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Gear leg braided brake line

JimMac

Active Member
The braided brake line on my RV-12 seems very tight where it has to bend a little to connect to the caliper fitting. The brake line is so stiff and wedged in so tight between the trailing edge of the gear leg and the caliper fitting that it seems that it would impede the caliper from moving on the pins. Has anyone else had any problem with this? I have had to replace my worn-down brake shoes after only 82 hours of use. My right brake pad was dragging and always trying to turn right (at about the 70 hour point). Would it cause harm if I tried to put a permanent bend in the brake line just above the fitting that attaches to the caliper to relieve the "wedged-in" effect?
 
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Be sure that there is no physical interference between the aft end of the inboard wheel pant attachment bracket and the aft-inboard corner of the brake caliper. If there is such interference, the brake caliper/linings may not wear evenly.

Also, be sure that your caliper guide pins are clean and free to move (albeit somewhat stiffly). MATCO suggests that no lubricant be used on these pins to avoid attracting grit. I typically clean the pins and sparingly apply a touch of "dry" lubricant (e.g., Boeshield, graphite, silicone, etc.).
 
The braided brake line on my RV-12 seems very tight where it has to bend a little to connect to the caliper fitting. The brake line is so stiff and wedged in so tight between the trailing edge of the gear leg and the caliper fitting that it seems that it would impede the caliper from moving on the pins. Has anyone else had any problem with this? I have had to replace my worn-down brake shoes after only 82 hours of use. My right brake pad was dragging and always trying to turn right (at about the 70 hour point). Would it cause harm if I tried to put a permanent bend in the brake line just above the fitting that attaches to the caliper to relieve the "wedged-in" effect?

Wont help resolve your problem but just a general comment...

A standard build RV-12 doesn't have braided hose brake lines.
 
Also, do not install gear leg bottom tie-wrap too close to the caliper. Bottom of braided hose needs to float. I'll take photo of my installation next time I fly.
 
Thanks for the responses, David, There is no interference between the wheel pant attach bracket and the caliper. Scott, I realize the standard RV-12 has the aluminum tube with the loop, but the builder of this plane (who I bought it from) had put these lines from TS-FlightLines on. These look like high quality lines but I may fabricate the aluminum lines with the loop and put those on. Jim S., I would be interested in seeing a photo of yours. Like I said in my initial post, The problem seems to be in how the tube was wedged between the trailing flat surface of the gear leg and the caliper attachment. The brake line is simply not going to be allowed to move as the caliper tries to move. Tom from TS FlightLines, No, there doesn't seem to be enough slack. It seems like this braided brake line might work better if it made a loop around the gear like the original design so that it would exert no resistence to the caliper movement. Well, I think I'll put the aluminum lines on as per the original design.
 
Jim---Steve and I have sold a bunch of them for the 12's, and havent heard of any issues. Lets talk and we'll see if we can help you out.
Tom
 
Jim, suggest you work with Tom and Steve to resolve your issue before reverting to the original lines, which you probably dont have readily available. Those guys are fantastic with their support!
 
Thanks for all the responses. I will call TS flightlines and talk to them about it. If I am the only one with an issue, I may be imagining an issue that really isn't there. When I think about it, I guess the caliper movement is actually very, very slight and maybe my dragging brake was caused by something else. When I first removed the right caliper, The piston WAS stuck in a "braked" position. I'm not sure what caused that. I took it out and cleaned it and put it back in the caliper. I'll put everything back together and keep the braided lines on and maybe everything will work fine. I was probably over-analyzing it. Thanks again. All of your comments were very helpful.
 
I should mention that the reason I switched to the braided lines is that I fly off grass and the soft aluminum "loop" in front of the gear leg was taking a beating from tall weeds. Braided lines are routed behind and are shielded by the gear leg. Zero problems for almost two years now...
 
Jim===possibly the master cylinder was slightly depressed, allowing some residual pressure, and not allowing the piston to 'retract'. Some have installed springs on the masters to aid the master cylinder piston retract.
You might check to see how much free play you have in the master piston.

Tom
 
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