Trailer Brake Dragging

[Hawke]

In preparation for the first race of the season, it was time to check over the trailer.

Found one trailer brake dragging. Four axle trailer, disk brake on one axle, hydraulic overrun. Stripped caliper, found slides seized and piston stuck. Noticed that it had not been working properly for some time, as disk had unequal wear.

Cleansed all up, now slides great. Installed, still drags. Plenty of free play at master cylinder, other side does not drag. Releasing bleeder makes no difference.

Fit all new seals, as I thought they are not retracting piston enough.

Put all back together - getting good at this now - but still drags. It is not a lot of drag, you can still spin the wheel with your hand, but there is a noticeable drag. Using a screwdriver allows the piston to be pushed back in, and this totally frees it up.

Any ideas?

[Jamesbe]

Did you pop the piston out and look at it? Same symptoms on my truck last fall. Seemed ok, piston had rust on it, doesn't take much friction and it won't retract.

Extracted piston and used Emery cloth to clean it up. Which got me through the waiting period for a new caliper.

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[Hawke]

Did you pop the piston out and look at it? Same symptoms on my truck last fall. Seemed ok, piston had rust on it, doesn't take much friction and it won't retract.

Extracted piston and used Emery cloth to clean it up. Which got me through the waiting period for a new caliper.

Sent from my SM-G955W using Tapatalk

James, yes piston out, there was some corrosion, but spun it up on the lathe, and polished it up with 2000 paper. Just falls in the bore with no seals, and can be pushed in by hand with seals installed. Perhaps its cocking in the bore. I think new calliper?

[DanW]

I have had a flex brake line collapse internally and act like a check valve.

[Hawke]

I have had a flex brake line collapse internally and act like a check valve.

Dan, I thought of that, but when I undo the bleeder, there is no release of pressure.

[Hawke]

All fixed. Thanks for your help. It turned out to be two issues. The initial installation of caliper was too close to the disk, so with new pads, it dragged from new. Is this part of the world unique in having crap trailer builders? The bad build caused that side pad to wear and create its own clearance.

After 12 years, the piston and slides seized, causing the current problem. After overhauling the caliper, I put the thicker pad on the other side, causing it to drag. Swapping the pads over today, solved the problem.

[DanW]

Is this part of the world unique in having crap trailer builders? The bad build caused that side pad to wear and create its own clearance.

Hawke,
I'm afraid you're not alone. So glad you found the issue.

Regards,
Dan