Loaned the truck to a buddy of mine who said he was driving my 98 F150 (V8 Automatic 8ft bed) down the road at 40mph and the rear drive train fell out and rolled into the ditch at about 40mph. We had just changed the front and rear U-Joints on it about 3 days ago, and ever since the truck has really had a LOT of vibration after 20mph (so much that my exhaust pipe broke off too). When we changed the ujoints we hammered at the butt of the drivetrain to free up the old u-joints, and after reading some threads here, I take it we should have used a vise and sockets instead. Maybe we caused it to be unbalanced by using the mallet. Anyway, right now it looks like the U-Joint (the one closest to the rear bumper) is the one that gave out and lost the clips and caps we had put in, causing the drive shaft to slip down and since there are no bolts on the front end, it slid off once that U-Joint broke. I'm not sure how those clips came out though, I know we had them in okay when we did the change. I'm not much of a mechanic, but try to learn from my mistakes... first I'd like to know though how this might have happened. Any ideas?

Thanks,
Matt

 

you really need a vice or a press to do it right. they have to be pressed evenly. most shops will do it fairly cheap. also make sure you put the driveshaft back on exactly the way it came off.

 

I was driving through wyoming years ago in a 90 f-150 I had and the rear u-joint came undone at 65 mph. the force of the driveline whiping out broke the yoke off the back of my tranny and it bent the tail shaft. You might have just bent your tail shaft. I would pull the drive line out start the truck and put it in gear and look at the tailshaft there is a dimple in the center of it an it should remain straight no wobble at all if it wobbles you need to remove the tail of the tranny and have a new shaft installed. It comes off or at least it did on mine so you can remove it without removing the trans. Make sre you use lock tight on the u-joint bolts..

 

I had a mechanic look at the drive shaft. They think we beat it too hard, caused the holes to misalign a little where the u-joint goes it and that is why I had such bad vibration and how the clips holding the u-joint came out...

Live and learn I guess.

Matt

 

ive been there .beating the hell out of it feels good... not always the best result though.