99 Tahoe shake

[mmoss10]

I have a 1999 Tahoe LT four door 4x4 w/5.7 and 97000 miles. Sometimes, when I'm going down the freeway at around 65-70mph, the whole truck gets a vibration and it feels like it's down on power. It's not too severe, but it's bugging me. It seems to always happen right after I cross a rough section of road. I usually back off the throttle and it goes away in a mile or two. I have recently (in the past two weeks) had the tires rotated and balanced. I also did a complete tuneup with plugs, wires, distributer cap rotor and fuel/air filters. All AC parts. I also had the tranny flushed and fuel injector service performed. Monroe reflex shocks installed all around. I own a scan tool and there have been no codes stored. The vibration issue existed before all of this work was done. I have purchased u-joints but haven't installed them yet. I have been reading this forum for several months and I thought I'd register and ask my question. You guys (and girls) give some great advice and I usually check here before starting repairs. Thanks in advance for your help!

[777stickman]

Welcome to the forum. Next time this happens try this. When you feel the vibration put the tranny in neutral. Let the engine go to idle. This will isolate an engine vibration from a driveline vibration or even a chassis vibration. Make sure you get the rpm's back up before you put it back in drive.

Let us know what the results are.

[mmoss10]

Originally Posted by 777stickman

Welcome to the forum. Next time this happens try this. When you feel the vibration put the tranny in neutral. Let the engine go to idle. This will isolate an engine vibration from a driveline vibration or even a chassis vibration. Make sure you get the rpm's back up before you put it back in drive.

Let us know what the results are.

I drove the truck today and tried to make the vibration come back. When it did, I shifted to neutral. The vibration went away. I'm not sure if this is because the truck slowed, or because the drive train was disengaged but it did go away. Could it be the u Joints causing this type of problem? Maybe a wheel bearing? Thanks again for the help.

[aircrewman]

It's the U-joints, had the same problem!!!!!!

[777stickman]

From what you said I would suspect an engine/tranny problem. If you have bad u-joints you should be able to get under there and feel any loosness in them. As Colt450 said, maybe some professional advice is called for.

Check out this thread.

http://www.automotiveforums.com/vbul...d.php?t=611483

[mmoss10]

Originally Posted by aircrewman

It's the U-joints, had the same problem!!!!!!

Replaced the U-Joints this morning. They didn't show any signs of looseness, but I've been driving it this afternoon and I can't re-create the shake. I think the U-joints may have fixed it. I'll drive it for a week or so and let you guys know. Thanks.

[aircrewman]

cool.....glad it worked.