98 Sierra Vibration

[tinman2731]

I have a 98 Sierra 4X4 8600GVW ¾ Ton 5.7 Automatic 114M miles that I just recently bought thru a dealer with a vibration problem. Since then I have had Toyo Open Country tires installed but yet the vibration persist. I had Les Swabs totally go thru the front end just to find everything in great shape. The only problem they found was a little slop in the pinion gear which they said was not enough to warrant the vibration and a little play in the steering box. They even removed the u-joints to inspect and found nothing. The vibration is apparent at all speeds but more so between 35 and 45 mph. A little less at lower and higher speeds. Also it seems to be more of a body vibration and not thru the steering wheel. Thanks in advance for any help anybody can send my way.

[gmvortec]

Did you replace all the tires ?,if so were they balanced?, as the vibrations seem to come thru the body i would check propshaft for balance, check for bent driveshafts and just generally make sure all running gear mounts are good.

[tinman2731]

Thanks for your reply GMvortex. Yes, all tires were changed. After the change the vibration was still there so they took the tires off and rebalanced. Still no change. I looked at the drive shaft and it does not appear to be bent. As far as the balance of the propshaft and drive shaft goes, wouldn,t the vibration get worse at higher speeds instead of smoothing out a little bit? Also all of the bushings in between seem to be firm. Thanks for your reply. tinman2731

[gmvortec]

Originally Posted by tinman2731

As far as the balance of the propshaft and drive shaft goes, wouldn,t the vibration get worse at higher speeds instead of smoothing out a little bit? Also all of the bushings in between seem to be firm. Thanks for your reply. tinman2731

Maybe maybe not,bad tire balance evens out at speed.
Just a thought, are the wheels stock? as aftermarket sometimes don't have the recess on the back around the stud to allow for the disc/drum retaining washer that gm fit over one of the studs, that causes a vibration as well as brake judder.
Another thing to do is put both ends up on jackstands and get someone to drive the truck while you look at all the shafts,wheels,bearings etc

[tinman2731]

Well, I had the tires rebalanced again. Still no change. As far as putting the truck up on stands and running it, Les Swabs did that as a last resort. They said the drive shaft didn't seem to have any wabble to it but I think this weekend I'll try it myself and see if I can see anything. Thanks again for your reply's.

[JaVeRo]

Does it have a two piece driveshaft with a carrier bearing? If it does, the carrier bearing may be a place to look for the vibration.

James

[CobraCDN]

On the driveshaft theory... with it up on stands will any visual wobble justify a vibration? I have a 2 peice the rear does appear to have a bit of wobble to it..is a little or any normal or should it appear to be perfect when turning?

I also am trying to diagnose a vobration prob.
Thanks in advance.

[fuzzypuppy]

I have had drive shaft/driveline vibration problems before, they can be tough to track down.
There should be no visable wobble from the driveshaft.
Also being up on stands changes the geometery of your driveline and any small wobble while up on stands could be greatly increased with the driveline in it's normal position.
I just helped a friend track down a vibration in his truck, it turned out to be the torque converter.
Have also seen vibrations caused by slightly bent rims, out of round tires, flexplate/flywheels, dampeners, carrier bearing's are a common cause.
Your drive shaft may not be bent at all but may have thrown a weight.