AdvanceTrac Off-Road/Snow Questions & Discussion

[drdoom]

I am opening this dialogue about AdvanceTrac and it's application in poor traction conditions such as off-road or inclement weather, and less so as it applies to Roll Stability Control.

I have a 2nd generation Explorer with ControlTrac and 3.73 TractionLok so I am quite familiar with it mechanically and in usage. AdvanceTrac I am not as familiar with, i.e. brake traction control. I have watched the videos. And I have driven with the AdvanceTrac in some horrendous snow and ice, but never through the rugged and steep terrain off-road I have taken my '97.

So I am of course wondering what the comparison will be.

I have some questions also...
Did AdvanceTrac equipped Explorers have a limited slip option? Mine is open.

Did RWD Explorers have AdvanceTrac?

3G vs. 2G... thoughts?

Also if anyone has other experiences or input please post up.

 

[imp]

@drdoom
Suppose I could try B.S.-ing it, but no, here's what I know, and it's limited. My Gen. 3 has only one rear wheel speed sensor, so obviously PCM does not have a "handle" on both wheel's speeds. If it were L.S., it would come close, but still no cigar. Advance-Trac must use speed sensing on all 4 wheels. Some Gen 3s came with 4, without Advance-Trac. Why? Dunno. Stability control?

I CAN tell ya, if all this data is being "read" into the ABS Module, good luck! Took me several months to unravel that *****, get rid of the Forced Engine Idle, Limp Homes, etc. imp

 

[drdoom]

Yes Imp, I believe they put tone rings at the rear wheels and plugged the sensor hole in the third member. 4-channel ABS. I remember the epic you had with the modules on your truck, holy cow that was horrible I feel for you brother.

 

[imp]

Yes Imp, I believe they put tone rings at the rear wheels and plugged the sensor hole in the third member. 4-channel ABS. I remember the epic you had with the modules on your truck, holy cow that was horrible I feel for you brother.

@drdoom
Yeah, I refuse to resort to a dealer. At one point, I seriously considered converting the whole vehicle back to EEC-IV, 1990s level. Now, that would be an interesting challenge. Rework much of the harnesses, probably go to an AOD transmission.....imp

 

[drdoom]

Still interested in any input. Thanks.

 

[drdoom]

Bringing this back up. Any members have experience or commentary on 2005 4x4 Advance Trac RSC in poor / challenging traction conditions? Is it effective? How does 4x4 RSC compare to earlier 4x4 model years 2002-2003? Any other relevant commentary?

 

[camodown]

What questions do you want answers to? I can give you enough to bore even the most interested person.

System operation, module operation, capability comparison 2nd vs 3rd gen, all the way down to details such as why the rear knuckles and cv shafts are different between Advancetrac and regular, how roll stability functions both with slight driver error correction or impending rollover (because they are different) etc etc.

Yes, side by side, Avancetrac will run circles around non equipped with 3rd gen.

Yes, it is an effective system.

Yes it can be improved.

Yes, it reacts faster than Controltrac 4wd in a 2nd gen.

Yes, it requires a different thought process when approaching off road obstacles vs conventional process.

Yes, it does excellent in poor surface conditions without driver intervention. However, with deep wet snow and deep clay based mud where wheelspin is desired, deactivating can be more beneficial whether via switch moding off the switch (have to press and hold) or a switch you add to hard shut off the system (kill power to system).

 

[drdoom]

Camo, thank you for the information. Mostly why I ask, is in my experience, the 3G 4x4 is so inferior to the 2G.
Another question I have is about the open rear differential on my 2005 4x4. Is that pretty standard, due to the brake traction control?

 

[camodown]

So the biggest difference between the two is the gen 3 independent rear suspension. While the amount of independent wheel height difference is not terrible for IRS, it is far less than a live axle setup leading to the conclusion the 4wd is not as good on the 3rd gen. With wheels leaving the ground the traction situation becomes more challenging. Purely talking 4wd system (not offroad capability), the gen3 with Advancetrac is far superior.

The actual 4x4 system of the gen3 responds much quicker than the old Controltrac system in the Gen2s. And other than the short period in 95/96 where a front halfshaft disconnect disengaged the long cv for "2wd" via a vacuum disconnect modulator, gen2 and gen3 Explorers shared similar 4wd systems employing electromagnetic clutches in their transfer cases. Both were Torque on demand clutched systems with gear reduction.

The 4auto mode on both is not without disadvantages though. While yes it does work behind the scenes very effectively, there are situations, especially with limited articulation and low mu traction where locking the clutch to 100%lock can be the difference between being stuck and not. 100% engaged using 4high selection. The reason why 4high can be more beneficial is that wheel slip must occur before system intervenes and sends power to forward prop shaft. This can require anywhere from 1/4 free tire rotation up to 2+ depending on if the pcm sees brake pedal input, throttle desired, engine load, steering angle, and an algorithm developed to prevent high brake traction control induced temperatures.

The coefficient of static friction a tire has is higher than dynamic sliding friction. Therefore, if you spin any tire, by the time the traction control has determined need to shuffle torque, you have already given up a fraction of your traction. Combined with limited independent suspension flex can get you stuck very fast. A similar scenario exists with side to side traction on each axle (front and rear).

Locking into 4high solves front to rear torque seperation and wheelspin inducing a possible stuck situation. But the brake traction control combined with throttle control via pcm and spark retard combined with unlocking the torque converter to attempt shifting torque side to side also has a delay and needs wheel speed differential to activate and move power left and right.

The best way to mechanically boost the system and solve the side to side slip control is locker or helical gear limited slip. In the case of a helical ls, the brake traction control will significantly compound torque shift and capability as the brake system will allow torque bias of 0 become >0 moving torque to opposite wheel much more efficiently.

The limited slip option was initially offered with advancetrac for fall of 03 with debut of the system but was dropped for 04 model year. So there was only a few months of the OPTION to order limited slip but open differential was standard with Advancetrac. The limited slip Ford uses wears out clutches so quickly it becomes useless rapidly. Advancetrac also works as a limited slip in a sense negating the need for a limited slip for a majority of users.

Me personally, helical high bias worm gear limited slip in the rear diff with Advancetrac is the best combo.

 

[camodown]

I also forgot to mention, Advancetrac also has a disable speed limitation that typcially gets people stuck in sticky mud. Yes you can disable traction control completely by holding, not pressing, the button behind the frt cupholders. Most people just click the button which will not deactivate the system. Holding until the message center indicates system is OFF will turn off system and the vehicle functions like a regular 4wd system except for one hige difference. Engine rpm is limited and speed is limited. The system has an auto rengage speed. This will prevent sufficient wheelspeed to clean tires enough to get out of sticky mud.

I solve this with a power interrupt switch to electronically kill Advancetrac and elimination of engine rpm limit. Additionally, to mechanically increase traction I use 2 methods (which require a gear type LS). Foot on brake if a rear wheel is in the air, or parking brake partially applied. This allows differential to shift torque to grounded tire.