Trailer Brake Effectiveness

[Memphisdoug]

The brakes on my 5th wheel work very well at slow speeds (under 20 mph) but seem almost non-existent at road speeds. It is a Prodigy controller with the gain turned all the way up at highway speeds. Is this normal and if not what needs to be done to fix the problem?

 

[Kirk]

What makes you believe that the brake isn't effective at highway speeds? The Prodigy, like most modern brake controls, uses a combination of sensing the application of the brake via the brake light signal and also inertia. It isn't intended to apply much braking unless the tow vehicle is slowing significantly. If properly set up it will not lock the wheels.

Here are some steps for setting the power output on a Tekonsha Prodigy P2 brake controller:

1. Connect the wire harness and mount the brake control
2. Connect the trailer to the tow vehicle
3. Squeeze the manual override control and set the power to about 6.0
4. Tow the trailer to a dry, level surface
5. Drive the vehicle up to 25 mph
6. Reactivate the manual override
7. If the trailer wheels lock up, reduce the power
8. If the wheels turn freely, increase the power to just before wheel lockup

 

[Gary RV_Wizard]

It's certainly possible your trailer brakes are not properly adjusted. i.e. the shoes do not contact the drum firmly no matter how much the electromagnets try. Equally possible that the wiring on the trailer is in poor condition and doesn't deliver enough voltage & amps to get full braking capability. Corroded wire connections are fairly common on trailer brakes. And lastly, some low-end trailers skimp on the brakes to the point where they are barely adequate at best.

If your family car were doing that, wouldn't you head for a brake shop to investigate & repair? A brake shop, not an RV dealer? Most regions have shops that specialize in brake systems and at east some of those know electric brakes as well as hydraulic.

 

[SpencerPJ]

Short answer, no it's not normal. It most likely is as Gary said, brakes need adjusted. Not a hard project, but most likely you should have your wheel bearings repacked with grease as well. An option might be, Google, mobile mechanic or mobile rv mechanic and your zip code. Have them take wheels off, and evaluate. Good luck.

 

[DutchmenSport]

I've had 4 different trailers, 3 travel trailer and 1 fifth wheel. I've had 4 different tow vehicles, None of them locked up the trailer brakes at 50 mph even with the gain set on 10.

My current truck has an integrated brake controller. I keep the gain set on 10 (highest). Why? because with an integrated system, the trailer brakes will brake in proportion to the brakes on the tow vehicle.

If the gain is set to max, when pushing the brakes at max in the tow vehicle, the trailer brakes are maxed also.

If the trailer gain is set on 5, the controller is pushing out only 50 percent. So, if the vehicle brakes are slammed on at 50%, the trailer brakes are actually only 25% (half of it's full potential).

That is how an "integrated" system works. At a setting of "5", the brake controller is always going to spit out half of it's full potential. At 3, it will always be 33%, at 6, it will always be 66% (or close).

That's probably one reason why the trailer brakes don't feel like they are actually braking. Your tow vehicle is braking 100%, your trailer is braking proportionally based on your setting.

 

[Memphisdoug]

I installed self-adjusting brakes on my trailer but perhaps they aren't self-adusting themselves. As I said, the brakes work very well at slow speeds but don't seem nearly as effective at higher speeds.

 

[8Muddypaws]

Last time I checked self adjusting trailer brakes adjust themselves when you apply the brakes while backing up. Try backing up at about a brisk walk and hitting the brakes fairly hard 10-15 times and then test your brakes again.

If I had a trailer with self adjusters I'd take them off and adjust them manually once or twice a year. It's really easy. (See YouTube for instructions)

 

[Kirk]

I am wondering what you are going by to assess the braking at highway speeds? The only way that I know of to even check is by using the manul knob on your Prodigy. Even then the tires should not lock but you should be able to feel them.

 

[Rene T]

Even then the tires should not lock but you should be able to fill them.

Fill them with what? Liquid brake?

 

[CharlesinGA]

Last time I checked self adjusting trailer brakes adjust themselves when you apply the brakes while backing up. Try backing up at about a brisk walk and hitting the brakes fairly hard 10-15 times and then test your brakes again.

If I had a trailer with self adjusters I'd take them off and adjust them manually once or twice a year. It's really easy. (See YouTube for instructions)

Dexter has their PDF manual locked so I cannot highlight/copy from it, however here is a screen print of a description of the self adjusting brakes. You are thinking of the traditional self adjusting brakes of the 1960's like I too grew up with, however things are different now.

Dexter 600-8,000 lb axle service manual, all types of axles.


Charles

 

[8Muddypaws]

My last trailer was 14 years ago. I guess I'm a little out of date then?

 

[Gary RV_Wizard]

That's probably one reason why the trailer brakes don't feel like they are actually braking. Your tow vehicle is braking 100%, your trailer is braking proportionally based on your setting.

Good description, but the OP says the gain is "turned all the way up", so he should be getting 100% at the trailer wheels.

 

[CharlesinGA]

OP needs to remove the hubs and inspect the brakes. Make sure there is no wheel bearing grease on them (if EZ-lube) and make sure the adjusters are free to turn, reinstall the hubs after packing bearings, and adjust the brakes so you get a shhhh......... shhhh......... shhhh......... as you spin the wheel. Not constant light contact but intermittent contact as the drum rotates. Thats as tight as I will go with them.

I cannot feel the trailer brakes at highway speed, the only way I can tell if they are working is to let off the accelerator and gingerly actuate the lever on the brake controller and feel the trailer and truck slow down. At low speed with the gain set high, you will feel a lurching when you release the brake pedal.

Charles

 

[Lou Schneider]

There is a slight but observable interval between the time electrical current is applied to the trailer brakes and when they start to apply. The force is supplied by an electromagnet dragging across the face of the rotating brake drum when it's activated, which means the time it takes for it to take up the slack and start pressing the brake shoes against the drum is affected by the vehicle speed. The difference is in the range of a few tenths of a second but the longer reaction time at slow speeds may be why you can "feel" the brakes engage then but not at higher speeds where they activate essentially in synchronization with the vehicle brakes.

 

[MoInEd]

To adjust trailer brakes I us8drive at slow speed and try braking lightly. If I feel the tow vehicle is pulled back trailer brakes are too highly and if I feel the tow vehicle isnpushed when I brake I need to adjust the trailer brakes higher. When none of these happen and I feel braking in the tow vehicle feels like what it should be without a trailer behind then it's more or less right, I adjust it a tiny notch higher sometimes.

This is hard to notice at highway speeds....

 

[tlmgcamp]

The brakes on my popup seemed a bit lame. Repair guy didn't see anything obvious. He took apart all the crimp and wire nut connections and soldered everything and protected the connections with shrink tubing. Noticeable improvement