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Non-functioning brake.

B

bifft

Well Known Member
Tried to go fly my 8A this morning, but the left side brake didn't work. Felt firm, but it didn't seem to keep the tire from rotating. At least not enough to get the plane to actually turn left. Had to turn 270 right to get back to the hangar.

So, back in the hanger tested it and it did hold well enough to keep me from being able to push the plane back by the tire when pressing. No noticeable leaks. Pads are still thick. Drained out some fluid and bled it. Push back out and no change, still couldn't get enough brake force to turn the plane to the left against the slight slope in front of the hangar.

So, would this be a rebuild the caliper situation? Master Cylinder? Do both? (parts are cheap at least). If doing the left side, do the right while I'm at it? Right seems to be working fine so far. I just don't know where to start with these things other than the shotgun approach.
 
Hmmmm… does the pedal move the same as the other one? These master cylinders don’t have much travel, it could be air in the line and you are bottoming the master.. you mentioned you bled the brake, how did you do that? Top down or bottom up? If the caliper isn’t leaking fluid, then you don’t NEED to rebuild them, although you should do the VAF service instruction where you install the new Viton orings and high temp Royco 782 fluid..
 
The pedal seemed to move about the same, but my feet aren't too sensitive. Was at the normal angle. Bled from the top.

Sounds like I should do that service instruction, can polish the pins at the same time (they didn't move very much when pushing on the brake.
 
bifft said:
The pedal seemed to move about the same, but my feet aren't too sensitive. Was at the normal angle. Bled from the top.

Sounds like I should do that service instruction, can polish the pins at the same time (they didn't move very much when pushing on the brake.
Click to expand...
Here’s the link to the Service Letter..https://www.vansaircraft.com/wp-content/uploads/2022/03/SL-00047-R1-Brake-Caliper-O-Ring-Improvement.pdf

also, aircraft brakes are bled from the bottom up. Get a oil pump can and a hose, and you pump it in from the lower bleeder.
 
Got it apart today. Was that the brake couldn't slide in the holes on the mount. The one on the right came out easily, the one on the left took quite a bit of persuading.

Now waiting on the new O-ring from the service letter before I put it all back together.
 
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