Control Trac? Thumb up or down?

[Robert]

Don't take this as continueing a debate, I'm hope to help if I can. If your '95 Auto mode worked better than your '99 then your '99 likely has something wrong with it. My '97 works completely behind the scenes. Go and read the thread at Dead Link Removed to see how you can gain back the 2WD mode that you miss from your '95. I have done this modification to my '97. I used a lighted switch that I wired to light up whenever my TOD clutch is getting power. This morning is the first time we have gotten rain since I did the mod. All I can say is that I was amazed at how seamless my Control Trac works. When making a right hand turn this morning, I had my Auto mode enabled. I gave it a bit too much gas and my switche lit up briefly. I didn't even feel the rear tire break free before the fronts started getting power. Just for the fun of it I gassed it again and watched the switch light up again. I never felt a thing. It felt just like I was on dry pavement. If I would have had my switch off, putting me in 2WD I would have had a self induced power slide

 

[Silverblade]

About 10 people have said that on hard acceleration from a stop they have a clunk, and there wasnt that straight of an answer that i noticed from that, can someone who knows their stuff just re-assure me that when i am in auto(4x4 auto, 4x4high, 4x4low) on my 97 and i punch it when it is raining(really raining, hard hard hard, almost hail and slippery) that the LOUD clunk I hear that makes all my passengers ask what we just broke is nothing to worry about. I have a warranty should I make them fix it? Doesnt seem like like it should be so loud if that is only the speed i get up to from one fifth of a tire rotation.

 

[JasonF]

No that does not sound normal. The only time it should clunk is on very slippery surfaces where the back tires break loose quickly and the fronts are a split second behind. Unless you are trying to impress your friends by peeling out at stoplights you should not be spinning and it shouldn't be clunking.

Jason

 

[rokke17]

Robert & Nweibley

Originally posted by nweibley
Ever heard of the brown and/or yellow wire tricks? They can pretty much turn auto into 4x2... mabey since it bothers you alot a little toggle switch might make all the difference in the world.

I have perused that thread many times, and have already completed that mod. It still doesnt work like my 95 did. In fact I did that mod like 3 days after I got my 99.
It still clunks and makes noise when I am drifting in the snow and stuff with the auto disabled. It makes a weird noise when I hang it really far out there.
I dont really know what the deal is, but it works fine if I dont screw around.

I really miss my 95 now that it is winter.

Chris

 

[Jason_25]

Silverblade, the clunking is not normal. In 4x4 auto on my 95, there no odd noises at all, even in the rain. I'm sorry but I can't tell you exactly what may be wrong.

 

[Nate1]

Sounds normal to me. From a dead stop, if you punch it hard, you can easily accel rather fast in these new Xs, they are very resposive. If your rear wheels are spinning from the start, your front are entirely (or very nearly) stopped. When 4x4 Auto throws the power into the front wheels, they go from stopped to the speed your odometer is reading almost instantly. Think about being in a stick shift... crusing at 5-6 mph and then totally dropping the clutch into first gear. Its a similar concept, all of the sudden there is a large difference in torque to the wheels, which causes a sometimes very loud thud. I dont THINK you have anything to worry about, but next time you go in for a checkup, ask them about it... it never hurts.

 

[yob_yeknom]

Originally posted by Silverblade
can someone who knows their stuff just re-assure me that when i am in auto(4x4 auto, 4x4high, 4x4low) on my 97 and i punch it when it is raining(really raining, hard hard hard, almost hail and slippery) that the LOUD clunk I hear that makes all my passengers ask what we just broke is nothing to worry about.

I can. I know my stuff pretty well, anyways. nweibley explained it well. When you punch it and your back tires start spinning that fast that quickly, it sends all that power to the front. But the front won't spin as easily as the rear since it has all that weight sitting over the tires (engine, axle) and the power is 'pulsed' to the front, so it makes traction during each pulse. That's bound to be pretty rough on the drivetrain, so don't 'punch' it in the rain and end up breaking something.

 

[Silverblade]

Nah I can break stuff I have a warranty, jk.

Ok that all makes sense except one part.
Think about being in a stick shift... crusing at 5-6 mph and then totally dropping the clutch into first gear. Its a similar concept, all of the sudden there is a large difference in torque to the wheels, which causes a sometimes very loud thud.

That doesnt work out because the auto 4x4 has a clutch as it engages so it shouldn't just crunch down on it, it should use the clutch and eliminate the clunk.

 

[Robert]

Whereas the front wheels are engaged in increments, it happens pretty quickly. When I have all four wheels on jackstands and idle in drive, my rear tires only turn about 1/6 of a revolution before I get a clunk and the front tires start turning. Of course with all four tires off the ground, there isn't any load to dampen the transfer of power. I can't remember ever just flooring it from a stop in the rain, but I have gotten on the gas pretty hard. I usually roll into the throttle. I avoid full thriottle starts in the rain for the same reason you are seeing. I would fully expect it to put all sorts of strain on various components by flooring it from a start in slippery conditions. When you do, your rear tires start rotating very quickly. By the time your GEM recognizes the speed difference front to rear, your rear tires are going very fast. Torque will then start getting tranfered from the rear to the front. Once all four tires get traction, your Explorer will lurch forward. The sudden lurch can cause all kinds of noises. If there is anything at all loose in your drivetrain, you will hear clunks.

 

[Nate1]

None the less, the idea is the same. Even if the clutch pulses in increments to deliver power, when it is engaged for a fraction of a second, it is locked in place (I believe), so therefore the big difference is noticeable as the wheels jerk into motion. I'm no control trac expert... but if I had to guess... I would say it's normal for what you are doing... only that you should STOP doing what you are doing.

Hope its easier to understand,
----Nate

 

[Silverblade]

Dont worry I dont do it regularely, The first time I did it I was curious about Auto 4x4 and wanted to see how well it engages so I decided to break the rears loose. When I heard the clunk I immedietely let off the gas and crept forward and I figured it was just the front biting down so I didnt think much of it and the only other time was I was stopped on a hill facing up in heavy rain and if I didnt punch it then I would have been rear-ended from some a$$wod in a van.

 

[Nate1]

Well, if you want to be able to do it safley... do the brown-wire mod. I just did it with a relay and, WOW, it is amazing. I am in love.... my car is peel-out king! Anyways... I'm getting over this new-found fun cuz I know its not good for my tires... but if you want 4x2 on demand... the brown wire mod is a must.

----Nate

 

[dogfriend]

Originally posted by Robert
I can't remember ever just flooring it from a stop in the rain, but I have gotten on the gas pretty hard. I usually roll into the throttle. I avoid full thriottle starts in the rain for the same reason you are seeing. I would fully expect it to put all sorts of strain on various components by flooring it from a start in slippery conditions. When you do, your rear tires start rotating very quickly. By the time your GEM recognizes the speed difference front to rear, your rear tires are going very fast. Torque will then start getting tranfered from the rear to the front. Once all four tires get traction, your Explorer will lurch forward. The sudden lurch can cause all kinds of noises. If there is anything at all loose in your drivetrain, you will hear clunks.

In the interest of science (and because it was raining on the way home after I read this thread the first time) I did floor it on wet pavement (in a safe empty parking lot) to see what would happen.

As the rear wheels started to spin I got a good thunk as the transfer case engaged and the front wheels started to pull forward. So I think that it is probably normal to hear and feel this if you floor it from a dead stop because my transfer case seems to be working well in all other respects.

Like some others have described here, usually the application of torque is pretty seamless in 4wd Auto; I really only notice it working when the street is wet or in the snow. If you have a 97 or later Control Trac system, and you notice clunking or other noises while driving normally on dry pavement, then based on my experience you probably have something wrong with your system.