Not so Good Vibrations

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
575
Reaction score
252
Location
Winchester, VA
So I've been chasing vibrations in my '04 Expedition for quite a while, 288k miles. One I was certain was the A/C compressor, and had made plans to replace it. I'm totally lost on this, but after replacing the fuel pump my wife said the engine was running smoother and the vibration was gone. Sure enough the vibration I thought was the compressor is now gone.

I still have a speed related vibration with maybe more than 1 cause. Speed range is 40-70mph, 47-56mph is the worst, and almost all with the torque converter locked. 2WD, AWD, 4WD makes no difference. I got rid of most of it with new rear cv axles and wheel bearing hubs, all Motorcraft parts. I couldn't find the rest for a long time, but it wasn't too bad, my wife couldn't feel anymore. Seemed to be getting worse a couple months ago so I started looking again and found a rear driveshaft u-joint and the slip yoke both with a little play. So I replaced the slip yoke with a new Motorcraft yoke and put in new Dana SPL u-joints. Still not satisfied I had the driveshaft checked. It was .007" out of round, but was straightened anyway. Also got new tires around this time. Once again the vibration was back to fairly minor, I notice it, my wife doesn't. The last few weeks it seemed to be increasing once again and only present when the torque converter locked in 4th gear. As soon as the converter locked it started and got worse up to like 52-53mph and then subsided entirely by 70mph. I started thinking the converter or lock up clutch was failing. Trans shifts smooth still. The vibration would get much worse under coast, mostly in the 47-57mph range. I am confused because coasting vibration is usually rear drive line not transmission. Dropping into neutral resolved most of the coasting vibration, but it was still present in the 47-57mph range once below 47mph it would settle to a gentle vibration again and below 38mph it's gone.

Monday night on my way home it shook violently like something broke for ~1/4mi once I got to about 50mph. I peddled the throttle and it calmed a bit while I was off the throttle, but came right back when I got on it, but I was almost home. Once I stopped and turned into my neighborhood I had no vibration again. It's always smooth under 35mph. So of course I looked even closer at stuff. Couldn't find anything in the garage. Took my wife for a ride, she felt the passenger floor vibrating, but nothing near as harsh as what I had felt a little earlier. The rear diff was still properly filled to around .9" from the fill hole. Now I'm wondering if it's a rear pinion issue. I decided to just fill it up to the fill hole, adding about 1/2qt. Since it's easy to drain and if it is associated with the pinion that might help a bit. Well that helped get rid of like 50% of it, my wife said the floor wasn't vibrating on the passenger side now. So that tells me that it might actually be a bearing in the rear diff that's worn out, likely on the pinion, and the extra gear oil kinda covered it and calmed it a bit.

Having been really focusing on this over the past week I found that there is a very slight vibration in 3rd, a tiny bit more in 4th, but still when the torque converter locks it gets worse.

I am familiar with torque converter shudder and this is not it. Shudder is kind slow, like rumble strips, this is a more typical speed sensitive vibration. Now that said the brief episode last Monday could have been violent shudder I suppose.

My thought is maybe the vibration of the pinion in the rear diff is only noticeable at certain speeds and certain loads. Since in gears 1-3 I'm usually accelerating there is slightly more load on the pinion than when the torque converter locks which can occur at 38.5mph or faster. Then the load on the pinion decreases and it can shake around. By the time it gets up to 70mph it's just too fast to feel it.

If this was a solid axle I'd have pulled the cover for inspection and measure the backlash. There is a bit of play between the pinion flange and the cv axles, but it's not much and very hard to identify if it's too much.

Any other thoughts? It may be that I have a trans and a diff issue, I hate vibration it drives me crazy chasing it down.
 
Last edited:
OP
OP
whtbronco

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
575
Reaction score
252
Location
Winchester, VA
I forgot to mention that I put it on jack stands this evening, started it and put it in drive, and then moved around listening with my stethoscope. The only bearing noise I heard that I didn't like was at the front of the rear diff. It just sounded like a dry bearing. Of course that's the only bearing in the rear diff that can be sort of isolated form the outside too.
 

SafariGoneWrong

Well-Known Member
Joined
Apr 26, 2022
Posts
80
Reaction score
29
Location
30126
I feel your pain, once had a driveline vibration that was caused by an axle shaft bearing surface in my Bronco that had gone egg-shaped; that took a while to find. I don't think that's your problem as you've replaced both rear half shafts. Regarding the pinion bearing, I'd think you'd have heard whine first before devolving into vibration. Years ago after replacing the rear differential pinion seal in the Bronco, I didn't torque the pinion nut enough (crush collar paranoia) and it backed off. No vibration, but noticeable whine during zero load condition and slight whine on decel as the pinion was going deeper into the ring gear. I suppose you can remove the driveshaft from the pinion flange and see if there's any wobble to the pinion/flange. I'd think it would be very noticeable if you had a failed bearing causing driveline vibration. Since you're noticing significant vibration, I'm thinking of mass is out of whack and what would cause that. My diveline experience over 26 years is rebuilding the Bronco BW 1356 transfer case, setting up the Ford 8.8 differential and all things for the 3-speed C6 transmission...nothing yet in my '06 Expedition. You replaced the slip yoke, any chance that's binding? I had to get all the old gummy grease out to get smooth movement but that was for the infamous clunk when stopping/starting. Is you rear differential limited slip? I doubt that would have anything to do with what you're feeling... And how's the cushion/bushing on the differential mounting arm? I'm running out of ideas... I have no experience with a transfer case failing (thank goodness) and causing vibration but maybe it's worth draining the fluid to see if any metal chunkies or glitter come out. And of course there's significant rotating mass in the 4R70/75 and I don't think it can be discounted at this point.
 
OP
OP
whtbronco

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
575
Reaction score
252
Location
Winchester, VA
Most of my prior experience with vibrations is with Broncos as well, though slightly older. I had a 78 and 79. The 78 had an NP203 transfer case which had a neutral so it made isolating drivetrain components easier, it also made the truck handle great being full-time 4wd. The Expeditions AWD does not even compare to full-time 4WD.

I am still leaning towards the rear diff, but you're right I probably can't dismiss the trans or transfer case yet. I actually have a rebuild kit on hand for the transfer case, but I don't think that's the issue. 2WD, AWD, 4WD High does not change the vibration. I would think one of the 4 wheel options would change it a bit.

I doubt the slip yoke is binding, it had a nice coating of Amsoil chassis grease on it when installed a couple months ago. Easy enough to pull it and check though. I have not pulled the driveshaft during this instance of troubleshooting so I guess that's a good place to go.

I guess I need to get it on jack stands again, check the driveshaft again and then have my wife run it through the gears and listen and feel everything behind the engine more. It's a bit intimidating laying under a vehicle with tires running 55-60mph. Last time I focused primarily on the rear diff, wheel hubs and cv axles running at idle.

I agree it would seem that an audible whine would be heard with a failed pinion bearing.

I have found the last couple days it's not consistent now. Sometimes it's much worse than others. I got to thinking what if this is the differential, it is a LSD. I don't know exactly what it would feel like if the spider gears are worn or loose.
 
Last edited:

Drae

Full Access Members
Joined
Sep 16, 2010
Posts
104
Reaction score
31
Location
Anchorage AK
Did you check your front driveshaft u joints? I had the same vibration at the same speeds with my 03 5.4 until one night my wife was driving and the u joint broke when the transmission downshifted going up a steep hill. That driveshaft did some damage to the fuel line, heat shields, transfer case vent, MLPS sensor and a few others I'm sure I'm forgetting. I was terrified when she called and told me it felt like the transmission dropped out of it only to find out it was the driveshaft.
 

SafariGoneWrong

Well-Known Member
Joined
Apr 26, 2022
Posts
80
Reaction score
29
Location
30126
Drae brings up a good point. Maybe a check of the 4WD IWE system to see if the vacuum lines, check valve and solenoid are working right. Maybe the IWEs are engaged at times when they shouldn't be... I'm in the middle of pulling the valve covers and front cover for another issue... I decided while everything is easy to reach to replace the IWE vacuum check valve and vacuum lines (it's actually one part 4L3Z-3A788-AA, that should be good for an '04) and the IWE solenoid. Just a thought. Back to chasing what appears to be an oddball lash adjuster on the right side.
 
OP
OP
whtbronco

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
575
Reaction score
252
Location
Winchester, VA
Well I think it's a long shot, but it's easy enough to check the front end again. Thanks for the idea.

I hadn't really considered maybe due to the following, but I could certainly have a part that's failed already. The IWE's were replaced with Motorcraft parts in October, 5k miles ago. All the vacuum lines were replaced or tested multiple times. This was due to a vacuum leak and a faulty IWE. The solenoid was tested and pulling the vacuum line from it I was able to hold vacuum to the IWE's for more than 12hrs. The front hubs were replaced in December again with Motorcraft units. Of course during all that my 20+ year old plastic MityVac vacuum pump finally broke unrepairably and I have tried multiple units to replace it, all junk. The current one is the best I tried, MityVac MV8500, I hate it.
 

CLMA

New Member
Joined
Jul 3, 2018
Posts
2
Reaction score
5
Location
Texas
I recently fixed a similar continuous vibration problem in my 2004 (4X4) Expedition. For about 2 years I had noticed a vibration that would start at about 40 mph and would get progressively worse over 40 mph. So I replaced both u joints of the rear drive shaft but no difference. Then I replaced both IWE's and both front wheel bearings but the vibration was still there. So eventually I took my Expedition to a local shop to check the vibration. When it was up high on the lift the technician spun both front wheels with his bare hands while he looked at the front drive shaft and called me over. He said, "look at your front drive shaft". As he kept spinning both front wheels I immediately noticed that the front drive shaft was bent and was wobbling as it turned. So the next thing I did was to buy a used driveshaft and installed it. After it was installed I drove my Expedition on the freeway to speeds over 80 mph and the vibrations were completely gone. So put your Expedition on a lift so you can stand underneath it and observe your front drive shaft for straightness. I hope this helps you.
 
OP
OP
whtbronco

whtbronco

Full Access Members
Joined
Nov 13, 2021
Posts
575
Reaction score
252
Location
Winchester, VA
The problems have been identified. I had to, as several responses have indicated, stop looking at the same thing. Basically start over with troubleshooting and stop thinking anything was good simply due to recent repair or testing. I know this, but I was being stubborn, not uncommon according to my wife. Heck I could feel the vibration in the steering wheel at times which doesn't usually point to the rear end.

So I decided to start up front and work my way back due to the multiple suggestions and well I had spent too much time in the back already. IWE's are still working fine. Vacuum hoses/lines are still good. Solenoid is good. However, as my wife moved the truck the driveshaft and axles were still turning. Jacked up a wheel with it running and it turned freely, the axle did not turn. So the transfer case is not going into 2WD and the rear u-joint in the driveshaft has some play in it. So DRAE, SafariGoneWrong and CLMA were spot on.

I have new front u-joints on the shelf. I just need to figure out the issue with the transfer case. It shifts between AWD to 4H and to 4L just fine. Time to study the transfer case and shift motor again.

LOL, at the moment I also need to get the driveshaft out. I got 1 of the 8 bolts to come loose, so they are soaking with some penetrating oil right now. It's been years since it's been out.
 

Latest posts

Forum statistics

Threads
54,136
Posts
506,230
Members
48,078
Latest member
Wayneo
Top