Replacing Elec brakes

[Jethroish]

Could not find anything on this here.
I have a horse trailer with dual 7000# axles. I suspect the brake magnets have weakened. Visually they appear good, but with the brake controller set at the highest setting, only one wheel will lock up on the gravel driveway. Trailer is about 8000# empty. I have adjusted the brake shoes out and they lock up with the trailer off ground.
I know things wear out and eventually need replacing.

Anyone here ever have a similar experience? Did you change out the brakes with a full assembly that included new magnet?

The brakes on the trailer are original (2015 model). Rough guess is the trailer has been towed approximately 60,000 miles in 6 years.

[ajriding]

Those old 3 speed transmissions did not have locking torque converters either.

[Jethroish]

ajriding wrote:


I still cringe to think dear old dad towing the family trailer with the station wagon equipped with 4 drum brakes, on the car, not the trailer, none on the trailer.

LOL. I think of that every time a discussion arises about tow vehicles. The old 72 Buick station wagon with 350 - 4 barrel had plenty of power to tow. My grandparent used one to tow a tt from Washington to Michigan and back.

[ajriding]

yep, highway miles is different that city miles.
I used to turn the brakes almost off in the city back when I had a cheapo controller. I just did not need the braking power to stop fast when speeds were low. On the highway I just never needed to do a lot of braking, so my brakes could go miles and miles.
Now that I have a high-end controller I leave it alone, it brakes softly when the truck does, and brakes harder when the truck does, less wear than a timed controller that brakes soft a second, then increases braking forces over a few seconds. Best $200 spent.

I would not replace the drums until they need replacing. $400 (4x100) might be pocket change for some, but most would rather not toss that money away needlessly, and I would never go disc on a regular trailer. Drums are fine for most sized trailers. DIsc are wonderful, but I cannot justify the expense when the drums are more than enough. Most tow vehicles do not need trailer brakes to begin with, which of course is of opinion. I still cringe to think dear old dad towing the family trailer with the station wagon equipped with 4 drum brakes, on the car, not the trailer, none on the trailer.

[valhalla360]

Jethroish wrote:
Follow up:
After another quick check of things (adjustments, elec connections and voltage), along with finding 2 elec brake distributors to chat with, I am going with the magnets are just worn out. The wear hole indicators are either gone or barely visible. This trailer rolls 10k to 12k miles per year at 12k to 13k pounds, so I guess it is no surprise.
IMO, I highly doubt the brake assemblies are meant or expected to last that many miles. Realistically, unless you are a full timer, most TTs or 5ers probably do not see 30k miles in their life time.

Beat me to it...people talk about years and that works OK for typical use but your average RV may only get 2-5k miles per year. Miles will provide a better estimate of wear. Really it's brake use that wears them out, so non-freeway driving is the killer.

[Edd505]

Look at the wires where they come out of the axles. It's a wear point the insulation on the wires get chaffed and cause a lot of issues. If that's the issue run a wire outside upper part of the axle, secure with zip ties.

[dougrainer]

1. If I was doing this, I would replace all 4 Drum assemblies at about $100 each. This gives you new BRAKE SHOES and Magnets and is very EASY to do. Also have a local shop turn the drums
https://www.etrailer.com/Trailer-Brakes/Dexter-Axle/23-180-181.html
2. The CORRECT test for the brakes is NOT using your brake Controller. If you suspect Magnets, I would apply 12 volts direct to the Brake Pin on the 7 way tow cord or just pull the break away and see if all 4 lock up. Doug

[Jethroish]

Follow up:
After another quick check of things (adjustments, elec connections and voltage), along with finding 2 elec brake distributors to chat with, I am going with the magnets are just worn out. The wear hole indicators are either gone or barely visible. This trailer rolls 10k to 12k miles per year at 12k to 13k pounds, so I guess it is no surprise.
IMO, I highly doubt the brake assemblies are meant or expected to last that many miles. Realistically, unless you are a full timer, most TTs or 5ers probably do not see 30k miles in their life time.

[opnspaces]

I will second or third or fourth agree with checking or just plain redoing the wiring connections first.

[theoldwizard1]

wa8yxm wrote:
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"

Check for bad connection FIRST !

They may have come from the factory with just bared wire, twisted together. If the copper is not shiny, cut it back to where it is shiny. Twisted is acceptable BUT then you MUST use marine/dual wall heat shrink !

[Mike134]

Jethroish wrote:
Could not find anything on this here.
I have a horse trailer with dual 7000# axles. I suspect the brake magnets have weakened. Visually they appear good, but with the brake controller set at the highest setting, only one wheel will lock up on the gravel driveway. Trailer is about 8000# empty. I have adjusted the brake shoes out and they lock up with the trailer off ground.
I know things wear out and eventually need replacing.

Anyone here ever have a similar experience? Did you change out the brakes with a full assembly that included new magnet?

The brakes on the trailer are original (2015 model). Rough guess is the trailer has been towed approximately 60,000 miles in 6 years.

Yes, the magnets are a wear item, the ones on my trailer have 4 holes in them that function as wear indicators, less metal to magnetize equals less gripping power on the drum face to pull in the shoes.

I change out the entire assembly only thing not replaced if you piece meal it is the backing plates.

[wa8yxm]

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"

[12th_Man_Fan]

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.

[Jethroish]

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?

[Gdetrailer]

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..