does this mean too much backlash, or are there other reasons? it also clangs a bit when i'm going downhill and the drivetrain shifts from accelerating to decelerating. so, if it is backlash, and the gears all look ok, and i buy a rear end shim kit, it looks rather simple, assuming the mesh pattern is ok so i don't have to mess with the pinion. i have the ford shop manual, and it looks straightforward. the manual shows the backlash spec as about 0.012 or so optimum, which seems to be measured with a dial indicator near the outer edge of the ring gear. the "fine art" of rear ends is the mesh pattern, right? assuming that is fine, setting the backlash is not that complicated, or am i missing something? thanks in advance

 

Are you sure it isn't the universal joint that is worn out? If you haven't checked it yet
you might want to first before going into the rear end gears.

 

I second what Hickory is saying here, check the universal joints at both ends of the driveshaft. Even though they may not be giving any vibrations or anything else to make you suspect they are bad, most of the time any clanging coming from under there is related to your U-joints.

 

Sounds like U joints

 

thanks for all the replies. i put new u-joints in a few weeks ago, and the old ones didn't have any play that i could see. i pulled the cover and there is very little backlash between the ring and pinion. i'm starting to think the CLANG is not the axle housing ringing like a bell, but the driveshaft, which is a long one-piece - it's a long bed, and a prior owner appears to have gotten rid of the center support bearing. so, i think the pinion yoke is shifting a hair whenever the torque reverses enough, and the shock makes the driveshaft ring like a bell. a few decades ago, i had a 65 F100 that made a loud metallic click under similar circumstances, and a mechanic friend said i could put red lead on the pinion spline to fix it. i have never seen "red lead" in a parts store. is there another name for this? i need a new oil seal, so i'm going to pull the pinion yoke and put one in. i can't just torque the hell out of the nut because there would be too much preload on the pinion bearings. so, is there anything readily available that i could put on the pinion spline?