vibration
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
Willie,
That's a good point. When multiple tires are out of balance/round it is common to get a cyclic droning. That is, the vibration is usually high frequency and fades in and out. The tires imbalance are adding and subtracting from/to each other. A good way to test this is to pull off the road when the vibe starts, turn the vehicle in a 360 tight circle and get it back on the road to see if you can repeat the vibe. If you can pull the tires out of sync, you should be able to change the vibe. Does that make any sense?
Consider it,
KingFisher
That's a good point. When multiple tires are out of balance/round it is common to get a cyclic droning. That is, the vibration is usually high frequency and fades in and out. The tires imbalance are adding and subtracting from/to each other. A good way to test this is to pull off the road when the vibe starts, turn the vehicle in a 360 tight circle and get it back on the road to see if you can repeat the vibe. If you can pull the tires out of sync, you should be able to change the vibe. Does that make any sense?
Consider it,
KingFisher
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
All,
Honestly, the easiest way is to, take it to a tire shop and have them balanced, DUH! But, of course this takes money and time. I guess I should have recommended that right off the bat. Alignment is anther time and money issue but usually when an alignment is done the mechanic will tell you all the whoes of your truck. It's actually a strong investment. Get an expert's opinion and use your own judgement as how to solve the diagnonsis.
KingFisher
That's what I will do. It will save me hours of work.
Honestly, the easiest way is to, take it to a tire shop and have them balanced, DUH! But, of course this takes money and time. I guess I should have recommended that right off the bat. Alignment is anther time and money issue but usually when an alignment is done the mechanic will tell you all the whoes of your truck. It's actually a strong investment. Get an expert's opinion and use your own judgement as how to solve the diagnonsis.
KingFisher
That's what I will do. It will save me hours of work.
Senior User
Joined: Jan 2000
Posts: 315
Likes: 0
From: Virginia Beach
I have this same problem on my truck that I've noticed. It does not vibrate at all when I am driving normally, it only happens when I slow down, like for a stop-light. It usually starts as I slow through about 45 until I get to about 15-20 and goes away until I come to a stop.
I have new and balanced tires. Only thing I can think is last time I had the brakes open in the back, they weren't wearing even from side to side. I changed the pads, but one drum was more worn than the other. I'll have to have it turned I guess, only thing I can think off. I have new and balanced tubes on my driveshafts and the rear was rebuilt about 10k ago. Have to check the tolerances.
It is pretty dang annoying.
I have new and balanced tires. Only thing I can think is last time I had the brakes open in the back, they weren't wearing even from side to side. I changed the pads, but one drum was more worn than the other. I'll have to have it turned I guess, only thing I can think off. I have new and balanced tubes on my driveshafts and the rear was rebuilt about 10k ago. Have to check the tolerances.
It is pretty dang annoying.
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
Sig,
Youare describing a harmonic balancer or possibly a two-piece driveshaft (out of phase) vibration problem. These type of vibes show up on the decels. I would bet on the driveshaft being out of phase. Do you have a two-piece shaft?
KingFisher
Secondly, Is your brake pedal pulsing during braking? this is a low frequency vibe caused by out of round brake drums. fairly unusual?
Youare describing a harmonic balancer or possibly a two-piece driveshaft (out of phase) vibration problem. These type of vibes show up on the decels. I would bet on the driveshaft being out of phase. Do you have a two-piece shaft?
KingFisher
Secondly, Is your brake pedal pulsing during braking? this is a low frequency vibe caused by out of round brake drums. fairly unusual?
Senior User
Joined: Jan 2000
Posts: 315
Likes: 0
From: Virginia Beach
I'll take some pics of the driveshafts and post them. I had each one re-tubed and re-balanced a few years ago.
But if they are out of phase, all I have to do is unbolt one end, rotate 180 degrees and rebolt it, right?
But if they are out of phase, all I have to do is unbolt one end, rotate 180 degrees and rebolt it, right?
Elder User
Joined: Mar 2003
Posts: 588
Likes: 0
From: AZ.
I.M.H.O. Dfisher1 got it . A harmonic balancer will do just what you discribe . Had your truck backfired lately ? Do you jump on it once in a while ? The rubber between the two pieces of the balancer gets dry and they slip, putting the motor out of balance. It will slip back and forth depending on how you drive. Check the timing when it's vibrating. If it seems to be way off, that's probably the problem .. The timing won't actually be off, just the marks will have slipped ...Drive shafts hardly go out of balance unless they loose the weights or get damaged.
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Elder User
Joined: Mar 2003
Posts: 588
Likes: 0
From: AZ.
IMHO, dfisher1 got it ..When the rubber between the two parts of the balancer gets old and hard, they slip . Has it backfired lately? Have you "jumped "on it ? Check the timing. If it's off the marks, the timing of the engine is probably O.K. but the marks are wrong ..To double check, remove #1 spark plug. Bring the piston to top dead center and check the timing pointer on the balancer.
One for my '73 was a little over $100. at Ford...
One for my '73 was a little over $100. at Ford...
Senior User
Joined: Jan 2000
Posts: 315
Likes: 0
From: Virginia Beach
Hmm, I'm not describing it right. There is no vibration when the truck is sitting still, no vibration on acceleration when you leave the stop sign or stop light. It only happens on deceleration.
Both driveshafts were retubed after being bent last time it was taken offroad.
Both driveshafts were retubed after being bent last time it was taken offroad.
Elder User
Joined: Mar 2003
Posts: 588
Likes: 0
From: AZ.
Josh79........ Were your new U-joints made in USA ? Foreign made bearings of any kind aren't worth crap ..Your new ones may be trashed already .. They don't know how to make good steel nor make a perfectly round bearing ..
Sigtaunenus....... It is my understanding that on a two tube drive line, all U-joints should be in line .. I've used this theory and haven't had any trouble.. Maybe yours is off a spline or two.. ...How's the carrier bearing and rubber in the hanger? .Just a thought ...
Sigtaunenus....... It is my understanding that on a two tube drive line, all U-joints should be in line .. I've used this theory and haven't had any trouble.. Maybe yours is off a spline or two.. ...How's the carrier bearing and rubber in the hanger? .Just a thought ...
Thread Starter
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Senior User
Joined: Apr 2003
Posts: 330
Likes: 0
well i have got to notice that it does not vibrate all the time and most of the time it is not too bad when it does. it seems that when i hit the brakes at around 45 mph range it vibrates worse. it gets pretty violent. it has new front brakes so is something wrong with the rear drum brakes?
Lead Driver
Joined: Sep 2003
Posts: 5,241
Likes: 3
From: Other side of the sunrise
On radial tires, if the belts are sepparated from rock crawling or such, this will cause vibration at certain speeds. You'll notice the vib set in at a given speed then go away when you reach a higher given speed.
Mountain Pass
Joined: Jun 2000
Posts: 242
Likes: 9
From: earth
sigtauenus,
Is the vibration felt on decel like someone is rhythmically jumping up and down on the front bumper or is it an electric massager type of shake? I've had a vibration since I bought my truck and still haven't found the answer. The only time my truck ran smooth was when I slipped the clutch in once @ highway speed and it ran smoother than a babies butt. Came to a stop 100 miles later and the vibration was back (this was on the old engine). Dunno, but I've learned to deal with it for now.
I would check for out of round tires or bad shocks.
Good luck.
Chris
Is the vibration felt on decel like someone is rhythmically jumping up and down on the front bumper or is it an electric massager type of shake? I've had a vibration since I bought my truck and still haven't found the answer. The only time my truck ran smooth was when I slipped the clutch in once @ highway speed and it ran smoother than a babies butt. Came to a stop 100 miles later and the vibration was back (this was on the old engine). Dunno, but I've learned to deal with it for now.
I would check for out of round tires or bad shocks.
Good luck.
Chris