Replacing Elec brakes

Though it is possible for a turn. or several turns, to short out the only thing that would WEaKEN the magnets is a bad electrical connection.

Measure the resistance brake lead to ground. Look up the magnets
If the resistance is too high. Bad connection
Too low, Shorted coils.
Note plus or minus 10-20 percent is "normal variation"

They should last more than six years unless they have been abused.

I would check and make sure you are getting the full 12 volts to each magnet.

Good luck.

I am very comfortable working on brakes. Completely removed drum to make adjustments. Not grease or oil on shoes.
Never really worked on elec brakes before other than adjusting.

Not worth the $ to me to convert to disc since I can replace 4 assemblies for under $500.

I guess the real question is what is normal lifespan od the magnets?

time2roll wrote:
Not that expensive to replace the complete assembly. For superior braking I recommend going to disks.

$2K+ parts plus labor for disc conversion..

Look, the drums obviously worked well for the OP in the past, with a little detective work and not much more than $250 the OP can rebuild their existing drum system to work just as well as it did when new.

Unless the OP was having brake fade as an issue (which does not seem to be the case) how about sticking with troubleshooting the OPs existing system without needlessly throwing out the baby in the bath water?

Troubleshooting electric brakes is extremely easy and low cost to do, replacing with discs is not easy nor cheap and can introduce a few unwanted side effects like possible incompatibility with the OPs existing brake controller..

Not that expensive to replace the complete assembly. For superior braking I recommend going to disks.

Everything he said....

Magnets do wear and do go bad without wear, but at only 6 years old I suspect they are either worn or other issues exist.
Magnets are cheap to try. Trying is not the worst solution.

The grease on the brake pads sounds likely since it locks up in the air but nothing on the ground.

Check wires. Trailers are notorious for having terribly done wiring for brakes.

Check that the mechanism physically works (it should that you said it locks up in the air).

etrailer dot com has a wealth of info and also great prices on everything you will need.

Are you sure you actually were tightening the brakes?

Did you use the little peep hole in the back of the backing plate?

If so, you can easily back off the brakes instead of tightening them.

Might wish to pull the drums and get a good visual on the condition of the brakes, you can measure the lining to makes sure you have sufficient brake lining. In my state you need the thickness of a nickle to be considered legal any thinner and they must be replaced.

If you are using EZ lube axles or Bearing buddies, you could also have grease buildup that bypassed the inside seal and that grease can get on the brakes and the magnet..

With the drums off, you can now easily adjust the star wheel so the drums just slide on with a slight resistance. Temporarily add the outside wheel bearing and hand tighten it and give the drum a spin. Drum should have a slight resistance, you should here the brakes touching the drum as you turn it, if it stays turning the brakes are not adjusted out correctly. If drum is hard to turn, then you have the brakes set too tight.

Depending on the age of your trailer, you might wish to rework all of the brake wire connections before replacing brake parts. Not unusual for trailer builders to use splices not suitable for outdoor use. The connections get damp, corrode corrosion on the wires in the splices acts like an insulator and now you have weak brakes.

As far as replacing the brakes, yes, generally the most cost effective and easiest way is to replace the entire backing plate. This gives you all new parts including magnets.

Electromagnets generally do not "get weak" with age, they do wear on the contact surface so you do need to inspect the magnets contact surface to make sure the windings have not been exposed.