Not so Good Vibrations

[whtbronco]

Thanks SafariGoneWrong, that was interesting and a bit different than my AllData info. I thought the clutch was only used in AWD, it looks like from that the clutch is engaged intermittently in AWD and basically fully/constantly engaged in 4H and 4L.

I've only done a bit of troubleshooting today. Though there is just a single click when the switch is moved to 4H. It does nothing from 2H to AWD, sound wise at least. My OBDII scanner reflected the transfer case setting selected with the switch, so that's a good thing. That suggests that 4WD module and the PCM are trying to do what's requested and report that they are successful. This makes me wonder if there's a physical issue and not an electronic issue. I'm sure I'll end up opening the transfer case at some point. I wish I knew if the moving the switch from 2H to AWD should in fact move the 4WD shift fork as I suspect and that the difference between AWD and 4WD is simply the duty cycle of the magnetic coil engaged clutch pack. I kinda think the click I hear when selecting 4H is the coil energizing and engaging the clutch pack.

There is a spring that appears to disengage or return the 4WD shift fork to the 2H position. Since the transfer case seems to be effectively stuck in 4WD I wonder if that spring has failed.

The good news from today is that with the front driveshaft removed the vibration is almost entirely gone. In fact it's just barely noticeable nd primarily in the steering wheel. Tomorrow I'll run at least 75miles so I'll get a better feel for the little bit that's left. My gut feeling is that it's the front tires so i may rotate them to isolate it.

 

[whtbronco]

I've not been able to do much more troubleshooting on the truck. I did get to do some driving and found that there is still a very light vibration under power I still think is related to a bit of heal to toe wear on the outer tread blocks of the front tires. I push it too hard through turns and cause this. There's a bit more vibration under coast that remains, but probably not enough not enough to worry much about and it certainly feels different. My wife can't feel any of it. I also got both u-joints out of the front driveshaft this week and cleaned it up to install the new ones.

I found very slight rotational play in the slip yoke and it requires pretty much all the grip strength I have to induce it. Clearly there has to be just a tiny bit of play for it to slip smoothly so maybe I'm just being paranoid and it does feel the same fully collapsed as it does at the installed length. My wife and son said there's no rotational play and that I'm crazy, they might be right.

My next planned step is do some more hands on troubleshooting of the transfer case.

 

[whtbronco]

The last few days the vibration has been getting a bit worse again, most noticeable coasting. The front driveshaft is still removed. So I spent 3hrs troubleshooting this afternoon, I'm slow and try to take my time due to severe rhuematoid arthritis. Short of it is 2 separate issues 1 electrical and 1 physical inside the transfer case.

First up was seeing if I could get 2WD at the transfer case. The switch is in 2Wd and hthe scanner shows that as well, but I found the front transfer case output flange would not turn. It was certainly connected to the rear driveshaft. This was the case in all 4 switch settings. With my scanner I was able to send a clockwise control command it went into 2WD. I was then able to shift between the 4 options on the switch and get them all. In AWD the coil reported 1.96% which is a little low based on the minimum range of 3-8% in AllData. In 4H the coil shows N/A rather than 100%, but locks the clutch as it should. The good news is now I am getting 2WD. As soon as I started the truck and dropped it in gear the front output flange was turning and I could not slow it down by hand. The scanner still showed 2WD and the coil showed no power. Turn the truck off and the front output was free again. So I messed with shifting and watching the scanner data streams. Thre results were consistent, but not right such as the open contact would change to a single letter when the switch was changed, but a few seconds later it would show all 4 (ABCD) on again. The individual contacts would change from open to closed and just like the open contact would all change to open. Afterwards I checked for codes and got U2023, external node fault. This leads back to an issue I started on in December of '22 and clearly it's time to revisit it. So there's an electrical issue.

Time to find the vibration before my body quits. I checked all over, it was now clear it is the transfer case and the rear bearing on the front output shaft sounds terrible. The transfer case was obviously vibrating and with the stethoscope there is no question the issue resides inside the transfer case, everything else sounds and feels good. I went ahead and change the ATF in it for grins. I change it every 2yrs, but it sure was intersting. Almost milky looking when I would stir it up. I ran a magnet through it several times and got nothing and found nothing while emptying the drain pan. Sorry about the photo, I suck with cell phones and I should have moved it into the garage, but I'm stupid. Anyway, now I need to decide if I am going to open my transfer case, inspect it and replace the bearings and seals or buy a used or reman'd unit. Used at this age is questionable, but the local yard only wants $125 with a 60day warranty. Reman'd is $1400. The bearing and seal kit is already on hand.

Hmm, is there any chance that there's feedback from the shift motor or the coil to the 4WD module? I kinda wonder since it seems to work with the truck on, but not when it's running. Though there is power either way so maybe not.

 

[SafariGoneWrong]

Yes, there’s a position sensor that provides input to the 4WD module. I’ll get something from the shop manual and post. Very nice write up.

 

[SafariGoneWrong]

“The shift motor sense plate, an integral part of the gearmotor encoder assembly, informs the 4WD control module of the transfer case position.”

But it’s not broken out in the attachments.

“The electric shift motor is mounted externally to the gearmotor encoder assembly at the rear of the transfer case.”

 

[whtbronco]

Huh, I've not seen anything about that, but it makes sense and certainly fits with my thought. That might explain why my scanner can control it fine, but the module not so much. Thanks @SafariGoneWrong.

 

[whtbronco]

So I decided on a plan forward. I'm gonna replace the bearings and seals in my transfer case. The overhaul kit from USA Standard Gear is on hand already, and it really doesn't look hard. The only concern is if there's any parts inside that are worn beyond use. The front output shaft is a concern, but my guess is the bearings are failing. I'll find out. The local salvage yard wants $125 for a transfer case so I'm gonna pick one up and disassemble it. Then I'll know for sure how to and I'll know where the bearing in the pic goes as it is not identified in AllData. The salvage yard transfer case will hopefully having some usable parts should I need them.

I'm also gonna replace the shift motor. The current case is rusted which is not a huge issue, but the wires are hard as a rock. Oddly enough the wires on the other side of the connector are just slightly stiff, like you'd expect from 20yr old wires. I ordered a new Motorcraft replacement.

The best price I have found for a reman is $1460 and I'd rather avoid that expense. If my plan works out the transfer case will run me about $160 since I already have the overhaul kit.

 

[whtbronco]

I forgot to attach the pic of the bearing I'm not sure about.

 

[whtbronco]

It looks like in a 4406 there's a similar bearing in the planetary gear. Maybe the 4416 is the same.

 

[whtbronco]

I picked up a transfer case from a 2003 with 230k miles at the salvage yard today, $125. Man that things was dirty. Some areas had nearly 1/8" of sludge. It sounded terrible turning the shafts by hand and while I could hold the front output shaft still while turning the input shaft it wasn't easy. It was pretty clear the fluid wasn't changed often if ever, it was dark brown. As soon as I pulled the clutch pack forward on the output shaft it seemed to release. Maybe it was a stuck some and causing the drag on the front output shaft. It took 4hrs to fully disassemble, but that included a break for dinner, pictures along the way, bag and tag of the parts and cleaning up. It's really not hard to disassemble them. In fact easier than I thought it would be. I did need my son to help me with the front output shaft snap ring, otherwise it went really smooth. I took quite a few pictures since I did not find any BW4416 pics or vids online.

The seals pulled out with little trouble using my seal puller. The bearings came out very easily with a bearing driver handle, a 65mm disk and some gentle taps with my 3lb mini sledge. Except the thrust bearing in the planetary, that was tough to get out. I could not find a socket or pipe that the bearing would fit into. I didn't like the idea of simply placing the planetary on the table and using the bearing driver handle to knock it out, but that's what I did. Turns out that small bearing was the most difficult to remove. 36mm impact socket was too small inside, 38mm socket was too big outside.

Now I have to decide if I want to put bearings and seals in this one or pull mine apart and see what damage I have in it. On the salvage yard parts I see some wear marks on the shafts and such, but there appears to be no damage and I can't feel or measure any grooves. However, I wonder if the pump in mine may be less worn and if the chain has less slack in it. I have no idea how much slack there should be in the chain, but I'd think not much.

I need to keep the truck drivable if at all possible so I'm leaning towards getting the salvage yard transfer case ready to swap in and seeing how it is. I can tear mine down if needed, another bearing and seal kit is $117. I suspect it'll take 2.5-3hrs to put it back together. I'll work on getting the disassembly pics uploaded.

I'm still waiting for a shift motor. I ordered a replacement shift motor from Tasca. I've had good luck with them in the past, but not this time. They showed 14 in stock, yet sent me an email that they were able to find one, but it couldn't be returned for any reason. Then they said the price was going from $116 to $148($168 shipped) so I cancelled and ordered an OEM motor from eBay.