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Discussion Starter #1
This may seem that I am a cheap bast*rd but the trailer I am asking for some perspective on is a trailer that isn't mine. And given I've just resurrected myself from living through a Chapter 11 employer, I'm still on the financial mend so that is in play as well.

Patient in question is a 24' enclosed double axle trailer, probably has 5200# leaf'd (not torsion) axles under it. Riding mate and I use it to haul 6+ off-road Enduro machines to desolate destinations for much needed off-road tomfoolery. All four drum brakes function but have absolutely no braking power. With my controller maxed out, in drive at idle, the trailer brakes will not hold the truck at a standstill on a level surface. I've lifted and tested all four wheels on the trailer and determined in fact they are all functioning, they just have no stopping power. Pulling rig is a 2015 2500 CCSB Duramax with a brand new trailer brake module in it due to a recent total failure which I hear is not all that uncommon.

My controller is fully functional on my electric-over-hydraulic disc brakes on my 5'ver RV - it'll lock those brakes up if desired as well as with one other trailer I've tested, so I am fairly confident I've isolated the issue to this particular trailer. The drum surface the brake assy magnet makes contact with is grooved and I am thinking why not just find a lathe and have the surface turned smooth so the magnet will have a full contact patch for maximum friction? I'm thinking this is actually the issue. I don't know if the magnets can get weak and maybe in fact, the grooving isn't the issue, it's the strength of the magnet that is the issue, but I don't know if this is a possibility? Assuming its the grooving and assuming I can find a machine shop that has a large enough lathe that the chuck can hold the drum, my thinking is simply resurfacing the contact patch in the drum and see if that resolves the issue. The drums are otherwise in perfect shape at the brake shoe contact surface. No glazing, no grooves so other than the magnet contact patch, no issues with the drum.

The round trip cost to buy every part is roughly $1200 and the labor $400+ to simply replace everything - drums, bearings, seal, brake shoe assy's, etc.. I can do the labor no problem other than finding the time. I could also just buy new drums and I've also given thought to just buying full new axle assy's.

Anyone have a suggestion or life hack idea I haven't mention above? Anyone with experience on the magnets or otherwise will know more than I do - this is my first trailer brakes diagnosis challenge. I've called several shops and they all seem to immediately jump to replace it all because we are a throw-it-away society now. So that's why I am here because I know we've got a lot of knowledge here. I've benefitted from it greatly, particularly from one "Horned" member.

Any pointers are very welcome and appreciated!!

Thanks!
 

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Premium Member
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Discussion Starter #3
I adjusted them but no measured improvement. I think I agree magnets. The drums are number two.
 

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4,964 Posts
How is the wiring? Measure resistance from the plug to brake wiring connection. Bad grounds?
 

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I went through the same thing with a trailer a couple years ago. I replaced shoes and magnets and all the wiring was good to the brakes. They all worked but wouldn't stop my truck idling in drive. The only thing left was the drums but on 10k dually axles, drums were about $1000. I too looked at having the magnet surfaces of the drums cleaned up but ended up selling the trailer and buying a new one. The drums were literally the only part of the system left that could affect braking power that I hadn't checked or replaced.

I think the hubs and magnets wear gradually enough as the brake shoes wear down that it's not an issue. The hubs and magnets wear together and even grooved, maintain good enough contact to work ok. Then when you replace brake shoes and bring all the adjustment back, the worn magnets are now in a different spot on the hubs where the grooves no longer match so the magnets can't get much grip on the hubs. So you replace the magnets and same thing, grooved hubs and smooth magnet surfaces still don't grip enough to have any power. They'll work and stop the wheels from spinning when you have it jacked up, just not with any power.

I don't think you'll get anywhere until you either fix or replace the hubs. After I replaced brakes, magnets, bearings, seals and hub caps on mine, I wished I had just bought all new axles to start with.
 

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LHN...We ARE the Joneses
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I think I agree magnets. The drums are number two.
Magnets don't last forever. And their mating surface on the face of the drum, needs to be smooth as well, for maximum bite.
And then you have the warp on the drum that turning can't fix.

I've never yet seen brake shoes on a trailer wear out, it's always the mags.

Wiring, can also be an issue. Needs to be seamless, with soldered connections.
NO scotch block clip on connectors (Lighting too, IMO). A little hand held mini butane torch from Wally's works great, for both the solder and the shrink wrap over the joints.

Less than $10.

And then there's the hardware in the backing plate....I've pulled drums before for greasing the bearings, and have all of the parts and shoes just fall out. 'dunno;

Turning the drums; Unlike a car drum, you need two turns - one for the magnet, and one for the shoes. Double the price....Might as well by new drums, they're not expensive and will be 'bout the same price as paying double for turning on each one.

Le$$ if you buy the whole axle brake kits.

Adjustments; unlike car drum brakes, trailers are not self adjusting. So regular maintenance involves periodic adjustments to keep the bite up to par.
Although, there are aftermarket trailer brakes that ARE self adjusting....for only a few $$ more per axle. (highly recommended)

I source all of my trailer brake parts from SW Wheel (based in Dallas).

A complete axle brake kit (drums, 2"x12" backing plate assembly, inner/outer bearings, seals, washers, keepers, spindle dust cap, wheel studs and nuts, plus all of the nuts, washers, bolts to mount the new backing plate assembly) for your 6-lug starts @ $240 per axle (free ground shipping).


Self adjusting, with Timken bearings, $280/axle (my choice).
https://www.southwestwheel.com/p-9262-6-55-bolt-circle-5200-lbs-trailer-axle-self-adjusting-electric-brake-kit-with-timken-bearings.aspx

Simple install too. Just 5 bolts/nuts. :wink2:
 
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