Brake dragging?

buz · #1 02-22-2007, 05:54 PM

After my last flight my right brake seemed to be dragging (binding up) while taxiing back and pushing into the hangar. It was pretty tight when pushing in the hangar.

I went out today to check it out and it rolled freely?!

It only got tight when it was hot.

Any ideas before I dive into this problem?
The calipers were rebuilt not too long ago and the pads and disc were also pretty new.

Buz

airguy · #2 02-22-2007, 06:02 PM

Vapor pressure in the line?

lucky333 · #3 02-22-2007, 06:37 PM

Including one I started..

Brake Failures
.. and others in the forums as well.

Don't know if its vapor pressure unless you have air in the lines but ANY drag in the brakes for whatever reason, and lots are dealt with and solved in the posts, can be very bad news. Heating can scorch the 'O' rings in the calipers with potentially *real bad* results.

John

Richard L Bentley · #4 02-23-2007, 08:02 AM

Is your brake resevoir vented or capped? if capped and full the fluid gets hot and applies the brakes ,when cooled brakes O.K. Don't ask me how I know..Fix, drop the quanity down about 3/4 inch.. Room for expansion.....Good luck, Dick

Low Pass · #5 02-23-2007, 08:09 AM

You sure the calipers are floating freely? Might be marginal (cold) and when hot, dragging.

dan · #6 02-23-2007, 08:25 AM

Quote:

Originally Posted by Richard L Bentley

if capped and full the fluid gets hot and applies the brakes ,when cooled brakes O.K. Don't ask me how I know..Fix, drop the quanity down about 3/4 inch..

Or use a vented cap?

sf3543 · #7 02-23-2007, 09:08 AM

Some brakes drag because the spring in the Master Cylinder isn't releasing the pedal all the way. In order to test, when the brake is dragging, reach in and pull the pedal back toward you to make sure the brake has released all the way. If that is the problem, you can add a spring to the master cylinder shaft. There is a string on this site about how to do it. I had that problem and adding the springs cost about $2 and solved it.

buz · #8 02-24-2007, 05:58 AM

O.K. Heres what I did.

I read the other thread about the single bolt, so I happened to have some AN3-56 or 57 bolts (-60 is too long) and I did the mod. This helped. I also put 1 set collar on top of each spring for extra measure. This helped. I discovered while messing with the pedals that the passenger right brake pedal was pretty tightly squeezed in the rudder pedal, so I had to gring off the paint and a little bit of weld buildup from the mounting tabs(the weld bead was gouging into the aluminum of the brake pedal), after doing this it was much better. This was my real problem.

I also have another issue, on the pilot right pedal, the master cylinder is rubbing the rudder pedal(the vertical bar) , enough to where the paint is rubbing off. Any reason why this is? My others have a 1/8" gap , I was thinking maybe it got drilled a little off or the tab was welded a little off?!
I used a few extra washers to space it over so it didn't line up with the bar as much and it seems to work.

My reservoir is vented.

Thanks for the help!

Buz

Richard L Bentley · #9 02-24-2007, 10:26 AM

Yes vented cap works and when you go inverted RED brake fluid all over the firewall. Dick

dan · #10 02-24-2007, 07:28 PM

Quote:

Originally Posted by Richard L Bentley

Yes vented cap works and when you go inverted RED brake fluid all over the firewall. Dick

Alex Peterson, you out there? Check out his "Reservoir Dog." It's designed to vent when upright and seal when inverted. I've got one on my RV-7 and have yet to see a single drop. I don't go negative G on a regular basis, so take this not as a recommendation -- but rather something at least to look into.