I have removed the nut on the lower kingpin bushing bolt and put all my muscle, including with a breaker bar, to get tthat bolt to turn. It won't budge. The bolt seems to be frozen in the bushing. (The nipple won't accept grease easily.) I had a bottle jack under the control arm to relieve force. I did not apply heat and I did not use an extension pipe on the breaker bar. The reason for no extension pipe is that my imagination envisaged snapping off the bolt head, leaving the bolt shaft stuck in place inside the bushing and really screwing myself.

Before trying the breaker bar, I soaked the whole area, including the zerk hole after degreasing it, with penetrant for a couple of days. I also vibrated a hammer drill on the bolt ends to attempt differential vibrations to try to break up internal rusting.

For those experienced in kingpin suspensions, is that fear warranted? How hardened are these bolts? If breaking the head on these bolts is a legitimate concern/fear, what are the suggestions for getting the bolt to turn for partial or complete removal?

Many thanks.

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Douglas
1959 M-B 220S cabriolet

Unfortunately, if what you have tried doesn't get it then your only choice is force till it breaks or the gas axe. If you note in the blow-up I enclose item 158 is all the parts involved if I understand you correctly. Many a time I have burned them apart.

Since the only reason to take it apart is to replace it sometimes the torch is quicker.

BTW also notice that the bolt 142 is threaded all the way. When the car flexs at this point the mechanism of flex is the threading and unthreading of 142 into the un-numbered part in item 158 the carrier. If you are frozen here then all your flexing has been done by the the bolt turning in the control arm. This often wears out the control arm.

In any case burn it into small pieces and replace those involved.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve, thanks for the thorough reply. Yes, you understood me correctly.

Your explanation has informed me how to proceed. When working on this item, I saw that the bolt holes on both ends of the lower control arm have been widened. When I put the jack under the spring, I observe that the whole bolt apparatus move up a bit. I can even see part of the hole in the control arm behind the head of the bolt. The control arm holes seem to have been reamed wider than appropriate by the flexing that no longer occurs with the bolt. Therefore, from what you point out, I conclude that I need to replace the lower control arm as well as at least no. 142 in your diagram but, more likely, all of no. 158.

The kingpin itself is well greased via the middle nipple and showns no sign of wear or wobble.

Should I anticipate that when doing this job, the unnumbered carrier in no. 158, which is where the bolt is frozen, will slide down off the kingpin easily? Or will I inevitably damage the kingpin in the process of dissassembling the lower bolt apparatus?

Have you any information as to the tightening torque for the castle nut on the lower control arm bolt?

Finally, I cannot get the top kingpin nipple to accept much grease either. This serves the eccentric bolt for wheel alignent. I do not detect any widening of the control arm hole, though. I may have forced a small amount of grease into it with a hand grease gun because I got loud squeaking to stop. Perhaps I shall try an air-powered grease gun at a shop.

Thanks for your kind help.

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Douglas
1959 M-B 220S cabriolet

If you look at the picture of the kingpin you can see that it is tapered. It can be quite a pain to get it off while saving the Kingpin as the natural tendency is to beat up on the kingpin, which won't work.

You should support the suspention off the spindle (to some extent). This will lift the kingpin against the force of the spring against the lower cont arm (sitting on its wheels would accomplish this). Loosen the lower kingpin bolt numerous threads (do not fully remove for safety), and strike the carrier a sharp blow. By having the nut still safely on the kingpin it will not fly apart when it comes. Once loose the lower control arm can be removed with your frozen part after dealing with the spring.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Very helpful, Steve. You are assuming that somewow I get the bolt to turn. What if I cannot?
How badly am I screwed if the head snaps off?

If a breaker bar and pipe extension don't do the trick, that leaves me with the cutting torch alternative that you suggested. Is it a viable option for me to apply heat on the bolt head, the bolt thread end, and/or the carrier to try to break the bolt free from the internal rust inside the carrier? Or does experience reveal that this never works? Would this surely damage the lower end of the kingpin or any of the items in no. 58 on your diagram, especially item 41?

If no bolt turn or if its head snaps off, is a Sawzall a viable option instead of a cutting torch? Again, thanks for putting me in the right direction.

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Douglas
1959 M-B 220S cabriolet

Which nut? Nut 54 is what you need to remove partially to remove the lower control arm from the kingpin. That nut should come easily. It will probably be impossible to get the trunnion bolt #142 out if its froze to the carrier (un-numbered part in #158). The bolt 142 is about .75 in in diameter if I remember correctly. It will be hard to break it. It will be hard to cut it and it is even tricky cutting with a torch and saving the control arm and the kingpin. Since you seem to need 158 and probably a control arm. I would remove the carrier with the control arm as I said. You won't have to remove bolt 142 in that case.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve, again many thanks. Very informative and helpful.

You asked, "which nut?" I meant that, when reassembling everything, what is the correct tightening torque spec on nut item 150 in the diagram? Is there a tightening torque spec for nut item 54?

If the carrier (unnumbered item in no. 158) fails to come off easily, even with a sharp rap on the carrier, after loosening bolt item 54 part way, I would guess that I might slowly/slightly lower the bottle jack where I shall have previously placed it under the lower control arm to relieve spring pressure on the arm. Of course, I shall also have clamps on the coil springs as well.

From what I now understand, it seems that I will not be totally screwed if I put so much leverage on the head of bolt item 142 that the head breaks. The carrier is coming off anyway to change the control arm.

Now I have to hope that the lower control arm and the item 158 are not outrageously expensive.

Given the apparent reaming wider of the bolt holes in the lower control arm, clearly I will have to replace that arm. I just hope they are not outrageously expensive.

Again, Steve, thanks.

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Douglas
1959 M-B 220S cabriolet