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Old 09-03-2017, 11:47 AM   #1
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2007 27' International CCD FB
San Diego , California
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Brake Controller Ability to Mitigate Sway

This got brought up in another thread, and it's an important enough topic that it deserves it's own thread. There's a variety of brake controllers out there, with some better than others.

The Prodigy P3 I use, has a boost feature, in increasing levels (B1, B2, B3).

This goes beyond just setup of proper brake bias/balance/gain (which is also hugely important)

What it does is essentially have the trailer brakes lead the tow vehicle brakes by immediately applying higher brake pressure to the trailer, as it senses any brake application at the tow vehicle (via brake lights). It keeps the lash-up in tension, by reducing trailer momentum first, such that the trailer does not want to overtake the tow vehicle. Trailer momentum and it wanting to overtake the tow vehicle is a primary energy source for sway.

I always run some form of boost (B1 or B2) on the highway. B2 during higher speeds, winding roads, or steep declines. I tend to turn it off in the city as it can be a bit grabby at lower speeds.

There hasn't been much discussion on this, but I believe this type of feature is critical to minimizing sway, especially under braking. As it allows less reliance on the manual override when trying to stabilize a trailer in initial sway upon braking, or reducing sway with brake application instead of it provoking additional sway. At a minimum, it begins engaging the trailer brakes much more quickly than one can by reaching for the override in emergency situations. Though as a habit, my hand is near the brake controller during more tenuous scenarios.

While I'm not familiar with all braking controllers, I think this would be a good thread to allow those to share capabilities of various systems. I know there are controllers that will detect and reduce way after it happens, but this is more about reducing the likelihood of entering a sway condition.

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Old 09-03-2017, 01:32 PM   #2
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In most of the sway videos out there, the sway begins before braking begins (that being most brake lights aren't illuminated)

Once sway has begun, I agree maximizing tension between the two vehicles is key, immediately applying manual trailer brakes and slight acceleration of TV is one, if not the, best thing to do. But it needs to be practiced enough beforehand to be automatic in panic situation. (Like having to practice emergency landings all the time)

Expecting to only hit the brakes, is doing yourself a disservice and eliminates the ability to practice proper techniques. FOR SWAY.

The boost, in my opinion, is excellent as a preventative measure to jack knifing and it does help with keeping tension on the downhill, to fight being pushed.

Nothaving a "boost" I will turn up the value, from 6 to 10, on my factory installed controller, for the downhills.

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Old 09-03-2017, 04:00 PM   #3
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Slightly off topic but related - on our drive back from Maine today we were in a very heavy downpour and I slowed down to not be out of control for the conditions. We were nearing a jammed exit and I could see the traffic beginning to stall and back up on the far right lane, so I moved in to the center lane (using my mirrors and Voyager rear view can I could see the Lane was empty) and as I did, I could see this lane was also going to jam up. Without looking, I reached down to grab the trailer brake controller (integrated in my Chevy 2500) to practice an "emergency" braking maneuver (and to ensure if I had to brake hard that I could actually be prepared). With several hundred yards between me and the next vehicle, it wasn't quite and emergency but it felt good knowing I could find the controller with my left hand without having to look for it and man that thing does the trick on those trailer brakes! I squeezed slowly so I wouldn't lock them up and kept the gas pedal going (not gunning it). Felt good to practice that motion to try to have it feel more like muscle memory without having to think about it.

I could not find any information in my user manual about whether the software applies the trailer brakes ahead of the truck brakes when connected. I assume it doesn't. So being able to implement this procedure feels like good practice to me.
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Old 09-03-2017, 07:56 PM   #4
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Good thread.

The user manual on my 2016 Ram 2500 contains zip for info on whether the truck brakes lead the trailer.

It'd be nice if it did. I mean, the truck does know its towing a trailer when the umbilical is connected.
2016 30' Flying Cloud / 2016 Ram 2500 Diesel 4x4

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Old 09-03-2017, 08:20 PM   #5
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I have the OEM anti-sway brakes on my 2014 F150 (with max tow package). I am not very impressed by Ford's software package. I was in a sudden, strong cross wind going slightly downhill and the trailer started to sway a little. I was starting to react (trailer braking), when the automatic system cut in pulsing the brakes left to right and back. It felt very abrupt to me and unnecessary harsh given the situation (which was not that bad). That is the only time, however, that the system has ever cut in and I have experienced worse sway. Not sure why this was different. My system (F150, Blue Ox and 28 foot AS) is generally very stable when under 70 mph.
2004 Airstream Classic 28 "Willard"
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Old 09-03-2017, 08:31 PM   #6
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To be effective in terms of anti-sway, the brake controller needs to be able to *detect* sway. That's not as easy as it might seem.

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Old 09-03-2017, 09:36 PM   #7
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Hard to imagine almost 25 years after the first projected pivot point hitch went on the market to eliminate the possibility of trailer sway we are discussing reaching for the brake controller before the whole rig goes out of control. I know, I know, they are expensive. But relative to the $100k+ cost of these truck/trailer combinations and the consequences of out of control sway?

Okay, so much for alternatives. Back to the discussion on using the brake controller to prevent a loss of control accident.
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Old 09-03-2017, 10:33 PM   #8
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Brake Controller Ability to Mitigate Sway

Even in the absence of sway, I have been in emergency situations where being able to manually put max braking on the AS while standing on the TV brakes with both feet was necessary.

Have I mentioned how much I hate the traffic (and so-called drivers) in Phoenix, Arizona?

Rocked to a 8-tire smoking stop inches from the fool's rear bumper.....had I the time, there would have been an interesting discussion when I ran him to ground....punctuated by some percussive tuning....
Rich, KE4GNK/AE, Overkill Engineering Dude
'The Silver HamShack' ('07 International 22FB CCD 75th Anniversary)
Multiple Yaesu Ham Radios inside and many antennae sprouting from roof, ProPride hitch, Prodigy P2 controller.
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Old 09-04-2017, 04:28 AM   #9
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Thank you for starting this thread!

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Old 09-04-2017, 04:49 AM   #10
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It is very important to check and practice using the trailer brakes to stop sway if it begins. Usually, when it does begin, you have mere seconds to react before the situation is beyond saving.
Now, I'll add something I discovered when teaching a new trailer owner how to do this-- Some new vehicles are designed to return the throttle to idle when you hit the trailer brakes. THAT was extremely disconcerting, and can distract a driver in an emergency situation. Imagine that for a moment. You find yourself in a "perfect storm" where you are traveling downhill on a windy day, you pass from behind the shelter of a hill or trees, a gust of wind hits the trailer just as an 18-wheeler blows by you at 80+, and the trailer begins to sway violently. You immediately grab the manual lever for the brake controller, and pull it hard over, while stepping on the gas pedal harder. As soon as you hit the brake controller lever, the engine drops to idle, and will not do anything but idle, no matter if you floorboard the accelerator pedal. You are now completely at the mercy of your trailer brakes, because you can't perform the second action to stop the sway, which is speeding up slightly. Instead, you're slowing down, which could make the situation even worse.
So, before you need to do this for real, check to see if your tow vehicle is too smart for your own good.
The ones I've noticed this happening to seem to have been mid-size SUVs, but that doesn't mean they are the only ones.
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Old 09-04-2017, 04:56 AM   #11
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As for muscle memory and practice, it is always hard to just do this on your own, you can practice the location movement, but in a true panic situation, that reaction practice is more difficult.

A good method is to set up with your significant other, to screech as if impending doom awaits (agree beforehand that this will not happen in busy situations, at least until the proper response is ingrained). The good part to this is that if you ever find yourself day dreaming, it just may be the way you are alerted anyways.

Reminds me that I had to train my wife that she isn't allowed to grab my right arm in a panic situation, although that was in a smaller car...
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Old 09-04-2017, 08:16 AM   #12
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Originally Posted by pteck View Post
I always run some form of boost (B1 or B2) on the highway. B2 during higher speeds, winding roads, or steep declines. I tend to turn it off in the city as it can be a bit grabby at lower speeds.
Every year I get a little more active in my use of boost. I don't use it for sway control, as the ProPride handles that job. However, I do use it to lighten the load on the truck brakes when on winding or steep roads. B1 for moderate situations, and B2 when we're in the mountains. We have the trailer brakes serviced every year due to the miles we put on it, so I have no hesitation on using them aggressively.

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2014 Tundra DC 5.7L / ProPride / Tekonsha P3
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Old 09-04-2017, 10:57 AM   #13
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Old 09-04-2017, 01:09 PM   #14
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Originally Posted by uncle_bob View Post

To be effective in terms of anti-sway, the brake controller needs to be able to *detect* sway. That's not as easy as it might seem.

False. Sway situations are setup well before sway actually occurs.

It generally is a combination of lash-up in compression, with the trailer having excess momentum over the tow vehicle, speed, and an initiating lateral movement.

It should be noted that using engine braking specifically puts the lash-up in the above scenario. With more engine braking, and more speed, being a scaler on the forces. Engine braking is great for saving brakes over a long descent, but not so great for stability, especially in certain scenarios. Also consider how engine braking is applied to a single axle (2WD), vs all axles when real brakes are applied.

The likelihood of sway depends on the margin of stability and speed, governed by all the other setup things we like to talk about including hitch WD&AS/hitch type/specific tow vehicle/WD of trailer, etc.

To your point Bob, there are other mechanisms that come into play with more advanced brake systems after sway is detected. I think we can all agree that we would prefer to stay away from sway to begin with.

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