W126 Brake Bearing Bracket question...
 

So as I am rebuilding the suspension on our 1989 560SEL, I am also doing the bushings in the bearing bracket and of course the guide rod mounts.

One of the Febi bushing packs came with new bracket nuts that you slide into the side of the body. These are the nuts into which the two bolts holding the bearing bracket go into. So I bench tested them for fit, and found that the bolts on both bracket nuts I was testing would only go in a few turns and then stop dead. The bolt would never even fully poke out the other end of the nut - it is almost like it was cross-threaded.

You are supposed to tighten these bolts at 80 NM.

So my question is: Is this intentional? Is this really a stop nut that is not supposed to let the bolt go any further, and the 80 NM really just wedges the bolt into the thread securely, but there is no pressure between the bearing bracket and the body/bolt? Or should I rethread the nuts so the bolt goes through, use locktite, and torque to 80 NM with the bolt/plate pressing the bearing bracket against the floor?

Answer
 

Re-tap the nuts so the bolt goes through.

The bolt must go through.

Use blue locktite for assembly.

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Thank you so much! That is what I figured.

What the heck is wrong with those FEBI nuts?

A full pictorial write-up will follow when I am done. I'll post it on my web site and provide you and the forum with a link.

I used your parts list and bought the whole kit and kaboodle from Phil.

Addendum for anyone reading this post or researching this topic!
 

For anyone else in the future looking for information on this and reading these posts: The jury is still out on if there is a problem with the part, and if re-tapping the bolt is advisable. It turns out I have ruined two bushings by screwing the bolt too far in (which could not have happened had I not re-tapped the nut). So maybe these are indeed intended to be stop nuts that by design do not allow the bolt to go all the way through. The issue is still being looked into...

FYI
 

FYI:
The FSM torque spec is 80 NM = 59 LB FT.


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Right. I have the FSM. I sent you the crushed bushings today...

UPDATE: RHunter is right - the nuts are not up to snuff...
 

RHunter is right that the nuts are not stop nuts.

However, when I tapped the nuts to make the bolt go through, their threads became too efficient, and did not provide enough friction. Therefore, as I torqued to 80 NM, I was crushing the metal parts of the giant rubber/metal bushings, in effect destroying them.

My recommendation: If you buy the Lemsförder guide rod repair kit, also order two Mercedes-original bracket nuts (per kit you are ordering, i.e. 4 nuts per car. Phil at Fastlane was able to get them for me.). DON'T use the ones in the kit, but use the ones you ordered separately. The original Mercedes bracket nuts with their clips are different, and have the correct thread tightness for you to hit 80 NM without crushing the bushing.

just whatever you do, do not allow the bracket nuts to break loose and then you have a big problem. I did the install this weekend and the nut came loose from the bracket so in turn it was just spinning as I spinned the Bolt. I had to open up the sight hole slightly so i could get a vicegrip in to hold it while I turned the bolt. This is NOT a fun job if this happens!

That bracket can be a real pain...
 

Re-installing the new parts you have to be careful too. I'd go with the "golden" original Mercedes parts, not the "silver" OEM Lemsförder parts. Be very careful. There are some tricky things going on with the thread design - it is conical. You can do the actual rubber oem, but for the bolt bracket and the actual bolt, go Benz.

On the other hand, getting that suspension back in shape is a huge reward.

I ran into the same problem when I did the 420SEL's front end.

I only got one of the original bolts to thread into the replacement nuts. I got #2 stuck. I said the hell with it and just ordered new bolts and nuts from Mercedes.

The bolts were pricey at $20 a pop, the nuts were cheap though.