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6.9 Strut Ball Joints - R&R

Started by wbrian63, 26 July 2016, 07:45 AM

wbrian63

I'm going through all of my spare parts, trying to determine what's good to keep and what's good to throw.

Most all of the struts have worn-out lower ball joints. I've got parts to replace these, but I'll be hanged if I can figure out how to get the ball joint loose from the strut.

For the rear struts, it would appear to be easier than the fronts as I can see there is a flat on the ball joint stem and a flat on the base of the piston shaft.

Obviously, I can't clamp on the shaft, so I'm left with putting the strut in a vise and attempting to separate the ball joint from the shaft with a pair of opposing wrenches.

Naturally, I'm unable to position the wrenches so I could "maybe" squeeze them together to balance the forces, so I'm stuck with trying to hold one while I whack the other with a hard rubber mallet.

This usually results in the struck wrench coming loose and flying across the room.

The front joints are going to be even worse with the cup at the base of the strut assembly. Looks like I need some sort of pin wrench to hold the cup while I use a thin-form wrench to loosen the ball joint.

Any suggestions?
W. Brian Fogarty

'12 S550 (W221)
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'76 450SEL 6.9 Euro #1164 - parted out

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter V

daantjie

#1
Brian all I can tell you is brace yourself, this was by far THE toughest job I have had to do on my 6.9.  The rust in that area is insane :o.  I tried an adjustable pin wrench, then I drilled out the pins to leave holes, then what I did was drop 2 bolts into the cup holes from the top to bolt the wrench to the cup to give a handle and lever to hold the cup steady.  Problem is that there is very little room to get a good bite on the joint itself, so of course I ended up stripping it.  In the end I got desperate and cut a slot into the cup so I could get a wrench in there, and this worked for the one strut  but on the other one I gave up and just cut off the ball joint, then drilled it out, which in itself was a fun exercise.  So unfortunately  I have no good tips as none of mine really worked well.  Man it was torture :'(
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

For the front I bought a box wrench and cut  a lot of it away until I could slip in on the bottom of the ball joint.  the cup was held in a vice. 

worked for one, the other I never did get apart.

'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

rumb

If you are serious about getting these apart, then I would fab the pin wrench.  You need every advantage you can find to get stuck ones apart. I would incorporated the pin wrench with a open end that fits the bottom portion of the ball joint.

The one I tried we twisted the cup loose from everything somehow, and it still didnt come apart.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio