P3 settings for 21

[Rossue]

Have a problem with the passenger-side real wheel locking up. To avoid this I have to set the P3 to no boost and at 3.5 or below.

Had a mechanic pull the drum off and everything looked good to his eye and the magnets were getting the proper voltage. Other that perhaps the hub being out of round am not sure other than is 3.4 a setting others use?

Have spoken with Dexter and am getting a call back from them tomorrow to discuss further.

What settings are being used out there and is anyone else out there having any problems?

[gbaglo]

My Prodigy instructions say not to use boost on trailers as light as my Escape. You might want to review those instructions for the weight of the 21.
I suspect that having boost turned on was the problem. Mine accidentally got turned on, and I had a few disturbing moments until I realized what had happened.

[Rossue]

Looking closely at the instructions one might infer that Boost 1 could be correct for the 21. In fact the boost was set on 3 somehow, however with boost turned off the wheel is still locking up when controller is set above 3.5. It seems odd to me that it is just one wheel that is locking up. At 3.4 it doesn't seem to have enough grab- not like it did with my Prodigy RF and the 17. It was set around 4.5

[gbaglo]

Think I'm at 4.5 with my 17.

[Brian B-P]

To me, the fact that just one wheel is locking certainly suggests a mechanical issue with that brake.

Torflex suspensions don't load-share, so the leading and trailing wheels on the same side of the trailer could carry different loads, and thus have different traction, causing the less-loaded one to lock more easily. In this case, since the trailing wheel is locking it could indicate the trailer is a bit nose-down. Since it only happens on one side, I doubt this is the actual problem... although if the trailer is driver's-side-heavy and nose-down the trailing passenger-side tire would be least loaded of the bunch.

Since the brake magnets are simply connected in parallel, I can't imagine any way it could be an electrical problem, unless the brake magnet itself is defective. A defect causing more braking action seems unlikely to me.

Something is likely bent or mis-adjusted in that one brake assembly. I would open it up and see; unfortunately, that means taking the hub off, bearings and all. I realize this has already been done, but that still seems like the place to look.

There are so many factors in determining the right controller gain setting that I won't guess what the right setting might be, but 3.4 is pretty low in the range of possible settings, so it seems likely that when the grabbing is resolved the appropriate setting will turn out to be higher. First things first... need to fix the brake at that wheel.

[Brian B-P]

Originally Posted by gbaglo

Think I'm at 4.5 with my 17.

Interesting.... with twice as many of the same brakes and less than twice the weight, the 21' should require a lower setting. On the other hand, there are still questions of tire diameter differences.

[Klem]

I'd check the ground wire is well bonded and solder the connectors too. You could hang a volt meter across the brake wires at the 1st connection nearest to the brakes and see if there is a bad splice dropping voltage to one side.

I'm running boost 1 and it's working well. 19' and 2005 4runner V8. Makes sense with below, vehicle heavier then trailer.

A boost setting of b.1 is for trailers that weigh less than the tow vehicle. A boost setting of b.2 is the for a trailer that weights nearly the same as the tow vehicle. A boost setting of b.3 (the highest) is when the trailer weighs up to or more than 40 percent of the vehicle.

[Rossue]

Originally Posted by Brian B-P

To me, the fact that just one wheel is locking certainly suggests a mechanical issue with that brake.

Torflex suspensions don't load-share, so the leading and trailing wheels on the same side of the trailer could carry different loads, and thus have different traction, causing the less-loaded one to lock more easily. In this case, since the trailing wheel is locking it could indicate the trailer is a bit nose-down. Since it only happens on one side, I doubt this is the actual problem... although if the trailer is driver's-side-heavy and nose-down the trailing passenger-side tire would be least loaded of the bunch.

Since the brake magnets are simply connected in parallel, I can't imagine any way it could be an electrical problem, unless the brake magnet itself is defective. A defect causing more braking action seems unlikely to me.

Something is likely bent or mis-adjusted in that one brake assembly. I would open it up and see; unfortunately, that means taking the hub off, bearings and all. I realize this has already been done, but that still seems like the place to look.

There are so many factors in determining the right controller gain setting that I won't guess what the right setting might be, but 3.4 is pretty low in the range of possible settings, so it seems likely that when the grabbing is resolved the appropriate setting will turn out to be higher. First things first... need to fix the brake at that wheel.

The mechanic noticed the rear end rising up during parking lot braking with controller only. He thought the rear end was light and it might be better to fill the empty fresh water tank that sits behind the rear axle. Might have made some difference but the problem still persists and think there is still some undiagnosed problem with that brake assembly. Wondering what Dexter's input will be.

I prefer the stronger settings, especially when we're traveling down grades, but cannot be sure the wheel isn't locking then either, which of course can be dangerous. We can only hear it at slow speeds, especially when coming to a complete stop. The original tire is now only suited to be a spare due to the skidding over time. We have about 3K miles on the trailer now.

[Devil Dog]

It may be that there is not enough weight over that tire.
Try a 24 of Canadian on that corner it may help temporary.
Until there all gone.
Or it could be a twisted frame . You may want to have the frame checked.

[Donna D.]

Okay, this is old SKOOL and maybe totally wrong, but I thought only the leading axle should provide brakes on a tandem axle trailer. The rear axle shouldn't even be braking unless extreme conditions.

But what do I know...

[rbryan4]

Originally Posted by Donna D.

Okay, this is old SKOOL and maybe totally wrong, but I thought only the leading axle should provide brakes on a tandem axle trailer. The rear axle shouldn't even be braking unless extreme conditions.

But what do I know...

The front and rear axles (and their brakes) are the same on an Escape AFAIK.

I would think that brakes on all 4 wheels would mean better braking and less wear than only on two. I do know that some states require brakes on all 4 wheels of a tandem axle, depending on the weight of the trailer. The common maximum for only requiring brakes on one axle is usually around 3000 lbs. Over that, you need them on both.

[Brian B-P]

Originally Posted by Rossue

The mechanic noticed the rear end rising up during parking lot braking with controller only.

The rear will rise relative to the front under normal braking. Since the ball is below the centre of mass, it will even rear up if just stopped by the tug. I don't think either is a good indication of a problem with load distribution between the axles.

Originally Posted by Rossue

He thought the rear end was light and it might be better to fill the empty fresh water tank that sits behind the rear axle.

I get the logic, but it is hard to fix bad distribution between the axles by minor load shifts. Adjusting the ball height, on the other hand, rapidly changes the distribution. You could deliberately shift the load to the trailing axle and if the same wheel still locks, it's definitely a mechanical problem with that brake.

Originally Posted by Devil Dog

It may be that there is not enough weight over that tire.
...
Or it could be a twisted frame . You may want to have the frame checked.

I think that much frame twist would be really noticeable at the ends. I've seen photos of a trailer with a frame twist problem that caused suspension issues, but that was the notoriously flimsy Fiber Stream frame, not the robust Escape frame.

[Brian B-P]

Originally Posted by Donna D.

Okay, this is old SKOOL and maybe totally wrong, but I thought only the leading axle should provide brakes on a tandem axle trailer.

Very "old school", and as Robert pointed out, not even legal in some cases. For example, in British Columbia any trailer requiring brakes requires them on both axles of a tandem.

Other than just being cheap, there was a reason for brakes only one axle, and specifically the leading axle. Long ago, when there was only crude control of the trailer's brakes, braking risked locking up the trailer wheels. With brakes on only the leading axle, the trailing axle wheels kept rolling and so the tires retained traction and the trailer remained in control. The trailing axle tires are better placed for control than the leading tires.

With a modern trailer brake controller, there is no reason to have brakes on only one axle. Not putting brakes on the other axle means you can't use the traction of that axle's tires, and have no hope of achieving any reasonable level of braking.

Originally Posted by Donna D.

The rear axle shouldn't even be braking unless extreme conditions.

Unlike a car or pickup truck, a trailer doesn't have a proportioning valve to vary the braking effort between front and rear - let alone the now-standard computer-controlled Electronic Brake Force Distribution system - and it doesn't need one. The leading and trailing axle brakes do the same thing at the same time.


Similarly, long ago a big truck might have no brakes at all on the front axle. With poorly controlled braking systems and low standards for braking performance, skipping the front brakes entirely ensured that the steering axle tires were never locked up so steering control wasn't lost. Imagine if a trucker brought a rig into a modern inspection station with the front brakes entirely missing!

[Brian B-P]

Originally Posted by rbryan4

The front and rear axles (and their brakes) are the same on an Escape AFAIK.

Yes - two identical axles, with identical brakes on them. That's normal trailer practice, and specifically the case for tandem Escapes.

[Rossue]

Problem fixed: having the hub machined resolved the wheel locking up. Now have the P3 set at Boost 1 and 4.8.

[gbaglo]

Excellent.

[rbryan4]

Originally Posted by Rossue

Problem fixed: having the hub machined resolved the wheel locking up. Now have the P3 set at Boost 1 and 4.8.

Good! Interesting that the hub was defective since the trailer is so new. Manufacturing defect?

[Rossue]

It was likely a manufacturing defect which means this has been going on since it was new. Am a little hearing impaired and it was my wife who noticed it-she does sit on that side as well. Seemed to only be an issue coming to a stop, but who knows for sure.

Dexter has been excellent from the start and they are going to pay for a new tire as well as the labor- I didn't have to ask!

[Jubal]

Originally Posted by Rossue

Problem fixed: having the hub machined resolved the wheel locking up. Now have the P3 set at Boost 1 and 4.8.

The brake drum was machined and cut true ??

[Rossue]

Originally Posted by Jubal

The brake drum was machined and cut true ??

Yes- just called the shop and they verified that is what was done.

When I mentioned to Dexter the mechanic's suggestion to do this they replied that was what they were going to next suggest as well.