Electro Magnetic Brakes

KSCCM10

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Jun 1, 2017
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28
Location
Kansas
I have a 2017 Reflection 315 RLTS, towing with a 2016 RAM 2500 diesel. My brake magnets are chewing up all four brake drums. Everything was replaced at the beginning of 2023. I towed for 6188 miles in 2023 and 2775 miles in 2024 for a total of 8963 miles on the new drums and brake magnets. Before the replacement, my gain was set to 9 and lowered to 7.5 at the recommendation of the maintenance shop. 99% of my braking is what I would consider normal - gradual slowing and stopping.

I have read many of the threads here on brakes, but it appears most of the discussion concerns brake pad linings and brake wear. So will welcome inputs on possible causes.

Thanks in advance.

John
 
The question is: What could cause the magnets to put gouges in the brake drums.
 
Have you checked the amperage of each brake when the brakes are applied? I believe 3 amps would be the max you should see per wheel. There will be some polishing of the interior of the drum, but shouldn't really gouge it. Did you see the brake drums that were replaced? Can you take a photo of the present gouges on the drums? Perhaps your shop was overly ambitious about replacing the drums when it may not have been necessary.
 
Hoopy, thank you for the reply. Yes, I did look at the brake drums last year prior to authorizing replacement, and they were definitely destroyed. No photo of the drums unfortunately. Another shop is doing the work this year. My original complaint was that a wheel was making a clicking noise when it rotated. (Found that when replacing a tire.) Thought it might be the wheel bearings but was the drum and magnet. I will try and get a photo later.

I will be working with the repair shop to find a cause and solution. Just hoping to gain more knowledge from the members prior to meeting with the technician again. When I talked to the technician over the phone, he had not formulated a possible cause, other than excessive brake gain.
 
Yeah, a gain of 9.5 certainly sounds excessive. I usually have mine at around 5.

But you don't want to have overly optimistic expectations of braking ability either. Mine is pretty mediocre, but it seems to work for us.
 
Go down a back road about 25 mph. manually apply your trail brakes to 100%. Don't slam them on, just work your way up till your at 100%. If they lock up the wheels, that is too much. If they just give you good braking, that's good.
 
My last trailer had drum brakes, and I pulled it with a '19 RAM 3500. The max setting on the trailer brakes was 6.5 when I was heavy, and usually 6.0 if not.

Setup the brakes like @redfernclan mentioned, otherwise your trailer brakes are being overworked and trying to slow the truck, not just the trailer. Don't trust what others say to set it at.
 
It also depends on where the shoes are adjusted. New shoes break in. Basically meaning they are wearing into the same arc as the drums. Once they are broken in, the shoes my need adjusted again. Each time the shoes are adjusted, the gain my also have to be adjusted.
Each time the brake pedal is pushed, the magnets are drawn to the drum. Metal to metal contact and this is normal. it is how the brakes were designed. The turning force of the drum transferred to the magnets that then push on the shoes that then push on the drum and give you stopping power.
Brakes not adjusted right require more gain to compensate for the distance between the magnets and the drum.
Because magnetic drum brakes are designed and operated as they do, the magnets and drums are consumable wear items.
That's why they sell pre-loaded backing plates. You get the backing plate, shoes, magnets, all in one package. Four bolts, one wire, your done.
 
One thing you didn’t mention was the driving conditions. Obviously, going down the freeway for long distances won’t add much too the wear. Earlier this year I was traveling through LA and hit incredibly bad traffic - 3 hours to go about 40 miles. Literally hundreds of brake applications. I dropped the gain way down to help reduce wear - we seldom got over 5 miles per hour so stopping wasn’t too difficult.

I would agree with everyone that suggested that the high gain was the cause. If you understand that “gain” is simply the starting point when you first press down on your brake pedal - the voltage/current can only go up from there. Every brake controller will increase the voltage/current from that initial starting point - some based on the time you have your foot on the brake, others based on motion or feedback from the truck. Whichever the case, with a high gain, simply tapping the brakes will almost fully engage that magnet every time. A low gain setting will gently apply the magnetic force and allow the brake controller to increase it as needed.

I am in the habit of adjusting gain based on travel conditions. To be honest, I couldn’t even tell you what the gain is set to since I change it so often.
 
I think it is your gain setting. It is very high. Why so high?
Because it seems I had minimal breaking at lower settings. As Hoopy said, perhaps I was overly optimistic in breaking on such a heavy travel trailer. I admit to not breaking the last new brakes in as I was not aware of the need. Will do so this time.
 
I’m a little confused. The magnets are soft compared to the drums. Copper and plastic mostly. I’ve worked on a lot of trailer brakes and never seen the magnets damage the drums. There has to be something else going on.
 
I’m a little confused. The magnets are soft compared to the drums. Copper and plastic mostly. I’ve worked on a lot of trailer brakes and never seen the magnets damage the drums. There has to be something else going on.
The magnets I've seen are a metal core surrounded by the plastic, but that metal is hard magnetic steel. I can see it gouging the cast brake drums.
 
If you look at electric brake drums, they have a wear surface on the inside face for the magnets. Much different from hyd drum brakes.
 
I have my gain set high also on a 2500 Ram. Started this past summer's trip at 9, then 9.5 and now at 10 (max) and only get a little braking power. Going to take a look and maybe new assemblies this winter when I do the bearings (Lippert 4400 lb axles).
 
I have my gain set high also on a 2500 Ram. Started this past summer's trip at 9, then 9.5 and now at 10 (max) and only get a little braking power. Going to take a look and maybe new assemblies this winter when I do the bearings (Lippert 4400 lb axles).
Sounds like the brakes are greased
 
Sounds like the brakes are greased
That is certainly one possibility. But all axles were repacked by hand (by me) with new seals in March. And I do not use the zerks and definitely do not over grease.
I'll know when I pull things apart once the weather cools down here in Fl.
 

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