Not so Good Vibrations

[whtbronco]

The transfer cases have been swapped, took me 6hrs. Removing the transmission to transfer case bolts was much easier a 13mm ratchet wrench. I replaced the input seal on mine quite a few years back, that was tough with a traditional box wrench. My jack platform needed a few more mods today, but it worked out okay. The transfer cases both stayed in place unless I was trying to move them around. I had a tie down strap front and rear. The front one was just draped over the transfer case input shaft housing and the rear strap was looped over the end of the output shaft housing. There is just barely enough room for the transfer case to slide back and down. I had maybe 1/8" between the input shaft and cross member, the passenger side of the case and the exhaust, the driver side of the case and the fuel tank, the shift motor and connector to the tank as well. Just gotta take your time and keep checking as you lift it back into place.

The USA Standard Gear bearing and seal kit proved for a 2nd time to have an improper seal. The transfer case to transmission seal bolt holes did not line up. I could have fixed that of course, but I had a new Dorman seal and it fit perfectly. In general I think Dorman parts are poor quality, but they have some things that are very good. So the mount seal in the kit was not right and the front output shaft seal did not have the lip on the front to help keep dirt out of the actual sealing surface.

I found with the engine running and in drive, the front output shaft turned, but it was fairly easy to hold it from moving and I could also grab and stop it at will. I only tried this at idle. There was no chance I could hold it still or stop it with the factory installed transfer case. I can now hear the coil engage as well. In drive everything sounds much better now, though the rear bearing for the front output shaft sounds interesting. It doesn't sound bad like the factory installed transfer case, and it may simply be due to sort of like cup it's installed in.

Road test, I only went 8 miles so I'll know more over the next several days. Currently it is smoother and quieter, but seems to still have a very little bit of vibration under power, that cannot be felt at all until the torque converter locks up. Under coast below 55mph I can't feel any vibration. Under coast from 80mph I can't feel it as much, but it's still present in the steering wheel, brake pedal and seat. I can still hear the vibration under coast from higher speeds. I have no reason right now to think it's the transfer case.

Tomorrow I'll see what my scanner thinks of the new parts and test shifting more.

 

[whtbronco]

The transfer case is shifting fine now and the 4x4 module did not throw any errors after testing. After clearing all codes and shifting the transfer case through all 4 settings 6 times I got no error from the 4x4 module. The scanner also showed the response expected from the switch, clutch coil, contacts and motor rotation direction while monitoring the data streams. The one thing that caught my attention was that the coil showed 1.96% just like the factory coil had. AllData shows 3-8% minimum, maybe that's only when driving and I didn't test that today.

Stored 4x4 module codes were:
P1867 - Transmission transfer case contact plate general circuit fault.
P1891 - Transfer case contact plate ground return open circuit.
U2023 - Receiving error from external node.
The 1st 2 codes may have been from putting the truck in neutral to rotate the rear driveshaft during removal while the shift motor and clutch coil were disconnected.

Still have a couple errors, but that's for another time and thread.
B2320 - Driver's mirror horizontal position sensor circuit fault. Driver Seat Module.
U1262 - SCP data link fault. Hybrid Electronic Cluster.
C1991 - Module Calibration Fault. Vehicle Dynamics Module, basically air suspension.

 

[whtbronco]

After the 75 mile round trip to work today I can confidently say it is much smoother and quieter at all speeds. The minor vibration under power is just the engine and only felt in the throttle pedal. There is still a bit of vibration under coast, but it's vastly better. The coasting vibration does subside by maybe 50% in neutral. I think I'd need one of the multi-point vibration sensors, also called chassis ear, to figure it out at this point. I may consider buying one as it would help augment my lack of troubleshooting experience.

I can actually hear my tires now at 20-25mph. Seems at that speed range there is just enough speed to hear the tread a bit and almost no wind noise. I thought something seemed louder, but I sure didn't think it was the transfer case.

 

[whtbronco]

All I can do is laugh. The front output shaft seal is leaking. It's leaking enough that overnight it dropped a 1" spot on the garage floor and peppered the tank and rear suspension today. So I was debating whether to open my factory transfer case and work on it, I have my answer.

I did not like the seal that came with my bearing and seal kit, not did I really like the National brand seal I got at Advance. The front shaft also had a slight groove in it so I can't say I'm too surprised and in hindsight I should have tried to pick up a replacement.

 

[whtbronco]

Now I remember why I didn't try to pick up a replacement front output shaft. The only 1 I found also had a groove so I thought there was a slim chance it was normal, and maybe it is. It could simply be a crappy single lip seal causing it. This output shaft is $61 plus shipping and tax. I'll try to tear mine open this weekend and take a look at the shaft. Mine did not leak.

 

[whtbronco]

Another bearing and seal kit has been ordered along with a Dorman gasket and an SKF front output shaft seal. Then I found that a Motorcraft front output shaft seal was $20 full retail so I ordered that from the local dealer. I want to compare the SKF and Motorcraft seals, already know the USA Standard Gear and National seals don't look good.

So the fun will begin again soon.

 

[whtbronco]

The 2nd bearing and seal kit and the SKF front output shaft seal arrived. Both were ordered from Rock Auto, same part # of course. This kit appears to be higher quality and certainly is not the same kit that I received last time. This one shipped from Zumbrota, MN, my guess is it's from Randy's Worldwide. Anyway, same part number nearly totally different contents though. The 1st kit I got was all vacuum sealed on a single card. This one has a vacuum sealed card with the 5 bearings and the 4Lo fork inserts. There is also a bag containing all of the seals.

The seal kit indicates it fits BW4406 and BW4416 which explains why there are 3 seals I don't need, both kits had these. The shift shaft seal is metal clad rubber(I like this better), the other was just rubber. The input seal and included front output shaft seal are identical(both kits), still no dirt shield on the front output shaft seal as pictured. The rear output shaft seal is metal clad with a thick rubber cone and larger seal contact area, just like the picture. The rear output shaft seal in the 1st kit was metal clad also, but with a thin rubber cone and thin seal contact area.

The bearings in the 1st kit were vacuum sealed onto the card. The 2nd kit has plastic wrapped bearings in a box and then vacuum sealed to the card. The 1st kit had 2 identical bearings for the input shaft and forward front output shaft. The 2nd kit has 5 different bearings which matches the listings I have found to buy the bearings separately. We drove more than 100 miles yesterday with a slight increase in vibration again. I can't help, but wonder if the bearings in the 1st kit are the cause partly because the ATF leaking out is red and black and it should be just red. Either the bearing is having issues or the seal is actually deteriorating which may be the case.

Attached are pics of the kit contents.

 

[whtbronco]

Not having been pleased with the front output shaft seal included in my 1st bearing and seal kit I picked up a National brand seal locally, $28. I wasn't pleased with that one either, but it's what was available that day, I should have waited. Anyway, this time I ordered an SKF brand from Rock Auto, $5 +$10 shipping, and picked up a Motorcraft seal from the local dealer, $20. The SKF and MC seals appear very similar, they are not the same though. The molds are certainly different. The MC seal reads USA molded in and has grease inside it. The SKF otherwise is nearly the same. Pics attached, Motorcraft seal on the left, SKF on the right. I'll be using the MC seal when I rebuild my original transfer case.

 

[whtbronco]

After the transfer case swap on the test drive there was a bit of vibration that remained. The next day it was amazingly smooth on my way to work. It has slowly gotten worse yet again under both power and coast. Clearly I am not quite done chasing vibration.

Yesterday I did some testing. Dropping the transmission into neutral reduces the vibration about 50%. It can be felt through the pedals, steering wheel and seat, I think it's coming from mid-vehicle to up front. I feel the same vibration, though reduced, stopped in neutral when I rev the engine to 1000-1200rpm. Put the transmission into any gear, hold the brakes and rev it to 1000-1100rpm and it's worse than under power while cruising at a steady speed and more closely feels like it does when coasting. This also eliminates the rear diff and axles, front diff and axles, transfer case and transmission except for the torque converter(TC) and pump. It kinda reminds me of when I had cracked a flex plate many years ago. I have wondered for a while if I had a TC vibration though and I'm not sure I'd be able to identify the TC or flex plate without inspection/removal. The vibration follows rpm far more than load. Basically under cruise, normal acceleration or full throttle the vibration at a given rpm remains about the same. Under coast as noted it's worse. Since the transmission continues to shift fine both up and down I kinda doubt the pump is the issue. I also checked pump pressure this evening and found 10psi at idle, 24-25psi at idle in gear and rev'd to 1500-2000rpm pressure jumped to 48-50psi.

Using my stethoscope this morning I checked at idle and through cyclic rpm increase/decrease the accessories and pulley's on the engine and all seemed okay. I did the same at various points around the engine that I could reach from the top and I found nothing that seemed abnormal. I'll get the truck up in the air again this weekend and do some more research from underneath. I suppose there's a chance it could be from part of the rotating assembly in the engine.

I did find some misfires this evening from ~1hr of runtime in the garage. My scanner showed 61. I had 54 when I first checked after about 30 minutes and 7 more misfires over the next 30 minutes. It was very rough at start up for maybe 30 seconds which was likely some or most of the 54 misfires I first found. It was also very rough rev'ing to 3000rpm and holding it there one time, this felt like more pronounced vibration than misfires. Kinda like something was out of alignment briefly. The vibration I'm looking for continued throughout the entire time. I found no coolant leaks, no apparent vacuum leaks.

I also hope to get new bearings and seals installed in my original transfer case this weekend.

Maybe all that rambling makes some sense.

EDIT: One thing I failed to mention is the last 2 days I drove it it to work I swear there's a faint humming sound right around the transmission bell housing. It kinda comes and goes and it's hard to hear, generally I can only hear it when coasting at low speed like right as you let off the throttle from 20-25mph. I think maybe I heard on the interstate, but there's so much noise at those speeds it's hard to tell.

 

[whtbronco]

I was thinking last night that the line pressures in my transmission are awfully low compared to the GM 4T65E trans I have messed with quite a bit. That trans is something like 90-100psi at idle in Neutral and 130psi at idle in 1st gear, mine is just 10psi in Neutral and 25psi in both Drive and 1st gear as I would have expected. AllData shows lower pressure than the 4T65E, but still much higher than I see in mine, which ran 35 miles to work this morning with varying vibration, but no other issues I noticed. I never saw more than 50psi last night, I did not check line pressure at stall nor did I even think to. Between the low line pressures and recently developed hum/whine maybe the transmission pump is actually failing.

Trans line pressures from AllData: