Need Some Brake Help - Hot Wheel

[10Smiles]

Hello. Here is my brake story...

I replaced the backing plates/brakes on our '05 30 foot Classic last month (low-bid Chinese made). So, this weekend (Thursday through Tuesday (today)) my wife and I went on a short get-away to Diamond Point, WA (close to Sequim). From our house it is about a 40 mile drive. When we arrived, my wife said "what's that smell?" Smelled like hot brakes. We felt the wheels, they were all slightly warm, one was HOT, could not hold my hand on the wheel for more than a second or so.

We parked and set up the trailer all the while I am wondering what could be wrong with this one wheel/brake. We slept on it, the only thing I could think of is that the brake was adjusted too tight, the bearing was adjusted (way) too loose, or something broke.

After breakfast, I broke out the Van jack and jacked up the trailer (a scissor jack, about a thousand turns on the screw - at least that's what it seemed like). The tire's off the ground and it turns easily with just the right bearing play. Hmmm, what could it be? OK, I'll take the drum off to see what the brake guts look like. Looks fine to me. The actuator seems to move freely and the brake shoes move out appropriately.

Put it all back together and sleep on it some more. The only other thing I could come up with is that the brake is adjusted too loose and the actuator is moving too far and jamming the brake on and not releasing. So, this morning before leaving I pulled the trailer onto a pile of leveling blocks so I could adjust this brake. It didn't seem to take very much to get it adjusted to just a slight brake rub.

So, off down the road, I am keeping the brake controller adjusted for very light trailer braking. We stop about seven miles along to check temperatures. The wheels are all cool, all of the brake drums are hot, but not burning except for the one that is acting up. Before pulling away, I backed up a bit and applied the brakes in an attempt to release a jammed brake (if there was one). Another seven or so miles down the road we stopped again. This time the acting up brake/wheel is hot to the touch, the others are barely warm. Just arrived home without any incident (thankfully).

I am wondering what is up. Did I get a defective brake assembly? It makes no sense to me.

Any ideas would be appreciated.

Thanks,
David

[Wingeezer]

Wish I could add some constructive comment - it surely sounds as though you are checking all the right things.

Presume that not only does the wheel spin freely but that it does not have any undue roughness or noise that might indicate a bearing going bad?

Brian.

[10Smiles]

Yes, the wheel spins freely and smooth, bearings look fine. Thanks.

[Protagonist]

In order for one of the wheels to get hot, there has to be a source of heat. That's idiot-simple, but since I'm an idiot, I have to start somewhere…

Possible sources of heat:
1 - Brake shoes rubbing on brake drum. You say that the brake shoe is making very slight contact, and you adjusted it that way. Is it supposed to make contact? Here's the way I was taught to adjust drum brakes:

Tighten the star adjuster while rotating the wheel in a forward direction until the wheel reaches a point where the brake shoes start to engage. Loosen the star adjustor one click at a time while turning the wheel in a forward rotation. Continue adjusting one click at a time until the wheel turns with little effort.

In other words, there should just barely be no contact when the brake is adjusted properly, and the absolute minimum brake motion is required to bring it into contact.

2 - Wheel bearing in need of lubrication. Have you actually looked at the bearings, or just spun the wheels to check the bearings? If the bearing needs grease but isn't badly worn yet, you wouldn't necessarily detect any wobble in the wheel.
3 - Tire is low on air, which leads to excessive sidewall flex. In such a case the tire would be hotter than the wheel.
Just to cover all of the bases.

[Zeppelinium]

I will bet that it's not the brakes.

It's the wheel bearing. Trailer axles need more play than your car or truck. If you grab the trailer wheel and it feels nice and firm, eg, maybe the edge of the tire moves slightly under your hand pressure (like your car), it's too tight!! Loosen the castle nut two or three notches until you can produce more movement than you are comfortable with, maybe 1/4" at the edge of the wheel.

I had this problem, finally got good advice about trailer bearings, and I've had 20,000 uneventful miles since then.

Zep

[TG Twinkie]

Perhaps it's the other three brakes that are out of adjustment and this one wheel is doing most of the braking.



Sent from my iPod touch using Airstream Forums

[10Smiles]

OK, I took the brake drum off again. Everything looks fine in there, the shoes are on correctly (front/rear), the shoes move out when I move the actuator arm and they move back when the arm is released. The power and ground are both fine.

The only thing I can see that looks different from the others I have checked is that the actuator arm seems loose on its bearing. For the others I have checked the actuator arm has very little (no) side-to-side movement. This one has about a quarter inch side-to-side movement. I wonder if it is flopping around and actuating the brake some. I was reading threads on this forum and someone else had a similar issue with a loose actuator arm and a hot brake drum.

I installed the four backing plate assemblies the same and this one is the only one that is acting up. I think it needs to be replaced.

One more note, when I pull the emergency brake pin on the tongue, the magnet energizes, and when the emergency brake pin is inserted back, the magnet is de-energized (not magnetic).

Thank you all for your thoughts, I think it is just a defective unit.

[perryg114]

I had problems with brakes dragging. They can drag if adjusted too tight. They heat up and get even tighter. I had to back off the adjusters. I also had a seal blow from the heat. This problem is more common with old brakes.

Perry

[ROBERTSUNRUS]

Originally Posted by TG Twinkie

Perhaps it's the other three brakes that are out of adjustment and this one wheel is doing most of the braking.



Sent from my iPod touch using Airstream Forums

Hi, I was also thinking along these lines. Three brakes not doing their job and one being overworked.

[perryg114]

They will stay on all the time if adjusted too tight.

Perry

[10Smiles]

When I jacked the trailer up yesterday, the wheel turned easily with very little (slight) brake drag. The brake was not adjusted too tight.

As for the others not doing their part of the braking, even when I had the brake controller adjusted for no trailer braking, the suspect brake still got hot.

[Protagonist]

Originally Posted by 10Smiles

When I jacked the trailer up yesterday, the wheel turned easily with very little (slight) brake drag. The brake was not adjusted too tight.

Return to my post #4, this thread. There shouldn't even be slight drag when the brake is adjusted properly. Rather than being just barely in contact, it's supposed to be just barely NOT in contact.

You're welcome to disagree, but why not just try it? Back off the brake adjustment slightly, until it's just one click away from making any contact at all without the brake being engaged. Then see if it still gets hot. Don't worry, it will still make all the contact it needs when you apply the brake.

[10Smiles]

Protagonist,

I appreciate your concern and idea. When I put the assembly on at first, there was no (zero, zip, nada) drag. Now there is only a slight (how can I say very little, or less than that, even less than you are thinking now, doesn't even slow the wheel down) drag. In both cases, the wheel got hot.

I am definitely open to all ideas, I just think I have eliminated this as a possibility.

Thank you,
David

[J. Morgan]

The brake is almost certainly adjusted too tight.

In my experience when a brake is set up too tight it gets tighter as it gets hot. If it is a little tight when cool it may be tighter when hot.

These assemblies are simple, if there is something wrong with it you can see it. The slight side to side movement of the arm probably is not an issue.

If the bearing is causing this much heat because it is too tight, it probably would have either failed by now or worn in to the point that it does not get hot anymore.

You are almost certainly looking at the brake adjustment being too tight.

[J. Morgan]

Back the brake way off, take a test drive see if it gets hot. If not tighten it in a couple stages testing in between.

[perryg114]

These trailer brakes can be real touchy which probably has a lot to do with brake compounds being too aggressive and the brake shoe not matching the inside of the drum. When the brakes are applied or if they are too tight, the friction throws the shoes into the drum and amplifies the braking force. Usually the leading shoe controls this process. That would be the front one. If you ever wondered why the front shoe is different than the back shoe this is why. Where the shoe touches the drum controls this braking force amplification. It is probably best to adjust shoes really loose till they brake in then adjust them again. In the old days when drum brakes were king they would grind the shoes to match the drum. Now they just throw them on there and pray. I had an issue with my Ranger truck brakes. The cheap shoes I put on there would lock real easy and drag the back wheels. I put better shoes on the back and the problem went away. Drums were not even turned. Drums need to be turned when they are no longer flat and there is a big lip on the edge. They can be out of spec (too big) which makes the braking in process take longer. Magnets are another variable. Both drum and magnets can wear. They need to be replaced as a set or the drum needs to be machined flat again. Also I think these Chinese made brakes have thinner linings which gives you less lifetime and longer break in times till they match the drum. Changing brake shoes that are not worn out is not always a good thing if yours are good and already broken in.

Perry

[Bill M.]

There is a leading shoe and a trailing shoe. The leading shoe can grab or self brake if it is not completely clear of the drum. Any grease on the shoes or the drum can cause this. Does the surface of the shoe and drum look the same as the others? I assumed you checked and greased the bearings? Not sure exactly what the acuator arm is but if it can move enough for the shoes to make contact with the drum it is a problem. Dragging brakes are not totally uncommon to Airstreams or any drum brake. If you do not find anything else I would be suspicious of the shoe material on that brake. Did you turn the drums and get the shoes arced to the diameter of the drum? Are the return springs working and the pivot points lubed? You might try loosening the adjustor more and dumping a little Ajax or Old Dutch Clenser in the drum when you reassemble it.

[HiHoAgRV]

I recall someone getting a set of loaded plates that ended up being semi magnitized, that could cause them to self brake just enough to heat up. Their clue was iron filings sticking to the brake parts. Just something else to look at.

[10Smiles]

I would like to thank all of you for your thoughts regarding my brake problem. I also realize that it is difficult to diagnose a problem from afar. Nothing was making sense to me on this.

I was in contact with the supplier of the brake assemblies who had some suggestions of their own. All of these failed to solve my problem. So they agreed to send me a replacement brake assembly.

I installed the replacement assembly last Saturday but was unable to perform a test drive with the trailer until yesterday. The brake on the affected wheel worked just like the others. They were all at relatively the same temperature. I now feel confident to take the trailer out (as we are planning for the coming long weekend).

Although I still do not know what the underlying issue with the "bad" brake assembly, I am satisfied that it is working now.

Thanks again!

Regards,
David