Anyone know how to properly tighten the upper control arm bolt that connects the steering knuckle. I removed the steering knuckle joint from the upper control arm to free up the steering knuckle to allow more downward travel while performing suspension work. When I went to tighten it, the bolt spins and laughs at me. See photos....

I've got a feeling it may be time to just replace those upper mounts as well. I just replaced the lower control arms with news ones with new bushings installed and E55 springs. (right front corner only so far. 3 to go and it only took me a month )

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Can't you place a floor jack under the lower arm and press the joint together before you try to tighten it? That ought to put enough pressure on it to hold the thread while you tighten. Also, try using an impact wrench rather than ratchet on it.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I tried that, that's how I was able to install the replacement shocks as the OEM shocks were longer than my replacements. I think I may just purchase a new control arm to complement the new lower control arm.

I'm not convinced a jack under the LCA would work, since the UCA will twist upward and the UCA bushing will take most of the pressure. When I did this job, I used an oil filter wrench like the one pictured here, plus a little block of wood, to compress the top of the steering knuckle against the ball joint until I got the nut on tight enough to keep the ball joint from turning. See arrows on second picture. Other tools might work too. Official MB instructions say to locally manufacture a device (a rectangular piece of metal with a U-shaped cutout on the end) to fit between the nut and the knuckle, and use it like a pry bar to force the top of the knuckle up against the ball joint while tightening the nut. Maybe a small pickle fork could work. Make sure the tapered surfaces of the ball joint and knuckle are clean and dry so they grip each other as well as possible. Any dirt or grease here is not your friend.

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Good suggestions. I will try again and report back of any success(es)

Tried this to no avail. Ordered some new front upper control arms. Will report back post installation

Installed a new left side upper control arm. These arms are one time use only for install. Simple solution.

Anyone have any tips on removing the upper bolt on the passenger side. I've removed the airbox and see the head of the bolt but don't see how to access the nut on the rear. Any thoughts?

Put the correct size hex key into the bolt to hold it while you tighten the nut.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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