Well the guys who built it haven't figured it out yet so I doubt if it will be all that easy.

Yeah the ring gear on the HEMI is 210mm, it is in what we consider the equivelent of a dana 44 center section. I'm not sure what its technical part name is yet. No one I know has done any work with it. The other ring gear is 198mm.

 

Posi is a GM term. On Mopars, at least in the muscle car era, it's called Sure-Grip. Yes, the Magnum has a Sure-Grip rear end. That's the only way (on a street car) you can leave 2 nice burnout patches. With an open rear end, you'd leave just one.

 

I was at the dealer last week, test driving a Magnum (I got paid $75 for it!), and asked specifically about the rear end. He told me that is actually a Mercedes piece, but it is limited-slip. I also asked if the traction control can be turned off. He said yes, but not while you are driving. He hinted that there is a sequence involving holding the button and turning the igntition key a number of times. I admit that he could just be telling me what I want to hear, but I would not be surprised if this works. Dodge seems to be imbedding technolgy in this way-- my 03 Dakota will display CEL trouble codes on the odometer display using a similar technique.

I told the dealer that the ability to turn it off is a major factor in my purchase decision. So, when I'm ready to order, I'll let ya'll know what I find.

 

I have some not inconsiderable experience working with modern traction control systems with respect to trying to get them to function properly in extreme environments. I am not directly familiar with the traction control system used on the LX platform (which I believe is the same one used on the AUDI's?) but if it works the same as all of the other traction control systems I've seen, there is a very easy way to completely disable it at will.

Bear with me as I explain how a typical traction control system functions and why it is so easy to get it to stop working.

Your car has a differential that splits power between the left and right wheels. For simplicity's sake, let's assume that it has a ratio of resistance under which the power will go to both wheels. If the ratio of resistance between the wheels exceeds the ratio the differential is designed for...all of the power will go to the wheel with the least resistance. In other words, both wheels on dry pavement...both wheels have the same resistance (from the contact with the pavement). Lift one of the wheels up and the resistance of the wheel in the air approaches zero and all power goes to that wheel.

It is possible to use the brakes to bring that resistance ratio back within the tolerance the differential was designed for. If you apply the brake with the pedal, brakes are applied at all four wheels so you have to apply pretty significant braking force to get the ratio where you want it.

Yes, this really and truly does work in the real world on some types of differentials. Specifically it usually works on limited slip differentials (it's worked on all the ones I have tried it on) and it always works on a Torsen differential (my preference for this type of maneuver). Fully open differentials require a lot more braking power which puts a lot more stress on everything so don't count on it working there.

Now, if you coul just apply the brakes on the one wheel that's in the air, you only have to apply enough brake to create enough resistance to bring the resistance ratio back within the tolerances of the differential. This is the most effecient application of the brakes to achieve the desired result.

That is how modern traction control systems work. They detect wheel spin and when one wheel has execessive spin it applies the brakes to that wheel alone, which transfers power back to the wheel that still has traction.

With that rudimentary understanding of traction control systems (along with my made up term of resistance ratio), you can imagine that if you apply the brakes at the same time that the traction control system is trying to do its thing...there's a conflict. Traction control systems usually preclude that conflict by deciding that if the brakes are pressed, you're trying to stop, if the brakes are off, you're trying to accelerate.

What this means is that if you apply the brakes while accelerating, the traction control system will assume you are trying to stop and will modulate the brakes if it detects wheel lock-up (modulate = release for our purposes) but it will not apply the brakes. Yes, this is really the way it works in the real world. If you're trying to get traction control to help you out and you tap the brakes...traction control cuts out.

This begs the question...how does the traction control system know when you are applying the brakes? In the ones I have worked with, it's via a sensor on the brake pedal control arm under the dash. In other words, a mechanical switch.

If the Magnum functions the same way (and I have every reason to believe that it does) then if you wire in a remote toggle switch to the brake pedal sensor, you could effectively cause the car to think you are braking by just flipping the switch. Of course, this would cause the brake lights to come on, but it should also disable all traction control.

The only point that I am not sure about is the braking assistance that the LX platform provides. I do not know exactly what its operating parameters are but I would be concerned that it may apply the brakes on your behalf if it believes the vehicle is accelerating while you want to stop. I don't think this is likely to present a problem for our application, but it is something to consider.

If you are good with left foot braking or heel/toe, you could achieve the same result by just lightly touching the brake pedal. Enough to cause the lights to go on but not enough to actually engage the brakes.

I don't know if a CAN scan tool will be able to tell you when traction control is working the brakes, but if so you should be able to easily test and prove the above information.

I have not worked with the traction control system on the LX platform yet, but I will be once my Magnum RT AWD arrives in a few weeks. My experience with other traction control systems leads me to believe that the above will work just fine on the LX.

Something I would like to point out, though, is the effectiveness of traction control systems. In my real world experience, traction control systems are actually much slower than you would expect. I have seen it take as much as two seconds of rock steady throttle before a traction control system will process all the data (throttle, wheel speeds, brake use, etc) and actually begin to engage the correct brake to transfer power between wheels. In my experience, it takes very smooth and steady application of the throttle in order for the traction control to work properly. A lot of jerking on and off of the throttle will defeat the attempts of the traction control to engage the brakes.

My point is that it's entirely possible that the traction control system on the LX platform does not have enough time to engage when you stomp on the throttle from a dead stop. If that's true, then it won't be until after the rear wheels are spinning that the traction control system realizes there is a problem (front wheels not turning as fast as rear wheels) and applies the brakes to both rear wheels. I don't know if the traction control system on the LX platform is that agressive or if it only limits wheel spin on a single axle and not between all four wheels.

I'm just applying my real world knowledge of modern traction control systems. It is possible that the LX simply doesn't posses the power to spin both real wheels on all surfaces, so keep that in mind. To test the above theory on disabling the traction control system, you would want to find a surface that you somehow KNEW would be slippery enough for the vehicle to spin both rear wheels on without traction control, but yet you KNEW was sticky enough that traction control would keep the tires from spinning. Then you can try mashing the throttle with ESP on, ESP off and with the brake trick engaged.

I get the feeling that everyone believes the LX with the Hemi posesses the power to smoke the tires at will, but the traction control system is holding it back. It might be that the vehicle doesn't posess the ability to smoke the tires at will and the traction control system is not a factor in most cases. If that's true, you need to be more selective about which surfaces you decide to smoke your tires on

I have a feeling a few Magnum owners are going to be lurching from stop lights with one foot on the brake trying to test this out

-Bulvot

 

Nice try, but no. The traction control is WAY MORE advanced that the Audi system. The LX platform uses no less then 50 inputs to determine not only acceleration and deceleration rates but also yaw and fore/aft g's. The system does look at brake pedal position, but not at the switch. It is monitored with a sensor, not on/off switch inside the booster. This arrangement determines not only how hard the brake pedal is being depressed but how quickly i.e. panic stop.

All 4 wheels are modulated AND applied in combination to keep the car straight and under control. Basically once the system engages it removes all throttle and brake controls from the driver and takes over. The class we go through just to learn this chassis' stability program is 2 days. To put that in perspective the engine class, for all the engines we produce is 1 day, and that includes teardown and reassembly.

As I stated before, all the stability programs and traction controls are all handles by the ABS. The system is designed so that if ANYTHING in the ABS, traction, or stability systems are out of sync the transmission goes into limp mode and speed limiter gets dropped to about 60 MPH.

Good luck guys with your quest to find a way around this system, I race and would love to hot lap one of these. My co-worker also races (170MPH 1ST gen Camaro) and he hasn't figured out how to bypass his own Magnum yet.

There is a cool video going around of a 300C with some serious over steer. The trick to getting around the traction system is to get the tires spinning hard enough that the brakes can’t bring them back. Then the system just gives up.

 

No offense, dodgemech, but you seem to be erring rather heavily on the side of negativity. BTW - you know "ESP" is registered, right? And Audi uses ESP? Perhaps the ESP system on the LX platform is using more inputs than the Audi's ESP, but I wouldn't be so quick to discount it until you know for a fact the systems are different. In fact, if you research the ESP systems on Audis, you'll find that they have the same exact complaint as LX owners...presing the ESP button (which look suspiciously like the LX's ESP button) does not completely disable ESP. Perhaps more research of the ESP systems in other cars is warranted since they have been working on this problem a lot longer than us.

I've been working with very advanced traction control systems in very extreme environments for awhile. Traction control systems designed to do a LOT more than the LX platform. You would be surprised at how simple it is to manipulate the most advanced traction control and abs systems into doing things they were never intended to do. And the solutions are never started with "it's not possible, you don't know how advanced this thing is, I went to more training than you, etc". They're usually based in "we want to accomplish A, the system is thwarting our attempts because it thinks B is happening, let's try the rest of the alphabet until we can trick the system into helping us accomplish A, if that doesn't work we'll always have numbers left to try, anyone have thoughts on where to start".

Your opinion is noted. Don't take offense if it's not taken as gospel. So far all you've done is said "it can't be done, and the reason is because I know more than any of you". If you really want to contribute, try providing a detailed description of the system as you know it.

Once I receive my Magnum I'll find my own way around this supposedly insurmountable barrier and share the results.

Remember, this thread is not about how all knowing dodgemech is. It's not about thumping chests. It's about the rear end on the Magnum and turning off traction control.

At this point I would submit that if you can't provide the actual technical parameters of how the traction control and abs systems function (flow chart stuff, not general descriptions) than the amount of information available to work from is not increasing. If anyone else can provide that information, please do.

-Bulvot

 

Well said

 

My intent was not to attempt and show everybody how smart I am, it was simply that I spent a great deal of time with engineering in an attempt to bypass this system and the conclusion we came to is that it is not possible. The simple fact that the ESP/ABS systems are tied into the TCM make it impossible to disconnect one system and allow the other to work normally. Many of the sensors used in the ESP system are piggybacked and can work independently, others unfortunately are interpreted by the ABS module and then bussed out to the other modules. If the ABS module (which is also the ESP) is disabled or a fault is stored that would render ESP in-op it busses a message to the TCM to default and therefore limit speed (defeating the reason you would want ESP off).

I’m not sure how the ESP system can be registered. DCX uses a Teves 25 system, is that the same system all manufactures are using who have an ESP system. Possibly the term ESP is registered. The Crossfire, which is totally Mercedes also has a very nice ESP system, I don’t have the specs in front of me though and don’t recall which system it is using.

Here is the tech garbage Bolvot is so intent on learning. The wheels spin and therefore spin tone wheels at each hub. As the hubs spin the tone wheels create/break a magnetic field in the wheel speed sensors. This action is translated by the ABS module as a sign wave. The ABS module broadcasts a square wave over the buss network to the PCM, TCM, MIC, and climate control I believe. When one wheel is not spinning at the same speed as the other 3 the ABS module sends a message to the PCM to back off throttle and then modulates the opposite side caliper to allow both wheels to spin at the same rate. As the wheel speeds match each other the system returns to normal. In an ESP situation, the yaw sensor detects lateral slip and the ABS controller goes into action. Based on TPS, VSS, steering position sensor, brake pedal position and yaw sensor readings (there are others but theses are primary) the ABS controller will buss message to the PCM to roll back throttle. If throttle does not help then the ABS controller will apply the brakes to the wheels it determines need to be slowed in order for the vehicle to regain traction. As the driver attempts to counter steer the system will recognize this and release and reapply a different caliper or combination of calipers to straighten the vehicles path. If you want I’ll send you a copy of the tech handout on the system, it is just too long to post the whole operational workings of the system.

I’m not trying to knock you guys for trying to figure it out. Being somewhat negative about it, maybe. Let me share why though. You find a way a to bypass it a go out and get into wreck. A lawyer (scumbag) gets his hands on you and the 2 of you sue the holy hell out of DCX. Chrysler has to raise vehicle prices again, to cover the costs of the general public being stupid and blaming someone else for it. The NHTSA gets involved and decides we need to recall all the LX lineup to “fix” the flaw that allowed our system to be tampered with. Chrysler again has to raise prices to cover costs. People stop buying the now overpriced car and I am now out of a job. Exaggerated a bit, perhaps. The bottom line is that I spend a lot of my days doing recalls on parts that really are not “bad”, I’m not getting into the bal joint thing, that legit. Anytime somebody gets “stupid” and decides to blame the car instead of themselves new car prices go up. This ultimately affects my position as a tech (no new car sales, no cars to fix).

There is also the whole other issue of you bypassing the system and then wanting Chrysler to fix things under warranty that probably would not have broke if the system were left alone. You can ask the truck guys about cutting the wire for torque management, I think is pin 25 in C3 at the PCM. It will over time cause transmission damage. Why should the customer be entitled to have his vehicle fixed under warranty for damage he caused. I know your saying you would never do that-yes you would, just wait until something breaks and the estimate comes back at some astronomical number, you will cry warranty like everybody else.


Enough of this, if you guys figure it out great. C-ya

 

Don't bother, you're going to p**s off the airforceguy more.
As for me, I am a USMC guy.

 

BTW, I happen to agree with dodgemech that it's stupid to disable it. Lawsuits from stupid people (also known as frivolous lawsuits) end up costing all consumers money.

If you don't want to use the ESP, then you should'nt have bought the car.

The reason for my anger is that mile long posts are not necessary. Especially since the question that they are trying to respond to is still unanswered when they are done.