Intermittent vibration

Not sure how best to describe this. I have a 2001 F150 with less than 70K on it, runs fine mostly. For the past few months while driving at speed, say 60 or so, it will start vibrating as if it's running on something less than 6 cylinders. I can see the steering wheel shaking and it's hard to tell if it's the engine or something else. I watched the tach today when it happened and it was spot on at round 2K RPM, didn't move one bit, so I'm not sure if this means it isn't the engine. I've never heard of out of balance wheels cause this intermittently. I would think if it was that, it would always act the same way. Then if I slow down to 40 or so, it seems to go away and I can get up to speed again with no problem.

Any ideas would be appreciated.

thanks

Reply to
stonecreek
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On Sun, 20 Apr 2008 12:18:13 -0400, stonecreek rearranged some electrons to say:

Front end out of alignment?

Reply to
david

Vibrations can be caused by wheel balance, irregularly worn or faulty tires, and road surface imperfections. Tires can bruise like humans do, but don't have the ability to heal. Once a tire is damaged, it only gets worse. Worn front end and suspension parts, and wheel misalignment can make those vibrations much worse, but worn parts and misalignment don't CAUSE vibrations. A shaking steering wheel would indicate the shake is coming from the front end of the vehicle, as opposed to the seat of the vehicle shaking indicating the issue is coming from the rear of the vehicle. A pulsation in the brake pedal AND the steering wheel would indicate front rotors/brake caliper issues.

You should rule out engine tune and drivability issues, then focus on the front tire/wheel/suspension area as the culprit.

Wheel balance often shows up worst at one particular speed or another.

45mph, 60mph, etc.

When I ran a repair/service center I always recommended wheel rotation and balance with every other oil and filter change. More often for severe service. Wheel alignment should be checked at least once a year, twice to stay ahead of problems, or immediately after striking something in the roadway or off roadway.

Spdloader

Reply to
Spdloader

My guess is a tire balance problem.

Have the tires balanced.

Tire balance sets up a harmonic that might not exist (have an effect) at 58, but shakes like crazy at 62. It could then go away at 72. This is a very common occurance when tire balance is the problem. Shock wear plays into this too. The shocks work within the same narrow range more than 90% of the time. If they wear in this narrow range AND the tires go out of balance, then the shaking that results from the balance and might otherwise be soaked up by the shocks will get transmitted throught he steering wheel or the seat.

My guess is you are on the stock shocks and have tires worn down about half way.

Reply to
Jeff Strickland

If intermittent, I doubt it is a wheel/tire problem. Something to look at is your E-brake. If it gets hot due to rubbing, you will get just that symptom. Vibration that comes and goes. Had that problem on my 04. Check and make sure that the e-brake shoes are not loose and rubbing. I know of someone else who had shoes separate from the backing plate and cause similar and other problems.

Reply to
Marlin Singer

Except that the OP says his symptoms are speed related. Once the brakes get hot they will remain hot, and whatever vibration is set up would return as soon as the speed comes back. That is, if the brakes get hot and cause a vibration, the speed is dropped to 40 then returns to the previous level, the vibration would also return. He stated that he could drop his speed then resume and the vibrations do not return.

My money is on tire balance.

PS If some moron comes along and top posts, it makes it better for everybody if you would bite your tongue and top post too. The only thing worse than a top poster is the person that follows and refuses to follow the format.

Reply to
Jeff Strickland

Thanks Gents. I rotated the tires front to back after I posted. Wow. I've taken lots of wheels off in my time, but two of them just wouldn't come off. I even drove a couple of miles with the lug nuts loose to try to break them. Eventually had to use the torch. But I won't know if the rotation did anything for a couple of days. Thanks for the posts. Don't be too hard on the top posting guys.

Reply to
stonecreek

You need to have the tires balanced. Rotating is never bad, but if the tires are out of balance, they are still out of balance at the other end of the car.

Reply to
Jeff Strickland

"stonecreek" wrote: (2001 F150 70k)

Recently, while driv My guess is a tire balance problem. Have the tires balanced. ________________________________________________________

"Marl If Except that the OP says his symptoms are speed related. Once the brakes get hot they will remain hot, and whatever vibration is set up would return as soon as the speed comes back and they reheat. My money is on tire balance. _____________________________________________________

Yes, imbalanced tires can vibrate intermittently. There is some speed at which they are ready to break into harmonic oscillation. The next time they reach that speed a slightly different road surface may not trigger the vibration.

I once had a similar intermittent vibration at 55 to 65 mph that was shuddering caused by a failing TCC lockup clutch. But the OP noted steering wheel vibration, pointing to tires.

Good luck.

Rodan.

Reply to
Rodan

While I agree most times this time perhaps not. By rotating the tires the symptoms should change,ie instead of feeling it in the steering wheel, he should start feeling it in the seat if the problem is wheel or tire related. I've seen control arm bushings cause the symptoms he describes and one thing to try but not in heavy traffic is to hit the brakes a quick hard stab and see if the vibration stops. I have also seen tires in the early stages of a belt seperation cause this. Also what tires are on it?

Whitelightning

Reply to
Whitelightning

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