I've posted about this before to no avail. Have a few updates and I'll sum up all my findings so far.

I drove my truck through a snowstorm in the mountains several weeks back and shot my automatic hubs in the process. Somewhere along the line when trying to get unstuck, twice, and driving with chains on the rear wheels for 20 or so miles, my truck developed a shake that it did not have before. Have since replaced the hubs with warn premium manuals, they work great.

Symptoms: the shake becomes noticable to me anywhere above around 20-25 miles. It is not a washboard effect, much less severe, almost like small bumps in the road but too close together; most people who don't ride in the truck often do not notice it. Shakes all throughout each the gears, not only at high or low rpms. Seems to come from the rear end because I feel it more in my seat than through the steering wheel, in fact I don't feel it much at all in the steering wheel. Also seems to be drivetrain related as it will shake when put into neutral at a constant speed.

I had a shudder from take-off when I first purchased the truck, which I fixed by shimming my carrier bearing. The drop bracket I bought was a little too tall and my drive shaft ended up being spaced just BARELY too far down. I removed the bracket this weekend and the old shudder came back, and the new shake persisted.

U-joints seem fine, although I have only checked them why twisting them with the driveshaft on the truck; all feel tight.

Tires have been balanced, twice. Checked for roundness too, no problems there. Changed rear diff fluid, made sure to use limited slip fluid.

I'm at a loss here. Does anyone have any other ideas?

Sorry for the long post,
Chris

 

Have you put that thing in the air yet to see if you get any variations in the rear end? A bent axle?
Another thing, I would pull the driveshaft and check the u-joints while disconnected. Sometimes it's hard to detect a dry joint with it still installed.

 

How are your brakes? Is your parking brake frozen? Got a caliper or shoe dragging somewhere? Warped rotor or drum? Spinning up wheels in snow is a good way to warp something--spinning tires get real hot, then hit cold snow...

Jason

 

I haven't tried running it in the air because I don't have a frame lift and I don't want to run it on jack stands because it could potentially shake right off the stands. I'm most likely going to replace the u-joints soon.

I already had warped rotors in the front for other reasons which I do not know, but I have since had my front end jacked up and the wheels spun fine, no dragging. I wasn't aware, though, that a warped rotor could cause a shake in the truck... Is that what you are driving at here? Plus, wouldn't I feel that in the steering wheel?

-Chris

 

My first guess would be a locked up u-joint. The only real good way to identify them is to drop the shaft and make sure all joints move in all directions without binding. I had a similar problem on one of my trucks years ago and after rebuilding the rear end I found one locked up joint while reinstalling the shaft.
Otherwise maybe a bad output bearing in the transfer case or pinion bearing in the rear end.

 

What exactly are the specific symptoms of a bad u-joint? I have heard about shaking etc, but specifically? What speeds? How severe of shake? Anything else that would give me a clue that u-joints are my problem here?

I also noticed that when twisting the driveshaft around the carrier bearing that there is a TINY bit of play there, I'm talking a fraction of a millimeter. Is this normal?

-Chris

 

I just replaced my U-Joints a little over a week ago. It started out as a minor vibration and then developed into a major vibration at anything over 30 or so. It's different depending on how they are going out and how bad they are. With mine, I couldn't tell they were bad until I dropped the driveline and looked at them. They are pretty cheap and fairly easy to replace, I would deffinatly start there.

 

Excellent, sounds like your problem was pretty similar to mine, would you agree? Did your shake appear pretty suddenly? Once you had the driveshaft off, how could you tell that the u-joints were bad? Were they seized?

-Chris

 

Mine were not seized, but the needle bearings were toast (some were broken and most were worn down pretty bad) and there was no grease left in them. It does sound like you have a similar problem to what I had. I am not about the throw money at it and see what fixes it method of repair but with U-joints being inexpensive and easy to do, you might as well. Another thing you want to check is your motor mounts and tranny mount, if you have a mean vibration it could be caused by those as well. I'd start with the U-Joints though.

 

My first guess would be snow is trapped somewhere. Check behind your rims. Or if you have beauty rings on your rims, take them off to see if it is packed behind. This happens to me with mud all the time. If anything, see if you can park it in a warm garage overnight. Maybe melt some unwanted snow? Worth a shot?

 

He said that he drove through the snow a few weeks ago and with him living in Cali, I doubt that there is still snow anywhere near the truck.

 

Heh, although this is a good idea, one that I addressed when the incident occurred, this incident occured about a month ago. Heh, I haven't been back to the snow with my truck since then and it was 80 degrees here yesterday so I don't think I've got snow up there

As for u-joints, is there any specific brand that I should use? I seem to remember Spicer, do they make u-joints?

-Chris

 

I'm not sure about a prefered brand, I just went to Advance Auto Parts and picked some up.

 

Spicer's are good. Precision are OK. Just be sure they are greasable and grease them with every oil change, any brand should hold up well with good upkeep.

 

I am also wondering if it is my carrier bearing or support assembly that could be causing my shake. Has anyone had experience with this?

-Chris