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Comments for Adjusting trailer brake controllers

  • We pull a TT weighing around 7,100# with a ’15 F250. I do a manual brake check rolling down the driveway, when we leave. I have my gain at 7.5% and that seems like a good balance. I also use my exhaust brake when towing. That alone is an awesome addition over our last truck.

  • Since this gave no helpful tips for adjustment, here’s my max and gain methods that I read nowhere else:
    1) Turn your gain higher than you expect neccessary, as a starting place.
    2) From a dead stop, use the manual lever to apply that set-maximum to your trailer brakes. Caution: work fast, because you don’t want to overheat your brakes holding it maxed for long.
    3) Using a low gear and preferrably on gravel, drag your rig a LITTLE, confirming the brakes are indeed locking.
    4) Quickly dial the gain downward until the brakes unlock and wheels turn again.


    5) Accelerate to 10-20mph, and come to a “typical urgency” stop again.
    6A) If the trailer drags the tow (likely if still set near max allowed), turn down the gain until you can’t feel the trailer during stopping.
    6B) If the trailer kicks/shoves the trailer, turn up the gain until you can’t feel the trailer during stopping. If you don’t have separate gain and max controls, again, do NOT exceed the max setting, ever.

    You should now be set for best brake performance. That said, changing trailer weight (water tanks full?) or brake wear may require tweaking if drag/shove recur.

    7) If you have a controller with advanced profiles (eg. Tekonsha P3) try the different boost profiles and/or speed compensated braking until you brake smoothly from any speed. That said, the LOW speed brake force setting is the most important once you prevent locking.

    Hope this is helpful!

  • BTW: issues of brake/hitch wear, passenger comfort, and “trailer mess” are really secondary. Death is primary.

    The DEADLY issue with badly misadjusted brakes is that all(?) tow vehicles now have antilock brakes and trailers never(?) do… As a result, in a panic stop, less experienced or scared drivers jam on their brakes, the tow begins to stop well, the over aggressive trailer breaks traction and acts like its on ball bearings, whipping around jackknife fashion until it regains traction, snags, rolls, and takes the innocent tow along for the ride.

    If the brakes are set too light, you’ll overload the tow vehicle brakes, taking either insanely forever to come to a stop in a straight line, or fishtailing when you brake in a turn and the trailer doesn’t. Either has the same nasty end result.

    …just so people understand the importance.

  • The trailer brakes should apply the proper amount of braking force (for any load or speed). The “proper amount” of braking is just what is necessary for the trailer brakes to slow the trailer at the same rate as the tow vehicle brakes slow the tow vehicle. That’s a complicated way of saying that the trailer brakes should do their share of the braking, but no more and no less. So how do you know when the trailer brakes are doing “their share?” I think it’s pretty simple; it’s when the trailer neither pushes on the hitch coupling (too little braking) or pulls on the hitch (too much braking). Sensing force at the hitch coupling and using that to control the trailer brakes is what the old hydraulic piston brake system used to do, and I don’t know why modern electronic systems can’t use an electronic force sensor at the hitch to control the electric trailer brakes the same way. With an electronic system, you could still provide for manual braking if desired, and also provide for manual off for special maneuvering (like backing up a driveway) when needed. Why do we still have stupid electronic systems with a sensor based on inertia inside the towing vehicle when we could do it the right way from hitch force feedback?