Symptoms of Bad U-joints?
 

Hi Folks,

I'm sure this has been covered many times, but my searches for (+u-joints +replacing) gives me hundreds of unrelated threads. Hmm...

Anyway, I recently lifted my 2002 F250 PS with a 3.5" spring-hanger kit, and now I'm starting to regret the decision. I love the look of the 315 R/75 tires, and the stiffer ride of the dual Bilsteins in front, but nagging ride issues persist.

After solving my "drive-away shudder" problem by shimming the carrier bearing, the truck was smooth at all speeds, but only for a short time. Then, I began noticing vibrations at speeds above 45 mph. I suspect it's drive-line related because it only happens under power, it still coasts smoothly. I had the tires rebalanced, anyway, just to rule out the easy fix.

Now, I'm thinking u-joints, but before I jack the truck up and start shaking parts, I wanted to see if you guys felt I'm on the right track. I'm a "shade-tree mechanic" at best, but I figure I can handle u-joints.

Any tips, or alternative ideas will be most appreciated.

Matt

My thoughts and a question
 

As for the U-joints, the best way is to get under your truck and wiggle each d-shaft at the joints and check for any movement at all, if they look like they are moving at all when you wiggle, then you have some U-joint wear as there shouldn't be any play.

As for the 'drive-awa shudder', you got my attention. When I pull away at a moderate pace, I don't get the sgudder, BUT, when I HONK on it, I get a shudder for about 2 seconds, I never thought to check the carrier bearing. This leads to my question, do you have a lift kit? I have an 8" lift with the drive-line geometry in good line, my next question, does the 'rubber' lining of the carrier bearing housing wear and create too much play???

Cheers!

Thanks for the quick reply Kalsc,

I just crawled out from under the truck. There's definitely play in the rear joint. Front and middle are tight. Looks like I have an afternoon project. ;-)

Yes, I have 3.5" Fabtech spring-hanger lift on the front, 4" blocks in back. I noticed the drive-away shudder the moment it was installed. Same as you described...only noticeable under heavy acceleration. (3) 1/4" flat steel shims eliminated the problem on my truck, but the amount of shimming varies depending on lift height and axle-to-axle length.

Matt

Figured. :-)
 

Hey TruckLuv'r,

Glad to hear it was a quick diagnosis. As for the shudder, looks like I have an afternoon project as well, thanks for the heads up. I have an 8" lift but I was sure the hangar was dropped, maybe not enough.

Cheers!
:-)

There is a 1/2 inch spacer between the hangar and the mount, not enough. Am going to try another 1/4 inch spacer, maybe two, should do the trick.

Are there any aftermarket hangars made that have a poly bushing as opposed to the stock rubber ones?

Just for reference sake, with an 8" lift, a one inch spacer for the drive shaft hangar eliminates the shudder. Half inch and three quarter inch didn't cut it, one full inch nailed it.