Req expert opinions about one trailer wheel locking up when braking

[gordon2]

Originally Posted by Raz

Thanks, I missed that. No problem locking brakes with a 10" drum. The drum that's not locking is the issue. ....

I'm not so sure.. when I picked up the trailer and went to adjust the brake controller according to the instructions, I did not have any luck getting the brakes to lock up at reasonable speeds with reasonable brake pedal pressure. I even tried on a gravel parking lot. Yet braking performance was good - smooth like I would expect it to be. And I read that others have the same experience with the 16, and 10 inch brakes. Even with aggressive braking when the controller was set on max 10 volts, the brakes never locked.. yet now the one side locks and leaves skid marks at slower speeds with the max voltage set at 4.5 volts (maybe even lower).

Yet I will admit that if the non-locking side was failing, and the other side was having to do all the braking, that would make sense. But as far as I can determine, the non-locking side is working normally. The only possible problem would be a bad connection that does not occur when testing, but does once in a while on the road.

[Jack L]

I would send the photo to Scamp with a detailed description of the issue. Asking for a warranty replacement of the brake assembly and a new drum and hub assembly seems appropriate here. I also see what might be a wear issue on the leading edge of the magnet.

[Carol H]

Originally Posted by gordon2

And I read that others have the same experience with the 16, and 10 inch brakes. Even with aggressive braking when the controller was set on max 10 volts, the brakes never locked.. yet now the one side locks and leaves skid marks at slower speeds with the max voltage set at 4.5 volts (maybe even lower).

Y.

I can get the brakes on my 16' to lock up no problem if I set the controller to high. When things get to the point that I can not that is when I know I need to do a brake adjustment on the trailer - which has become part of a yearly routine - done at the same times bearings get a repack or replacement.

[Raz]

My last trailer had 10" brakes. No problem getting them to lock up. My Trillium has 7" brakes. Pads are too small to lock. The one time they did lock was when the magnet clip fell off and the loose magnet got jambed.

I'm no expert, just a little further down the path. I initially suggested jacking the wheel and spinning it but I see you've already done that. Let us know what you find. Raz

[Raz]

Originally Posted by Carol H

Something tells me we will see that photo time and time again for years to come even if the party who took it does not share it again!

Did you save a copy? I did.

[gordon2]

Well I am still confused..

On the side that was locking up (starboard) I cleaned up the grease (without disassembling the brakes), did a partial bearing repack (they only had about 3100 miles) and replaced the seal. Then re-adjusted the brakes and did a parking lot test.

The starboard side still locked up (or at least locked up before the port side), so I backed off two more clicks on the starwheel. From the point where I could not turn the wheel with one hand, the starboard side starwheel was backed off 8 clicks and the port side 6 clicks.

Did another test drive and was still getting wheel lock-up at anything close to the setting I had been using without lock-up since picking up the camper (10 volts max). I backed it down and went back and forth on the setting while doing stops from around 15 MPH. I finally settled on 6.2 volts and then hit the road. At this setting the braking seems good from slow speed as well as about 45 MPH. The wheel is not locking up unless maybe I really hit the brakes hard. The starboard side does run hotter. Probably not too hot in normal use but after all my repeated braking for testing and adjusting, the right drum was too hot to hold my finger on but not the left.

So at this point I am wondering if there were two issues:
1. The obvious grease leak
2. And perhaps in fact the brakes were not adjusted right from the start, and I was using a higher controller setting to compensate. Is ~6 volts a reasonable max setting?

I feel good enough about it to head out in the next week and do about 120 miles on secondary highways so we will see how it goes.

PS. My photo has a hidden watermark and copyright

[Carol H]

Gordon what Make & model of controller are you using?

I have one of the original Tekonsha Prodigy Brake Controller's same as a P2 but just can't be mounted at as great an angle as the P2 can.... I have never needed to move the settings any where above the mid 3's (no boost on) to get the my 16' Scamps trailer brakes to work well. Anything above that and it would lock up way to soon.

[Raz]

The prodigy is inertia controlled. As far as I can tell, the knob sets the maximum voltage to the magnet and the boost level sets the steps to get there. The manual says set to 6 and adjust to lock up and then back off just below there. Where that happens will be determines by the weight of the trailer, the size and condition of the brakes, and the condition of the magnet to drum surfaces. As far as I can tell the distance from the brake shoe to the drum simply determines how far the swing arm has to move to engage. Mine are set barely touching. With a 7" drum I can't lock up, so I set things so the trailer brakes are compensating for the additional weight of the trailer as best I can. There's a lot of voo doo involved.

[mary and bob]

What I saw in the video; it's kind of quick so I didn't get a real good look, but when you moved the magnet by hand the forward shoe appeared to raise up, making it misaligned from the position it would be in if the brake drum was on. This may account for you having to hit it for it to retract. Looks like you are hitting it down. Another thought, is there a primary and secondary brake shoe or are they both the same. Cars and trucks with drum brakes generally have two different shoes on each wheel, one will have longer lining than the other, therefore primary and secondary. I can't remember which is what at the moment. I have a set of brake assemblies I pulled off my Casita, but they are in my shop at another location and can't look at them right now. Every time I pull the drums on any vehicle I blow out the dust and clean off the shoes with 80 grit or so sandpaper to remove any glaze. If the shoes have been heavily grease contaminated you may not be able to completely clean them, but may be worth trying. When you do your adjustment you want to tighten the shoes against the drum to the point you can barely turn the wheel. This centers the shoes. Then back off until the drum turns free with maybe a very slight drag. Check the axle manufacturers specs on that. Both sides should be backed off the same number of clicks

[gordon2]

Originally Posted by Carol H

Gordon what Make & model of controller are you using? ... I have never needed to move the settings any where above the mid 3's (no boost on) to get the my 16' Scamps trailer brakes to work well. Anything above that and it would lock up way to soon.

P3.
And thats good to know.. I thought that 6 might be too low but maybe its just right.

Originally Posted by mary and bob

What I saw in the video; it's kind of quick so I didn't get a real good look, but when you moved the magnet by hand the forward shoe appeared to raise up, making it misaligned...

After posting that I pulled the other drum and it did the same thing, so I think it is normal (with the drum off). You could pretty much give it a knock anywhere to get it to retract.

[Carol H]

Originally Posted by gordon2

P3.
And thats good to know.. I thought that 6 might be too low but maybe its just right.

Actually 6 still sounds high to me. I pull the same trailer with a mid size truck and used to pull it with a small cross over vehicle.... I do not need to set it over 4. Makes me wonder if the brake shoes are still maybe not set correctly. I know when I first got my trailer (used) its where not set correctly and I did have to set the controller much higher & use all the boosts on first tow home and even then it wasn't very good.

When you set it up where you using the manual emergency switch on the controller to test the stopping power or the cars brakes?

If I am not mistaken when setting it up you use the manual emergency switch to stop the trailer and if it locks up to fast you turn the power down and try and again until it stops well but is not doing a total bunny hop lock up. Then try stopping it with the cars brakes .... . I do not have the full instructions for set up with me but that is pretty well how I check it on the start of every trip as you never know what may have changed since last trip out.

[gordon2]

Originally Posted by Carol H

...

When you set it up where you using the manual emergency switch on the controller to test the stopping power or the cars brakes? ...

Using the manual knob, according to this procedure:

1. Connect trailer to tow vehicle. 2. Set power to indicate 6.0. 3. Drive tow vehicle and trailer on a dry level paved surface at 25 mph and fully apply Manual Knob. 3 If trailer brakes lock up then turn power down using Power Buttons. 3 If braking was not sufficient then turn power up using Power Buttons. 4. Repeat Step (3) until power has been set to a point just below wheel lock up or at a sufficient force as to achieve maximum braking power. 5. Using the brake pedal, make a few low speed stops to check the power setting.

At this point I suspect that I did not do the brake and/or controller adjustments right previously, but I think I am real close now. Maybe just a little more tweaking.

Thanks to all for the help.

[Raz]

Drive tow vehicle and trailer on a dry level paved surface at 25 mph and fully apply Manual Knob.

I suggest a gravel road. It's easier on the tires.

[Darral T.]

My 13' will slide on gravel and not on pavement. I use "Full" voltage but then select "P1" to have less "aggressiveness" when I first apply the brakes. If I set it to NOT slide on gravel, it would be basically ineffective on pavement.

I've always heard and use this method: When you stop with a trailer, your vehicle should not feel like it has a trailer behind it. THEN you know the trailer is stopping itself and not both and vice-versa.

Originally Posted by Raz

I suggest a gravel road. It's easier on the tires.

[Raz]

Darral, what type of tires are on your trailer?

[Darral T.]

DICO ST175/80R13 Class C tire Rated at 1360 lbs each @ 50lbs pressure.

Originally Posted by Raz

Darral, what type of tires are on your trailer?

[Carol H]

Originally Posted by Darral T.

My 13' will slide on gravel and not on pavement. I use "Full" voltage but then select "P1" to have less "aggressiveness" when I first apply the brakes. If I set it to NOT slide on gravel, it would be basically ineffective on pavement.

13's have a smaller brake system than the OP's 16's, so not unusually for someone to need to have full voltage on a 13's, with many reported they still can not get them to lock up.

[Raz]

Originally Posted by Carol H

13's have a smaller brake system than the OP's 16's, so not unusually for someone to need to have full voltage on a 13's, with many reported they still can not get them to lock up.

Yes, I can't get mine to lock up on gravel and I think it might be due to tires. Mine are Carlisle radials.

[Darral T.]

Wow...you've thrown me a curve with that one Raz. I would have to say that your brakes are possibly not set close enough? I know they describe running the knurled screw out until the shoes locks the wheel then backing off a few clicks. How does the trailer feel when you move the lever over on your Brake controller? When leaving the driveway, I do this on mine and it's quite "snappy" when the brakes engage on my Scamp. It will tug it AND my Nissan Frontier when fully applied.

My trailer only weighs about 1740 lbs... that would definitely make a difference as well....the weight. Interesting none-the-less.

Originally Posted by Raz

Yes, I can't get mine to lock up on gravel and I think it might be due to tires. Mine are Carlisle radials.

[David B.]

This is a real puzzler. I have had many different problems with electric trailer brakes over the last 50 yrs, such as the clip that holds the magnet on, broken wires, bad connections, glazed brake shoes, etc. The problem that best mimics the OP problem happened on our 13' Scamp when I purchased and installed new hub/brake assemblies. A call to Scamp solved the problem. It turns out that the brake assemblies are labeled "Left" & "Right", but if you have a leading arm axle (like on older Scamps), then you have to install the "Left on the Right" side and vice versa. Swapping the assemblies side to side solved the problem. I couldn't tell from the post what year the 16' Scamp was, so as to know if it is the newer "Trailing Arm" axle or the old style "Leading arm" configuration.
Do let us know what the cure is when you figure it out.
Dave & Paula
P.S. I really enjoy our hydraulic surge Disc brakes on our Lil Snoozy.