Brake magnets - <span class="highlight">a</span> decade long saga

Hi Warrie,

Let me state that I am not a brake specialist or a mechanic. Things that come to mind, is the brake drum and or wheel hub on that side perfectly round? Is the brake shoe spring on that side the same size/tension as the spring on the other side?

As I stated, I am not a mechanic, so I could be barking up the wrong tree completely.

Macca.

Seems excessive to me. Not our experience with the Ultimate camper and its brakes.
All brake adjustments , bearing play etc OK ?

Cheers
Jim

You are certainly have not had much fun there Warrie...there is one comment I'd like to throw in....I am referring to ALKO systems...to my knowledge two types of magnets are offered, standard and off-road, I seem to recall the difference is the material in the centre of the magnet, the standard being of metal, off-road a synthetic material. The latter designed to withstand the vibrations of corrugations.

Paul
Lockver Valley
Queensland

This is probably off topic, but....
Would you consider it OK if your 4WD was fitted with brakes like these?
I wouldn't.
Why then are they OK for a 1.4T caravan (and many that are 2+ times this weight)?
Why don't caravans get disc brakes? There is no mechanical or technical reason they don't that I am aware of. They can be operated by an electric over hydraulic actuator that costs about $1,000 retail, plus the same in-vehicle controllers as currently used.
Cheers,
Peter
OKA196 motorhome

Warrie. If you are wearing out the FACE of the magnets prematurely there could be a few reasons.
1. Often Brake backing plates FEED air and therefore DIRT/GRIT into the brakes which can accelerate wear. I don't like that INGESTING FEATURE AT ALL but do understand the brakes need to have a cooling flow.
2. Magnet face wear might be because the BRAKE magnet wiring is receiving some ERRONEOUS VOLTAGE and constantly holding the magnet onto the inner drum face, not enough to APPLY, but enough to constantly rub. I would suspect STOP LIGHT WIRING of TRAILER is different controllers have been used and same problem is happening!
3. The actuator arm of the brakes may be WORN and not OE SIZING and even though new magnets are fitted, the SLACK of the BENT ARM and inside of MAGNET BORE is FAR TOO GREAT. Allowing SLOGGING and PREMATURE failure to occur. IMPACT INERTIA is your enemy there! The OFF ROAD magnets should work the same, but they TOO will SLOG out if the ARM is not a fairly neat fit to eliminate INERTIA IMPACT and deterioration of the surfaces involved.
Does you van have shock absorbers fitted? if not the CONSTANT REPETITIVE HAMMERING of the TYREs on the road surface bumps will NOT BE DAMPENED OUT and the POOR MAGNETS are being "SHOOK TO DEATH" by 10,000 times more oscillations it is receiving!
Remember, correct tyre pressure is important but too high an inflation hammers the MAGNET MOUNTINGS. The TYRES ARE the PRIMARY SUSPENSION SYSTEM of ANY vehicle. ie, the TYRE is being largely ELIMINATED and greater suddenness is being transferred to the MAGNETS.
PS. controllers DO have a slight current flow to detect if there is a TRAILER connected, but is only a sensing, and any significant current or voltage traveling to the magnets will stuff them pronto!

ALSO, if YOU DON'T back off the brake adjustment they will ALWAYS BE DIFFICULT to get the DRUMS OFF. it is MECHANICAL INTERFERENCE.A flapper disc on an angle grinder, held correctly , can remove the LIP, not touch the brake drum surface and all is OK. EASY to do!

Hi Warrie, I cant suggest anything that others haven't said re possible causes. And theoff road magnets like in pic 7 will last alot better than those with a cross in the middle, but I can say that the mantscin the 10" brakes we had on our Tvan certainly lasted far better. In gnarly downhill off road situations I regularly turned our brake controller to manual mode with braking force turned up high so I could just very lightly touch the car's footbrake & use the braking on the Tvan to slow us rather than risking locking up the car's wheels. In 10 years of Tvan ownership (& a lot off road) I only changed the magnets once & none looked as bad as yours, although the old ones had worn at a bit of an angle. I replaced them with aftermarket non alko ones & had zero issues with them.

Just a thought which may or may not be nonsense. If the face inside the drum that the magnet magnetises itself to is worn - how do you tell? I couldn't tell so replaced the drums at the same time . (improved braking tremedously)....... but could a worn drum also cause the sort of wear on magnets that you have experienced?

I went 100% aftermarket with complete backing plates/shoes/magnets plus drums. Removed the Chinese bearings which the drums came fitted with & replaced them with quality Japanese bearings. The improvement was chalk & cheese (& remained so for the several more years we had the Tvan) . Cost was under half what Alko cost.

I must say that on the basis of this experience I'm inclined to suggest you do the same. Bear in mind that a complete backing plate doesn't cost much more that buying just the magnets!

I have the Alko "OFF ROAD" versions of those magnets, is that what you have? i think they are interchangeable with standard magnets if you change the arms at the same time. I forget exactly, its been a while since i have changed any parts. There is a standard and an off road version, you may already know that and that may be what you have but mine have not been an issue over many years.

Is the magnet wiring same length to both magnets from the plug. If one wire length is shorter than the other, it will have more voltage to the magnet and make that magnet stronger. Just a thought.