Front end noise saga (not quite resolved)

99 XJ (box stock) with 42k miles. Started hearing 1: a low speed grinding noise from the front, 2: a slight vibration when turning at 30- 40 mph and 3: a "clunk" when slowly backing up and turning the wheel. (like when backing out of a parking space - happens only in reversa and either when turning left or right)

After doing some reading on this forum, I concluded that the most likely suspects were front wheel bearings / u-joints. I tore into it last weekend and sure enough, the bearings were shot (one had rust leaking around the rear seals) and each of the u-joints had one or more dry bearing cups. (Advice to anyone thinking about trying this - go look at the axel replacement write up on MADXJ.COM - excellent stuff).

Anyway, the grinding and vibration when turning are gone but the darn "clunk" when turning while backing up is still there! I gave the front end a through greasing and that didn't help and I'm totally out of ideas. Any suggestions??? TIA.

Does it do it when you are in 2wd and 4wd? I don't know what the problem could be exactly but that would be another thing to try and allow you to narrow down the possibilities somewhat.

It makes the clunk in both 2wd and 4wd. (should have mentioned that in the original post...)

I also have the loud thunk when turning in reverse. I've not verified it yet but I was told the problem is caused by the bolts for trackbar/bracket getting loose.

Motor mounts?

Try your Lower Control Arms at the joint with the brackets on the front axle. I got this noise also and when I tightened the through bolt for the bushing at the axle end- the noise went away.