Hurts Taking One Like This

[YukonRog]

Guys, I have a question. Forgive my ignorance as I've never dealt with an Automatic TC. Does the chain run all the time, or only when going to 4 wheel drive? Also, been watching videos. Could that be "Pump Knock"?

 

[Mudsport96]

Man i can't answer that, i don't know for sure. I think maybe they do, and the front shaft engages when needed.

 

[YukonRog]

Man i can't answer that, i don't know for sure. I think maybe they do, and the front shaft engages when needed.

I've been under it when it was running and I don't recall the front shaft turning. Otherwise the front differential would be engaged. So my theory is the chain only turns via the clutch pack when 4 wheel drive is engaged. So therefore, that noise wouldn't be chain slap but pump knock instead. Hopefully someone with the knowledge will chime in.

 

[Fless]

The front propshaft should turn all the time, I believe, but I'm not quite sure about that in 2wd. It won't turn while the truck's not in motion. The front diff is engaged and disengaged with the front diff actuator that's on the diff.

In AUTO the transfer case engages when rear wheel spin is detected, and spins the front prop shaft -- there's a speed sensor for it -- at about the same speed as the rear propshaft so that all the AUTO function has to do is actuate the front diff when commanded by the ATCM. It takes a second or two to do the switch into 4wd AUTO. In 4wd everything turns all the time (obviously).

Can you put your TC in neutral? Wonder if it makes the same sound when it's in Neutral? (Be sure to set parking brake and chock the wheels.)

 

[Fless]

Here's a fairly in depth article on how the TC works:

https://atracom.blob.core.windows.net/gears/2006/2006-07/2006_07_10.pdf

 

[YukonRog]

The front propshaft should turn all the time, I believe, but I'm not quite sure about that in 2wd. It won't turn while the truck's not in motion. The front diff is engaged and disengaged with the front diff actuator that's on the diff.

In AUTO the transfer case engages when rear wheel spin is detected, and spins the front prop shaft -- there's a speed sensor for it -- at about the same speed as the rear propshaft so that all the AUTO function has to do is actuate the front diff when commanded by the ATCM. It takes a second or two to do the switch into 4wd AUTO. In 4wd everything turns all the time (obviously).

Can you put your TC in neutral? Wonder if it makes the same sound when it's in Neutral? (Be sure to set parking brake and chock the wheels.)

View attachment 347265

Guess that explains why there's two speed sensors right? I've never driven it in Auto, or put it in Neutral. I'll try that but 1st I think I should refill it with fluid. I'll try to pick some up tomorrow. And it makes sense the front shaft would turn while rolling. I had the "Service 4 Wheel Drive" warning on but I believed that was because I had the ABS Fuse pulled so we could drive it. Otherwise it "self corrected". That was until I replaced the Steering Wheel Position Sensor. After that was replaced and I put the ABS Fuse back in and cleared all the codes it ran fine. Other than my wife smoking the rotors and brake pads. LOL!

 

[YukonRog]

Here's a fairly in depth article on how the TC works:

https://atracom.blob.core.windows.net/gears/2006/2006-07/2006_07_10.pdf

Thank you Fless for sharing this article. It's great! Now if I can just find an in depth TC Rebuild book. One local place I called quoted me $1600+ for a Remanufactured TC with a 3-4 week lead time. A rebuild kit can be bought for $350.

 

[Mudsport96]

Not really anything to add here, just want to thank you for taking peoples advice into consideration after you ask for it. It is nice that people really want to learn things.




On another forum im on, right now we have a guy asking people to tell him what he wants to hear...not what reality is.
He wants to know what transmission he should swap into his truck to make it tow better. And refuses to take the advice of " its not the transmission, its the 2.73 gear thats your problem " for an answer. Even after being shown the actual ford documentation of his 300 i6, manual trans and 2.73 gear showing that ford does not recognize this truck to have towing capacity.

Sorry rant over.

 

[Ken Rolls]

The Remanufactured Transmission in my wife's 2005 Yukon has started making a noise that sounds like something is loose inside. Does it in all gear positions. The business that installed it has completely dropped off the face of the earth. So much for any warranty. I just hate the feeling of helplessness and feel totally ripped off. Being on a fixed income and old and having health issues, I still want to pull it and replace it. Is this possible to do in my driveway? I don't think I can get it into my garage. Or will I bite off more than I can chew? My wife thinks I'm nuts. Because of my health issues sometimes I'm down for weeks at a time. Could be the end of this stubborn old mule.

It sounds like the flex plate is either cracked or a bolt has loosened up. St least take the inspection cover off, and look to see if that's the case.

 

[YukonRog]

It sounds like the flex plate is either cracked or a bolt has loosened up. St least take the inspection cover off, and look to see if that's the case.

Ken thanks for your advice. I did inspect the flex plate as well as the torque converter bolts. After starting it up again I'm convinced the noise is coming from the transfer case. I can actually feel it there with my hand. My video is the length of the noise in park in this instance. Changing gears, drive, reverse, neutral, etc, the knocking only lasts 10 seconds or so.