I suddenly have a vibration that started about 3-4 days ago best I can tell. At 25-30mph, it feels like I am driving over a rumble strip. Then it smooths out until about 55-60mph when I can feel a very fast vibration/pulsation. It is almost audible too at that speed. Also, it is more noticable if I am on the throttle at those speeds. If it is doing it, and I let off, it almost goes completely away, still noticable though, just not as pronounced.

Of course i'll first check the simple stuff like having my tires balanced and an alignment, but I don't think that is it since it is more of a fast cycle vibration rather then a slow cycle like is common with an unbalanced tire. So if that stuff doesn't take care of it, what else could cause this? I want to compile a list so I know were to begin looking if it is still going on after the easy stuff is checked.

Here's what I thought of so far:
-driveshaft balance
-driveshaft u-joints
-motor/trans mount problems
-torque converter issue

-could a hub cause this?
-could the front axle u-joints cause this?
-could gears and/or limited slip cause this?

Thanks all.

 

My truckhad those same symptomsand it wasthe "permanently" lubed front u-joint on the rear driveshaft.
The u-joint was bone dry when I took it apart and most of the roller splines in the caps were disintegrated.

 

Mine was the ujoint on the back drive shaft.. put the ebrake on put it in N , go under the truck and see if you have play in the shaft and if you can look at the ujoints when mine went the bearings in the cap where gone you be able to see that... by the way silver i got my upper control arms in they are black to but what a PITA to put in....

 

I am suspecting driveshaft u-joints too, so interesting that you both said that.

Why was it a PITA? I'm planning to do mine on Sunday. Got any pics?

 

first i did it with the jack couldnt get it high enough then i said screw it and did it on the lift. couldnt do it 1 at a time i had to drop both control arms same time no biggie..but when it was time to line the bolts up that was a PITA ..up , down , up , down on the lift.. the lower control arms was easy , but the upper to get everything lined up (wow!!) turned into a 4 hr job...good luck with yours . wont have any pics till after tuesday.. of the install.. but i took notice the stickers are different then yours here is a pic of the control arms


[IMG]local://upfiles/40785/A1A4C5025F8D469BA97329578E9D81EE.jpg[/IMG]

Reason why no pics till after tuesday is that i just ordered the skyjacker swaybar drop kit and after i put that on then ill have some pics , next is the pitman arm drop..

 

Thanks for the info. So you let the axle hang when you did it right?
How do they feel when you drive it? Any improvement? Did it move your axle at all?

 

I think yours look the same as mine:

[IMG]local://upfiles/9095/DD66C2565D3044DEBA7FCFADEC975033.jpg[/IMG]

 

You can eliminate some things right off the bat, if its not changing with engine RPM then its not the motor mounts or anything else that rotates in direct relation to the engine RPM. If were un out of balance drive shaft, the vibration would increase with speed, same thing with out of balance tires.

The mentioned U-joint or an axle bearing are the only things I can think of, you might also check the slip yoke at the output of the driveshaft...unless you already installed an eliminator.

 

My mistake silver the stickers are the same.. as far as the ride got stiff (NICE !! ) so it does push the axle down some.. not front or back...its worth the work and look and ride.. now i just ordered my sway bar drop down kit from summit racing ..part # SJA-SBL20... next is pitman arm then the track bar...then bushwacker then the tires....did you crawl under the truck yet ?

 

I had checked the ujoints for play about 2 months ago when I had a noise from the rear that I suspected was u-joints, but did not see any play. Noise later went away and did not return, so I dismissed it. I'm at work now, so can't go check it right now, but i'll check them again this weekend when I am doing the control arms. Might even just replace them (I bought the ujoints I needed 2 months ago when I thought they were going out) if I have time.

Did you do the ujoints yourself? I've done them on several other vehicles, and plan to do these too. Seems straightforward on these trucks too.