No Brakes...well ,very little

BIGWOODY

BIGWOODY

Well-Known Member
Joined
Mar 21, 2005
Location
Thomasville
Is it possible to have bad brake magnets...or weak ones anyway? My trailer brakes began to suck so I pulled it in the shop for some routine service. Tightened the bearings a bit, greased them all, fixed a couple of wiring issues, etc.. As for my brakes, I'll tell you what I have checked. I've got close to 12 volts at the power wire (on the truck) to activate the brakes. It drops to about 10.5 volts at the magnets in the wheel, seemed like a normal voltage drop to me and certainly enough to activate the brakes. After adjusting the shoes to where the wheel was dragging a bit , I backed them off just a touch. So when I activate the brake I can hear the magnets energize and start to grip the drum, but it's like the slip and don't fully engage the shoes. I can move the emergency lever on the brake controller and feel them starting to grab, but every other trailer I've had and did that it would lock the brakes( this one used to). The only strange thing I noticed when checking the drums and shoes were some grooves cut in the drum where the magnets grab, didn't see any sign of what caused them. It does make me wonder if the air gap in the grooves could be causing my poor braking, but I feel like I'm reaching with that diagnosis. A trailer expert I'm not , any help, ideas?...Greg
 
Seems like a fair amount of voltage drop to me. Is the wiring to the magnets in good shape? What about your ground?
 
checked the wiring at the magnet, both sides and ran a seperate ground. Maybe it is to much voltage drop, I just thought small gauge wire spread over 16 feet or so it would lose some voltage.
 
I'm not sure how the brakes are wired, but that voltage drop bothers me.
A normal fully charged car battery should be about 13.1 volts, and if you are down to 10.5 at the brakes.....seems low.
Is that an unloaded drop? If it is then you may have a wiring problem.
I would check to see if you have any pinched wires or bad connections.

You could check resistance by tieing the ends together at one point and checking them at the other end.

But then again, no expert on trailer brakes.
But I am an electronics tech. :(
 
I just went through this on my trailer.. The PO saw fit to put those damned "bearing buddies" on the hubs, and of course, over-greased the bearings.. Is it possible that the friction shoes are contaminated?

My wires on the brakes is only 14-16 gauge, for what it's worth.
 
I asked my dad sometime ago when I was servicing my brakes. He told me that the magnets do wear out and have to be replaced every so often, depending on usage. But your issue sounds like it may pay to replace both drums and magnets?
 
You should see 12v at the magnet. You should have very little drop in the wire, your drop should happen across the magnet (thus brake action) I had a magnet go out, my prodogy kept going open/short for a few hundre miles.

Also don't just check the voltae but check the OHMs of the magnet, good one should be around 3 ohm mine was up around 46 iirc

and make sure have a dedicated (ground) to the truck, and NOT just through the ball..
 
Rob said:
I asked my dad sometime ago when I was servicing my brakes. He told me that the magnets do wear out and have to be replaced every so often, depending on usage. But your issue sounds like it may pay to replace both drums and magnets?
Click to expand...

Came back to give an update, but you beat me to it...new magnets and drums...good to go now, Thanks.
 
Interesting.. I just went onto Northern's site.. a new magnet was $26. Shoes were $24, but an entire brake assembly, fully assembled, (shoes, magnets, springs, etc..) was $45..

$180 would be great to pay for peace of mind. If my brakes act up again, I'll go that route..

But with YOUR problem, I guess you had to do the drums because of the grooving...
 
brakes

That is the way to go. I just buy the whole assy and swap them out. You start over new each time.
 
Actually the real way to go is buy the hubs/brake set up and the flange , then add them to the other axle. My 18ft Trailer only has brakes on one axle, but will have them on both very soon.
 
Mine has brakes on both, and lemme tell ya, I wasn't so overjoyed when I was working on all 4, instead of 2, while trying to figure out why I was getting no help from the brakes... :p
 
Big woddy - make sure your axle has the 4 bolt flange before you start :) When i upgraded mine it didnt have those welded on, finally found them at Tractor Supply (Note: NOT agri supply but they might have em also)
-mike
 
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