Author Topic: Idler arm shaft. Torque?  (Read 4874 times)

jan lauwers

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Idler arm shaft. Torque?
« on: August 18, 2015, 11:52:34 »
Gentlemen,
 
I am remounting the front axle which has come back from restoration.
 
With that job I also renew the idler steering arm shaft and bushes, since the rubber/metal head shaped bushes, were torn. I have mounted the new shaft. The books give a torque setting for that, from memory I believe it was 120 Nm.
I don't understand that because if I apply that, the arm will no longer turn. What am I doing wrong here?? I was thinking of torqueing it such that there is no play but still free movement, and apply Loctite on the bolt.

Thanks again!

Jan 
Jan Lauwers, Geel, Belgium 

White 280 SL 1969

jan lauwers

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Re: Idler arm shaft. Torque?
« Reply #1 on: August 20, 2015, 11:01:56 »
is there really nobody who can help me with the question please?

Thanks guys!

Jan
Jan Lauwers, Geel, Belgium 

White 280 SL 1969

twistedtree

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Re: Idler arm shaft. Torque?
« Reply #2 on: August 20, 2015, 13:31:17 »
If you are using the torque give in the manual, which it sounds like you are, and if the arm subsequently binds up, then I'd conclude something is wrong in the assembly.  I've only had the older style 230 idler arm apart, and it's a funky mechanism.  I don't know the details of the later 280 design, but have replaced may idler arm bushings on other cars and there is a certain sameness to all of them.  They typically are stiff, but you should be able to move it back and forth without a huge effort.  Perhaps a spacer washer is missing?  Maybe the bushing isn't pressed into the arm properly?  BTW, I've never seen one (other than perhaps the 230 variation) when the drag is set by the torque on the nut.   On all that I can recall, you crank the nut down tight.  So it doesn't sound like you have a torque problem, but rather an assembly problem.  At least that's where I'd be looking.
Peter Hayden
1964 MB 230SL
1970 MB 280SL
2011 BMW 550xi

Larry & Norma

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Re: Idler arm shaft. Torque?
« Reply #3 on: August 20, 2015, 13:37:45 »
There is a washer that should only be used if you have power steering, perhaps check this.
Larry Hall (Gnuface)
2023 Ioniq6
2005 C230
1970 280SL

jan lauwers

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Re: Idler arm shaft. Torque?
« Reply #4 on: August 20, 2015, 14:56:12 »
Thanks guys,

Everything you say makes perfect sense. I have mounted everything according to the drawing in the book, so I am assuming it is correct but I will have to take another look at it. I do have PS and I have mounted the washer.

Now if we think abut this one for a sec...:  if you have a threaded shaft in a tube, and you have to torque it while it still has to move, then I can only imagine that the length of the thread on the shaft is going to determine if it can still move or not. If the end of the thread is not above the top of the tube, then, torqueing will always prevent the turning of the shaft.

Jan

 
Jan Lauwers, Geel, Belgium 

White 280 SL 1969

Larry & Norma

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Re: Idler arm shaft. Torque?
« Reply #5 on: August 20, 2015, 15:07:44 »
I replaced mine ,a year or two back, with a kit from sls with no problems.
Larry Hall (Gnuface)
2023 Ioniq6
2005 C230
1970 280SL

tel76

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Re: Idler arm shaft. Torque?
« Reply #6 on: August 20, 2015, 20:10:38 »
Where did you get your repair kit from?
Did you compare the new bushes with the old?
If the bushes are not located far enough into the tube you will get binding.
Place the old bushes end to end and measure the length, then compare this with your installed bushes.
Eric

jan lauwers

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Re: Idler arm shaft. Torque?
« Reply #7 on: August 25, 2015, 12:32:17 »
Actually my repair kit comes from SLS, I attach a pic. I have read Dr Benz' explanation on the topic: 
http://www.sl113.org/forums/index.php?topic=3747.0, but I believe he is talking about the arm of a 230 which is different from 280, right?

In any case, I am still stuck with this, I just don't see how this can be torqued to 120Nm without tightening the arm...

Jan 
Jan Lauwers, Geel, Belgium 

White 280 SL 1969