I am about to replace a few HLC's (ball studs) on a 1989 420 SEL. I've read the service CD as how the job should be done. I received the HLCs today and I see there is small plastic wire and tab, about the diameter of a toothpick protruding from the underside of the top flange. Should this plastic wire and tab be pulled out prior to installation? What's the purpose of the plastic insert?

Also I noticed that some of the old ball studs come up right away, and some come up slowly, like in a few minutes. Is the speed of the rise any indication of a defect?

Can one expect the service cd instructions to be complete?

Any and all recommendations are appreciated.

Thanks,
Joe

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1989 420 SEL

There should be a torque value on the CD for the ball studs. I dimly recall removing the plastic pieces when I did my 380 - I think that they keep the oil feed holes clear.

Steve B did a post where he described how they compressed new balls studs in a vice before installation to be sure that they got a quick and accurate pre-tension measurement. You might poke around for that post.

You were planning to use the special tool to pre-tension the new ball studs, weren't you?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

What's this about pretension. I didn't read anything on the CD about pretension. Please tell me all about pretension!

I was just going by the CD. Oil the threads on the new one, tighten to 60 NM, check it with the go-no-go guage, adjust the thrust washer.

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1989 420 SEL