Travel trailer brakes - magnet question

[Almot]

No photos, sorry. Brakes are similar to those in Sticky thread here. 3 major parts - 2 shoes and magnet on some "arm", for lack of better word. Being not a mechanic, I hope my descriptions make sense.

Short story: I think magnet on one wheel is causing drug, rubbing against the wheel drum when brakes are NOT in use. I can rotate the wheel with my hands, but it won't spin, goes maybe one inch and stops after I let my hands off. I can hear constant friction noise like "shhh" when rotating. Magnet is sitting on the spindle of the arm, and there is a spring on this arm behind the magnet, and I think something is missing.

Q1: how far and how fast can I go with this? I'm in Mexico, closest good mechanic is 15 miles away, and charging US prices, for God's sake. Would like to go as is, 300 miles to where I want to be, if possible.

More details and Question 2:

I opened this one brake because it wouldn't spin after the hurricane with mud up to the axle. It turned out to be just mud inside. Bearings were fine, I repacked the front bearing since I opened it anyway. Could've lost some retaining ring from that "arm" that magnet is sitting on - while opening the drum, or some time earlier. So the magnet is now pushed by the spring from behind all the way to the inside surface of the drum. This is I think what happened. Sand is like water, you drop something and it's gone.

Q2: what this washer or ring might be?

Other 3 wheels I can spin, at first they didn't, I slowly rotated them back and forth, mud and other cr.ap came out and they spin now. Won't open them now, just will have mechanic to blast them with air and brake cleaning fluid. I can hear intermittent metal sounds like brake shoes or some garbage is touching the drum, but they spin.

[Ron3rd]

...and you can get a cheap brake adjuster tool that John referred to at Harbor Freight for about 2 bucks.

[JBarca]

Almot wrote:


A Question: how little drag is OK? It can spin now 3 circles on its own, but it also has a play when I apply the brake - I can move wheel a few inches back-forth, and then shoes grip tight.

You are trying to get a "light" drag when you set it up. Light meaning, if you rotate the wheel 360 degrees, it "might" have a light drag for approx 45 to 90 degrees and then spin free. Maybe more degrees if your lucky. The way they turn trailer brake drums in the RV world, they do not run dead true like an auto brake drum. So you will not feel nice even light drag the entire 360 degrees. If you do get one that is 360 degrees and a light drag, consider yourself lucky. I have seen trailer wheels run out 0.025" ( a lot on a brake drum and this is not a worn drum, just plain made wrong.)

Do not worry about the brake pedal thing you are trying to do. That is not needed in the setup. Once the brake actually engages rolling down the road the entire brake shoe setup will shift back and forth with the drum as the wheel goes through it's elliptical rotation.

The main thing to try and do, is get all 4 wheels with the same light drag as you can to so they all stop as equal as they can. If you get one wheel real aggressive over the others, it will try and stop the camper by itself as it is doing more work before the other 3 start doing work. That aggressive wheel will get hot fast. If it does, then crawl under and unscrew 2 clicks and try again.

A light drag means you can pull the wheel with a little effort by hand. You can fell a little and hear it. The drag may not be 360 degree of the wheel, then will spin free until it comes around again to start the drag and that is what trailer brakes are.

Over time that light drag will wear off and then you may not hear anything from drag. You are supposed to tweak non adjusting trailer brakes every 3,000 miles, as they wear and there is no self compensation. They do not self adjust like the older autos use to unless you buy the new self adjusting brakes which is an upgrade.

Good luck and hope this helps

[Lynnmor]

Almot wrote:
Jbarca - many thanks.

Adjusted the "teeth", good neighbor gave me the tool. Darn guy, he knew how to, but was too lazy to teach or get under the rig himself 🙂

A Question: how little drag is OK? It can spin now 3 circles on its own, but it also has a play when I apply the brake - I can move wheel a few inches back-forth, and then shoes grip tight.

I also noticed that some drag re-appears after applying the brake, ex. from 3 full circles of spin it goes to 2-2.5 circles, and even if I loosen the adjuster all the way, ~2.5 circles is all I can achieve, and then there is more play with brakes on.

Would you just forget about that brake pedal. You are looking for just a small amount of drag while rotating the wheel by hand. Also, quit counting circles. It is normal to have a bit of free play back and forth, so quit doing that too. You are reading way too much into this simple adjustment.

[Almot]

Jbarca - many thanks.

Adjusted the "teeth", good neighbor gave me the tool. Darn guy, he knew how to, but was too lazy to teach or get under the rig himself 🙂

A Question: how little drag is OK? It can spin now 3 circles on its own, but it also has a play when I apply the brake - I can move wheel a few inches back-forth, and then shoes grip tight.

I also noticed that some drag re-appears after applying the brake, ex. from 3 full circles of spin it goes to 2-2.5 circles, and even if I loosen the adjuster all the way, ~2.5 circles is all I can achieve, and then there is more play with brakes on.

[JBarca]

See this post with more pics and instructions Annual Brake Inspection and Axle Re - Lube (Pic's)

You do not need to pull the wheel to adjust the brakes. There is a rubber plug on the back side of the brake plate, use a screw driver and pry that out.

Then using a brake tool or a screw driver pivot and ratchet the adjuster.

The spring holds the adjuster from unscrewing. When you turn the adjuster wheel by the cutouts in the wheel, the spring snaps from groove to grove.


You go in the back of the brake plate where that rubber plug came out to reach to the adjuster wheel inside.


Since those are under slung axles, I made an adjuster tool. 1/4 rod and swedge (pound) the end then put a bend in the right place and adjust away.


If you adjust the wrong way, the brakes will lock harder. Then just turn it the other way.

Heads up, while you have to crawl under to adjust and spin the wheel, make sure you are rigidly supported with jack stands or heavy timbers. Do not trust a jack.

[Lynnmor]

Almot wrote:
Lynmor, forgive me my ignorance - the "adjuster" can be accessed only by opening the drum again?

About the drag - have just checked, it spins about 1/4-1/3 of full circle after I rotate it and let it go. This is 20-25" travel at the tire perimeter, not a "few inches" like I thought earlier. It was spinning less first, but after spinning and pushing the brake pedal at the same time the shoes moved towards where they belong. Other 3 wheels spin pretty well, making a circle or two on their own.

There is an oval hole in the back side of the brake backing plate. You would need to crawl under the trailer and remove the rubber plug in the hole. Sometimes these plugs are missing. Inside the hole is a star wheel that you rotate one click at a time by prying it with a screwdriver. Rotate it till it makes the brakes tight enough that you cannot turn the wheel by hand. Then back it off till there is just a very slight drag. Replace the plug, if you need one they are available at any auto parts store. Do all the brakes so that they work about the same.

Oh, and forget about that brake pedal and do this adjusting with the trailer unplugged.

[Almot]

Lynmor, forgive me my ignorance - the "adjuster" can be accessed only by opening the drum again?

About the drag - have just checked, it spins about 1/4-1/3 of full circle after I rotate it and let it go. This is 20-25" travel at the tire perimeter, not a "few inches" like I thought earlier. It was spinning less first, but after spinning and pushing the brake pedal at the same time the shoes moved towards where they belong. Other 3 wheels spin pretty well, making a circle or two on their own.

[Lynnmor]

Almot wrote:
Thanks people.

John - no, the pivot arm didn't freeze.

And - no, I didn't take the adjuster apart.

The emergency pin was not pulled, and why should it? The emergency brake was not activated, trailer has been sitting disconnected from the track during the flood and during the cleaning. I only connected the 7-pin after cleaning to check the brakes and help the shoes to "find their place" as described above, by spinning and applying the truck brake.

I tried to pull the emergency pin out, - when discovered first that wheel didn't spin at all, this is before cleaning. The 12V was on, and the pin pulled itself in when I let it go. Well, I am really a newbie with these things. Auto mechanics is not my forte.

Often a pin is accidentally pulled when working with the hitch. The pin probably should pull out completely to manually activate the brakes.

There is no need to connect the truck to the trailer to adjust the brakes, just turn the adjuster till the wheel is very difficult to rotate and then back off the adjustment till there is a slight drag. If you have difficulty doing this, then maybe there is more cleaning to do.

[Almot]

Thanks people.

John - no, the pivot arm didn't freeze.

And - no, I didn't take the adjuster apart.

The emergency pin was not pulled, and why should it? The emergency brake was not activated, trailer has been sitting disconnected from the track during the flood and during the cleaning. I only connected the 7-pin after cleaning to check the brakes and help the shoes to "find their place" as described above, by spinning and applying the truck brake.

I tried to pull the emergency pin out, - when discovered first that wheel didn't spin at all, this is before cleaning. The 12V was on, and the pin pulled itself in when I let it go. Well, I am really a newbie with these things. Auto mechanics is not my forte.

[ib516]

Best test is to tow it a mile or so then feel that wheel for heat. If it's the same temperature as the others, go a few miles, then check again. If it's still the same, you're good to go.

[JBarca]

I'll add my thoughts.

almot wrote:
I opened this one brake because it wouldn't spin after the hurricane with mud up to the axle. It turned out to be just mud inside. Bearings were fine, I repacked the front bearing since I opened it anyway. Could've lost some retaining ring from that "arm" that magnet is sitting on - while opening the drum, or some time earlier. So the magnet is now pushed by the spring from behind all the way to the inside surface of the drum. This is I think what happened. Sand is like water, you drop something and it's gone.

Q2: what this washer or ring might be?

I know you are thinking the magnet is the issue, however odds are high it is not the magnet.

The clip, yes the clip is in the middle of the magnet and the spring is behind the magnet pushing. However the clip really only comes into play when the drum is off so the spring does not push the magnet off the end of arm. See here

The brake before clean up. This is as it looks when the drum was just pulled off


Now cleaned up. As you can see the magnet is not flying off the pivot arm.


See here even better.


The spring creates light pressure to self feed the magnet up against the face of the drum. As wear comes, the magnet moves a little more. The magnet is kissing the inside of the drum all the time. Here you can see straight in. The magnet has room to move out on the arm as needed, just the clip comes into play when the drum is off. Think how fun it would be to put the drum on without the clip. The magnet would be falling off constantly.


There is one other thing about the magnet, it needs power to become a magnet. Unless you have power on the coil there is no magnet force attraction to the drum.

What you are describing points more to the brake shoes being forced to the drum by something other than the magnet. Did you take the adjuster apart to clean it? If so did you readjust the brakes after?

Is the pivot arm froze up? does it pivot? It may be froze, on.

If it is not those more common things, then be looking for something that is jamming the shoes outward.

As to how far and how fast, if the shoes are expanded to the point they stop spinning within an inch of moving, that is a lot of drag. Heat will build quick when moving at much any speed even 15 mph will create heat. Once the heat gets hot enough running a a level of speed, the lining can swell a little (thousands)and make the problem, even worse. At these temps you can start frying eggs on the drum.

Soon a brake fire, greases etc will set off if it runs like this long enough. And can affect the bearings and seals in time.

How long it takes to get to the real hot stage? That is a pure guess, but 1,000 feet with a brake locked on can create a lot of heat. Speed makes it accelerate rapidly. So how far do you have to limp? If this is miles, you need plan B. B = Short of a flat bed to haul the trailer, the drum has to come back off.

PS, By some odd reason, is the emergency break away switch pin pulled or partly pulled?

Hope this helps

John

[Almot]

Thanks guys.
The whole thing has been assembled already, and i would hate to go through this mess again - removing the wheel, drum, washing the 2-days old lubricant out, re-packing the bearing. There is nobody here to have them looked at. I have just learned that $$$ mechanic in town in inaccessible with trailer, small garage in back alley or a street like an alley, if you can imagine those Mex towns.

After some thinking, I "doubt" that the clip was lost, as the magnet didn't come off the cross-shaped pin completely.

Have just got an opinion from the camp neighbor, he says the shoes are out of alignment after my cleaning :), and magnet will eventually wear to where it should be. Says he always adjusts his drums so that there is some sound and some drag, and he likes it better this way. I realize that this is just an opinion, though he's got thousands miles under his belt as 8-wheeler driver. And, the word is, there is hole under the drum for adjusting with screwdriver if necessary - I don't know anything about this, and don't like doing something that I don't know.

Together with this neighbor, we "adjusted" it a little without taking drum off. I rotated the wheel and he pushed the brake pedal few times. It goes a little better now, spins a few inches when I let it go. Other 3 wheels spin like on a bicycle, and the guy says they are too loose, to his taste. The trailer has very little mileage, bearings are good.

Yes, I thought about loosening the bearing nut, but removing the dust cap and pin means re-packing the bearing, with all the sand and dust flying around.

[BenK]

Also check your wheel bearing

Both the bearing condition itself and the torque on the bearing nut...it could
be too tight

[Lynnmor]

Old-Biscuit wrote:


Without clip spring will push magnet out against face of drum which will cause it to drag.....as it drags lever will move out causing shoes to drag.

The spring will always push the magnet out to the drum armature. This is normal and a slight amount of drag and noise will result. If the OP had an unusual amount of mud and rust, then there will be more drag and noise till it wears in.