I have a 1997 F150 4.6V8 with 4spd auto. When I take off from a stop sign, there is a delay in getting going and then a clunk. At first I thought I had a bad u-joint but they are fine. Then I thought I might have a broken motor or trans mount but they look okay. I've had it looked at twice and no one can see anything wrong. It is like there is excessive back lash in the drive train. It feels like everything is turning but takes a while to get the wheels moving. Once rolling, no problems whatsoever. This weekend I thought maybe the wheels were loose. The lugs that hold the aluminimum wheels on bolt on flat. There is slop between the lug bolt and the wheel hole. I cleaned the back side of the wheels which were corroded and rebolted. Still clunks. The only other thing I noticed is that there does seem to be a fair amount of backlash in rear axle. Any ideas what I might look for? How much backlash in the rear axle is acceptable? Thanks!

 

Welcome ! Do a search here for transmission clunk or slip yoke. You could read posts here for an hour exactly like yours. To summarize them, the driveshaft needs to be removed and the slip yoke needs to be packed with grease. That's my first guess. Clunking backlash would be at the bottom of the list.

 

Do you have a lift with lift blocks?

 

No lift blocks. I'll check out the slip yoke this weekend.

Thanks!