ok, usually I can get my problems solved by searching here, but I am at a loss at this point. I've been chasing down a bad vibration from 45-70+mph. I found a couple threads with mention of a bushing in the extension housing of the 4r100 being starved for oil if the housing gasket goes bad, resulting in a vibration at similar speeds to what I'm experiencing. I pulled the extension housing off a spare 4r100 I have access to and I don't see any bushing. So what am I missing here?

For reference I've done the following trying to fix this vibration:
rebuilt entire front end (ball joints/tie rods/wheel bearings/new lockouts/brakes/all new bushings & seals)
rebuilt both drive shafts
replaced wheels
replaced tires
serviced rear end (note: the dealer obviously didn't put LSD additive in because the rear end chatters like a spool gear around corners)
serviced front diff
new shocks
new steering stabilizer

Additionally turning O/D off makes no difference. I do have a couple leaks I haven't identified yet, one of which is trans fluid. It's a very slow leak, just enough to wet the trans pan and drip off the rearward pan bolt heads. The other leak look like its probably the pedestal leaking.


So where is this bushing? Not sure why the extension housing would be bad?




wet trans oil pan


leak from (I assume) pedestal


I'm losing my confidence with this issue. I can usually figure this kind of stuff out myself, but I'm at a loss. The vibration is so bad I don't want to drive the truck until I can fix it...

 

I was chasing a mild vibration, but it "blew up" (dramatically increased) in a very short time. I'm following this and I'm seeking local help. I'll share what I learn.

To narrow this down some: Do you hear anything like bearing noise or what one might think is tire noise? Is the vibration tamed town when the torque converter is unlocked? Can you coast in neutral at cruise speed and not feel a lot of difference from having it in Drive at cruise speed? If you have a tow tune, is it more intense when that tune is selected? Does the vibration appear to go away when you do a hard acceleration?

 

Thanks for the reply! Answers in red below.

I have a couple things to rule out still, like the rear diff. I'm going to drain it and refill with LSD additive to eliminate the choppiness around corners. I doubt that's the issue, but only one way to be sure.

I'm also going to get the rear drive shaft balanced. I rebuilt it myself, and put everything back together as it came apart, and I didn't see any missing counter weights, but I guess you never know.

I know my front leaf bushings are worn, get a good clunk over big bumps, but it aligned perfectly and the vibration comes even on fresh paved roads with no bumps.

Anyone have any insight into my question about the extension housing? What bushing is being referred to in this thread: https://www.ford-trucks.com/forums/1...l#post12317249, post #17? I've seen it mentioned on other forums too.

Also this: Found here: Excessive Vibration Felt in Vehicle While Driving - Fluid Leaks From Rear of Transmission : Ford E-350 Common Drive Train Problems

 

well, I pulled the drive shaft and had it balanced, no joy. Still get a bad vibration at 45mph. I also tried shifting into neutral and the vibration doesn't go away. At this point I'm at a loss...

 

I just replaced my 4x4 tranny the other day. When I mated the xfer case back to the extension housing, there is a weep-hole in the back of the extension housing that spewed fluid continuously all over me after I removed the "protective plug" while I got the xfer case re-installed. There is definitely fluid being pumped to that extension housing. The "bushing" might be behind that gear and output shaft where you can't easily see it, OR the bushing could be on the xfer case side?

 

Only the 2wd versions have a bushing in the extension housing. There is a bushing that supports the output shaft in the transmission, but is a non issue on the 4x4, as the transfer case supports the end on it and the shaft is shorter. The transfer case shafts are all supported by bearings.

 

Did the vibration by any chance start at the same time the F350 blocks were installed in the rear end? Just throwing ideas at the wall, could be a driveline angle problem.

Edit, and is the vibration a fast high-pitched literally vibrating the change in the cupholder or a slower like a wheel hop that shakes the truck up and down or something in between?

 

so is that fluid being pumped through the ex housing into the transfer case? For some reason I though the xcase had its own sealed fluid.

ok, so then the TSB I referenced is only for 2wd trucks? That leabves me back at square one...

no, I bought the truck with the blocks and it ran smooth as butter.

It's a steady but intense vibration that shakes the whole truck from what feel like the center. It's not in the steering, and it's nothing like when a rear tire threw a belt and shook the bed. It hit hard at 45mph and smooths out around 60mph, then starts getting worse again around 70-75mph. This really has me stumped...

 

The transmission and transfer case do not share fluid.

 

Have you verified that the front hubs are unlocked and that when they are unlocked that both wheel shafts turn freely?

When the 4x4 selector is in the 4x2 position, the front drive shaft should turn freely. Have you checked that as well?

 

Thats what I thought, so there's nothing that the extension housing in a 4x4 could cause to create this vibration...

yep, both Mile Markers were just rebuilt and lubed. I verified the drive shaft can easily be turned by hand, and both wheel shafts turn freely.



I drained and refilled the rear diff today, adding the proper limited slip additive. It fixed the chattering around corners, so doesn't feel like a spool anymore. Still have the vibration though. It feels like I've been chipping away at other small issues since the truck rides like new at every speed except the 45-55mph range the vibration shows up at. If I can fix this vibe it will ride like a new truck!

 

4X4 does not have a bushing in the extension housing. Look at the drive line angle.

 

Slip yoke on the rear driveshaft have any play in it?

 

Drive line angle is stock f350...

nope, just had the shaft rebuilt and everything was fine, balanced perfectly, new joints, and slip yoke was greased and fit together nice and smooth.

 

Pinion bearings on the rear axle good? No play there?

Other than that, you have looked at everything I would when chasing a vib