Control Arm Inner Bushings

[PeterPortugal]

Gents,

A few of you have rebuilt front subframe assembles recently.

I have re-attached my control arms to the subframe and am trying to work out:-
1. How much to tighten the large (32mm) bushings with the female thread which are fitted to each end of the pivot pins
2. Whether the control arms should be completely loose or a bit stiff to move by hand (I have both !!)

Any advice welcome

Peter

[dirkbalter]

Peter,
Me again.
1.    The threaded bushing torque is 180Nm (see chart).
2.   One side on my front end is relatively loose (moves down by itself when I lift it )and the other side is a bit stiffer (I have to slightly push it down) after everything (exept springs) is installed. I played a bit around with the bushings and arms but cannnot get them to be exacetely the same. 
Dirk

[PeterPortugal]

Hi Dirk,

Thanks. 180Nm. Wow !! I was hand tight with a 12" spanner at best. It does explain though why judicious use of a lump hammer was required to shock these parts loose in the first place.

Next question - what is the issue if one of the arms becomes too stiff when the correct fastening torque is applied? Can you have too stiff? The forces applied when the car is in use must be considerable.

Thanks again Dirk. I am glad you are just ahead of me on this same project !

Peter

[PeterPortugal]

Hi all,

Any advice on how stiff the control arm can be? Torquing the bolts doesn't increase the force required to move the arm too much but it is substantially stiffer than my other one.

I was looking to buy a replacement arm but mine are the type with an additional stiffener welded in and I couldn't find a like for like replacement online. If anyone knows where I can get one then let me know please.

Regards

Peter

[Aaron h]

If it's of any consolation to you, the W113 shared the same control arm with W108, W109, W110, W111, W112.  Part number 112-330-31-07.  The Pagoda didn't have a control arm made specifically for the W113.  While there may be differences in construction between early and late, using a control arm without the stiffening plate won't hurt the car or affect anything.  Though, if you're set on maintaining originality I can understand that.  Just food for thought.  

[PeterPortugal]

Hi Aaron,
Thanks for your advice. Do you know whether the control arm with stiffener was fitted to all models for a certain period of time or whether it was specific to certain models only?
My car is a 1963 220Seb Cabrio.
Thanks
Peter

[Aaron h]

No.  In my last comment I stated that the control arms were the same for all models (except the W100 and W114/W115)) from 1961 until 1972.The control arm with the stiffening plate was fitted to all early models.  It wasn't specific to any model.  However, Mercedes did not note when they started using the ones without the stiffening plate.  So unless we do our own research according to which car VIN ranges have or don't have the early style control arm we'll likely never know when the change happened.  The part number never changed, either....which is somewhat odd, but not uncommon. 

[PeterPortugal]

Hi Aaron,
I appreciate your advice again. Thanks for replying.
Regards
Peter