Problem Setting Power On Prodigy Brake Controller After Upgrading To 15" Tires

[Philip]

Hello Again Folks,

I recently upgraded my 2720 TM to 15" wheels. After doing this I thought it would be a good idea to check the power setting on my Prodigy brake controller which I purchased in 2009 and used on my TV and TM when I had the factory 14" wheels. I assumed that I would have to make minor adjustments to the power setting with the slightly larger and slightly wider
15" tires.

When I did the original power setup for the 14" tires I ended up with the power at 6.1 and boost at 1. A setting slightly above 6.1 power level locked the wheels as recommended in the manual for power setup.

After installing the new 15" tires, I again went out on a quiet section of road to check the power setting. I went throught the procedure to set the power level by increasing the power setting and driving at the prescribed speed of 25MPH and manually applying full power. No matter how much I increased the power setting, I could not get the wheels to lock up. Eventually I ended at the Max. setting of 13 but still no wheel lock up. It was, however, quite evident that as I went up the power setting that the TM was holding back the TV more and more. Eventually, out of desperation or perhaps frusteration, I changed the boost setting to 2 with the power still at Max.(13). This should, I thought have no effect on wheel lock up since boost just controlls the rate you reach Max. power. Low and behold the wheels locked up on the test run with this boost setting. Just to check I reduced the boost to 1 again(leaving the power at Max.(13)), I did the test again. The wheels did not lock but just as before it felt as if the TM was really holding the TV back.

Since I did not like how the TM reacted to braking in boost 2 - it seamed to brake in an excessive manner during slow braking - and the Prodigy manual did not recommend boost 2 for the TM trailer weight vs. the TV weight, I switched back to boost 1. Just from the feel of braking in the TV, I also reduced the power to 10 from 13. During hard braking the TV does not feel as if it is being pushed by the TM and brake peddle force in the TV does not feel greater than when I make a similar stop without the TM attached.

Just so everyone knows, I checked and adjusted the brakes on the TM when I put the new 15" tires on. Brake linings, drums and magnets looked very good. No scoreing and good lining thickness.

Has anyone else run into this problem and if so what did they end up doing? Also, it would help to know the power setting other Prodigy controller users end up with when towing a 2720 TM with 14" and 15" tires.

I have a feeling, certainly not sure, that the 15" tires greater leverage(diameter) on the brake and larger surface on the road may make it difficult for the 2720 brakes to slide them. It really should not be necessary since the 15" tires are probably giving me more stopping power than the 14" tires.

Comments greatly appreciated!

Take care,

Phil

[Bill]

Ideally, a controller will make the rig seem to stop at the same rate, and with the same "feel" and the same brake pedal pressure, when the trailer is hitched up as when it is not. And it will do this at all speeds. Unfortunately, this is difficult to achieve, because disc brakes (in your car/truck) perform differently than drum brakes (in the TM). So your goal is to find the best compromise. All the hints up about "lockup at 25 mph" and "boost" and so forth are just intended to help you find that best adjustment point.

My choice - and it is strictly mine - is to find a setting where braking at high speed feels the same with the trailer as without. Braking at high speed is likely to be more important than braking at low speed, so I figure if it grabs or lurches a bit at low speed (and it does), I'll put up with it.

Bill

Originally Posted by Philip

Just so everyone knows, I checked and adjusted the brakes on the TM when I put the new 15" tires on. Brake linings, drums and magnets looked very good. No scoreing and good lining thickness.

When was the last time you did the lockup test with your 14" tires? If it was a a few years ago then the following may be a remote possibility. You may have corrosion in the wiring to the brakes which is adding resistance to the circuit, decreasing your braking current and your braking power. It could be anywhere in the brake circuit common to both wheels but some areas are very vulnerable. The wire nuts used to connect the magnet wires to the brake wires are open to the elements and the wire can turn to powder over time. Corrosion in the drivers side connections (which feeds both brakes) could effect braking of both wheels.

I have had to replace both my brake assemblies because the magnet wires corroded right back through the backing plate into the drum. That on a 5 year old TM with no road salt exposure. In my case the circuit to the drivers side magnet went completely open which lead me to find the corrosion.

I have upgraded to 15" tires and will be upgrading my controller to a Prodigy II in a few days once I finish the brake replacement and rewiring. It will be interesting to see where I get lockup.

Hope you don't have creeping brake crud.

Peter

[T and C]

Originally Posted by kokilo

When was the last time you did the lockup test with your 14" tires? If it was a a few years ago then the following may be a remote possibility. You may have corrosion in the wiring to the brakes which is adding resistance to the circuit, decreasing your braking current and your braking power. It could be anywhere in the brake circuit common to both wheels but some areas are very vulnerable. The wire nuts used to connect the magnet wires to the brake wires are open to the elements and the wire can turn to powder over time. Corrosion in the drivers side connections (which feeds both brakes) could effect braking of both wheels.

I have had to replace both my brake assemblies because the magnet wires corroded right back through the backing plate into the drum. That on a 5 year old TM with no road salt exposure. In my case the circuit to the drivers side magnet went completely open which lead me to find the corrosion.

I have upgraded to 15" tires and will be upgrading my controller to a Prodigy II in a few days once I finish the brake replacement and rewiring. It will be interesting to see where I get lockup.

Hope you don't have creeping brake crud.

Peter

Many folks on this board have reported that they cannot achieve brake lockup by simply following the Prodigy instructions. Remember that those instructions are general in nature, and that most travel trailers nowadays have two axles.

Since TM only has one axle, the weight on each tire, and therefore the traction of each tire is double that of a two axle travel trailer. It is therefore harder to lock them up.

In my case, my Prodigy p2 is set on 6.0. The truck and trailer stop normally, and when I trigger the trailer brakes manually I get a good solid tug from behind. I have never gone "all the way" on the settings to lock them up, but I'm satisfied with the braking power I have.

Tom

[Mr. Adventure]

The 15" tire/wheel will have a bigger diameter than the 14" wheel, and therefore have more leverage against the brake pads. No matter where I set my brake controller, I can't get a trailer wheel lockup on dry pavement.

Buy you don't really want a lockup anyway. The TV has anti-lock brakes that have more stopping power than the trailer brakes because they prevent skidding, and if you actually achieved a trailer lockup in a panic stop, the trailer would be skidding around to one side or the other.

You don't have time to work out the details once your foot is on the brake pedal and things are already happening too fast. So I set the controller like Bill, and I also set it a little lower and drive a little slower in the rain.

[Philip]

Originally Posted by kokilo

When was the last time you did the lockup test with your 14" tires? If it was a a few years ago then the following may be a remote possibility. You may have corrosion in the wiring to the brakes which is adding resistance to the circuit, decreasing your braking current and your braking power. It could be anywhere in the brake circuit common to both wheels but some areas are very vulnerable. The wire nuts used to connect the magnet wires to the brake wires are open to the elements and the wire can turn to powder over time. Corrosion in the drivers side connections (which feeds both brakes) could effect braking of both wheels.

I have had to replace both my brake assemblies because the magnet wires corroded right back through the backing plate into the drum. That on a 5 year old TM with no road salt exposure. In my case the circuit to the drivers side magnet went completely open which lead me to find the corrosion.

I have upgraded to 15" tires and will be upgrading my controller to a Prodigy II in a few days once I finish the brake replacement and rewiring. It will be interesting to see where I get lockup.

Hope you don't have creeping brake crud.

Peter

Hello Peter,

Thank you for your comment.

Oddly, I removed the wire nuts that connect the power to the brakes just before I did this test. The wires were somewhat corroded. I cut of the corroded section and stripped the wires back to good wire before reinstalling the wire nuts. As I mentioned in another comment on a different post, I am going to replace the wire nuts with high quality crimp connectors that have adhesive sleeves. It is rediculous that they ever use wire nuts in an exterior application - especially an item as critical as brakes. When I inspected the brakes at tire size change, I did not notice any problem with the magnet wires.

I would be interested in your results with brake controller setup after you install the 15" tires. Let me know your setting.

Again, thank you for the comments,

Phil

[Philip]

Hello Folks,

From the comments so far it appears as if what I am experiencing with my brake controller and 15" tires is fairly normal. Good to know since the setup for the brake controller in the manuel cannot be really achieved.

I have done much the same as most of the comments indicate. I try to judge the tugging force on the TV from the TM as I apply the TM brakes manually without applying the TV brakes. I have also tried to estimate TV brake peddle force during hard stops with and without the TM attached in order to get brake peddle force about equal in both conditions.

I am now at a 10 power setting and will probably reduce this to ~8 and see how that feels. I would rather not have the TM doing a significant part of braking the TV. The TM brakes are certainly not sized for that.

I am still interested in power settings people arrive at(especially with 2720 TM's) and additional comments.

Again, thank you all for the comments so far!

Take care,

Phil

I have installed all new brakes on both wheels for reasons noted in my previous post and out of paranoia I replaced all wiring from the refrigerator bay junction to each wheel with marine grade wire. I could not get lockup at any setting of my prodigy 2 controller with brakes warmed up as required. I adjusted the brake shoes twice with no great effect.

After I replaced the suspect wiring from the refrigerator bay junction to the wheels I got about 10% more current flow to the brakes than by just replacing the obviously corroded sections found earlier.

At this point I am satisfied that I have achieved adequate braking considering the high traction of this single axle system. A setting of 9 with no boost seems to work ok. The trailer seems to be taking care of itself and not pulling the TV back which could lead to fade on long downhills. It is not pushing the TV at all during braking.

[Philip]

Originally Posted by kokilo

I have installed all new brakes on both wheels for reasons noted in my previous post and out of paranoia I replaced all wiring from the refrigerator bay junction to each wheel with marine grade wire. I could not get lockup at any setting of my prodigy 2 controller with brakes warmed up as required. I adjusted the brake shoes twice with no great effect.

After I replaced the suspect wiring from the refrigerator bay junction to the wheels I got about 10% more current flow to the brakes than by just replacing the obviously corroded sections found earlier.

At this point I am satisfied that I have achieved adequate braking considering the high traction of this single axle system. A setting of 9 with no boost seems to work ok. The trailer seems to be taking care of itself and not pulling the TV back which could lead to fade on long downhills. It is not pushing the TV at all during braking.

Thank you for the feedback,

I agree with your wire upgrade. I am at least going to replace the wire nuts with high quality crimp on connectors with adhesive sleeves. Will do the wiring when I get a chance.

I plan to reduce my controller setting to ~8 from the 10 I am at now. Will probably stay at boost 1 as I am now. I get the same feel as you when towing.

Take care,

Phil

I noticed the wheels would not lock when I picked up my TM, new. I've been using the max setting to get as much trailer braking as possible.

Koz