99 f150 4x4 with 191 thousand miles. recently and it doesnt do it all the time but when accelerating from a stand still (straight line) a little hard i notice there is a shudder feeling and then it catches and accelerates. It does not always does it, (somewhat has a mind of its own) (also rear end has been serviced about 3k ago with friction modifier as well). Could it be rear end slack, u joints, drive shaft, transmission? i mean, i believe the rear end is strong, ive gunned it off the line and it hooks up well.

also. idk if this helps at all, but going around 45mph when it shifts into overdrive and accelerating for it to downshift, i got a jumpy feeling from the underneath while it dropped a gear. (i am not too sure if its just me hitting a bump in the road because its only happened twice). could it be related?

i swear i love my ford, the engine is absolutely amazing, but once i fix one thing, its me again making another thread because something just broke.

im hoping it could just all be caused by play in the rear end.

- John

 

It sounds like it might be a u joint and an easy way to check that is after you have drove it a bit get under the truck and see if th u joint is warm to the tuch and if it is its bad

 

There is a TSB on a clunk or bump when starting from a stop - Something about lubing the slip yoke as a solution. Definitely check the U-Joints first.

 

Mine started doing that after making a nice loud bang. Crawled under it little later and had needle bearing sticking out of the caps.

 

thanks for all the replies. i appreciate it. im going to check the u bolts. once the truck has driven a while, it goes away. its usually when the truck isn't warm.

also, what and where is a slip yoke.

so it shouldnt be the transmission or anything too major?

 

The slip yoke is on the front of your rear drive shaft right at the t case

 

Even the M5R2 equipped 2WD's have a slip yoke.

 

yup they do and i wish i could have been with my brother and dad yesterday. they pulled out a tractor with his superduty and 97 150 hooked together

 

My father got our Kubota stuck down by the pond a few years ago. Tried pulling withe the Cummins, the Jeep, hooked them up in tandem, hooked them up side by side, still no good luck. Eventually I went and got the hi-lift and used the Dodge as and anchor and winched the 6200lb tractor sideways with the jack. Moved it 3ft, but it was just enough to bite on dry ground.

 

ya that's all it takes is to get it to a little dry ground