# Brake Performance - Will Not Lock Up On Gravel Or Pavement



## arbee (Feb 3, 2005)

On a trip down a mountain last fall, our suburban started shaking each time I put my foot on the brakes. It was getting worse and I pulled over to check things out. The wheels on the suburban were extremely hot and the wheels of the camper were pretty much air temperature. This event was the cause for my concern. After cooling the brakes, we were able to get home. On the way home I tried to test the brakes and they seemed pretty weak and in no way would they come close to locking up on pavement even at max power (pulling the lever). They would not even lock up on our gravel drive.

After the trip, I pulled one of the wheels and inspected the shoes etc and everything looked pretty normal (ie no grease). I adjusted all 4 brakes and tried them out on our gravel drive and on our paved street and still no lock up.

Next, I swapped tow vehicles and tried it with a different controller. (Burban has a Prodigy, Truck has a Tekonsha) No lock up gravel or pavement.

I checked the resistance of the magnets across the wires and relative to ground and everything was normal.

I bypassed all the wiring in the trailer and ran a line straight to the front left wheel only. Could not lock up this wheel alone even on gravel.

I gave up and let it rest for the winter. A couple of weeks ago, I ordered all new brake assemblies for all 4 wheels. I figured for $140, I could replace everything myself cheaper than the labor of taking it in.

None of the wheels were contaminated with grease. I replaced all 4 assemblies. No lockup on gravel or pavement









Yesterday, I did some more electric double checking. With the controller at max setting. I do get 12v at the end of junction box at the end of the harness that plugs into the tow vehicle. I checked the voltage at each wheel. 10.5V on left side, 10.1V on right side. Tested them again and still no lock up.

Lock up aside, I don't thing the brakes are working very well. I used to have to set the controller at say 30% of full scale. Any higher and the trailer would brake much harder than the tow vehicle. I can hear them clicking at this setting but I can't feel much.

What should I expect out of the brakes? Will yours lockup at least on gravel? The instructions for both controllers say they should lock up at 25 mph on dry pavement.

Anything else to check? What will they do if I take it in?

(we have a 2004 26rs. The brakes are 10x2.25". AL-KO axles and hubs and brake assemblies.


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## battalionchief3 (Jun 27, 2006)

I read the directions for the prodigy controller and followed them, I also did not get a lock up. My camper only had a thousand miles or so on it. I adjusted the controller all the way up and mine felt like the trailer was stopping way to hard. So I set it back to where I had it and have drove another 9k miles or so. I have never had them lock up on pavement and I never tried on a gravel road. Either were both normal or were both broke....


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## Nathan (Jan 2, 2007)

You never acutally want a lock up on the brakes (other than for controller setup purposes), but it sounds like you have a bigger problem. I can't see why you would get only 10V at the brakes if there's 12V at the junction box.









What happens if you hook a 12V batt directly to one of the brakes (bypassing everything)?

I think this is a question for Andy.


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## arbee (Feb 3, 2005)

Nathan said:


> You never acutally want a lock up on the brakes (other than for controller setup purposes), but it sounds like you have a bigger problem. I can't see why you would get only 10V at the brakes if there's 12V at the junction box.
> 
> 
> 
> ...


The drop between the junction box and the first brake I assume would be just due to the voltage drop in the wire itself. The brakes are supposed to draw around 3 Amps each at 12V and the wire isn't that hefty.

I haven't hooked a 12V battery to just one wheel with new wire but that would be kind of hard to turn off and on while driving.


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## Oregon_Camper (Sep 13, 2004)

Nathan said:


> You never acutally want a lock up on the brakes (other than for controller setup purposes), but it sounds like you have a bigger problem. I can't see why you would get only 10V at the brakes if there's 12V at the junction box.
> 
> 
> 
> ...


Let's hear it for Andy!!!

BTW...if you find yourself in that type of overheated Suburban brakes again, remember to use the engine to slow you down. Drop the transmission down a gear and let that help slow you down vs 100% of work being done by the brakes. My new F-350 does this for me..which I think is pretty cool.


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## CamperAndy (Aug 26, 2004)

The wire from the Battery to the controller and from the controller to the 7 pin connector should be 10 awg at a minimum.

What was the actual resistance numbers you got when you loop checked the brake magnets?


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## Nathan (Jan 2, 2007)

arbee said:


> The drop between the junction box and the first brake I assume would be just due to the voltage drop in the wire itself. The brakes are supposed to draw around 3 Amps each at 12V and the wire isn't that hefty.
> 
> I haven't hooked a 12V battery to just one wheel with new wire but that would be kind of hard to turn off and on while driving.


Do you have kids that you could have run along beside and hold the battery?






























Sorry, had to ask.


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## arbee (Feb 3, 2005)

CamperAndy said:


> The wire from the Battery to the controller and from the controller to the 7 pin connector should be 10 awg at a minimum.
> 
> What was the actual resistance numbers you got when you loop checked the brake magnets?


Andy,

The wire from the junction box back to the brakes is nowhere near 10 awg. I'd guess it is 16 or 18 and of course came that way from the factory. One thing I noticed is that the brake wire that leaves the junction box is not the same wire that comes out at the wheel. I guess they switch over to a different wire somewhere in the belly. Don't think they are using the trailer frame for ground but have no way of being sure without dropping the coruplastic belly. As I said in my original post, I did bypass all the wiring to a single wheel in the fall and it would not lock up. I have thought about replacing all the wiring just to rule it out. The other side of the coin is that I am getting >10 v at all wheels.

I measured 1.5 ohms with all 4 wheels connected.


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## CamperAndy (Aug 26, 2004)

For the junction box are you referring to the 4 square box mounted on the frame? If there are other connections that are poor it will cause additional voltage drop and reduce the power of the brakes. On trailer wiring is typically 14 awg but should be larger IMHO. The wire on the TV is normally much larger then what is on the trailer and that is also where it should be 10 awg if possible.

A reduction of supply voltage to only 10 vdc means you have about 25% reduced power available to the brakes, so what ever is causing the voltage drop needs to be identified. Also the magnets they do use the frame as the ground loop of the circuit.

BTW lock up is not required for the brakes to operate satisfactorily, but yours need to work better then you are reporting.


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## arbee (Feb 3, 2005)

CamperAndy said:


> For the junction box are you referring to the 4 square box mounted on the frame? ...
> 
> BTW lock up is not required for the brakes to operate satisfactorily, but yours need to work better then you are reporting.


Andy, Yes I was referring to the 4" box mounted to the frame behind the propane tanks.

Next up... When I previously pulled the drums/hubs, the 2 on the left had worn rather unevenly where the magnet hits. I ordered new hubs from Southwest Wheel. I am going to replace those hubs hopefully this weekend. I also plan to run heavier wire all the way to the brakes from the junction box (will try to get 10 AWG). I still have to take the camper in for the fridge recall so if the brakes still seem anemic after the changes above, I'll ask to have them assessed by the service dept.

Regarding lock up or not, I understand that I don't want lock up in normal operation but I really don't think they are working that well and believe they used to work better. The fact that both brake controllers I own say they should lock up is also on my mind.

I would really appreciate if anyone who reads this thread reports back about whether the brakes on their trailer can be make to lock up on gravel or on pavement.


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## folsom_five (Jan 10, 2008)

arbee said:


> I would really appreciate if anyone who reads this thread reports back about whether the brakes on their trailer can be make to lock up on gravel or on pavement.


Yes, I can easily get my brakes to lock up on gravel, and with a little more adjustment can get them to lock up on dry pavement as well.
I would agree that if you cannot get them to lock up at the controller's highest setting then it sounds like something is not working quite right.


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## Nathan (Jan 2, 2007)

With the OB, I never got a lockup at 25mph. I set it to where I felt it was good. Then I did experience a lockup at highway speeds during a panic stop







NOT GOOD. So I dailed the setting back a little. That was with the Prodigy. With my built in controller, I again didn't get a lockup at slow speeds, but haven't had a problem at higher speeds either. Both would lock up on dirt by the way...


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## California Jim (Dec 11, 2003)

Mine will lock up on pavement and cause my eyeballs to be deposited on the dashboard.


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## Scoutr2 (Aug 21, 2006)

California Jim said:


> Mine will lock up on pavement and cause my eyeballs to be deposited on the dashboard.


X2. Mine can be very aggressive, if I don't tune them down. I think the number displayed by my Prodigy (made by Tekonsha) is 8.0. I have things set so they do not lock up and the trailer brakes come on just a bit before the truck's brakes.

I'm with Andy on this one. I think you must have a bad or a corroded connection somewhere above the belly pan, or one of your brake wires is grounding against the trailer frame, because you should be able to see 12V at the brake mechanism.

I'd say you need to do a little exploring above the belly pan - probably not what you wanted to hear.

Mike


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## fshr4life (Feb 7, 2009)

I have a brand new 2010 270BH with a Prodigy controller and my brakes don't lock up on dry pavement at 25mph even at the highest setting on the controller. However, on the high settings I can feel them really working as the trailer quickly pulls my truck to stop and everything bounces forwards when I release the brakes. It certainly feels uncomfortable to apply the brakes at these higher settings. I ran it at about a 7 or 8 on the Prodigy and towed all the way from Lakeshore in Michigan back to New York without any issues. Everything always braked smoothly to a stop even from highway speeds off a short exit ramp or coming off hills and I didn't feel like my truck was doing any more braking that the trailer. However, I was also pretty worried when I was doing the set-up and couldn't achieve lockup even at the highest setting like it says you should in the prodigy manual. Granted, I have brand new tires and I was driving on brand new pavement when I was testing, so the coeffiicent of friction doesn't get any higher for the tires. I never tested them in gravel. I'm not super worried after towing 800+ miles, but I would have felt better if they would have locked up like it says they should.

JD


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