Electric brakes, how it works - Page 3

Hugo-H · 10-20-2022, 06:52 AM

electric connections... it is a possibility... but I have no clue how to remove the cover underneat the TT... and I have also no documentation at all from my TT, since I cannot access the keystone's website from within Europe

**chuckster57** · 10-20-2022, 07:08 AM

You’ll have 2 sets of wires coming out of the underbelly. At one side the brake, wire from the underbelly, the brake and the wires going through the axle will be connected. On the other side you’ll have the wires from the axle and the brakes connected.

They are not polarity sensitive.

Hugo-H · 10-20-2022, 07:16 AM

the wires going through the axle from one side to the other are ok...
the wires coming from the underbelly are ok too...but I cannot see how/where they run in the underbelly... since they are connected in parallel...and then to the front?
One of each pair is somehow connected to the ground (=chassis)...or not?

jasin1 · 10-20-2022, 08:34 AM

at this point i’d order new brake assembly’s / hubs and just start over….brakes are very important obviously and if your towing in the mountains maybe you overheated them and warped something…drum surface maybe …those drums look pretty sketchy to me but like you said my just be a bad picture…this is just an example of the cost

Hugo-H · 10-20-2022, 11:19 AM

I include a better pic of the drum... looks more clearly, shiny..
I have 4400 lbs axles..
I suppose your pic is from Etrailer website?
Unfortunately they don't send abroad... lot of US based companies don't seem to do it...
Meanwhile, I've sanded the brake shoes, so they look more to normal now...

WDPatterson · 10-20-2022, 02:17 PM

Quote:

Originally Posted by Hugo-H

Is there any point on the brakes that need to be lubrificated?... like the magnets are mounted on a pivat arm...perhaps that pivot point and what else?... anybody has experience with it?

If you get any lubricant on those shoes or those drums, you'll have bigger problems. Do not use any lubricants on your brake system.

WDPatterson · 10-20-2022, 02:23 PM

Quote:

Originally Posted by Hugo-H

my brakes don't have enough braking power when I was at the vehicle inspection... Since my van (E350) didn't have a brake controller installed from the factory (but is pre-wired), then my question was about the possibilities and the how-to's, to determine the problem...
Secondly, my van doesn't have a tow / haul mode...and that makes driving in the mountains little bit less relaxing.. Even squeezing to 100% still does not give enough braking power...
Can it be the the brake shoes are "vitrified"? (glazing of the shoes)... but how does that look? (pic included of one of the brake shoes on my TT)
Today I will check on the current used by the magnets after pull out of the breakaway pin...

I'm confused.. are you saying that you are not using a tow truck with a brake controller to do this test?

WDPatterson · 10-20-2022, 02:29 PM

Quote:

Originally Posted by Hugo-H

batt voltage stays on 12.70 V... what is a "tad low"?

I would recommend getting your battery tested. 12.7 volts is okay, 12.8 volts is nominal. Nevertheless, you want to see what it's going to do Under load.

WDPatterson · 10-20-2022, 02:35 PM

Quote:

Originally Posted by Hugo-H

don't think there exists a factory brake controller...my van is from 1996.
Since it is a van, there is no tow / haul mode... and it's a OBD1 ECU...
This is my first time I did a brake service... I own the TT since 2020... and we have an obligatory vehicle inspection every 2 years... When I came back from a road trip this August, I felt I had to adjust the brakes...without any dissambling at all...but due to a failed vehicle inspection, I dissambled the drums, and then I saw they looked like "glazy"...Transmission rebuild?...

After looking at the pictures you showed, it looks like maybe your pads may be a little thin. Have you seen a set of new pads? They may be a lot thicker. That has something to do, as a thicker pad doesn't have to move as far if they're out of adjustment. If you have them adjusted, they shouldn't be having to move far at all. Properly adjusted, you should see a slight drag on your drums. You should barely hear them rub. Only turn them in the forward driving direction, do not turn them backward.

Is this the brake controller you're using?
https://www.tekonsha.com/product/90885_trailer-brake-control-proportional

Terryj · 10-21-2022, 06:24 AM

the brakes where working ok until you checked and adjusted, I would be suspicious that the magnet face and where the magnet rubs the drum is not flat. Adjusting the brakes moves the location the magnet contacts the drum and can result in high points on the magnet contacting the high points on the drum, which reduces the friction that applies the brake shoes. While checking the drum and magnets make sure the magnet lever moves very freely.

Also check the voltage to the brake magnets by connecting meter leads to the wires going to the brake assemblies. Check this at each wheel with the manual lever on the control to the full brake position and controller gain at the highest level and TV engine running. Compare those readings to running battery voltage. I have seen as much as 5 volts difference, which is away too much difference.

all of the below tests need to be done with the controller at full gain and manual lever at full on. You need to do these tests quickly or release the trailer brakes between tests to prevent overheating of the magnets.

If the difference is more than than 1 volt I would go looking for the reason, by checking voltages at the input to the controller, output of controller, at the the trailer connector, at the trailer cord to trailer wiring junction box and at trailer brake magnets. The neg lead of the volt meter should be connected to the TV battery as high resistance in the ground circuit can distort readings.

The next test is checking voltage on the ground side, this is also done at full brake application, neg meter lead connected to neg post of the battery and done at brake magnet, junction box and trailer connector. the lower the readings the better.

By this time you should know where you have a high resistance area in your brake system. You may have multiple issues

I have ended up running an another wire from the junction box to the trailer brake magnets on several trailers.

hope this helps

jasin1 · 10-21-2022, 06:31 AM

as i stated earlier can drum brakes warp from overheating? the op said he tows in the mountains without an exhaust brake and seems probable that the brakes are under severe operating conditions

**chuckster57** · 10-21-2022, 06:34 AM

The magnet is mounted on an arm that pivots at the point the shoes are attached at the top. Adjusting the shoes does not change the “placement” of the magnet, it will rotate, swing, or whatever you want to call it in a fixed circle.

The flatness of the drum surface, magnet surface and cleanliness can affect its operation.

**flybouy** · 10-21-2022, 07:11 AM

Quote:

Originally Posted by jasin1

as i stated earlier can drum brakes warp from overheating? the op said he tows in the mountains without an exhaust brake and seems probable that the brakes are under severe operating conditions

Typically they will get hard, glossy looking and blued from excessive heat. No amount of sanding will correct that. Depending on the severity it may or may not be corrected by turning them on a brake lathe. If it's severe the I'd change everything out, including the wheel cylinder if was hydraulic.

Pathfinder75 · 10-21-2022, 09:35 AM

Quote:

Originally Posted by chuckster57

You have 4 magnets. Average is 3-4 amps for a total of 12-16 amps.

Yours added up to 10.6 amps. I’m not an expert in brake electrics, but you might want to inspect all the connections.

I only saw ground mentioned once. You can have all the power you want in the blue wire but if the ground don't return to the source you have to much resistance for the magnets to energize.
Remember the brake away is it own circuit. Apply power from trailer battery with breakaway switch the power returns to that battery.
Apply Van power to brakes it must ground back to van. So all trailer grounding going through trailer harness to van must be good. Don't expect trailer ball to ground trailer to van.

While you can test axle brake with break away switch remember the Van power system is independent from trailer power.
Don't leave breakaway active very long. Will overheat magnets. Not designed for constant application.

**chuckster57** · 10-21-2022, 11:20 AM

Break away is not in its “own” circuit. It is powered from the battery, but the other end is joined to the same brake circuit as the TV brake circuit.

Terryj · 10-22-2022, 07:09 AM

Quote:

Originally Posted by chuckster57

The magnet is mounted on an arm that pivots at the point the shoes are attached at the top. Adjusting the shoes does not change the “placement” of the magnet, it will rotate, swing, or whatever you want to call it in a fixed circle.

The flatness of the drum surface, magnet surface and cleanliness can affect its operation.

You are correct adjusting brakes does not move the initial placement or point of contact with the drum, how ever adjusting the brakes does move the magnet point of contact with the drum when the brakes are applied.

Any ridges on the drum and magnet will affect the amount contact surface between the drum and magnet. A reduction in magnet/drum contact surface will reduce the amount of braking available

**chuckster57** · 10-22-2022, 07:14 AM

If you look closely at the picture you can clearly see the magnet "rotates" on a different post BELOW the point where the shoes attach. When you press the brake pedal the magnet grabs the drum and the "block" at the top of the arm pushes on the shoes. you cannot change/adjust the magnet, and adjusting the shoes only spreads the bottoms of the shoes.

https://www.etrailer.com/Accessories...ter/23-26.html

Terryj · 10-22-2022, 09:47 AM

tighter widens the gap at the bottom of the shoes, and also reduces the travel of the magnet due to top of the shoes not having to open as far to apply the brakes. This reduction in travel can lead to the magnet/ drum contact to being less than ideal

**chuckster57** · 10-22-2022, 09:50 AM

I think we are having a misunderstanding, you said the magnet will change its location of drum surface and I stated that it doesn't.

**flybouy** · 10-22-2022, 11:43 AM

Quote:

Originally Posted by Terryj

tighter widens the gap at the bottom of the shoes, and also reduces the travel of the magnet due to top of the shoes not having to open as far to apply the brakes. This reduction in travel can lead to the magnet/ drum contact to being less than ideal

This makes no sense to me. If the shoes open up at the top it would only fe fractions of an inch. The magnet swivels on a stationary pin at the top. The arc of travel would be miniscule as the magnet does not have room to swing much where the magnet is attached.

You may also like: