1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Trailer brakes not engaging very well

Discussion in 'Truck & Equipment Repair' started by GSS LLC, Aug 31, 2015.

  1. GSS LLC

    GSS LLC Senior Member
    Messages: 639

    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.
     
  2. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    Time to replace them .buy the fully loaded ones.
     
  3. 1olddogtwo

    1olddogtwo PlowSite Fanatic
    Messages: 11,548

    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?
     
  4. GSS LLC

    GSS LLC Senior Member
    Messages: 639

    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.
     
  5. 1olddogtwo

    1olddogtwo PlowSite Fanatic
    Messages: 11,548

    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.
     
  6. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,983

    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.
     
  7. GSS LLC

    GSS LLC Senior Member
    Messages: 639

    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
     
    Last edited: Aug 31, 2015
  8. 1olddogtwo

    1olddogtwo PlowSite Fanatic
    Messages: 11,548

    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.
     
  9. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,983

    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.
     
  10. jhenderson9196

    jhenderson9196 Senior Member
    Messages: 615

    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.
     
  11. GSS LLC

    GSS LLC Senior Member
    Messages: 639

    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.
     
  12. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    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.
     
  13. GSS LLC

    GSS LLC Senior Member
    Messages: 639

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

    GSS LLC Senior Member
    Messages: 639

    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.
     
  15. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    hub pullers are cheap.
     
  16. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    the issue isn't magnet strength it's all in the activating arm and it's inability to move freely.
     
  17. jhenderson9196

    jhenderson9196 Senior Member
    Messages: 615

    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.
     
  18. GSS LLC

    GSS LLC Senior Member
    Messages: 639

    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
     
  19. 1olddogtwo

    1olddogtwo PlowSite Fanatic
    Messages: 11,548

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

    SnoFarmer PlowSite Fanatic
    from N,E. MN
    Messages: 8,592

    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
     
    Last edited: Sep 1, 2015