Brake pressure fitting questions

[WingnutWick]

I know this seems basic but I'm on a time crunch and got myself in a pickle trying to make a "quick" fix to a brake compression fitting that was starting to show signs of leaking on my RV-10's master cylinder. I disconnected the line and my plan was to just replace the 1/4 sleeve but I noticed, unlike my 8 which has stems the line goes onto, this one had brass inserts which I hadn't seen yet. Attempting to pull the sleeve off I was unable as it was compressed around the line/insert pretty well, so I just cut the line off just above thinking it would be an easy to just take the inset out and put it back in. Turns out getting the 1/8 insert out and especially back into the slightly smaller thank 1/8 line was nearly impossible and I totally destroyed it in the process with pliers. Of note the insert in thew pic was originally longer - I cut it trying to get this to work.

Questions are:
1. Is the insert type of compression fitting standard? Or is it normal to have a stem already attached to the 90deg fitting coming out of the mast cylinder?
2. I need to get this back together ASAP - can someone confirm the part numbers for what I have or recommend a different fitting if the brass tube insert style is not standard.
3. If it is standard, is there a technique to get this into the pretty rigid high pressure nylon brake line?

Thank you!

Charles

 

[JonJay]

Looks standard to me. Put a little heat on the tubing and the insert might go in easier.
Of course the order of your parts isn’t pictured as it goes together.
Nut goes over the tubing, compression sleeve next, then insert. Make sure the tubing is fully engaged to the fitting before tightening.
I’m sure you know how it goes together and just took the pic this way…..

 

[olyolson]

Charles,

I had the same problem with my -8 chasing down small brake fluid seeps here and there with the plastic lines and fitting. I never really cared for the metal brake reservoir on the engine side of the firewall with a plastic T fitting going to plastic brake lines to connect to a metal fitting on the brake reservoir. I ripped it all out and put the brake reservoirs on the back of the brake master cylinders and all my leaks went away. TS Flightlines set me up with some new braided lines from the master cylinders to the parking brake then there’s hard aluminum lines from there to the brakes. Granted I have an -8 with an access panel on the forward baggage floor so it makes it very easy to do maintenance on the brakes, fuel pump, fuel filter etc. All the pipe fittings were sealed with Loctite 565.

Not sure how it would work on your -10 but the cockpit is significantly wider so perhaps you could retrofit the brake system. The one drawback I see is how to service the brake fluid as it may be harder to access the reservoirs vs on the firewall. Just a thought……….

 

[Caveman]

Brass inserts that will work can be found at many local hardware stores in the plumbing section. I got a 3 pack at ACE recently. They are also available on Amazon. Like JonJay says, heat the tubing up. I insert the end of the tubing in some really hot water or use a heat gun.

 

[jaradtke]

the insert should have a flared end.

 

[mc607]

Questions are:
1. Is the insert type of compression fitting standard? Or is it normal to have a stem already attached to the 90deg fitting coming out of the mast cylinder?
2. I need to get this back together ASAP - can someone confirm the part numbers for what I have or recommend a different fitting if the brass tube insert style is not standard.
3. If it is standard, is there a technique to get this into the pretty rigid high pressure nylon brake line?

Thank you!

Charles

1. On the 14 the inserts, like yours, are standard.
2. I switched to Fairview fittings. My cousin runs the local Parker Hannifin shop and set me up with the fittings in the picture.
3. The 14 plans tell you to ream out the tubing with a drill bit to accept the Parker insert. No way I was doing that, so I switched to Fairview fittings. The Fairview inserts fit well with a bit of force but no heat. I also preferred the ferrels which have a seat and only go on one way. Because I was deviating from the plans on a rather important item, I wanted to test it. So we capped the ends of an 18” piece of my brake line with the Fairview fittings and pressurized it with hydraulic fluid and a test pump. Blew it up! Typically the burst pressure is 4 times the rated pressure. The brake line ruptured at 2000psi. YMMV. I was sure the ends would blow off but they held and the line ruptured. If you have a local hydraulic shop they may have these. Good luck