96 T100 4x4, 3.4L, Auto.
I dunno wtf it really is, but a mechanic friend noticed a vibration when we took my truck for a test ride.

We looked it over and he and the other mechanic at my shop found the carrier (center) bearing between the 2pc driveshaft no good.

We replaced it, it still vibrates. You can feel it on the floor only and only between take off and from about 25-50mph or so. Letting off the gas gives no vibes..

He thinks the trans is worn out, it does have 200k on it. Was thinking of doing a trans flush and filter but I am wondering if my problem really is the driveshaft is out of balance.

Anyway to check that without taking it off or taking it to drivetrain shop?

 

Mine did the samething from 90k top 195k when I sold it..Never knew what the cause of it was..

 

Probably is out of balance or one of the many u-joints is junk. I worked at a dealer and the other guys who had been there alot longer than I have said anytime that that shaft is seperated, it needes to be rebalanced. I don't think your trans is junk but just my opinion. btw, servicing it is not a bad idea though. just to give it some maintenance.

 

The shaft was never out before we did the carrier.. The U joints all apeared to be fine as well but perhaps ill change them.

I am thinking its axle wrap which is common to these trucks. This would explain why when I take off its most noticable and when it downshifts and upshifts but feels ok inbetween. I know the leafs are worn out as the truck sits totally level if not lower a wee bit in the back. For instances: If I powerbrake and give it a good bit og gas instead of breaking free it hops like mad.

 

The bearing may have been junk and now the shaft needs re balanced after it was seperated. sorry, I should have stated that before. I don't think it's the axle wrap issue. you wouldn't notice it untill you hit the brakes. Mine were broken and I never noticed it vibrate even with a load in the back which happened many times before I found out that they were broke oops, oh well. Good luck and let us know what you find. Edit: My truck still has nasty wheel hop even after I put the new springs in.

 

Ill give it a shot.. thank you.

 

Yea i highly doubt that the trans is the problem. I'd be willing to bet its a bad U joint or bearing somewhere or that the shaft needs to be balanced.