Electric Brakes Maintenance

mike
In Dire Need of Therapy

Posts: 220

Electric Brakes Maintenance Feb 23, 2011 22:21:26 GMT 10

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Post by mike on Feb 23, 2011 22:21:26 GMT 10

G'day everyone,

I recently had to investigate why our electric brakes stopped working while on a short local stopover.

How did electric brakes work?

Electricity.... volts.... current ... hmmm

So here's what I found out....

Started with the 'controller' unit in the car: Was there current at the plug at the rear of the car?

Well, I put the 'negative' probe into the earth terminal and the positive probe into the elec brake terminal and jammed the manual slider on the control unit ON. The volt readout measured 3volts!!!

Surely that indicated a faulty controller? I got the missus to operate the slider control back and forth to see if the current would vary? Volts did vary but only between 3 and 5 volts!!! Further evidence.

I then tried to hold the slider full-ON .... and smoke coming out of the controller indicated that if it wasn't before, it was now cooked!!!

Auto electrician said it would cost $165 plus installation.

An old mate gave me an old (1987?) spare controller he had. It worked, but got the same voltage readings?

Then I tried it with the engine running. Success: voltages varied from about 10-15+ volts!!

Soooooo it had to be something in the wheel hubs failing to operate the brake shoes...

Take the dust cap off, and remove the split pin locking the castle nut...

Remove the castle nut and jiggle the hub the get the outer bearing to begin to slide off the axle...

Bearing out...

Pull the hub gently off the axle...
The inside of the wheel hub exposed...

Notice the wheel stud heads are press/recessed into the hub, and the polished surface around their heads where an electro-magnet grabs the hub...

Here is the electro-magnet...

The magnet sits on this arm...

Here is the magnet hanging by its wires...

You can see some wear on the surface of the magnet...

Up close...

A pair of replacement electro magnets...
These AL-KO magnets were purchased from a designated distributor of AL-KO parts (Google AL-KO) for a bit under $48 each. (If you think that's a lot, Repco have these magnets made in NZ for $69 each.)
Note the small clip, and the two green wires on each (means you don't have to worry about positive and negative correctness).

In removing the two wires of the old magnet, be careful to pull the black plastic grommet out from the backing plate with pliers because it can be re-used on the replacement wiring...

Mounting the magnet on its operating arm, use long nose pliers to push the small clip thru the magnet onto the end of the arm...

Fit the old grommet over the new wires...

The new electro-magnet fitted. It has to be fitted in exactly the same way as the one that was removed: there is a leading and a trailing edge. The magnet tries to grip the inside of the hub when current is applied to it; as it does so, the arm on which it is mounted is pulled around the inside of the hub a few centimetres, and operates the brake shoes in braking the wheels.

This is the operating arm on the other RHS wheel...

And here is the mounted magnet on the other side of the van ie the RHS... note how the wiring and magnet are the other way around to the previous LHS 'done' piccie.

Brakes working again!!! ;D ;D ;D ;D

Cheers ;D ;D ;D
mike

Ps Photobucket problem occurred as follows...
I had renamed all photos in my own computer folder AND PUT SPACES BETWEEN EACH WORD OF THE RENAMED TITLE.
By eliminating ALL SPACES in the photo name in my computer file, photobucket worked, but only after deleting the old photobucket folder, and up-loading the whole folder again. ... This took another 5 hours to sort this prob out... Hmmmmm
Also, thanks Al for trying to solve the problem: surprisingly the direct link still works even tho that photobucket folder was deleted!!

Last Edit: Feb 24, 2011 22:08:39 GMT 10 by mike

atouchofglass The left hand side of God Class and Glass Posts: 1,909	Electric Brakes Maintenance Feb 25, 2011 6:04:44 GMT 10 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by atouchofglass on Feb 25, 2011 6:04:44 GMT 10 Well Mike all I can say is it was worth it. The photos make it a clear and easy to follow explaination on how to change the magnet. Thanks for putting in the effort and perservering Cheers Atog
	Restore the Restorable Love the Adorable Recycle the Deplorable If you find a good glue Stick with it Fibreglassing Thread Atog's '68 Olympic

mike
In Dire Need of Therapy

Posts: 220

Electric Brakes Maintenance Mar 5, 2011 20:13:47 GMT 10

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Post by mike on Mar 5, 2011 20:13:47 GMT 10

G'day Atog, ;D ;D ;D

Sorry I took so long to respond, but we just had to take off again to really test the operation of the brakes. My mobile internet modem contract is about to be cancelled: I can't get any connection in country areas... just main cities.

Did the brakes work?

Well, I initially didn't set the new in-car controller very well.
Had cause to brake urgently and ended up pulling up in choking clouds of acrid blue rubber smoke in the main street of Wollongong!
The missus said:" What are you trying to do???"
Children ran for their mothers, mothers gripped their shopping bags with white-knuckle steely grips, and men stood quite still wondering whether or not to applaud or just remain wondering!!
I'm sure that off-duty copper in every crowd was thinking that just as the anti-hoon laws were taking hoon cars off the streets, we now have a pair of senior citz doing screechies with their old caravan in the main street now!! ;D ;D ;D

After a bit more adjusting, the brakes work better now than before... the brakes engage smoothly and you can feel the van pulling back on the car very well. There's just a small throatie vibration that you hear and feel at very low speed, but that's all.

Good to feel that much safer again.

Cheers ;D ;D ;D
mike

Last Edit: Mar 5, 2011 20:16:07 GMT 10 by mike

Wassa41 Guest	Electric Brakes Maintenance Mar 14, 2011 9:47:07 GMT 10 Quote Select Post Deselect Post Link to Post Back to Top Post by Wassa41 on Mar 14, 2011 9:47:07 GMT 10 Mike a quick check if your brakes are working is to have some one apply the brakes and you will hear a humming noise at each van wheel which is the electromagnet working. Regards, Warren

Tony and Carol
Guest

Electric Brakes Maintenance Sept 11, 2011 20:25:47 GMT 10

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Post by Tony and Carol on Sept 11, 2011 20:25:47 GMT 10

This is a great description of how to change the magnetic brakes and we are very happy to see that somebody else has been able to do so successfully. Thanks very much for your assistance in posting to the internet for all to share. ;D

Deleted Deleted Member Posts: 0	Electric Brakes Maintenance Jun 6, 2012 9:21:02 GMT 10 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Deleted on Jun 6, 2012 9:21:02 GMT 10 Hi Mike, Thanks for your time and effort - an excellent post! Regards Bobbie

Deleted
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Electric Brakes Maintenance Jul 23, 2012 23:12:50 GMT 10

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Post by Deleted on Jul 23, 2012 23:12:50 GMT 10

Firstly Mike, great write-up and pictures.

The dimples you see on your new magnets are wear indicators, same as the grooves in your old magnets, or what's left of them. Once any part of these grooves/dimples have worn away, time to replace the magnet.

The controller you have is an older Tekonsha model, but still a good controller, if you have somewhere to fit it. They are quite a large unit. They don't have a short circuit shutdown like the later models, and a worn magnet that wears through the wires will kill the controller, as you've already found out. However, they can be opened up and repaired.

They work off a pendulum sensor internally built in to the unit. This is adjusted by the serrated wheel underneath the controller. This wheel levels the pendulum allowing you to mount the controller on an angle similar to the slope of your dash, and controls the voltage output to the brakes in relation to the braking effort from the car. Light braking moves the pendulum a small amount, the harder the braking effort, the more the pendulum will swing.

The fore-aft slide control (top left) is the power adjustment, and controls the maximum power output under the hardest braking, which in turn is varied by the swinging of the pendulum.
The slide control across the front of the unit is the spring loaded manual over-ride control, and allows you to apply brakes to the trailer/van without applying tow vehicle brakes. However, this will only supply a variable voltage up to the maximum set by the power slide control.

So, this should, hopefully, help to explain why you only got minimal voltage from the controller while the vehicle wasn't in motion. If the pendulum isn't swinging, then there will be minimal voltage put out by the controller. And if the power slide was set low, then this will be all you get, even with manual over-ride on full. To check you're getting maximum voltage at the rear of the tow vehicle, the power slide control should be all the way in, the wheel underneath pulled all the way towards the driver, and then step on the brake. Or, again with the power slide in, activate the manual over-ride control all the way to the left.

The way to set this controller up quickly, is while stationery, on level ground and everything hooked up ready to go, push the power slide all the way in. Then place your foot on the brake, and reach underneath the controller and pull the wheel towards you. You'll see the LED light glowing brightly red. Back the wheel off until the LED just starts to flash. It's right on that point of being between constantly on and flashing that the pendulum is set level. Once this is adjusted, the pendulum shouldn't need adjusting unless the controller gets knocked and moved, or the car and van are loaded differently, changing the levels.
Now, back off the power slide about half way. Start to move off. While moving, activate the manual over-ride all the way. If the van brakes lock, back off the power slide a touch. If not, increase it a little, and repeat the test. Ideally, with the manual over-ride all the way on, you want as much braking from the van as possible without locking. This way, you'll have maximum braking from the van under hard braking from the tow vehicle, and the van shouldn't lockup. You can also readjust this for gravel or wet roads.

Last Edit: Jul 23, 2012 23:15:15 GMT 10 by Deleted

Deleted
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Electric Brakes Maintenance Jul 24, 2012 14:07:08 GMT 10

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Post by Deleted on Jul 24, 2012 14:07:08 GMT 10

Mike

The controller circuit is only complete when the trailer plug is connected at which time the indicator LED should be lit and you can then measure the voltage being delivered to the brake solenoids. If the LED does not come on it indicates a fault in the brake circuit.

Bob

Post by mike on Feb 23, 2011 22:21:26 GMT 10

Post by atouchofglass on Feb 25, 2011 6:04:44 GMT 10

Post by mike on Mar 5, 2011 20:13:47 GMT 10

Post by Wassa41 on Mar 14, 2011 9:47:07 GMT 10

Post by Tony and Carol on Sept 11, 2011 20:25:47 GMT 10

Post by Deleted on Jun 6, 2012 9:21:02 GMT 10

Post by Deleted on Jul 23, 2012 23:12:50 GMT 10

Post by Deleted on Jul 24, 2012 14:07:08 GMT 10