A-B Comparison, Ram ITBC v. Tekonsha P3

[Al and Missy]

I have generally been unsatisfied with the braking performance of my Ram with its integrated trailer brake controller on my 2002 Airstream Classic 30 Slideout (9100#). With my Safari 25 (6300#) I could lock up the brakes, and the combination seemed to stop almost as well, if not as well as, the truck alone. I had previously measured the brake current using the breakaway switch and it was 12 amps, right where it should be so all magnets should be working properly, and I have recenty adjusted the brakes.

I've read posts on several forums about whether or not the ITBC was getting full braking out of electric trailer brakes. I remember having superior brakes with my 25 and F-150 using the P3, and many like the P3 for its boost function. I had the opportunity to purchase a used P3 at a good price and was thinking the boost function might be useful to mitigate the Propride/Hensley "bump" so I bought it. I hooked it up today and did an A-B comparison on the same course and under the same conditions.

Test Description:
I tested the stopping power of the controllers under full braking conditions using only the brake controller lever. As I understand it, the lever is supposed to apply maximum current to the brakes when fully actuated.
ITBC setup - Heavy Electric, Gain = 10 (maximum)
P3 setup - Electric, Gain 13 (maximum), Boost at each of 0,1,2,3.

I accelerated to just above 25 mph, put the truck in neutral, and when it passed through 25 mph I applied full trailer brakes with the lever.

There was no appreciable difference between the stop times exhibited by the two controllers. There may have been a slight (<10%) difference in the stop time using the boost function on the P3, but it was swamped by what I think was brake fade, as the most significant factor in stop time appeared to be time since last stop.

Bottom line, if you are considering replacing your ITBC with something else, be warned that it may not make any difference.

Al

[slowmover]

Nice work.

Going to ask the obvious to get it out of the way:

When my Dad bought his Silver Streak in about 1975, one of the tests performed was whether solo and towing brake distances were the same. They were, in fact somewhat better when hitched. It was understood before then that this was ordinary given that all else was correct.

I followed him a short distance out of town in my car to act as observer on wheel lockup on some unpaved roads after we'd done the same in a warehouse district with concrete streets. Nearly always saw lockup on rear axle first as it "unloaded" under hard braking (leaf spring axles). It was more a matter of which side, port or starboard, in order to check consistency, paved and unpaved. To find brake controller settings on the Kelsey-Hayes.

The best controller today appears to be the TUSON DirecLink. Several threads

Part of "all else" was WD transfer to TT axles. The more, the better given 100%+ FALR as to TT brake contribution.

Would this account for any difference between your two rigs? (the ability to lock brakes at lower speeds on hard surface roads); that your latest rig transfers less by total weight and percentage?

Also that the TT axles are seeing similar loads; not riding more on one axle than the other? Nothing is more common to see out on the road, it's nearly universal to see a one ton with an AS bouncing along behind it on the front axle (Brakes? What brakes? I got TWO on my trailer!!)

For the test, TT tire pressures at sidewall maximum? TV according to Load (not randomly high as seems popular with RV'ers)? Full fresh water and propane (more about consistency test to test, as well as TW).

It's not clear to me that voltage/amperage at each wheel is "equal". John Barca [JBarca] has excellent tech writeups on RV.net. His contributions (as well as LAdams and others) on re-wiring the TT brakes is worth a read for what is ideal in this regard.

Have you considered temporarily bypassing truck wiring harness with an aftermarket set?

You're correct that drums are pretty much useless after a single, full, application. One is then reliant on the already too-heavy pickup. (My rig is only a little lighter than yours, albeit longer with attendant concerns about being tail-out with inconsistent performance across all four brakes).

If you need an "excuse" to go to anti-lock discs, you've found it. The difference on Class 8 rigs is the same: really having to lay into it versus applying pressure with big toe; from all drums to all disc. Same for grade descents. I strongly recommend Gary's thread: "Disc Brake Lag: Pressure Versus Time". Also any and all by switz in re TUSON brake control components.

Dad stayed with 55-57/mph travel speeds (handy in the era of the 55) right into this century. Braking ability was a large part of that.

Complacency about braking ability is "magical thinking" for RV'ers; "bigger pickup" doesn't deliver. Sort of like fuel economy: magic devices or newer vehicle, but same bad habits at wheel. Never addresses the problem. In this case, disregard of WD plus testing braking ability to have hard numbers.

As a complementary issue, the leaf sprung suspension of mine has upgrades stock from the factory that others modify their trailers with aftermarket pieces. Already have shock absorbers, cross-members and sophisticated equalizers. But it will still not have the wheel travel and stability (even the ride) of torsion axles. Perfect alignment and equal loading per scale readings are lipstick on a pig.

One can fiddle the day away with electric drums till the cows come home. And still be where one started.

.

[Al and Missy]

Thanks, Slowmover for the input.

I think my axles are pretty well balanced. When I first set up the Equalizer hitch, the front tires were heating more than the rears. Looking at the rig, it was pretty obvious that the trailer was a little nose down. When I corrected that, the temps and pressures all were with in a few PSI and degrees of each other.

I tested total current using the breakaway switch. It was 12A, about what it should be. I had just about convinced myself that discs were in order until today. When I did this test last week I could have, but didn't, check the P3 controller output voltage and current. Today I did that. I used the P3 to indicate voltage and current and found that while the controller was putting out in excess of 12 volts, the current was only 8.5 amps. The specified current for four magnets, and the current I measured using the breakaway switch is 12A. 8.5/12 is 71% current, but I don't know the relationship between the current and the braking force. I'm guessing I don't have more than 71% of the braking I should, and maybe less.

The problem is somewhere between the breakaway switch and the brake controller. My first candidate is the umbilical connector. A quick inspection shows that some of the sockets are spread further than they probably should be and all are corroded. Since converting to the ProPride hitch I could probably use an extra foot or so of cable so I think I'll just replace the whole thing. If that doesn't improve the delivered current and get my brakes to the point where they will lock up, then I suppose I'll go ahead and order the disc brake materials.

Al

[slowmover]

Nice work. Drums are just frustrating. I've bumped an old thread on Dexter Self Adjusting, and also recommend "Re-wiring the Brakes" on rv.net. See links. Good overlap on them all. That crew over there can be sharp on tech.

The EZ Connector is also worth reading about. Mexray or someone here has had it awhile. And
Anyone who can decipher an ARRL Handbook shouldn't have trouble with mrekim brake thread discussion.