completely out of the lines. Brakes work, but the right is a tad less effective than the left.

I have bled them from the bottom, two or maybe three times. I may be doing something wrong so here's the steps I took.

1. pulled the brake pedals all the way in the up position (not depressed)
2. opened the top of the reservior.
3. pumped with oil can type hand pump through the fitting at the brakes.
4. as the fluid made its way to the reservior and filled the reservior
5. stopped pumping and closed the fitting.
6. replaced top fitting on reservoir.
7. after 3 trys, brakes work, but I still see some air in the lines and the right brake not as strong as the left.

Brake experts out there. What am I doing wrong? thanks, jack
 
I helped a friend with a brake conversion on an N3N-3. I made a pressure bleeder out of a garden sprayer with a soft plastic tube adapted to the wand. It enabled me to get enough fluid through the system to get all the air out. Be sure your master cylinders are at the top of their stroke before trying to bleed the system.
I'd always used a pump oil can to bleed the brakes on our Cessna and it had worked well. The system on the N3N-3 required more volume to bleed than the pump oil can would hold. I haven't had to bleed the RV-6's brakes yet.

Bob Severns
 
Roberta:

The fitting that is shown at the rear of the reservoir in your picture is the type that Van's supplied for my master cylinders as well. I kept looking for the brass type with the little brass insert all over the place until I realized that these plastic ones were substituted.

Dunno. Will see how it pans out........


Regards,
 
12 1/2 years with plastic lines in the cockpit with absolutely no problems.
Mel...DAR
 
Thanks!

Thank you all so much for the info. That is good enough for me. I'm going to build it as shown on the plans.

Cheers
 
On filling the brakes, I've read that tapping the brake pedals a few times as the fluid reaches that level will help dislodge any remaining air bubbles that might be trapped in the cylinders.

Roberta- It looks like you applied some sort of sound-deadening foam in your cockpit very early in the process. I was just thinking yesterday that it's going to be hard to install anything later with all of the wires, cables, and fluid lines running everywhere.
 
plastic connectors+

In 10 years no problem with plastic lines, but the plastic connectors would leak in cold weather at the pipe thread connection. No problem in 100 degree summer heat, in 10 degree winter plastic would shrink and would leak. I would tighten fitting and it would be ok until next winter. Then leak. Tighten again and would be ok until next winter. After doing this 4 times I replaced plastic fittings with brass ones and no problems.
 
Hey Jeff, For the RV-7A, the plans show those parts on sheet 36(A).

F 69-F-04X02 .....for the elbow, ferrule, and nut

F 63-PT3-25...... for the brass insert

This is used with PT-062X1/4 high pressure plastic tubing.

Van's has these items in their catalog. I think they will seal better than the plastic ones.


Hey Dave, I used Super Soundproofing Sheet from ACS to insulate my firewall and cockpit walls. 3/4" on the floor and 3/8" on the walls and firewall. It was nice to do it while the plane was still open and accessable and even nicer that my hubby, Rich, cut and glued all the pieces for the interior. That helped me so I could do other things. It's good to get the spouses involved wherever they can help.

Roberta
 
Hey thanks Roberta. I think I am going to change those out. I never did like those plastic jobs.

Regards,
 
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