My '84 SD with 97k Alaskan miles makes a 'thuummp' at the front end as the front wheels extend (say, into a chuckhole or on the other side of a speed bump). Sounds like something loose, but cant find anything loose in the front end (neither did a suspension guy). Also, when backing up and turning, the front end groans a bit. Is there a prime culprit in the front end that would act this way, yet not show itself to be loose, when shaking it up and down while inspecting it?

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ROBERT IN ALASKA
1984 300SD in Astral Silver
96k miles

Sounds to me like the "caster joints". These are the large mount/ball joint on the end of the longitudinal lower control arm. They are the point at which caster is adjusted.

These will give the thunk noise but not the groans. I would look to the idler arm bushing here or any of the ball joints or tie rod ends.

Definitely the track ball. If you follow the adjustment rod to the mounting you will see the rubber inside deteriorating. Have the same car and have replaced them both. The groaning is probably a dry upper or lower ball joint. Two separate problems.

Thanks. I looked at the caster joints / track balls and couldn't tell if the rubber was bad or not. But, based on your input I will replace them. Looks like a pretty simple bolt-in job. Any tricks to remove / replace these?

Help Translating!
 

I think the answer by stevebfl that it is the "caster joints" might be the answer for my '82 300SD with 97K original miles. Can someone translate "castor joints" for me into something more descriptive. I live in Costa Rica and have to translate this pointer then into Spanish!
Ron300SD 97Kmi