Vibration

Dartanion · 01-09-2008, 06:14 PM

Hello to all.

I'm a newbie to the forum, and ,I have a question about my wifes 1993 Chevy 4x4 it has a 350 with overdrive an its a extended cab. Yes my wife has a 4x4 a black beauty as I call it. Now the problem with this truck is that when we are driving down the road a vibration will occur from what I can,tell is in the rear part of the truck, if you let off the gas it goes away, if you step back on the gas it may reappear or it may not, if it does reappear and you apply more gas it goes away. Has anyone experienced this type of problem? And if so how may i go about correcting it? Will post a picture if I can figure out how to post it.

436'd skylark · 01-09-2008, 07:48 PM

definitly described the characteristics of a blown or seized universal joint. pull the shaft and inspect!

Dartanion · 01-09-2008, 09:19 PM

Will be dropping the drive shaft on Saturday and checking the u's possibly replacing them.

75K30 · 01-10-2008, 03:24 AM

May want to check the center support bearing, and the slip yoke. You ahve a 2 piece rear drive shaft and the slip yoke can get dry. Dry splines can cause all kinds of problems.
Believe it or not, I have had the best luck with Ford "blue" grease for these areas, as well as the problematic steering shaft problem. Seems to last longer than other lubricants.

Dartanion · 01-11-2008, 11:53 PM

Well i have drop the drive shaft tonight after work and the front u look to be ok and the rear u ok i guess i could move them. They didn't seem to be all that loose to me , or maybe i 'am not sure what i'am suppose to be looking for in the u joints, any suggestions from anyone?

75K30 · 01-12-2008, 12:01 AM

U-joints not all that loose? Any movement from a u-joint is bad. U-joints need to be tight with no movement, but should rotate freely, with no resistance. Siezed joints can appear to be tight. So tight that they do not move at all, and that is really bad.
Be carefull not to let the caps fall off, when you remove the retaining straps. Darn needle bearings and dirt are no fun.

Dartanion · 01-12-2008, 12:19 AM

Ok the u joints can move some with no resistance, I can take two fingers and move them back an fourth. I have a new rear one that I'm going to put in today.The front joint moves also but the slip yoke is still attached so i would say the front can just slap around with the weight, is this good or bad?

75K30 · 01-12-2008, 09:21 AM

Any movement is bad. If it can move, it will, especially under load.
That is the short answer, here is a little longer one; Since a u-joint works at an angle, it is important to keep the angles to a minimum, since the two ends will be spinning on a similar shaft, one would think that the joits spin at the same speed,,,,well they do not. This is where some vibration can com from. Just as a sphere that spins can have different speeds from the center to the top and the bottom, the same is true for universal joints. If they are allowed to spin (rotate) on a differnet axis than the one on the other end, it forms a different eliptical path, and creating a difference in the speed of one joint over the other. Now if the joint is loose, it moves at an even greater difference in eliptical path, and aside from it just flopping around, it is really this difference in path that creates vibration.
Know that got a little technical, but I thought an explaination was in order. Pretty sure someone can use this info if they perform a search later.
Your joints should have no play in them at all. The slip yoke in the trans should also have as little movement as possible.
Good luck, those factory universal joints have a plastic filler in the cap to retain them to the shaft, and require a "giant press", and an operator with no regard for saftey, or a torch with just enough heat to melt the plastic, and not too much that might ruin or deform the shafts ears.
This is probably not something you are going to do at home with a vice and a BFH.
Would take a mighty big swing to break the plastic that holds these things in. Replacements will have conventional clips to retain them making future replacement a snap, but the factory ones are tough.

Dartanion · 01-12-2008, 06:31 PM

Hey guys I replaced the rear u joint today the other u look to be ok not and took a test drive and low and behold that darn vibration was still there, but now it feels like maybe somewhere under front end now, you can feel it in the steering wheel when it starts also on the gas pedal to, so i have begun to pull out what is left of my gray hair, any ideas would be deeply appreciated.

Dartanion · 01-12-2008, 07:18 PM

Ok Gentlemen i just crawled out from under the vibrating truck was just looking at some things and I noticed the the exhaust pipe is resting on the frame. Would this cause a vibration? There is a spot on the exhaust pipe that appears to have been rubbing on it because there is some rub spots on the pipe.

01-09-2008, 06:14 PM	#1
Dartanion Full Member Join Date: Jan 2008 Location: Camargo Illinois Posts: 27	Vibration Hello to all. I'm a newbie to the forum, and ,I have a question about my wifes 1993 Chevy 4x4 it has a 350 with overdrive an its a extended cab. Yes my wife has a 4x4 a black beauty as I call it. Now the problem with this truck is that when we are driving down the road a vibration will occur from what I can,tell is in the rear part of the truck, if you let off the gas it goes away, if you step back on the gas it may reappear or it may not, if it does reappear and you apply more gas it goes away. Has anyone experienced this type of problem? And if so how may i go about correcting it? Will post a picture if I can figure out how to post it.

01-09-2008, 07:48 PM	#2
436'd skylark Senior Member Join Date: Mar 2007 Location: Buffalo Ny Posts: 620	definitly described the characteristics of a blown or seized universal joint. pull the shaft and inspect! __________________ Joe 89 K2500 Chevy, Wee-Oh-five 285K miles, completly rebuilt needs a motor, bad 1962 IHC Scout All Wheel Drive (Scout speak for locking axles) 152 ci, dana everything else

01-09-2008, 09:19 PM	#3
Dartanion Full Member Join Date: Jan 2008 Location: Camargo Illinois Posts: 27	Vibration Will be dropping the drive shaft on Saturday and checking the u's possibly replacing them.

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01-10-2008, 03:24 AM	#4
75K30 Senior Member Join Date: Jul 2006 Posts: 2,518	May want to check the center support bearing, and the slip yoke. You ahve a 2 piece rear drive shaft and the slip yoke can get dry. Dry splines can cause all kinds of problems. Believe it or not, I have had the best luck with Ford "blue" grease for these areas, as well as the problematic steering shaft problem. Seems to last longer than other lubricants.

01-11-2008, 11:53 PM	#5
Dartanion Full Member Join Date: Jan 2008 Location: Camargo Illinois Posts: 27	Well i have drop the drive shaft tonight after work and the front u look to be ok and the rear u ok i guess i could move them. They didn't seem to be all that loose to me , or maybe i 'am not sure what i'am suppose to be looking for in the u joints, any suggestions from anyone?

01-12-2008, 12:01 AM	#6
75K30 Senior Member Join Date: Jul 2006 Posts: 2,518	U-joints not all that loose? Any movement from a u-joint is bad. U-joints need to be tight with no movement, but should rotate freely, with no resistance. Siezed joints can appear to be tight. So tight that they do not move at all, and that is really bad. Be carefull not to let the caps fall off, when you remove the retaining straps. Darn needle bearings and dirt are no fun.

01-12-2008, 12:19 AM	#7
Dartanion Full Member Join Date: Jan 2008 Location: Camargo Illinois Posts: 27	Ok the u joints can move some with no resistance, I can take two fingers and move them back an fourth. I have a new rear one that I'm going to put in today.The front joint moves also but the slip yoke is still attached so i would say the front can just slap around with the weight, is this good or bad?

01-12-2008, 09:21 AM	#8
75K30 Senior Member Join Date: Jul 2006 Posts: 2,518	Any movement is bad. If it can move, it will, especially under load. That is the short answer, here is a little longer one; Since a u-joint works at an angle, it is important to keep the angles to a minimum, since the two ends will be spinning on a similar shaft, one would think that the joits spin at the same speed,,,,well they do not. This is where some vibration can com from. Just as a sphere that spins can have different speeds from the center to the top and the bottom, the same is true for universal joints. If they are allowed to spin (rotate) on a differnet axis than the one on the other end, it forms a different eliptical path, and creating a difference in the speed of one joint over the other. Now if the joint is loose, it moves at an even greater difference in eliptical path, and aside from it just flopping around, it is really this difference in path that creates vibration. Know that got a little technical, but I thought an explaination was in order. Pretty sure someone can use this info if they perform a search later. Your joints should have no play in them at all. The slip yoke in the trans should also have as little movement as possible. Good luck, those factory universal joints have a plastic filler in the cap to retain them to the shaft, and require a "giant press", and an operator with no regard for saftey, or a torch with just enough heat to melt the plastic, and not too much that might ruin or deform the shafts ears. This is probably not something you are going to do at home with a vice and a BFH. Would take a mighty big swing to break the plastic that holds these things in. Replacements will have conventional clips to retain them making future replacement a snap, but the factory ones are tough.

01-12-2008, 06:31 PM	#9
Dartanion Full Member Join Date: Jan 2008 Location: Camargo Illinois Posts: 27	Hey guys I replaced the rear u joint today the other u look to be ok not and took a test drive and low and behold that darn vibration was still there, but now it feels like maybe somewhere under front end now, you can feel it in the steering wheel when it starts also on the gas pedal to, so i have begun to pull out what is left of my gray hair, any ideas would be deeply appreciated.

01-12-2008, 07:18 PM	#10
Dartanion Full Member Join Date: Jan 2008 Location: Camargo Illinois Posts: 27	Ok Gentlemen i just crawled out from under the vibrating truck was just looking at some things and I noticed the the exhaust pipe is resting on the frame. Would this cause a vibration? There is a spot on the exhaust pipe that appears to have been rubbing on it because there is some rub spots on the pipe.