Bad vibrations at highway speeds

KB93z28

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Hi, I just recently about two months ago bought a 1999 GMC Sierra 1500 with the 4.8 v8, 4x4, reg cab, short bed, the truck is bone stock, with factory sized tires, which are maybe a month old. Just recently I have noticed an extreme vibration at highway speeds, it only happens when I am on the accelerator, but as soon as I let off the gas, it goes away, it is most noticeable at 55-60mph, but I only feel it when I put my foot into the gas. The vibration is very bad, the sensation is similar to driving on rumble strips. The vibraton feels like its mostly coming from my seat, not the steering wheel, so I dont think its a front end suspension, or tire balance issue, my guesses are bad u-joints, the drive-shaft needs to be balanced, maybe a bad torque convertor. I know my way around cars, I went to school for Auto-Tech, I was just wondering if anyone else has had this problem, and what they found was the problem. Any suggestions or help would be much appreciated. Thank you.
 

dlmiv

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Hey There, I too have a nasty vibration from about 68 mph until about 75 mph. I checked tie rod ends, upper and lower ball joints and wheel bearings. I replaced the main drive shaft u-joints 6 months ago and had new tires put on, balanced, and front end aligned. Took it to the dealer, they said the tires were out of balance, so they took care of that. They found the rear brake backing plates were just about rotted off, new rotors, pads and shoes. Just over $1000 and the brakes feel the same and so does the vibration. They said to bring it back, but I think I will try to find and fix it myself now. I used to spend a lot of time as a kid under the hood. This is a 2003 GMC 5.8l 4x4. I am going to jack up the rear axel and run her up to 70 mph, if no vibration, it will eliminate the main drive shaft and posible bent axels and I will work my way forward from there. Any suggestions or other thoughts would be appreciated. I will let you know what I find if anything.
 

ferretx9

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IMO -
I believe the problem lies within the transmission / torque converter .
My reasoning -

Tires - if out of balance / round the truck would vibrate at all speeds , it
would steadily get worse the faster you went but would always be there
. Its not like you can hit a magic speed that will cause them to become " balanced " .

Drive shaft / axles - The same principal as above , out of round / out of balance
doesn't appear than go away , it's constant.

It would seem ( to me ) then that you / we / us need to be looking for a moving part
that can and does have the capability to change characteristics at different speeds ,
weather its working correctly or not .

The only part I can come up with is the transmission /torque converter .
 

happy 2011

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ferretx9
Well what you think about balance is really not true. Many tire vib mostly only happen between 55 MPH to 75 MPH. Hardly ever below ot above this speed.
Also drive shafts can be very funny about when they vib and when they don't.
Sounds like you have a front U joint starting to freeze up.
Pull shaft and make sure it moves freely and has no play in the cups.
 

ferretx9

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ferretx9
Well what you think about balance is really not true.

Ya , you're probably right , just because I ran a TIRE shop for 3 years , dealt with hundreds
of customers , talked with and dealt with tire reps from most
brands out there and have read enough material to make War and Peace
look pale by comparison fool you .
 
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dlmiv

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Nasty vibration

Well, here is what I have found yesterday. I put the rear of the truck up on stands and ran her up to 70 mph. Though the vibration was not exactly the same, there was vibration. With it still in drive, I watched the driveshaft and there was a wobble to it. (The dealer said it was straight.) The local driveshaft shop is closed until Monday, so I pulled the shaft and took it to where I work to check the run out, its .070 out. I'm sure this is the problem. I work for an industrial pump and valve company and the machinist who straightens the shafts tries toget them to have no more then a few thousands run out. I'm just going to have a new shaft made and see what that does before I go any further.
 

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O sorry ferretx9 did'nt know you ran a "tire shop" for three long years!!!

But your right i Bet you know way more than i do!!! I have only ran a full service shop for 30 years!!!!!!!

Oya by the way if your so smart why are you asking us for help? You should know whats wrong.............. lol
I don't need to ask how to fix my stuff!
 

ferretx9

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O sorry ferretx9 did'nt know you ran a "tire shop" for three long years!!!

But your right i Bet you know way more than i do!!! I have only ran a full service shop for 30 years!!!!!!!

Oya by the way if your so smart why are you asking us for help? You should know whats wrong.............. lol
I don't need to ask how to fix my stuff!

To start ,
Unlike yourself , I never claimed to be a Mr. Know It All .

The man asked for thoughts / ideas / opinions and I told him
what I believed the problem to be based on reasoning and
and experience .

As for the " 30 years " , the good ones are able to retire
after 20...
 

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ferretx9
Well what you think about balance is really not true.

Ya , you're probably right , just because I ran a TIRE shop for 3 years , dealt with hundreds
of customers , talked with and dealt with tire reps from most
brands out there and have read enough material to make War and Peace
look pale by comparison fool you .

well frist off sounds like you were saying that well to put it nice.... Your the man lol with all the talk and so on If not then sorry.

2nd you only lasted three years and your all retired nice job!!
Me well i like money and what i do not bad for a 49 year old guy lol But maybe in 5 more years i will retire in style.
Maybe you could give me some pointers since you only had to dlo it for 3 years!!!:rolleyes:
 

dlmiv

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Hey, I got a drive shaft made. While they were taking the transmission yoke off the old shaft, they found that the ujoint caps were no longer a press fit in the yoke, so they got me a new one. Put the shaft in this morning before work and wouldn't you know it...........98% of all vibration is gone. Now I'm not sure if what is left is the replacement intermediate shaft they put in for the problems I was having with the notorious, intermediate steering shafts.
I am aware also that my left front wheel does not spin as easily as the right front, so that is another item I will look into.
 

dlmiv

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My reference to the intermediate steering shaft was not that it may be the cause of a vibration, but merely commenting that now I am feeling the road surface slightly, through the steering wheel. The original intermediate shaft was packed with grease and at times would begin to feel like the steering shaft was loose, the grease may have insulated some sensitivity. The replacement shaft may transmit more of the road serface to the steering wheel.
 

ferretx9

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2nd you only lasted three years and your all retired nice job!!
Me well i like money and what i do not bad for a 49 year old guy lol But maybe in 5 more years i will retire in style.
Maybe you could give me some pointers since you only had to dlo it for 3 years!!!:rolleyes:

I didn't say I retired , you came to that false conclusion on your own.

I " left " mainly due to the owner dying.

And - if you know it all , why are you here ? ?

Me thinks it's because all you've done for 30 years is
oil changes and lube jobs and have to come here looking for
answers.
 

ferretx9

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My reference to the intermediate steering shaft was not that it may be the cause of a vibration, but merely commenting that now I am feeling the road surface slightly, through the steering wheel. The original intermediate shaft was packed with grease and at times would begin to feel like the steering shaft was loose, the grease may have insulated some sensitivity. The replacement shaft may transmit more of the road serface to the steering wheel.

Glad you got it fixed , sorry you've had to read thru
the crap
 
G

G-6168

Im having the same vibration at 55 or 1.5 rpm For what I'm coming up with its the Ujoints.
 
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