Hey guys, another vibration thread... It's been a long process trying to track this down so I'll be as concise as possible but also descriptive... I have another thread going but the situation has changed a bit so wanted to start a new thread.

Chasing a vibration in my 2003 Excursion, 7.3, 144k miles, 4wd, no driveline lift/mods besides MM manual lockouts on the front. Has had a vibration when braking at highway speeds (above ~45). Primarily comes through the body. Steering wheel vibrates a bit but it’s a vibration as compared to a shake so I think it’s just picking up the body vibration. No pulsation in the brake pedal. Seems worst when braking at about 50 mph, vibration goes away when you get below 40 mph.
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Been trying to isolate and identify the braking vibration for several months with no luck. Recently the truck also picked up a rolling vibration-“rumble” above 55-60. Hooked up my buddy’s car trailer (empty – about 1700 lbs) to move it for him the other week and noticed that the same rolling vibration/shake starts above 20 mph and continues from there. I know it’s not the trailer itself as it doesn’t do it behind other vehicles. Lately the rolling vibration seems to start at about 20 mph even without a trailer hooked up. Rolling vibration also seems to come through the body instead of the steering wheel.<O</O
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Excursions DON’T have a driveshaft carrier bearing like the pickups, and mine doesn’t have a double cardan, just a regular shaft with a mid-shaft slip yoke.
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Braking vibration is there with the transmission (4R100) in gear or in neutral with the engine at idle RPM (trying to isolate engine/driveline/mounts/torque converter, etc.). I’ve not tried dropping it into neutral to see what it does to the rolling vibration.
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No noises that can be heard above the motor, just the vibrations.
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I’ve spent hours poring through Google results and forums, I think I’ve come close to reaching the end of the internet on this topic… certainly very close to the end of my sanity…
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What I’ve done/checked/spent a lot of money on:<O</O
- Brakes: New pads and rotors on all four corners. Old pads and rotors looked good but replaced them anyways. Caliper slide pins are good, fronts have the updated pins, and all slide freely. No signs of cementite, bluing/heat spotting, uneven pad/rotor wear, etc. No pulling or dragging. Parking brake shoes properly adjusted with no dragging.<O</O
- Rear driveshaft: had it rebuilt, balanced, and slip yoke greased. No play or wiggle in it. Even tried taking the rear shaft out and doing a test drive in 4hi – this was before the rolling vibration started but the braking vibration was still there with the shaft out. Had it rebuilt anyways. Didn’t help.<O</O
- Wheel bearings – new on all four corners. Fronts didn’t have any wiggle or noise to them but I was in a “frustrated” mood and shotgunned the parts. Replaced with Timkens. Rears – new Timken bearings/races/seals. Old looked just fine once I got into them but since I was 90% of the way there figured go on and just replace them with new. Followed AllData and torqued and “clicked” (rear lock nut) everything to spec. Spindles looked good.<O</O
- Front axle – I replaced the ESOF hubs with MM manuals. Old ESOFs were getting hard to turn by hand and I prefer manual ones anyways. Front axle shafts and driveshaft not turning (I “fishing lined” the axle shafts to the C’s and the driveshaft to the frame – no lines broke while test driving so tells me they’re not turning). I had a leaky inner axle seal on the passenger side so had a shop replace both as well as the knuckle seals and check all the front end components. No signs of issue inside the front diff or in any of the steering components/ball joints/spindle bearing/etc.<O</O
- Tires – rears at 55 fronts at 50 and also at 60 all the way around, all within 1 psi and lugs evenly torqued to 150 (“starred” to 100, then go back and ‘star’ again to 150). No signs of uneven wear/cupping/etc. Also swapped wheels/tires with a buddy (who doesn’t have vibes) and vibration was there when braking (was before rolling vibration started). After the rolling vibration started I swapped tires & rims with yet another buddy and both vibrations are still there.<O</O
- Transmission – no abnormal play in the mount. Thinking of a bad torque converter or cracked flex plate I got up to speed, dropped it into neutral, let the TC unlock and engine go to idle, hit the brakes and vibration still there. Tested multiple times. I’ve not tested if the new rolling vibration goes away with the trans in neutral. Fluid level correct and looks/smells fine, filter change and fluid “drain and fill” (just the pan volume) with the filter about 20k miles ago.<O></O>
- Transfer case – new fluid, no chain noise, old fluid looked used but good. Output shaft has no play, nice and tight.<O</O
- Rear diff – drained and inspected. Fluid looked old but no signs of issue and no metal. LSD clutches looked ‘good’ the best I could see and there was no clutch material in the diff fluid. R&P and spiders had no obvious sign of issue. Fill plug magnet had some material on it but nothing I wouldn’t expect (144k miles, first time I’ve changed the fluid, bought it with 120k and don’t know history). Refilled with 75-140 syn w/LSD additive. No play in pinion yoke, no leak from seal. <O</O
- Springs/suspension – all u-bolts and springs look good, no cracks, etc. U-bolt nut torque checked at 120 and all were good. Spring pack ‘sliders’ or bushings are all there and look to be in good shape, no signs of leafs wiggling around. Spring/eye bushings appear to be in good shape though I’ve not dropped them to check. No spit bushings and springs are centered in the mounts/shackles. Ball joints are not new but have no play in them. <O</O
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In general I’m a huge fan of specifications and always put every bolt back in to torque spec (per AllData) and “star” or cross torque where needed. <O</O
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I’m about to pull my hair out, or drive the truck off a cliff. My wife is about to toss ME off a cliff with all the money that’s gone into it without a solution. Any ideas? I’d be greatly appreciative of any insight or suggestions.<O</O

 

https://www.ford-trucks.com/forums/1...l#post12354798

 

If I were you I would check all four rotors with a dial indicator for run out. I know you have replaced the rotors and wheel bearings but that doesn't mean you don't have a bent or warped hub. We had a similar problem with a dodge stealth years ago at the shop and it turned out it smoked the curb pretty hard at one point and bent a hub. Good luck.

 

Forgot to add that although unlikely it's possible for new rotors to have lateral runout. Was the hub perfectly clean when you mounted the new rotors? I know mine were very rusty when I changed them. It wouldn't take much to warp a new rotor.

 

mecdac - thanks for the link. I had stumbled across that one before and unfortunately wasn't able to make sense of it as far as my problem goes - seems like I've addressed most of the issues based on the table... I'll go back over it again to make sure.

J ballan - could be. With the front unit bearings being replaced I don't think it could be them. Rears - hub seems pretty robust and unlikely but I supposed a spindle could have gotten bent somehow... I'll get the dial indicator and spec the corners. Hubs - front are new and rear were definitely clean when the rotors went on...

 

Yes I agree very unlikely but it's a relatively easy test and it sure seems like a rotor issue to me. Good luck and keep us posted.

 

I had the same problem,ended up being the pinion bearings in the rear end. I too pulled the driveshaft and no improvement. I then pulled the axles out so nothing turns and it was smooth as glass.I just took scrap plywood and used the axle flange for a template and bolted the plywood on where the axles go in so oil wouldn't fly out.

 

Well guys, improvement.

Embarassment to go along with it.

Was swapping my buddy's tires back off and putting mine back on and decided to check the pressures. Was at my buddy's garage so used his gauge - and my tires were all low! Turns out my gauge was reading 5-10 lbs high, so the pressure in my tires was actually around 40 lbs... Filled them properly and the rolling vibration is all but gone. I still get a tiny bit of it around 60 mph but overall its 99% better. With 140k+ on the odo I guess it could be considered maintenance but the $400 for front unit bearings, $150 for the rear, and $70 for the diff fluid change makes it an expensive oversight.

Still getting the braking vibration but at this point I gotta say I'm just glad to have figured out the rolling vibration, no matter how humbling...

7475ih - very interested in getting some more information/description if you'd be so kind. What problem were you having - the rolling vibration or the braking vibration? Either way, were you getting any leak from the pinion seal or did you have any play in the yoke/flange? Besides the vibration did you have any other symptoms? I have a line on a used rear end for $300 which would be much less than a rebuild of mine. But, its 2 hours away and does have 85k on it. Guy says its good to go but after throwing a bunch of money at this in general and putting over $200 into my rear end already I'm hesitant...

 

Glad to hear you have improvement.BTW, half of the new rotors I've bought have needed turned right out of the box,especially aftermarket rotors. Back to the rear end. I didn't have any pieces in the oil but I had a 1/4 inch of silver sludge in the bottom of the housing and when I shifted to reverse it had a double clunk in it. The vibration was not excessive at 70 mph but just enough to make the fuse panel cover rattle. When sitting in the second and third seat back it was really noticeable. I myself would not buy a used rear end but that's your choice. I had 500 in my rear end and that's with buying a dial indicator to set up backlash. My pinion seal never had any signs of leaking but the backlash was excessive.

 

Oh.... You may already know this but Rock Auto sells complete rear ends with backing plates.

 

Bringing this thread back to life.

Unfortunately have to say that the vibration is still present, both while braking and while rolling, and seems to be getting worse (vibrates at lower speeds both while braking and rolling). Vibration is greatly exacerbated while towing. Seems to be coming from the rear though at this point I'm beginning to doubt myself...

Since the prior postings I've replaced the rear shocks and also swapped in a used rear axle, both with no improvement. While swapping the rear axle I took the opportunity to check out the rear springs more closely and didn't see any sign of concern (isolator pads looked good, no signs of cracks, no unexpected bends, etc.). I also checked out the front - balljoints don't have any play in them when leveraged with a big a** pry bar, steering joints all seem tight.

I can't help but think that the issue lies in the rear, somewhere. The vibration mostly comes through the seat. The vibration being worse when towing (doesn't matter if its coasting, accelerating, with TC locked or unlocked or trans is neutral) a "light" trailer (unloaded 6x10 dump trailer) seems that it would have to be in the rear end as I doubt the front of the truck sees any real difference from the tongue weight.

Any ideas? I'm about to go bald...

 

Well let's just throw a spit ball and ask...misfire?

 

Thanks for the input. I had thought about that but unfortunately it does it regardless of what the motor is doing (RPM) or what it sees (load). It also does it with the transmission in neutral (the rolling vibration) and the braking vibration is also there when the toque converter is unlocked or the trans in neutral so I'd think it would rule out a misfire... In addition I've run CCT tests and they all pass except for injector #8 which is expected to fail based on it being an AE (long lead) injector.

 

long lead?

 

Injectors 1-7 on a late-model 7.3 are AD and #8 is an AE or "long lead." #8 sits at the end of the rail and fires immediately after the #6 cylinder goes boom. This means #8 gets shorted on fuel pressure and causes it to get an irregular rap at lower speeds, aka idle cackle. Ford addressed the issue by using an AE injector that has a longer primary shot of fuel to compensate for the lack of fuel caused by it firing immediately after #6. When running a CCT the #8 cylinder doesn't match the contribution of the other 7 so it shows as failing.