# Trailer brakes not engaging very well



## GSS LLC (Jul 7, 2012)

got a dual tandem trailer. Trying to get the brakes to work. I have 9.1v coming to the back of the truck. At the brakes, it has 7.5 v to the posts. When the brakes are pressed, you can hear the trailer brakes energize. But you can still spend a Tire by hand there is resistance but with four brakes, its not enough to stop my truck in an idle. You can barely feel any difference. 

I adjusted all the brakes. I cleaned the trailer frame ground. the previous owner never used the brakes because he had it hooked up behind a dump truck. What could be the problem? I tried running a jumper wire for positive and negative from the truck plug to the brake posts to get better power and ground. but it still doesn't work any better.


----------



## grandview (Oct 9, 2005)

Time to replace them .buy the fully loaded ones.


----------



## 1olddogtwo (Aug 6, 2007)

Check the drums for glazing

Are the inside of the drums rust free for the magnets to catch?
The brakes should be adjusted with slight drag while up in air on jacks.

What kind of truck, Ford with factory brake?


----------



## GSS LLC (Jul 7, 2012)

I think the drums are rusty. Like I said, the brakes have never been used. Ever. 
10-15 year old trailer. 

04 dodge, I have the other trailers that the brakes all work fine on. 

Getting the drum off of this thing is a nightmare. Spindle nut is off washer is off, outer beating is off. I can't get the drum to slide off.


----------



## 1olddogtwo (Aug 6, 2007)

I would replace all hardware, talking brake here that may save you or someones kid. As GV said, buy loaded back plates and new drums.


----------



## dieselss (Jan 3, 2008)

Unadjust the drums first before you bend the hell outta the backing plate.

Depending upon how bad everything is, might be cheaper to replace the whole brake asm
Fyi.....always use a ground wire to each brake. "Frame" grounds are unpredictable.


----------



## GSS LLC (Jul 7, 2012)

Grounds are factory. Just cleaned them up. I did UN adjust the drums. The pads are like new as I said the electric brakes have never been used on this trailer. The wires are not broken. Hopefully once I get the drum off I can clean everything up, turn the drums and have working brakes.

As long as the wiring inside the drum itself is ok and none of the parts are broken or damaged and I see no reason that anything will need replaced. Unless there something I'm missing hopefully cleaning the inside of the drums for continuity will provide me with well performing brakes


----------



## 1olddogtwo (Aug 6, 2007)

I hear what ur saying, but ur dealing with 10-15 year old fatigued/rusty springs that hold the pads.

Anyways, we'll try and help.


----------



## dieselss (Jan 3, 2008)

While the drums are off. Apply the brakes and run a screwdriver across the magnets, there should be enough power to hold back the screwdriver.


----------



## jhenderson9196 (Nov 14, 2010)

How much have you run the trailer? I'd put 100 miles on it before I started changing parts. A little rust on the drum face where the magnet runs will greatly lessen the braking effect. Have you pulled the breakaway to see if it's a truck problem? You should get 12 volts at the truck plug with full gain. Check to see if the voltage drop is at the plug or further down the trailer wiring.


----------



## GSS LLC (Jul 7, 2012)

jhenderson9196;2022631 said:


> How much have you run the trailer? I'd put 100 miles on it before I started changing parts. A little rust on the drum face where the magnet runs will greatly lessen the braking effect. Have you pulled the breakaway to see if it's a truck problem? You should get 12 volts at the truck plug with full gain. Check to see if the voltage drop is at the plug or further down the trailer wiring.


I know it's not a truck problem. I tow trailers weekly. I put a new plug on it this afternoon. I drove it a little over 100 miles with no brakes on the trailer (wiring was not right). So o don't think that was enough to clean them up. I'm going to pull one drum and sand it, see where that gets me.


----------



## basher (Nov 13, 2004)

have you lubed the activation cams and activation arm? often that is an indicator of frozen cams having so much resistance the magnets can't move them.

FYI your brake control voltages are awful low and that is A LOT of voltage loss.


----------



## GSS LLC (Jul 7, 2012)

basher;2022658 said:


> have you lubed the activation cams and activation arm? often that is an indicator of frozen cams having so much resistance the magnets can't move them.
> 
> FYI your brake control voltages are awful low and that is A LOT of voltage loss.


I'm going to. Gotta get the drums off first


----------



## GSS LLC (Jul 7, 2012)

Well I got one drum off and the brake pads are hard to get to move so tomorrow I'm going to disassemble everything sand down grease it and reassemble. I cleaned up the drum surface the magnet holds a large screwdriver up against it.


----------



## basher (Nov 13, 2004)

GSS LLC;2022672 said:


> I'm going to. Gotta get the drums off first


hub pullers are cheap.


----------



## basher (Nov 13, 2004)

GSS LLC;2022693 said:


> Well I got one drum off and the brake pads are hard to get to move so tomorrow I'm going to disassemble everything sand down grease it and reassemble. I cleaned up the drum surface the magnet holds a large screwdriver up against it.


the issue isn't magnet strength it's all in the activating arm and it's inability to move freely.


----------



## jhenderson9196 (Nov 14, 2010)

Why is there only 9 volts available at the brake assembly? That's only 75% of brake potential. There is more than 1 problem here.


----------



## GSS LLC (Jul 7, 2012)

Well I imagine because this trailer company used cheap spices to put the wiring together there is definitely voltage loss. But since I run 2 to 3 volts to my trailer brakes on my better trailers its still triple the amount of voltage that I should need to effectively stop. So on paper it should work more than adequate wants to get things freed up. If not it looks like I'll run new wires to the brake assemblies


----------



## 1olddogtwo (Aug 6, 2007)

With truck running, I think it should be closer to 14 volts


----------



## SnoFarmer (Oct 15, 2004)

I know, but are you sure you have the power turned up on your controller?
just asking...

as you know......
Electric Trailer Brake Controllers supply a variable voltage from the truck, from 0 to 12 volts, to the trailer brakes. The brake controller varies the voltage to the trailer to allow for brake modulation. Without the controller, the brakes would get full 12V and the trailer tires would lock up, every time.

ps
The engine of the tow vehicle should be running when checking the voltage, so that a low battery will not adversely affect the measurements.

Attach the voltmeter in parallel with any of the brake magnets. The voltage should be zero volts at the beginning of the test. As the controller is activated, or the brake pedal depressed, the voltage should gradually increase to about 12V, with the gain turned all the way up


----------



## GSS LLC (Jul 7, 2012)

Well I dismantled both passenger side brake assemblies clean them up and greased them and reassemble. I've got brakes for days now. Going to do the drivers side tomorrow


----------



## basher (Nov 13, 2004)

GSS LLC;2022833 said:


> Well I dismantled both passenger side brake assemblies clean them up and greased them and reassemble. I've got brakes for days now. Going to do the drivers side tomorrow


while you're at it replace any scotch locks with good connector or solder, and clean up any suspect grounds, see if you can't find some of that missing voltage. If its a Ford, disassemble the RV (USCAR) connector and look for corrosion.


----------

