Vibrating resonance + rough driving at highway speeds.

Hiya

I just bought a 1995 Ford E250 Cargo van with 3-speed auto, 4.9L L6, 176k miles. The tires are brand new Kumho Road Venture AT (P225 75R16 104S) truck tires. The car drives fine at normal speeds but I do hear some knocking/wobbling sounds coming from the passenger side front wheelwell that goes away while the brakes are applied. The major problem is that when driving at highway speeds from 55-70mph a loud deep vibration/resonance is felt throughout the cockpit.. it feels and sounds like I'm sitting on a huge vibrator for lack of a better description. There is also a quiet high-pitch whining sound that increases along with the deeper rumbling/vibration. It seems like the entire vehicle just starts resonating at this speed and it increases as I accelerate from 55 to 65mph. Above 70mph the problem seems to taper off. I've tried opening the windows with no effect. Also just had to put in a new radiator and fan clutch for cooling reasons which didn't alter this problem at all. This is going to be a major problem for me because I'm about to do 1500 miles highway driving cross country not only for comfort but I worry about gas mileage being affected as well. Already had the alignment and tire balance checked and corrected without fixing the problem. The mechanic has also checked everything over underneath the car and could find nothing loose or seemingly wrong that could cause the rough highway driving. Is it possible these Kumho 'AT' tires are to blame for the problem or should I check other things? I don't do any off road driving and I'm wondering If I should have forced them to install some less aggressive tires.

Any help is appreciated as always

thanks Jay

Reply to
Ford Warrior
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It seems like the entire vehicle just starts

It really sounds like your front tire is out of balance. Bring it to another tire shop. Balancing a tire correctly isn't as simple as one would guess.

Reply to
Lance LaFrinier

Also have the tires checked for OUT OF ROUND. I had this problem on a vehicle and this was the cause. Balancing did nothing for the out of round and dealer replaced tires (2) WW

Reply to
Warren Weber" <hiview68NO

You could easily be describing a bad u-joint in the driveshaft. It can act just like you describe and the sound/vibration is really sneaky about 'seeming' to come from one area or another.

To check them, you need to block the wheels and put it in neutral so you unload the drivetrain, if it's in gear or park it cannot be tested, then go under and look for any slop or rust stains around the u-joint caps. Only 'no' play is acceptable and if you see rust stains, that usually means the needle bearings are dead or very soon about to be dead.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

Ford Warrior wrote:

Reply to
Mike Romain

Mike,

Thanks again for your help.. I remember you posting some tips a week ago on an overheating problem I was having with the same vehicle that helped me out. I have no experience working with the drivetrain, but I have Haynes, Chilton, & Ford Factory service manuals for the van and will definitely start digging around this week. Regarding the rust.. this vehicle originally came from Florida.. and 75% of the chassis underneath is covered with rust.. including splotches all along the driveline.. so what you are recommending may be the route I need to go. I was originally thinking it must be the aggressive tread on these new tires but now I'm not so sure. If you have any further tips or items to check out while I'm under the van just let me know.. all the help is appreciated.

Over and out Jay

Mike Roma> You could easily be describing a bad u-joint in the driveshaft. It can

Reply to
Ford Warrior

IIRC, you have a 2 piece drive shaft in that one. If so, check the center support and bearing very closely. Sometimes the rubber deteriorates and lets it more or less float free causing a vibration.

Lugnut

Reply to
lugnut

Because brake application seems to lesson the vibration, check out your wheel bearings.

bradtx

Reply to
bradtx

Hello Jay,

To start, have your tires checked for balance, spin balance not "bubble" balance. At the same time have them checked for "out of round" and "true" (side to side). Check for bubbles in the tread area (tread separation) and broken steel belts (twisted tread), also watch for deformations in the sidewalls (broken body cords). Some of these conditions are a blowout waiting to happen. Also, check to see if your wheels are bent, cracked or have broken welds or rivets.

Have your wheel bearings checked, make sure they are lubed and adjusted properly. Rear wheel bearings are lubed by the gear oil in the rearend, make sure it is full. On drum brakes, make sure that there no loose or broken parts floating around side the drum. If there are, they will be trying to lockup your wheels (this can sometimes feel like a vibration, however this usually makes a grinding sound).

As noted in other posts, check your u-joints, center support bearing and slip-joints. Make sure all are tight, with no powdered rust coming out of them. Make sure there is no play in them, rotationally, side-to-side, up and down or front-to-back. Replace and lube parts as needed.

Also, the driveshaft may be out of balance, or it may have been reassembled wrong at some time in the past, this will most likely have happened at the slip-joint at the center support, all u-joints "MUST" line up. Or, you might have a bent drive shaft, not to likely, but I have seen it.

Be sure to block your wheels, or support the vehicle on jack stands, before placing transmission in neutral. (I like jack stands, gives me more room to work.)

Any of the above problems can give you the problems you are describing.

Oh, two more I was forgetting about, a vibration dampner that has "shifted" and a cracked flex plate. The only one of these problems that stepping on the brakes will have no direct effect on is the dampner, as there is no change in the loading on that part, only the engine speed.

If you get no vibration while sitting still, in neutral, while changing engine speed, then it is probably not the dampner. A cracked flex plate vibration will normally only show up while under load, unless it is very severe.

Some of these problems will very hard to spot in the shop, unless one is very through and willing to take the time. Some of these are easier to spot during a road test, with a "chase car" to look for problems.

Yes, I have seen or experienced all of these problems. Once I had a tread seperation on a right front tire, mimic a sever vibration in the left front, before coming apart and beating the hell out of the right front fender and ripping out the inner fender liner.

I once saw some retread tires that were so out of round, that the only thing that allowed the owner to drive his truck in to the shop was the trucks soft "worn out" suspension.

Yours, BigDave

Reply to
bigdave

Big Dave & others.. thanks a ton for the responses and suggestions... I just replaced the U-joints myself today but am still having the problem.. so I'm back to the drawing board as they say. There is no center support bearing on this driveshaft as it is a one piece type. There is a large amount of corrosion/rust spotting the entire surface of the driveshaft and I was thinking I may need to have a professional check out the balance. Also since checking this further it seems to me the vibration/rumble is increased greatly when I really give it the gas and reduced when I let off. ie if i'm just coasting along without much acceleration, the vibration is lessened. The peak of the vibration/rumble seems to be centered around

65mph. I can feel it most right through the driver's seat and also In the steering wheel.. but of course it really is penetrating the entire vehicle i guess. I did notice when I let someone else drive that it is felt much less on the passenger side. The mechanic claims the tires are good and has balanced them twice since first installing them new a couple weeks ago. I've noticed some references in other group postings so something called a harmonic balancer. Any idea if such a thing exists on this E250? How do most shops check driveshaft balance?

thanks Jay

Reply to
Ford Warrior

I know of 4 instances where the drivers had the same problem and the same report on tires. After they got the tires changed, the problem went away. Did you buy the tires? How amenable does the dealer seem to be? Will he consider perhaps changing out tires in the name of customer good will?

Maybe, if the spare is a full-size one, you might replace the one that sounds funny with the spare for a month or a week - and if this is not the one, do the same for all - replace each by the spare for a week or two and see what happens. (?)

H.

Reply to
Rowbotth

Another update: As I said before I put in new U-joints with no improvement and the driveshaft is the one piece type. I have pulled the driveshaft out again and now that I look more closely I'm noticing further issues. The rubber transmission extension output seal where the driveshaft yoke meets the transmission output has some small tears and is leaking slightly. Also there is a fairly large amount of play in all directions from the transmission output shaft spindle. ie If I put the vehicle in neutral I can wobble it by hand. Is this normal? I'm thinking perhaps I need to replace the bearings in the output shaft of the transmission. Would this require complete transmission tear-down? Any thoughts as to whether this could be the culprit of the vibrations?

thanks again Jay

Reply to
Ford Warrior

If it is similar to vehicles that I have worked on, the output shaft bushings actually support the slip yoke of the driveshaft, so not necessarily. Are you checking this with the driveshaft installed or removed?

Are your rear springs sagging/do you usually drive the van heavily loaded? you may have a pinion angle issue

the knocking/wobbling sounds from the front end sound like a loose caliper and/or some anti-rattle hardware was left out at the last brake job, might want to take a look at that corner

good luck,

nate

Reply to
Nate Nagel

The noise in the front could also the front anti-sway bar vibrating, they are known to get loose in, and even come out of, the bushings.

Spdloader

Reply to
Spdloader

The vibrations you described sound exactly what I had on my car, they even happened at similar highway speeds of 65-75 mph. Above that the vibration sort of became less pronounced. I should say that my tires were pretty worn out at that stage.

Perhaps your car's body has some resonance frequencies that are amplified in that speed range.

Once I got a new set of front tires (properly balanced), the vibration disappeared.

While you probably think that the problem is not with the tires, at least swap the front and rear ones and see if the problem persists. This would rule out the possibility of something being really screwy with the front tires.

Mike

Reply to
mrpresident0002

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