question about trailer brakes.

[tewitt1949]

I have an older 32 ft pull behind trailer which I bought new. When new I could feel the trailer breaks working but I could not get them to lock up and slide the tires. On a gravel road they might sort of slide a tire but not 100% lock up. I put all new magnets, shoes, backing plates etc in it a couple years ago. Still won't lock up.

The trailer weighs 8500 empty which is not all that heavy, or is it heavier than the normal trailer? Maybe I should have questioned it when it was under warranty but it too late for that now.

With max voltage going back to the brakes, will your lock up the tires? I'm curious if some do and some don't.

[wnjj]

My bet is on the wiring and/or connectors in the wiring. Been there, done that with my flatbad and cargo trailers. On my flatbed, the brakes were crappy until I discovered they used Scotchloks on them. Once I re-did those the brakes were much better.

My other experience is when adding brakes to my little cargo trailer. It came with 2-conductor heavy gauge thick jacketed wire. When I connect that trailer to the same brake controller as my flatbed, I have to dial the power level way back. My controller lights up LED's for the power being sent. Even with the fixed cargo trailer connectors I only ever saw less than half of the LED's with max power. I assumed that was because it was only one axle of brakes and the controller supports two. When I connected the cargo trailer it went full scale for the first time ever.

[tewitt1949]

The trailer in question has 12 inch drums. 8500lbs empty, double axle. I think they are 3500 lbs axles and are 8 lug hubs. I'm 71 and have been a mechanic all my life so I have worked on many drum brakes. I realize if you get them adjusted with slight drag they will work better and may lock the tires easier. But over the last 71 years there have been a couple of times I adjusted them too tight and after a few miles they got too hot. (on cars). So I probably tend to leave them a looser than some people.

On my trailer it has drop axles and the drop part of the axle is right in front of the little adjusting slot which leaves maybe 2 inches to get that little brake tool in there. All most impossible. So, if I remember correct when I put the new brakes on, I think I adjust the shoes out as far as I could and still get the drum on. There was no worn area where the shoes rode so I'm guessing they are fairly close to being adjusted close enough.

One thing that will affect lock up is the height of the tire. The trailer came with Goodyear 235/85R16 which is a good size tire. The taller the tire the more force it takes to stop it.

[azdryheat]

Locking up the brakes depends also on how the trailer brakes are adjusted. My expensive trailer came with manually adjusting brakes, why, I don't. If I adjust the brakes a little tighter I can lock of the wheels but I keep them a little loose so they don't lock up but they still work.

One thing I changed on my truck was going from ceramic pads to semi-metallic pads. My trailer grosses 19,000 and the ceramic brakes just weren't up to the task when the trailer brakes needed adjusting.

[mr_andyj]

The big question unanswered is:
Did you adjust the brakes?

Voltage will not help if the brakes are not adjusted.

With dual axles (4 tires) and on gravel you should probably be seeing one tire lock up at max braking unless all 4 brakes are perfectly adjusted.

One axle will be carrying less weight than the other and those tires on that axle will be the first to lock up, while the other axle may never lock up due to weight (strength of the brakes versus the traction of the tires due to so much weight on them).

Use the link to learn how to adjust the brakes then let us know...

Also, contaminated brake pads or drums will not work anywhere near as well as clean ones. The hubs sometimes get greased up via the hub grease fitting and too much grease will spill into the brake drum and greatly decrease braking power.

The size of the brakes are a huge factor, 8, 10, or 12 inch drums - the bigger the better for power.

[MFL]

Lynnmor wrote:
The number of clicks and the number of revolutions is not the correct way to adjust drum brakes. Why not use the instructions from a brake manufacturer? See page 13.

I was giving an example of what works for me, and approximates of clicks/revolutions, to get where I want my brakes to function. You may not have enough brake adjusting experience to know how much revolution is normal when having a light drag. Every ones light spin of the wheel may differ, as to revolutions. Like most important adjustments, if you are not confident to do it safely yourself, you should have a competent person perform this task for you. 🙂

Also...new brake shoes are hard to get to a proper adjustment, until after some break-in time.

Jerry

[time2roll]

Get a DC clamp-on ammeter and look for 3 amps at each wheel when the controller is manually applied. Next check the brake adjustment at each wheel.

Drum brakes need to run in a bit if they have been sitting in storage. So you need to drive some to get them worked in and warmed up. In a clear and safe space fully apply just the trailer brakes manually at 30 to 40 MPH. They may lock and they may not but they should pull you firmly to a stop. This should give you a comfort level that they are working properly. There is no guaranty the wheels will lock.

If you are not comfortable with the braking force you will need to remove one or all drums to inspect.

If you really want superior braking I recommend converting to disk brakes.

[jkwilson]

The heavier the trailer, the harder it is to lock up the brakes. I can lock up my aluminum stock trailer empty, but can’t with a few cows in it.

[Lynnmor]

The number of clicks and the number of revolutions is not the correct way to adjust drum brakes. Why not use the instructions from a brake manufacturer? See page 13.

[MFL]

tewitt1949 wrote:
Thanks for your relys. I understand you don't want the brakes to lock up under normal or emergency conditions. I would prefer that they would lock up them have to dial down the voltage going to them. Since I can have max voltage to them without them locking up, it almost seems as though they are under sized for my trailer.

What size are your brakes? How heavy is your trailer? Not sure if some 4,400 axles come with 12 inch brakes, but 5,200 axles do. In my experience the 12 inch brakes are much superior on a similar wt trailer. My IBC in rig, in sig, is set to 5.5, and works great! At a setting of 6 or more, with up to 10 possible, it will lock/squeal the tires on pavement at 25 mph when squeezing lever quickly.

Are you testing your lockup capability, by quickly squeezing the manual lever, or stepping on the TV brake, with gain set to max?

It does not take new brakes long to require adjustment, and not all people adjust the same. Myself...I adjust to can't turn the wheel, and normally back off 3 clicks, but never more than 5 clicks. I go by drag sound, and with a light spin with hand, watch for the valve stem to make 1-1.5 revolutions before stopping.

In some cases, the wiring may not be heavy enough to allow max voltage to the brakes.

Jerry

[agesilaus]

You do need to adjust those BRAKES unless you have disk brakes and most RV's do not. I'm about to do it on our RV and just ordered a $5 brake spoon tool on Amazon to make it easier. You can do it with a flat head screw driver tho. Here is a youtube video that I found interesting:Adjusting RV drum brakes

[tewitt1949]

Thanks for your relys. I understand you don't want the brakes to lock up under normal or emergency conditions. I would prefer that they would lock up them have to dial down the voltage going to them. Since I can have max voltage to them without them locking up, it almost seems as though they are under sized for my trailer.

[Sjm9911]

I never could lock up my breaks nor do i want to. They say to lock them up then dial down the gain so they dont lock up. Breaks are made to slow the trailor down some so the TV dosen't do all the work. If they engage and slow the camper , not the TV , they are most likely fine. 8500 empty is plenty heavy bud. They are countermuserate to the xamler. Smaller campers have smaller breaks.

[Lwiddis]

Yes, my TT brakes lock up. 8500 pounds is a heavy trailer if your brakes are defective.

You tried. Have a professional repair the TT brakes.

[12th_Man_Fan]

Get out on the hwy and do an emergency stop. I think you will find the brakes are working just fine.

All of my trailers have been heavier than yours and I could not lock up the brakes on any of them.

You do not want the brakes to lock up if you are trying to stop in a hurry.