Not so Good Vibrations

[Drae]

Yeah definitely not fun to do on your back. It caused quite of bit of damage in my situation so now I check it more often to make sure it's not getting to that point. I changed the oil a few days ago and I felt a little play in it so now it's on my radar but there's no vibration so probably not so bad. I hope it solves your problem as you have thrown quite a bit of parts at it.

 

[whtbronco]

Yeah, but everything replaced was needed and addressed most of the issue at the time. I'm a bit excessive about making sure things are faulty before replacing them.

I'm not yet convinced that this will resolve all of the vibration, but it'll get most of it I'm sure. We shall see.

 

[SafariGoneWrong]

I pulled the front driveshaft a while back when replacing the passenger side exhaust manifold since I noticed the front pinion seal was sweating. I really needed the SUNEX 312ZUM 3/8" Dr. 12mm 12 Point Universal Impact Socket for Ford Driveshafts. https://www.amazon.com/gp/product/B000RLHUD2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I never suspected your transfer case was stuck in 4WD. Nice troubleshooting.

 

[whtbronco]

I sprayed the rear u-joint cups with penetrating oil last night and that actually helped a bit. I'm sure they are pretty much dry, maybe if it can move just a bit it self centers better when spinning.

I had my wife order that swivel socket last night actually, but thank you. It does look like a good match for the driveshaft. Also ordered a set of impact 12 point metric sockets and a new impact 1/2-3/8 reducer. I have never needed anything more than my non-impact 3/8 drive 12mm 12 point socket, and I've had the front driveshaft out before. This time it's being tough and my body isn't what it used to be. I got 5 of the 8 out tonight before my shoulders were done if I want to be able to work tomorrow.

I also took the shift motor off the transfer case to verify operation, it works fine. The transfer case has just 3 settings, 2H, 4H and 4L.. I expected 4, ya know another for AWD. I could do without the AWD, I only ever use it in dry and wet pavement. In the snow it's flat out dangerous I think, true 4wd is superior. The shift motor was in the 2H position when removed. It does not move when the switch is moved from 2H to AWD, but it appears there's no AWD setting in the transfer case. It does move as expected when the switch is moved to 4H. I repeated this 6 times and put it back together. I did manually shift it as well. I was also intrigued to find that the shift rod is spring loaded, just start turning it from 4H to 2H and it jumps for ya, startled me the first time. It has be turned all the way from 2H and 4H, which I expected.

I need to do so more research on the transfer case and how this AWD setup really works. The IWE's are releasing as expected so the transfer case must not be actually disengaging, even though it's not stuck in 4H. That said there is a differential in the transfer case when the AWD setting is selected and it does send power up front it's easy to feel.

 

[kep5niner]

I’m keeping my eye on this discussion. I’ve developed a similar vibration that I have not isolated yet. Only between 70-80 MPH. Sometimes enough to make the rear view mirror vibrate enough so that’s it’s almost unusable.

A cursory inspection did reveal what could be slop in the front driveshaft u-joint(s), but that does beg the question, if in 2H, why would that driveshaft be spinning in the first place?

Time available for troubleshooting is my enemy. I may just have to drop it off at the dealer and ask them to be gentle.

 

[whtbronco]

I’m keeping my eye on this discussion. I’ve developed a similar vibration that I have not isolated yet. Only between 70-80 MPH. Sometimes enough to make the rear view mirror vibrate enough so that’s it’s almost unusable.

A cursory inspection did reveal what could be slop in the front driveshaft u-joint(s), but that does beg the question, if in 2H, why would that driveshaft be spinning in the first place?

Time available for troubleshooting is my enemy. I may just have to drop it off at the dealer and ask them to be gentle.

I heard that. I've been doing this round of troubleshooting when I can find 45-60 minutes at a time. Course it has delayed my rust repairs.

That's what I don't understand. My transfer case is in 2H and the IWE's are working so the driveshaft should not be turning. With the truck on jack stands, engine running, transmission in drive, the rear end turns as expected, the front driveshaft turns along with the front axles of course, front tires were still. So the transfer case is sending some torque up front, but it the differential is not locked in AWD it does not bind at all like it would in 4H.

Once I can get the front driveshaft out I can verify if that's the source of the vibration.

If your truck is vibrating enough to shake the rear view mirror it's dramatically worse than mine. I'm a stickler about vibration though, I think it should only occur because my stereo is thumpin', . Try pulling the front driveshaft. It'll be easier to check the u-joints, always is for me, and you can drive without the front driveshaft so you'll know if that resolves it. Might still have an issue, like I suspect in my transfer case though.

 

[whtbronco]

I believe our transfer case works in basically the same way and this suggests that there will be some turning of the front driveshaft due to viscous coupling. That does not, however, explain my front driveshaft turning all the time.

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I have been wondering if the clutch pack in our transfer case could have some viscous coupling like a torque converter does and also if that clutch pack begins to wear if that coupling could become more pronounced.

I also want to learn what the cam/coil in our transfer case does and how it works. It's mounted to the clutch pack assembly and I suspect involved in my issue.

I also saw mention on a TSB describing our issue, that suggests 2 bearings be replaced. I'm hunting that TSB.

 

[whtbronco]

There are 3 positions on the shift motor and 3 matching positions in the transfer case. Wo just why in the heck are there 4 signal wires and yet another called differential lock solenoid control. The later is what I am thinking is the difference between AWD and 4H.

 

[whtbronco]

Finally got the front driveshaft out. I had to get my son to holds the brakes, otherwise the impact just The rear u-joint had a cup with no grease and rusted needle bearings. There's basically no grease left in the other 3 cups. Front u-joint is still in, it's not smooth, but I don't feel any play in it. Tomorrow I'll find out of that's the cause of all the vibration or just part of it.

I also believe the clutch pack or the coil are stuck engaged in the transfer case. More testing tomorrow I hope.

This text line from AllData has me a bit confused. Is 4WD module basically acting like a 3-way switch for this wire. Otherwise I see no way to have ground or power, most of our circuits are just open or closed.

• Solid state clutch relay (pulse width modulated signal: grounded when relay is on, battery potential when relay is off).

 

[SafariGoneWrong]

System description is provided in the attachment from my service manual. Also, the manual clarifies the 4WD module is integral to the PCM. From what I can tell, like any PCM controlled solenoid/actuator like an injector, etc., 12V is always available and the PCM provides the ground on a calculated duty cycle.