Community Forums

oldeguy · 02-13-2017, 07:44 AM

Can anyone help me trouble shoot my electric brakes without pulling the 5er. I think you can hear the coils humm when brakes are actuated. But does that mean they are really creating stopping power? I did use an IR temperature gun to measure temp after a drive in the lug nut area. front rim was 105* while the rear was 125* (tire temp was 122*) So...ant advise from our hands on folks out in IRV2 land.

dayle1 · 02-13-2017, 08:12 AM

The magnets will hum IF you activate them with the brake controller, because it is pulsing DC voltage. But they will not hum if you use the break away switch because it is straight DC voltage. You can use a compass in either case or a small piece of steel. Also if using the controller, set the gain to MAX.

While much more work, you can jack up each tire and rotate it by hand to see if it locks up. This will also tell you if any of the brakes need adjusting as they should all rotate a similar distance for the lever arm to push the shoes against the drums.

Data from an IR gun is not conclusive, too many variables. Tightness/lube of the bearings, differences in tire pressure/loading, etc. If the brakes have been worked hard, I would expect the drum temp to be many degrees higher than the tire temp.

DJNCJ · 02-13-2017, 08:34 AM

The IR gun is a great tool to use when traveling. It is not un-common to have slightly varrying temps from wheel to wheel. Load on a particular wheel position can vary its running temp. Lower air pressure will cause additional heat. Alignment off can cause added heat.

What you can check while stationary is: 1) Wiring. Use a volt meter to measure the voltage sent to each drum. 2) Adjustment. 3) Shoe condition. Pull drums and check for cracked linings, grease contamination and correct spring positioning/tention. 4) Magnet performance. Have your assistant apply the brakes while you see how hard the magnet grabs the blade of your screw driver. 5) Pack the bearings and replace the seals while appart.

HTH

Chuck_Hammer · 02-13-2017, 01:58 PM

find a sandy or dirt based area... SET controller to MAX. going 5 mph .use brake controller to lock trailer wheels.. for 1 second.. then roll slowly away .. look at ground .. if all 4 locked . you can see it.. and if not same.. you can see it...

not perfect.. but can tell..

other wise as above stated.

jelag · 02-13-2017, 08:44 PM

drum type trailer brakes have self adjusters to keep the brake shoes adjusted to the size of the drum.... as the shoes wear... its sad to say, but almost all trailers never back up enough with the brakes applied as required to self adjust, so almost all trailers have brakes that are out of adjustment....

A simple amp meter at each wheel will tell you if the magnets have current draw... however that's no guarantee that the shoes are adjusted and will work....

Here is what I do, once a year... I raise each wheel... put it on a jack stand and than rotate the wheel and listen for the brake shoes to have a little drag... if no drag is heard.... mind you... you hear it first before you can feel it when you roll the wheel... I use a brake spoon and adjust each wheel until it starts to drag... I than have someone apply the brake override in the cab of the truck... and expect the wheel to lock to a point where I can't rotate it.... once done I move on to the other wheels... if after adjustment and I apply the power to the wheel, and it won't lock I take it apart and diagnose what's wrong....

In addition, I do use a point and shoot temp gauge... I expect the tires running in the shade to be one temp, and the tires running in the sun to be about 10-15* higher.... all tires can't exceed 140*.... its the same for the brakes... when we roll into a rest area I expect all drums to be within 30-50* to each other... remember that on hard braking a brake drum can exceed 400*.... but its important they are all the same... as you can't actually judge how much work they have done to stop... I also check the rotors on the truck... and the truck tires...

Over the years I've gained a simple understanding of what to expect... however... I do know when one of the tires, or one of the drums is HOT... or cold from not working... that's what's important to me...

Roosters 67 · 02-13-2017, 08:57 PM

Actually, most trailer brakes are of the non-self adjusting type, Probably due to cost. So trailer brakes unless upgraded or factory equipped with self adjusters, will require periodic adjustments. I found on my last fifth wheel it was around every 5-7.5K miles.

if you are doing brakes, i suggest upgrading to the self adjusting type.

nosticks · 02-14-2017, 06:29 AM

A simple compass pointed at each wheel while someone activates the brakes will tell you if the brake magnets are functioning. Dragging it down a dirt or gravel road with the brake away switch activated will also indicate if the brakes are working.

oldeguy · 02-14-2017, 07:24 AM

Thanks all..

I had the brakes and wheel bearing serviced about 4000 miles ago because of an issue. One of the magnets was shorted, causing total loss of brake function. So, the shoes looked good, bearing were good, new seal and greased up and brakes adjusted. Brakes worked fine. I like the compass trick...never thought of that. Well, going to be crawling under the 5er here in the next few days and checking some stuff out.

oldeguy · 02-14-2017, 07:32 AM

Another of the questions I have is...driving at 5 MPH and then applying full manual trail brakes...should the trailer brake skid the tires?

how about the Ohms of resistance measurement? internet etrailer states 3.2 - 3.5 ohms of resistance...comments?

How long should tire brake shoe last? I know this is totally subjective question but...

nosticks · 02-14-2017, 09:12 AM

On mine, the brakes would lock up on gravel. On pavement, I had the misfortune to really stand on the brakes, as near as I could tell at the time, they did not lock, but did provide ample stopping power. As far as the ohms measurement, I never really checked mine.

xrated · 02-14-2017, 09:23 AM

Quote:

Originally Posted by oldeguy

Another of the questions I have is...driving at 5 MPH and then applying full manual trail brakes...should the trailer brake skid the tires?

how about the Ohms of resistance measurement? internet etrailer states 3.2 - 3.5 ohms of resistance...comments?

How long should tire brake shoe last? I know this is totally subjective question but...

If you are going to try and check the resistance of the brake coils, here is how to do it.
Lets say on a tandem axle trailer that has brakes on all four wheels, and each wheel has a coil that is approx. 3.5 ohms. Since all four coils are connected in parallel and power is applied from the brake controller to all the brakes at the same time, it is a simple ohms law parallel resistance calculation and here is a link to a parallel resistance calculator...

PARALLEL RESISTOR CALCULATOR

As you will see, if the resistance numbers (3.5 ohms) per coil is plugged in and calculated, the total circuit resistance is .875 ohms. The problems with that number is whether you have a digital meter or not, AND how accurate it is....in other words, how many decimal places does the meter go to.

The other way, although more work on your part, is to disconnect each brake coil individually and read the coil at where the wiring harness connects to it. Make sure that you disconnect BOTH of the wires going to the brake coil. Taking your read there, will result in your 3.2 - 3.5 ohm reading. Do this at each coil.

If all coils are reading within the specified ohm range, the coil is not open. One other test you can do though while you are there and have the coil disconnected (both coil wires) is to put the meter on ohms again and touch one of the leads to one of the brake coil wires. Then place your other meter lead to the ground/trailer frame/bare metal. If you get any kind of ohm reading, basically anything other than infinity, and especially if it is a low number, you have a grounded coil and will need to be investigated and or replaced.

xrated · 02-16-2017, 05:30 AM

Hey oldeguy......any progress or updates on the brake issue?

oldeguy · 02-17-2017, 06:26 AM

no...been socializing way too much.

Nice cool day today, think i"ll be getting the truck hook up, try the magnet first. will post results.

DJNCJ · 02-17-2017, 07:47 AM

Quote:

Originally Posted by oldeguy

Another of the questions I have is...driving at 5 MPH and then applying full manual trail brakes...should the trailer brake skid the tires?

how about the Ohms of resistance measurement? internet etrailer states 3.2 - 3.5 ohms of resistance...comments?

How long should tire brake shoe last? I know this is totally subjective question but...

There has been good discussion about magnet ohms. Do not forget about the wiring though. Current may be lost due to old thin gauge wires on the trailer. The voltage at the truck connector may be lower than at the back of the drums. I recently needed to replace the wiring on an older enclosed trailer I own because of this. Moving from a 14 to 12 ga signal wire improved the braking on this particular trailer.