[zilik]

My right brake was a little weak, so weak that it did not want to hold the plane during a run-up. So I resorted to doing run-ups while rotating about the left axle in my 6A. The tower finally asked one day why I did circles in the run-up area all the time. I pretended not here the question. I also had to plan my taxi route for left turns wherever I was going. Well, I'm here to tell you this finally got old.


So this weekend I pulled the wheel pants, tire and brakes on the right side. I found the tire had a big flat spot on one side so at one time the brake worked pretty good. This could also be the root cause of the rumbling sound on take-off and landings. The pads were at the point of needing changing but were also damp with fluid. It was obvious the seal in the caliper was seeping so I pulled the caliper for cleaning and a new seal. No obvious problems were found so cleaning and installing a new seal was all I did to the caliper. I replaced the brake pads also. The brake pads told another story.


Upon careful examination of the pads and rotor I noted that the pads were worn down the center along the rivet line more that on the edges. The rotors have a similar wear pattern only getting fatter in the center of the contact area. Sort of like a Brontosaurus, skinny on one end, fat in the middle, skinny on the other end. This uneven wear pattern on the rotor would cause the pads to wear faster than on a virgin rotor. The reason we turn the rotors on automobiles when replacing pads.


Anyway, I ordered new rotors and am wondering how many RV'ers have replaced their brake rotors.

 

[Geico266]

Brake fluid and brake pads don't play well together. The brake fluid was being wiped off in the rivet holes (double the wiping edges) allowing for more slippage on the outside.

Check the fluid level in your reservoir.

 

[RV6_flyer]

The brake discs do wear out. It you read the service manual, they are only allowed a very small amount of wear before they need to be replaced.

If you can find a copy of the Cleveland Wheels and Brakes Technician's Service Guide, download it and reference it. Page 5 and 6 of the Rev C copy that I have has the info you need. The file I have is 8.87 Meg PDF so it could be emailed. I looked to find you a download link but was unsuccessful.

We use Cleveland 40-78 wheels and the 164-01700 disc. Brake Disc minimum thickness from the table for 164-01700 disc is 0.167" or 4.424 mm.

Here is a copy / paste from the above referenced guide:
Under average field conditions a brake disc should give years of trouble free service. However, unimproved fields, standing water, heavy industrial pollution, or infrequent use of the aircraft may necessitate more frequent inspection of discs to prolong the life of the brake lining.

Generally the disc faces should be checked for wear ( Figure A2 Dim. "A), grooves, deep scratches, excessive general pitting or coning of the brake disc. Coning beyond 0.015 inch (0.381 mm) in either direction would be cause for replacement.

Single or isolated grooves up to 0.030 inch (0.76 mm) deep should not be cause for replacement, although general grooving of the disc faces will reduce lining life.

Discs are plated for special applications only; therefore, rust in varying degrees can occur. If a powder rust appears, one or two braking applications during taxi should wipe the disc clear. Rust allowed to progress beyond this point may require removal of the disc from wheel assembly to properly clean both faces. Wire brushing followed by sanding with 220 grit sandpaper can restore the braking surfaces for continued use.


I ran my original set well below the manufacturer's recommendation thickness. I replaced them because of grooves. Once off the airplane, I started reading the manual and then measured the thickness. That is when I found out that I had worn them twice as much as the manufacturer recommends.

 

[keithschult]

Yes, I wore mine down to .166

Recently I had to replace my rotors. They had been on my 6A for 760+ hours. They wore down to the minimums and the pads were pushed out too far while the O-ring also popped out.

On a recent very cold day, I was doing run-up prior to departure when the right brake failed completely, putting hydraulic fluid all over the ramp. It was a half-mile taxi back to the hangar with only the left brake, while the right rudder worked when against the wind. A couple left turns and I found the wind at my back, rendering the right rudder useless in the last turn to the hangar. The result was the airplane continued to drift left at about 6-7 mph heading directly for a row of hangars. There was no grass to slow me down.

I pulled the mixture, switched off the ignition, undid the seatbelts, opened the slider, pulled myself out of the cockpit onto the wing, dropped to the ground, grabbed my step-up and stopped the plane before it ran into the hangars. The plane stopped 3 feet short of a propstrike.

At least I'm now ready to head to Las Vegas this week.

 

[Sheldon]

I have replaced my rotors also...at about 300 or so hours... low hours sure... I did a long taxi with a down hill too boot... heated the brakes up enough to smoke.. caused one of the brake caliper's 'o' ring to fail, loosing fluid.. upon repair, replaced the rotors because they were burnt..heated up from the long taxi..
That's when you gave me a ride to Copperstate Gary... remember...
Sheldon