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Dragging brakes

awmuhs

Well Known Member
My RV10 has about 750 hours on it. I replaced the brake pads 3 or 4 hours ago. I had a long taxi back to the hangar and noticed a very strong burning smell while getting out of the plane.

Turns out the right side brake was dragging. The wheel pant was so hot I couldn’t touch it. Left side was fine

I removed the slave cylinder checked the pads and slave cylinder. everything looked OK. I put it back together and taxied the plane. It was still overheating.

Anyone have an idea on how to fix it?
 
When you changed the brakes, you should jack the plane and spin the wheel. Often the brakes may drag with new pads when you tighten the bolts. If that’s the case, make some shims from .025 or .032 aluminum to be between the caliper and the inside brake shoe. I think what happens is the disks warp slightly in a cup shape, like a tulip, and the brakes may drag. If you don’t shim it and you taxi with them dragging, they get hot and warp more. Check the cup warping by removing the wheel and laying a straightedge across the disk.
 
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Whenever you replace pads you should ensure they are not dragging/locking up, verify the caliper still 'floats'. Just rocking the airplane back and forth with the tire will tell you if they are locking up when you tighten the caliper bolts. Some pads are thicker than others which can cause this. I've changed lots of pads without jacking the aircraft and never made shims but occasionally had to sand a pad for a little for more clearance.
 
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You could add return springs to the brake cylinders if you have not already. This thread describes a cheap and easy way of doing it.

https://vansairforce.net/community/showpost.php?p=1279781&postcount=36

I used the following parts on my RV-10 from McMaster and am happy with it:
6389K625 Nylon Sleeves x 4
6294K441 Nylon Sleeves x 4
9946K13 Shaft Collar x 4
9657K435 Spring x 4

Without the springs it is basically impossible to tell if you are dragging since the movement is very small and with your feet high on the pedals it is easy to drag. You may have something else going with your brakes if it is always dragging, but this is helpful in general.
 
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Happened to me on my RV-10. There are more than one causes, but for me it was a rolled brake piston O ring. Replace it and see if that solves the problem.

When you do this, clean and lightly lube the caliper pins as well.

Carl
 
possible solutions

Thanks for the suggestions.

I am going to try the shim spacer tomorrow. If that doesn’t work I am going to change the O ring. I am hoping to avoid adding return springs.

When I installed the new brake pads the caliper puck was easy to compress so I don’t think either of the masters are sticking.
 
Same here and the shims solved the problem. Removed them at next annual when pads had worn a bit.
 
Fixed the problem

Thank you Tom!

I added a .032 shim as instructed to my right slave cylinder. Left side had not been overheating.

When I went for a test flight at KTUS without the wheel pants I had a long taxi out to 29R and a long taxi back. Over heating problem is gone.

Thanks
 
Late add on

I am experiencing a similar issue with my RV10 Matco brakes. But am not sure where you are adding the shim? Thanks for a picture or more description.
 
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