Normal brake wear?

**Deb Mac** · 06-04-2023, 05:55 PM

First time working with electric brakes so not sure what is and is not normal wear.
I’m have a set of complete assemblies coming - shoes were cracked though barely worn.
I know you want flat surfaces on magnets and drums (armature surface?) but what is considered acceptable/normal wear, before you want to replace or reface?

That “scoring” is so light that it doesn’t even catch a fingernail. It’s a little rough but not what I would call scored. Attaching pics of the magnets and drums, looking for opinions. Backplate assemblies are already en route, but having a little trouble tracking down drums separately after the fact if I need them.

I am in Canada so options are more limited for sourcing.

**Deb Mac** · 06-05-2023, 08:55 AM

I opted not to futz around and have ordered new hubs as well. If I was going to use the existing back-plate and just change out the shoes (longitudinal crack on the curb side shoes), I might have left them. But since I'm changing out the whole back-plate assembly, the new magnets wouldn't meet up properly with the surface. Checked and looks like it would be hard to find someone in my neck of the woods who would/could machine those surfaces, so... what's another $250 at this point

Wavery · 06-05-2023, 05:44 PM

Quote:

Originally Posted by Deb Mac

I opted not to futz around and have ordered new hubs as well. If I was going to use the existing back-plate and just change out the shoes (longitudinal crack on the curb side shoes), I might have left them. But since I'm changing out the whole back-plate assembly, the new magnets wouldn't meet up properly with the surface. Checked and looks like it would be hard to find someone in my neck of the woods who would/could machine those surfaces, so... what's another $250 at this point

Your brakes look hardly worn at all. The magnet wear sensor show little to no wear. I've never seen electric trailer brakes in that good condition. Usually, when I check the brakes on a trailer, that I just bought, they are in such bad shape, that I just replace the brake assembles and clean the magnet surface on the drums.

As far as the armature surface on the drums, just hit it with a wire brush on a drill motor to knock off rust & dirt. That surface is merely a metal surface to draw the magnets too. You don't have to get real picky unless the surface is really torn up. Like if a brake spring comes off and get between the surfaces and grinds down the springs. Those are pretty strong magnets and when current is supplied, the magnets get pulled out to that surface an that is what the the brake shoes out.

**Deb Mac** · 06-05-2023, 05:51 PM

Thank you! Not knowing what electric brakes wear like, it was hard for me to tell. I do have new hubs coming, but they won’t be here till late next week and I can return them if I don’t need them . The new assemblies will be here this week. Had to do at least new shoes because of the nasty cracks in the shoes on the curbside. See the pics. I was quite sad when I saw those shoes. Hoped I could get away with a clean and repack of the bearings. So decided to replace the whole backplate. Easier and almost the same cost as just finding shoes! And easier to replace. The moving parts are stiff - surface rust and a lot of sitting before I got it. I actually wonder if the PO had his controller set up properly and the brakes ever engaged completely. He was in the prairies, so no hills to worry about - flat terrain all the time. Drove 45 km to a full service campground once a season. Figure to keep the magnets from the old back plates as spares.

I’ll reassemble those hubs when the brake assemblies get here - bearings and races also look wonderful, have been cleaned of old grease & repacked. Seals are coming so I can put everything back on by end of the week. I’ll test the new brakes with the original drums before I take it on the road for a trial run and seat the shoes. Want to make sure the magnet has got a good grip on that surface. If anything seems off, I’ll put the new hubs on. If it’s all good, I’ll return them and save a few hundred $$!!

**Deb Mac** · 06-06-2023, 07:14 PM

Wavery - Read your reply on the other thread about cracked brake shoes... I have decided to replace everything - brake assemblies and hubs.

**tacoma11** · 06-07-2023, 01:02 PM

FWIW, here's the page from the Dexter Electric Brakes doc about cracks in the brake lining.

**Deb Mac** · 06-07-2023, 01:06 PM

Quote:

Originally Posted by tacoma11

FWIW, here's the page from the Dexter Electric Brakes doc about cracks ion the brake linig.

Thanks - I have that. But these are far from hairline... they are deep and wide. Heat!! New brake assemblies are coming. I'm not going to mess around with swapping out shoes, and magnets.

New drum/hub assemblies coming too. If the shoes overheated that badly, then the drums likely did as well, so starting from scratch.

Wavery · 06-07-2023, 04:09 PM

Quote:

Originally Posted by Deb Mac

Thanks - I have that. But these are far from hairline... they are deep and wide. Heat!! New brake assemblies are coming. I'm not going to mess around with swapping out shoes, and magnets.

New drum/hub assemblies coming too. If the shoes overheated that badly, then the drums likely did as well, so starting from scratch.

It looks to me like the previous owner either left the emergency brake plug out and drove the vehicle until it stopped resisting (because the got too hot) or he kept using the maximum lever on his brake controller while the brakes weren't broken in (which is more likely the case).

The reason that I bring this up is to let you know that brake shoes have a brake-in period and if the owner abuses that, the brake shoe lining will become very hard and crack (just like in your picture). It's sorta like putting bread in the oven at a high temperature. It becomes brittle, shrinks and cracks apart.

I seriously doubt if your brakes drums are bad. If they were over-heated, they would have blue spots on them. If you take them to an automotive machine shop, they will turn the drums (usually about $10 each) and he will tell you immediately if they are bad and probably won't charge you.

**Deb Mac** · 06-07-2023, 04:28 PM

The new drums are on their way, and trying to find an automotive machine shop that can get anything done in less than 2 weeks around here is hard… not many and they are busy. I’ll see if I can track down a shop though.

I’ll probably put the new drums on it - will have new surfaces to go with the new shoes and magnets, new bearings…. I’ll hang on to the old drums and get them in to a machine shop and see what they say. I still have the bearings, races are still in the hub. If they need it, and can be machined - armature and brake surface - then I’ll hang on to them, and maybe swap them back in when the time comes - they are Dexters after all.

I’m just limited for time right now. I’m heading out in early July and don’t want to be pushing things right to just prior to leaving. I want to have the time to get brakes on, tires on, get it out on the road to seat the brake shoes (burnish) and have lots of time to spare. And I still have to get up on top and install the soft start in the ac and adjust the shell heights.

I would like to have at least 1 week before I’m heading out that I don’t have to do anything except pack

. And I can’t work 4 or 5 hours at a stretch anymore. As Danny Glover would say “I’m getting too old for this s***”. Takes about 3 tries to get my backside back up off the ground these days….