Re: Vibrating resonance + rough driving at highway speeds.
> On Sat, 08 Oct 2005 19:23:27 -0500, Ford Warrior wrote:
>> 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
>> Above 70mph the problem seems to taper off. I've tried opening the
>> 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
> 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
> 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.
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?