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nailing down a shudder and vibration

JB3

Active Member
Joined
September 18, 2014
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City, State
RI
Year, Model & Trim Level
1999 Explorer sport
Just bought a 99 explorer sport with 80k on it. Very pleased with the truck over all and most everything has actually worked, which is a new experience for me.

Truck was sitting about 2 years and was last started a year ago. Was trapped in the chaos of a deceased persons estate where the executor didnt know or want to bother with the difficulty of selling it out of the mess, but i know a relative and we spent a couple weeks putting together the paperwork. Just giving you a backstory to basically say the truck sat trapped in paperwork untouched and deteriorating for that time. Plus side is its a one owner truck.

Anyway, got it started, did a lot of brake work, tires, fluids ,and now its running and driving.

Ive got a pretty noticable shudder over bumps, and a vibration at speeds over 20, that goes in and out the faster you go. Stays pretty constant, doesnt get more severe.

Tires are balanced and i have checked bearings and u joints. Shocks i have not done yet but plan to. First 4x4 vehicle, so curious if anyone has tips or comments on things i might be missing i should check.
 



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Did you purge the sir from the power steering system after the work was done? Are you driving it around now? Do a few lock to lock turns of the steering while moving very slowly. See if the shuddering goes away.
 






Did you purge the sir from the power steering system after the work was done? Are you driving it around now? Do a few lock to lock turns of the steering while moving very slowly. See if the shuddering goes away.

I didnt do anything with power steering apart from check fluid level. Driving now, will do a few lock to lock turns and see what happens

The shuddering isnt while turning, the steering is smooth, its when you go over any road bump. Like when you hit a crack in the road, there will be residual vibration from the bump. Im assuming its gotta be shock related, will see what happens when i replace those
 






Not sure about your rotational vibration that changes with speed. Also uncertain about the earlier models such as your 1999, but the 2001-03 TWO door Sports are notorious for deteriorating body mounts, especially the orange colored MCU foam mounts. Crawl under and inspect, IIRC there are five locations on each side. Definitely replace shocks. If they're black, they are probably original.

http://www.agcoauto.com/content/news/p2_articleid/183

http://www.daystarsuspensionparts.com/proddetail.asp?prod=KF04009BK
 






Yikes.

Just ran out there ,i do have orange mounts ,but they look ok. Being very experienced with GM body mounts on my work vans, not a job im looking forward to down the line on this truck ,but at least i have some time.

At least ford has an accessible top bolt. Better than a rusted out blind nutsert trapped in a welded shut channel
 






So to follow up ive had a few other issues since i started this thread which resulted in a number of new parts.

All 4 shocks have been done, new front sway bar links, front sway bar bushings. I also swapped the tires around front to rear and rebalanced.

The persistent vibration is not related to tires or shocks. At highway speeds, its a constant tremor, and when you hit a bump, the truck will shudder a but every time. It wont just absorb the bumps, but its a very noticable skittish shudder every time.

Something is wrong, but its nothing obvious yet. I know body mounts were mentioned, could this still be related?

What else should i be checking?
 






Did you purge the sir from the power steering system after the work was done? Are you driving it around now? Do a few lock to lock turns of the steering while moving very slowly. See if the shuddering goes away.

I did end up having this exact problem with a very violent shake suddenly, but ended up wasting a few bucks at a shop with them throwing parts at it. I ended up doing a bunch of lock to lock purges and its never been that violent again. This issue seemed separate from the constant shudder over bumps i still have, but related in a way, like that big shake was a multiplication of the minor shudder
l
 






You stated that you checked the u-joints. Not sure how what procedure you followed, but vibrations from the drive shafts are not uncommon. There is a slip joint in the rear shaft that may need lubrication along with checking the two u-joints. However the more common issue is the CV joint in the front drive shaft (goes between the front differential and the transfer case). If the boot is ripped, it is toast. Don't assume that it is okay when the boot it intact and the shaft seems solid when you pull on it. It is best to remove the shaft and take a short test drive to immediately tell you if it was the source of your issue.

There are plenty of other things to check. The list can become fairly exhaustive and chasing around for the source of vibration is not always as simple as we could hope. Things to test include: worn bearings/hubs, bad tires/bent rims (which may or may not show up when balancing if the operator is looking for the issue), exhaust parts touching the frame, loose mounts on the motor transmission or front differential, worn ball joints, worn inner or out tie rod ends, worn control arm bushings or torsion bar pads, and loose or deteriorated body mounts. Obviously there can also be internal issues with the differentials and axle seals.
 






long overdue to update the problem.

Bad rear shocks, and front shocks were not tightened down properly by the shop that was employed to install them.

the were tight enough to not make noise, but could be moved by hand, so the truck had a good 1/2 inch of suspension travel undampened by shocks, which once I properly tightened down, eliminated a weird drivability issue I would call a quaver in the front.

this combined with new rear shocks, and the wife no longer wants a new car :D

bushings not even compressed-



how much I was able to tighten it-



Just goes to show, anything worth doing is worth doing yourself. Was so busy with work when I first started this thread that I outsourced this work, only to not really fix the problem until I finally took things apart myself this last weekend when I had the time.
 






rear shock blown AGAIN. This makes 3 times on the left rear. Shudder is worse than ever.

I am now replacing the monoleaf springs with an aftermarket 3 leaf spring pack for this explorer, and doing the shocks again.

After all this, it has to be the left rear leaf spring causing all these problems. The most recent shock was blown in under a week, but it rode great up till then. The first replacement shock I thought was a fluke and just a bad shock, but its happened so many times that I decided to replace the leaf springs and be done with it.

We shall see what happens now.
 






ok new springs and shocks installed. That was a bit of a pain, but I was able to reuse the U bolts and replaced the rusty shackles, so it was worth doing plus the truck sits higher and leve with the front finally which is nice. The driver side rear spring was flat, and the ride is better, but this shudder over bumps still persists.

I really have no idea what it could be.

All the body mounts seem ok, none are even cracked and they are all pliable to the touch. I have had people jump on the running boards with me underneath seeing if the body moves separately from the frame even slightly, and everything seems nice and tight.

I followed the truck in another car over rutted roads looking for any strange wheel reaction, and no bad shock behavior. The only thing I can think of is doing body mounts now over time. Ive literally replaced the whole suspension trying to find this problem, apart from the front torsion springs.
 






Romeo may have touched on this... but I had the same exact symptoms on my 98 SOHC 4x. Bad vibration and shudder that would change with speed and get worse over bumps. >Turned out to be bad driveshaft u-joints, both front and rear.< One way to test is to go somewhere where you can get up to speed (35-40 or so) then drop it into neutral and coast at speed. Then rev rpms a bit. If no shudder then it's got to be drivetrain related. And it sounds like you've got the suspension components eliminated. Just a thought...
 






Romeo may have touched on this... but I had the same exact symptoms on my 98 SOHC 4x. Bad vibration and shudder that would change with speed and get worse over bumps. >Turned out to be bad driveshaft u-joints, both front and rear.< One way to test is to go somewhere where you can get up to speed (35-40 or so) then drop it into neutral and coast at speed. Then rev rpms a bit. If no shudder then it's got to be drivetrain related. And it sounds like you've got the suspension components eliminated. Just a thought...

Not a bad idea, i think i will try this out.

I mentioned earlier i checked the U joints, the way i went about this was shaking the driveshaft for any in and out play on the universals an both their axis, and looking for rotational play. All 3 seem nice and tight, but its an inexpensive part that i could replace anyway to get rid of the rusty ones in there which are certainly original.
 






Not a bad idea, i think i will try this out.

I mentioned earlier i checked the U joints, the way i went about this was shaking the driveshaft for any in and out play on the universals an both their axis, and looking for rotational play. All 3 seem nice and tight, but its an inexpensive part that i could replace anyway to get rid of the rusty ones in there which are certainly original.

If you hold your foot on the brake and shift from park to drive, or from drive to reverse, is there and audible *clunk* or odd noise that you hear or feel? That also could be an indication of bad u-joints. Mine did not seem to have much rotational play, but after doing some research here and elsewhere, I decided to swap them out not really expecting to have a solution to the vibrations. But yep, that what it was. New u-joints, no vibrations.
 






the speed related sound seems like wheel bearings. Have you checked the upper and lower ball joints for play? could be the cause of your shudder over bumps.
 






You stated that you checked the u-joints. Not sure how what procedure you followed, but vibrations from the drive shafts are not uncommon. There is a slip joint in the rear shaft that may need lubrication along with checking the two u-joints. However the more common issue is the CV joint in the front drive shaft (goes between the front differential and the transfer case). If the boot is ripped, it is toast. Don't assume that it is okay when the boot it intact and the shaft seems solid when you pull on it. It is best to remove the shaft and take a short test drive to immediately tell you if it was the source of your issue.

There are plenty of other things to check. The list can become fairly exhaustive and chasing around for the source of vibration is not always as simple as we could hope. Things to test include: worn bearings/hubs, bad tires/bent rims (which may or may not show up when balancing if the operator is looking for the issue), exhaust parts touching the frame, loose mounts on the motor transmission or front differential, worn ball joints, worn inner or out tie rod ends, worn control arm bushings or torsion bar pads, and loose or deteriorated body mounts. Obviously there can also be internal issues with the differentials and axle seals.

I think i will also try removing the front drive shaft as you suggest here. Somehow i missed this suggestion, i will double check, but i cant recall there even being a boot on that driveshaft at all. Its 4 oclock in the morning and i might go out there and check it

EDIT- yes there is an intact boot, will try this out tomorrow
 






If you hold your foot on the brake and shift from park to drive, or from drive to reverse, is there and audible *clunk* or odd noise that you hear or feel? That also could be an indication of bad u-joints. Mine did not seem to have much rotational play, but after doing some research here and elsewhere, I decided to swap them out not really expecting to have a solution to the vibrations. But yep, that what it was. New u-joints, no vibrations.

There is no audible clunk, but i think im going to replace them anyway out of hand as well
 






the speed related sound seems like wheel bearings. Have you checked the upper and lower ball joints for play? could be the cause of your shudder over bumps.

Ball joints are nice and tight, and there is some improvement since the first post. That speed related noise seems to be gone.

Whats left is the shudder. Ill try and describe it more effectively, it seems to manifest itself up through the driver rear to everyone, but im betting thats an illusion.

Its like if you are driving an old truck and hit a bump and the rear suspension hops to the right or left. That jarring sensation. The suspension isnt hopping, but there is a definite jarring shudder that seems to reverberate after each bump.

Its bad enough we dont take this vehicle on long highway drives as its sort of scary to hit a bump on the highway. It can definitely be felt through the steering as well. I was complaining elswhere about a steering "quaver". A skittishness up front as well. That was greatly improved by tightening down the shocks properly, but something is still up. The core problem still persists somewhere

My next plan is to remove that front driveshaft and see what happens
 






Yeesh, totally defeated removing front driveshaft. 4 bolts on the front U joint are seized pretty bad with rust. Broke off a socket and a torx head bit after a good soaking. Transfer case side came off great.

Had to put it back together so the wife could get to work, will have to go round 2 later with heat, but im going to order the Ujoints and the pinion seals for the diffs first. Might as well do it all at once if its going to be a 4 hour ordeal undoing those 4 bolts
 



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Have you checked the front bump stop clearance? Bottoming hard could cause major oscillation and shudder. New front shocks will do little to dampen weak torsion bars. A good test might be putting chalk on the bump stops and checking for witness marks on the LCA's. Solution may be simple as tightening torsion bolts. Rear should be OK since you installed new 3 leaf packs. Look anyway.
 






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