Thread: Grabbing electric brakes

Assume they're electric drum brakes, not discs?

These are stone-age technology. I have them on my CT. They need regular servicing.

I could give you some guesses but you'd get better advice with a post on any of:

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Good luck.

Thanks Ern. General consensus seems to be magnets or springs, but no clear front runner, so I figured I'd try here.
Yep, they're drums. I'm not aware of electric discs.

Yes. AFAIK there are light and heavyweight versions of the electric drums.

You don't have someone you can borrow to press the brake while stopped and you have the drum off?

Could you not back off the brake shoe adjuster so they only become effective with moderate to heavy braking?

As for the Commodore, if you plan on keeping the car long term it may be worth seeing if you can upgrade to VT brakes - if it's a known issue there could be an off the shelf conversion kit.

Hey Mick, hope the rest of the trip is going OK.

Couple of questions first.
Whose brakes are they? Dexter, Kelsey, Al-Ko or other?
Did you buy them as an axle assembly with the brakes already fitted up, or as bit and pieces which you assembled yourself?

The biggest issue with Electric Drum Brakes is adjustment and how it's performed. If the backing plate is not centralised, it can cause the brakes to either grab violently (even at low speeds), or not to perform well at all. Whenever I have a customer whose brakes are not performing as required, my initial response is to centralise and readjust. In 90% of cases this will fix the problem.

Centralising is done by loosening the four mounting nuts of the brake backing plate, then while spinning the drum, tighten the adjuster screw as far as it will go, until the drum is locked solid. Then re-tighten the mounting nuts. Then back of the adjuster until the drum strats to spin. Correct adjustment is reached when the drum spins freely, but you can still feel/hear the shoes lightly rubbing.

Originally Posted by smidsy

Could you not back off the brake shoe adjuster so they only become effective with moderate to heavy braking?

This can result in the brakes becoming even more savage as the magnet get up a bit of momentum before contacting the shoes with the drum.

Originally Posted by smidsy

As for the Commodore, if you plan on keeping the car long term it may be worth seeing if you can upgrade to VT brakes - if it's a known issue there could be an off the shelf conversion kit.

Originally Posted by mikm

(The engineers at Fishermans Bend realised their mistake in the design for the VT, since I'm told they increased front pad swept area by 50%)

VT brakes not only have larger pad area, but larger diameter & thicker rotors and 4 spot calipers, and are a bolt on swap to VR/VS's (VB to VP require separate hubs). All you need is a pair of calipers and rotors, and some mechanical aptitude.

Centralising issue ounds very plausible, Yonnee. I will check this out and get back to you.

Brakes came assembled on an axle, ready to roll. Complete assembly (drums on, bearings packed and assembled) was supplied by a Northern suburbs trailer parts supplier but originated at Holroyd. From memory, Holroyd use Al-Ko or Dexter backing plates with their own drums.

I looked into a VT conversion a couple a years ago (I've rebuilt early falcon front ends with late model brakes and suspension in the dim dark past), but then and since have been 'about to get rid of it', so didn't bother. Ideally the master cylinder needs attention because the line pressure requirements of the two calliper types are different, but plenty of people just put up with it.

I knew the original Holroyd Engineering. They were a Dexter agent for a while, telling Dexter they weren't in competition with Melbourne Trailers as all they dealt with was agricultural trailers... They've now been bought out by the previous General Manager.

Good luck with it Mick. Let us know how it goes.

Just another thought... have the magnets been changed recently?

And do you know which brakes you have, Dexter's or Al-Ko's?

I am having the same issue. I have an Outback Off Road camper and i have built and fitted a small rack to carry my Aluminum Boat. This took my trailer above 750 kgs so i fitted brakes. Drum brakes! they are not alko i think maby cheaper Chinese ones. Now just a thought. Incorrect adjustment is the first thing that comes to mind. Secondly on my trailer its the drivers side that is locking up, this is the side that has the wire going down the draw bar, and then a crossover wire to the passenger side. I believe i should have wired it so the wires are the same length or same distance from the plug. I think what may be happening is you are getting Voltage drain to one side, and all of your braking power is going to the other wheel. My trailer has done this from the day i fitted the brakes. I have towed it from my home in the Latrobe Valley to Tocumwal on the Queens birthday weekend and thats as far as its been. I'm planning a trip in September to the Dartmouth dam and at some stage over the next couple of weeks ill drag the trailer out and re do the wiring. Not sure if its going to help but its my plan of attack at this stage. When i fitted the brakes I lined up the backing plate very well and shimmed them a little so they are square to the axle. I believe i adjusted them properly. (have done it plenty of times on drum brake cars successfully) As i said just food for thought

Originally Posted by Yonnee

have the magnets been changed recently?

Nup. The brakes (complete axle) were brand spanking before I started the trip. Before I started this thread, Holroyd replied to an enquiry to say they thought the problem was the magnet 'not releasing'. Sounded like a bit of a crock to me.

Originally Posted by Yonnee

And do you know which brakes you have, Dexter's or Al-Ko's?

I haven't had a chance to check yet. It's a pain in the R's being on the road trying to get a chance to do any maintenance. I need to have the tent packed to access both wheels, usually getting in too late to start anything before I set the camper up and pulling the trailer apart isn't appealing when you've packed up in the morning and just want to get on the road.

I'll make a bit of a concerted effort to get stuck into it and get back to you.

Jack of, unless you've used really small cable for your wiring, the voltage drop over the 1200 or so across your axle will be tiny. You shouldn't need to worry about running two cables from the plug. As long as you used something in the order of 6 mm wire, your problems shouldn't be electrical. I confident my dramas are mechanical - I get lock up with the controller showing only 1 to 1.5 amps output current. I just have to make some time to track the mechanical gremlins down.

Originally Posted by mikm

Nup. The brakes (complete axle) were brand spanking before I started the trip. Before I started this thread, Holroyd replied to an enquiry to say they thought the problem was the magnet 'not releasing'. Sounded like a bit of a crock to me.

It is something I have come across before, but it's a pretty rare occurence, and usually it's under severe braking, and if they've cocked up the machining of the drum, the magnet gets caught on the boss of the drum. But also, it will not want to release, causing the brakes to constsntly drag, which doesn't sound like the symptom you're describing.

I haven't had a chance to check yet. It's a pain in the R's being on the road trying to get a chance to do any maintenance. I need to have the tent packed to access both wheels, usually getting in too late to start anything before I set the camper up and pulling the trailer apart isn't appealing when you've packed up in the morning and just want to get on the road.

I'll make a bit of a concerted effort to get stuck into it and get back to you.

I can sympathise with that.
The reason I asked about the magnets and whose brakes they were is that Dexter recently changed their magnets and made them slightly larger, but didn't tell Melbourne Trailers. There were a few dramas initially, but they have it sorted now.

Quickest way to identify the brakes... Dexter's handbrake lever hangs vertically from the top of the backing plate and swings fore & aft like a pendulum. Al-Ko's handbrake lever protrudes out from the backing plate horizontally, and is held aft by a large return spring. Both of these can be seen externally by tucking your head under the chassis either in front of or behind the tyre.

Just an obs from a sometime user ..

Going off-centre is a poss after that many k's, but the symptoms you say are showing up at low speeds only.

If off-centre it is, you'd still get signs above that.

PS, I'm not a fan of Holroyd. At all.

Ok, I pulled the drivers side apart today (tent is in the way of the passenger side at the moment) and found what you see in these photos...

Keeping in mind that these brakes have done about 6000 k's of highway driving with no off-road to date.

Things I noticed:
-How thin the linings were, compared to those on a car.
-How un even the wear is on the linings. I assume the bottom of the shoes are the same as the tops - I forgot to check.
-The prominent wear ring on the inside flat face of the drum.
-Grease contamination of the magnet. Assembly was carried out by a trailer parts supplier, so I (naively, perhaps) hope this is not as issue?

As shown in the pics, the backing plates are Dexter.

I carried out the suggested centralisation procedure (one hand on spanner, finger tips of other feeling for any movement between flange and backing plate), but I felt no change so they must have got it OK the first time.

Brakes needed adjusting as they were too loose. I assume the other side will be the same. Could this be causing the low speed lock up and uneven wear, perhaps?

There is more movement in the bearings than I would like to see, but the castellated nut wont allow any more than 60 degs of turn with only one hole in the end of the axle.

Hope this clarifies things a bit.
Cheers,
Mick