Vibration

[Tazman]

That is a very good question.For the last eight weeks my truck has not gone much due to a coworker doing all the driving to work.So the truck was only used around home where you never go over 45.A couple of weeks ago I had to dive a day or two and that is when I started to notice it,yet still not driving a lot to worry about it.Slowly that changed and I thought it was the three year old tires.So with the alignment already done I had them rebalanced.That is when everything else took place.Like I said the bearings were replaced when I did the rotors and pads.I will check the bearings first and go from there.Thanks

[Captkaos]

Is the vibration coming from the front as in the steering wheel is "twitching" or you feel it is in the front.
Check the idler arms and tie rod ends also.

[diphthong]

Automotive vibrations are the product of unbalanced kinetic energy.  Vibrations can not be achieve by loose or worn front end parts.  They are a phenomena, created by (usually round) unbalanced heavy objects spinning at high speed. Period.

KINETIC ENERGY
"The energy an object displays or possesses because of some kind of motion or action."


SPINNING THINGS.
What would the results be if a two ounce wheel weight was installed on the blade of a perfectly balanced ceiling fan?  If turned to high, The fan would fly-apart or be a wobbling mess.   Now, Imagine if you could increase the RPM's of this fan by four times.  Tires on a car traveling 60 MPH rotate 400% faster then any ceiling fan on high. The energy this rotating action creates is called kinetic. Basically; the faster an object is moving, the larger the radius, and the more it weighs, combined to determine how much energy an object can possess.

Why do vibrations have the pattern or frequencies they have?  Why do vibrations intensify with speed?  The reason is;  Vibrations usually come from the tires on the non-drive axles, which are propelled by the forward motion of the vehicle's own kinetic energy.  Meaning, Tires rotate at speeds relative to their radius and the vehicle's speed. 

There is a difference of dynamics going on between front and rear wheel driven vehicles, i.e. Vibrations coming from a front tire on a (rear wheel) drive vehicle, can produce more energy then a front tire on a (front wheel) drive vehicle.  The reason is; the drivetrain seems to hold back the kinetic energy some, it's not so free flowing.  I have personally never seen a front wheel drive vehicle bounce a front tire off the road, unlike the early F-150 I saw on the freeway the other day.  The left front tire had to be bouncing up and down 3 inches.  I'm not 100% sure physics will back up my last point, but I bet it does.

Vibrations that come from Driveshafts, torque-convertors, and the like, rotate relative to the engines RPM's not the vehicle's speed. The large radius, weight, and RPM's of tires and wheels make them the best suspects for vibrations.  The amount of energy they can display is astonishing!  Enough energy can be produced to bounce a tire off the road - on a vehicle weighing thousands of pounds, is in-effect stuck to the Earth by gravity and simultaneously hurdling down the road with it's own kinetic energy
 


LOOSE THINGS
Say you forgot to install an inner front wheel bearing.  How would this manifest into a drivability issue? The truth is; at most, you'd hear (save for the casual clunk) is a slight to moderate growl, or maybe feel a slight vibration with no discernible pattern. Actually; all you really have here is, the rotor grinding down a spindle.  The type of energy created here is heat not kinetic.  Save for the "casual clunk" there is nothing here that would suggest the area where the spindle and rotor are grinding, would be forced apart.  And certainly; never in an rapid up and down motion, which basically is - what a vibration is.

On the other hand, loose parts can... "contribute" to a vibration.   But in 15 years of brake & front end work, and another 15 years of servicing a rural UPS fleet.  I've seen only one time, what I would call a loose front end part proportionally more responsible for a vibration, then the balance problem was. It was 1983 the car was a 1976 Ford Capri, the write up said "check vibration."  The relatively thick rack and pinion bushings had become so oil soaked, they had completely deteriorated.  Nothing was supporting the rack, it was basically free floating between the U brackets and the car's body.  Even with this unusual condition, it still took a balance problem in one of the tires, for me to experience that unforgettable test drive.

CONCLUSION
How many times have you said, or heard anyone say "man that camshaft sure was causing a bad vibration?"  My guess is, you've never heard this, nor will you ever.  The reason for this is; camshafts don't have the mass or radius to get a detectable vibration going.  Sure it has the speed but it's missing the other two essential components; namely, weight and radius.   Parts like; idler arms, steering dampeners, tie rod ends, ball joints, are in fact missing all three components needed to generate a vibration.  And that is why it's nonsense to suggest these front end parts can cause vibrations.  Look guys, it all breaks down to this; vibrations require energy, energy requires movement. It's that simple, and once you understand this, 90% of your vibration issues are over.


Hope this helps...


   

[diphthong]

On the other hand, loose parts can... "contribute" to a vibration.   But in 15 years of brake & front end work, and another 15 years of servicing a rural UPS fleet.  I've seen only one time, what I would call a loose front end part proportionally more responsible for a vibration, then the balance problem was. It was 1983 the car was a 1976 Ford Capri, the write up said "check vibration."  The relatively thick rack and pinion bushings had become so oil soaked, they had completely deteriorated.  Nothing was supporting the rack, it was basically free floating between the U brackets and the car's body.  Even with this unusual condition, it still took a balance problem in one of the tires, for me to experience that unforgettable test drive.

CONCLUSION
How many times have you said, or heard anyone say "man that camshaft sure was causing a bad vibration?"  My guess is, you've never heard this, nor will you ever.  The reason for this is; camshafts don't have the mass or radius to get a detectable vibration going.  Sure it has the speed but it's missing the other two essential components; namely, weight and radius.   Parts like; idler arms, steering dampeners, tie rod ends, ball joints, are in fact missing all three components needed to generate a vibration.  And that is why it's nonsense to suggest these front end parts can cause vibrations.  Look guys, it all breaks down to this; vibrations require energy, energy requires movement. It's that simple, and once you understand this, 90% of your vibration issues are over.
   

[79 chevy]

i had the same thing going on in my truck but didnt think to much becasue when i put my new wheels and tires on one one wheel is a little bent so i put it in the back but i went to get it inspected and tie rod was bad so i changed it and the vibration was gone so maybe this is what ur having problems with.

[diphthong]

Loose front end parts do not cause vibrations. In over 30 years of fixing cars and trucks, I've never seen it. Somebody please explain to me the physics behind a loose tie rod end developing or contribute to sufficient enough kinetic energy being produced to shake a car. 

What will happen in the case of a very loose tie rod end is this. The force of the road on the tire will force that tire to toe out, (or in, but probably out ) but the point is, the car's own forward energy and gravity will hold the tire either out or in. It's not going shake.  Here's what you can do, find a mechanic engineer and explain to him/her your idea.  You will real fast get a lesson in kinetic energy.

Think about it, in your scenario the only possible explanation is,  the looseness in the tie rod end would allow the spindle and tire the move rapidly in a left and right direction
perpendicular to a vehicle.  Have you ever seen that on the highway?  a tire moving rapidly perpendicular to a vehicle left and right.  The answer is no, unless the wheel is bent or the tire is coming loose.  But you probably have seen a tire moving  up and down rapidly.  Now, that will cause a vibration.

Really, I'm only trying to help.

[ehjorten]

Driveline?  Bad u-joint?

[Irish_Alley]

seen a loose lug nut cause a vibration

[diphthong]

Yes! Loose lug nuts can cause vibrations.  That's because, were getting back to the tires... Where the kinetic energy is being created.  Drive shifts yes, all day long can cause vibrations. 

Remember this, vibrations need energy, and energy comes from movement.
Ball joints, tie rod ends, steering dampeners, idler arms, they don't move, other then
their attached to a moving vehicle.




I once had a shop owner tell me "it's not impossible to have just one plug wire crossed"   :-)

[Irish_Alley]

ball joints and tie rods have ball joints which do move.

[diphthong]

ball joints and tie rods have ball joints which do move.

Yup... But this type movement is not what cYup... But this type of movement doesn't create kinetic energy. Here is something I wrote, and posted yesterday.

"Vibrations can not be achieve by loose or worn front end parts.  They are a phenomena, created by (usually round) unbalanced heavy objects spinning at high speed. Period."

 There are three things required to developed sufficient energy to be noticed as a vibration.  Weight, speed, and radius.
 
The more it weighs, the larger the diameter, and the faster it's spinning, all combined to determine how much kinetic energy
an object can display (and, it's this displaying action that manifests it's self as a vibration.)   How much does the pivoting end of a tie rod end weigh?  Not much.  How fast does a tie rod end spin?  Actually, it doesn't spin, it just twists a little, probably less then 50 deg.  in both directions. 

Round heavy spinning objects create and store large amounts of energy very efficiently.  That's why objects like, tires & wheels, torque convertors, brake drums, driveshafts, crankshafts, are balanced before they start to do their job.  How many times have you heard said, "Man that cam shaft sure was causing a bad vibration."  odds are you haven't, the reason is, camshafts don't weigh enough and their radius isn't large enough to cause a problem if they were to become off balanced.

Vehicles traveling down the road are an amazing thing.  They have all this stored energy. And, going on inside and under, are all these other spinning heavy objects with there own dynamics.  But, once that apple cart gets disturbed, things happen very rapidly. People do get hurt, one time I've seen the results of a out of balanced tire, after it had torn a spindle apart.
 

Hope this help...


I once had a shop owner tell me "it's possible to have just one plug wire crossed"   :-)

[diphthong]

Sorry guys, for the multiple posts. I been using an iPad app to post.  It would sometimes leaving off half my words, and other times,  appear to post none. 

[Blazin]

I've been working on vehicles for 30 plus years as well. I have had bad tie rods create a vibration. They have to be really lose to do so, like ready to fall apart lose, but they can. If they are lose enough they will cause a wheel, and tire to wobble the simalar to a lose lug nut.

[79 chevy]

yes mine was very bad i cant believe i was driving with it i knew it had to be it becasue that is all i changed and the shacking stopped

[diphthong]

Ok, so what kind of a pattern would the situation, a tire wobbling like you suggested,
from a loose tie rod end, leave on a tire? 


I once had a shop owner tell me "it's possible to have just one plug wire crossed"   :-)