ok i searched and read the owners manual and still scratching my head a little.
What is the difference between traction control and ESP? I know you cant turn off ESP in 2wd. 4wd you can...etc..etc..

Example: Today i went into a snowy field trying to fishtail. I heard a bunch of ABS noises every time i yanked the wheel going about 25mph and the traction control light was coming on. NO ESP light ever came on. i could fishtail a little. It was tryin to straighten me out.

The other night in a snow covered parking lot i was "playing" (2wd) and took the traction control off and did some donuts/fishtailing and it acted the same with traction control on or off. Same ABS noises and NO esp light has ever come on. I put it into 4h and turned it all off and drove like a normal old jeep.

I can tell its correcting me by braking...but what feature does turning off the traction control eliminate? Maybe i should read the manual again.

 

Traction control is where the computer reduces throttle in order to keep wheel slip under control. So when you push the ESP button that is all that is happening, you can now spin your rear tires all you want, but the Electronic Stability Program (ESP) is still active. Therefore it will still try to use the brakes to keep you pointed in the right direction.

I will also add that BLD (Brake Lock Differential) is always active. Even with ESP off, this will apply short pulses of braking to spinning wheels to help keep forward momentum. It tries to act like a limited slip differential and I believe it's the reason the Jeep will shudder/jerk when you really lose traction.

 

ESP tries to correct for you using the brakes to keep you pointed in the right direction and not turn over. The traction control system doesn't want your wheels to spin, so it cuts power, applies brakes to keep that from happening. BLD, (brake lock differential,) doesn't care if the wheels are spinning, just as long as they are spinning at the same rate.

Now, in 2wd, or 4hi, both esp and traction control are on all the time. In either of these modes pressing the esp button once will turn off traction control only. You will get a little amber light of a car with squigly lines coming behind the tire. This only disables the part of esp that doesn't want you to spin the tires, but it will still try to keep you on course and from rolling over.

In 4hi, if you step on the clutch or slip it in neutral and hold the esp for several seconds, it will disengage esp and traction control. This means no electronic nannies, just like an old jeep. You will have the amber traction control light on, and also a message in your info center that says ESP off. (We will talk about BLD in just a second.)

In 4lo, there is only one setting, everything off, like the above paragraph, but it does it automatically, and cannot have either traction control or esp turned on.

Read next post for how BLD figures into all of this...

 

BLD's are not as good as lockers! However they greatly expand the capability of jeeps that were not ordered with lockers. IMO, they are better than a plain lsd, although on a wrangler with lsd and bld, it enhances both systems. Now for how they work.

all jeeps have an open differential unless the lsd is ordered in which case the rear diff only has the limited slip differential installed, I include jeeps with lockers here since when the lockers are disengaged they function as an open rear end.

In an open diff, both wheels get the same amount of torque from the motor at all times. The problem of this is easily demonstrated in a worse case scenario where one wheel is in the air, and the other is on solid pavement. You would think that since one wheel was on good footing it can pull the jeep right? Wrong. What will happen is that when you give it gas, the wheel in the air will spin and the one on solid ground will do nothing. This is because it may only take 10ft. lb. of torque to turn the wheel in the air since there is no resistance. Both wheels will get 10 lb. of torque, but 10 lbs of torque is not enough to move the wheel with the resistance (solid traction,) so it does not move.

Here is where BLD comes into play. It will apply the brake to the wheel in the air, increasing the amount of torque needed to overcome the resistance, when the torque is high enough, it can and will move the wheel on the ground, both wheels are still getting the same amount of torque, but the brake is creating a need for more torque to turn the wheel in the air, which means the one on the ground gets enough torque to turn it.

Next post is how a locker would handle it...

 

Lockers in the JK function just like the described above, until the lockers are engaged. when they do there is a mechanical link between both wheels so that they are physically unable to turn any faster or slower than the other wheel. This is the maximum traction set up.

Back to our example if one wheel is in the air and one on the ground, no problem, if the air wheel spins, so does the one on the ground. This is the best set up for offroad situations, but locked diffs when engaged greatly reduce your turning capabilities and could not be used on pavement.

BLD equipped jeeps can go through many things that the ones with true lockers can, but it is sometimes jerkier, not as smooth, and you have to apply more power, (gas) to overcome the force of the brakes clamping down on the spinning wheel. Lockers are the way to go for ultimate traction, and control.

Next up LSD....

 

I think lsd is the hardest to explain, but to keep it simple, it can by itself without the use of BLD transfer up to 2.7x the amount of torque across the wheels. This means if one wheel has slightly less traction and only needs 20 lbs torque to spin, the lsd can send almost 60 lb. of torque to the other wheel. There is nothing wrong with driving an lsd on the road, it is always active and is better than an open diff for offroad, but not as good as a locker. Why?

Well back to the original example one wheel in the air with zero traction. 10 lb of torque x 2.7 equals about 30 lb of torque, probably not enough to move the wheel.

So if you had a choice, I should think that BLD is a better offroad system than lsd, but jeep one ups me, because the bld is on the lsd too(omg all the acronyms.) It functions the same way, but does not have to intervene as much, and in situations such as dirt or sand where the torque bias is not as high as one wheel in the air, the lsd can transfer torque quicker and smoother across the wheels, but the bld's are stil there to step in if the torque bias is higher than the lsd can overcome and neither the bld or the lsd have to work as hard as they would were it only one or the other. This is a pretty sweet setup.

One more thing, When you're lockers are engaged, there is no need for bld since there is no way for there to be a speed difference across the axle.

BLD is on both the front and rear differentials.

That is the short of it, I know a few more things if you need to know, as well as have plenty of first hand knowledge of these systems.

 

Read this thread and read the post by HITMAN, i read it and i disabled my esp and traction control without any complications. I used to try it before and could not get it off but this post helped me alot. And today i spun the jk on road and on gravel and no computer interfered. Good luck.

 

Thanks, here is the article I got most of the technical stuff from, the rest is my opinion based on personal driving/experience.

http://blog.chryslerllc.com/blog.do;...id=270&p=entry

 

lots of good information. Bumpity bump!

 

Hah, I always wondered why my brother in law would have me apply the brakes and gas at the same time when one wheel was spinning and the other wasn't in my 01 TJ. Now I know!! Thanks