How do you separate the top of the ball joint form the steering knuckle, all bolt are removed. I want to take to shop to have new ball joint and bushings in the a arm installed.

I use a tool that looks like a fork, designed just for this job.
It is wedged in between the joint and steering knuckle and tapped
with a hammer.
Another tool designed just for this grabs on sort of like a big clamp
and allows you to push it out.

If you have an auto parts store nearby it would be a common tool
for them to lend.
This link has a good picture and discussion of removal:
http://www.peachparts.com/shopforum/showthread.php?t=142212&highlight=removing+ball+joint

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

Just to make sure I understand you are not talking about the tool to actually press the ball joint out of the a-arm, is that correct?

You are talking about just separating the top of the ball joint from the knuckle, right? If so then that would be the same as separating tie rod end which I do with an pnematic fork mount in my air hammer. Will separating the ball joint with a fork and hammer ruin the boot?

I've just never done ball joints so I want to be clear.

you might find some tips on the DIY I posted last year. what model?

http://www.peachparts.com/Wikka/W124BallJoint

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89 300te 222,222
92 300e 190,000

Most times I've purchased new ball joints, they come with the new rubbers. Have you gotten the new ones yet?

Very informative and well thought thru. Luckily for me I run a metal shop and have access to arbor presses and all kinds of different diameter tubing to make those alot easier. Usually I take the whole assy. out of the car, but I haven't done one of the MB's yet.

If you have the strut unbolted from the knuckle you can hammer up on the knuckle to free it from the ball joint. (knuckle is pretty solid) Spray some penetrating lube onto it first ... it should come off no problem.

Good Luck

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

You've got to wedge a flat head screwdriver into the slot in the steering knuckle. It is the slot that the tightening bolt narrows when torqued to squeez the knuckle around the ball joint shaft. The slot is filled with wax to keep moisture out so the balljoint shaft does not rust to the steering knuckle.