Restoration Difficulty Level

[andyburns]

To re-spline or cut... that is the question.  Just come off the phone to my trusted engineer.  I asked him which way he would go.  He considered for about 3 milliseconds and told me it was my choice but if it were his shaft and was difficult to replace that he would definitely cut and weld.  His thoughts were based around thousands of splines he has commissioned over the past 40 years amongst many which have gone wrong effectively destroying the job.  So decision made shaft off to be 'properly' cut, insert made and a re weld.   Interested in anyone who has gone down the re-spline track.

[drmb]

Do you realize a 108 & 113 P/S droparms are different,and RH drive 113 P/S droparms are very very rare.

[andyburns]

Hey Lloyd,  I didn't realize that.  Thanks a million for pointing that out.  Am interested to know the difference.  Is one longer than the other?  Can I not take the one off the old non power steer 113  box and swap it over to the 108 PS box?  I wonder how Andru did his.  I thought he just swapped an entire 108 box lock stock and barrel including the arm.  Have you got any arms if I run into trouble?  Cheers  Andy

[andyburns]

Back to the books.  Doesn't seem there is anything on paper between the 230sl and the 280se the pitman arm came from.   The length and angles both seem the same.  The only thing I can eyeball between them is the nut which hold the arm on seems to be larger with the   Lloyd can you please let me know where I will go wrong if I use the 280se pitman arm.  If anyone will know the difference it will be you.  Cheers  Andy

[w113dude]

Andy,

I have mine out of a 280se for my 67 250sl, the power steering arm is just right, what you should look is a match between the idler arm and the power steering arm , if the angles  and the length of the arm are the same then you are good, this way the right and the left turn will result in same distance travel. make sure to set the power steering box in dead center position, lock it in then install it.

[andyburns]

Hey Shaun,  I tend to agree with you.  Lloyd is an expert on rhd 113's and restores full time so I am still interested to investigate what he is referring too.  Perhaps there is some strange right hand drive peculiarity that he knows about through trial and error.  The last thing I want to do is go ahead with the conversion and hit some barrier after the car is all back together.  Attention to detail might be prudent in this situation.  I am going to spend this morning taking some very careful measurements as you suggested and will post the results back latter in the day.

[drmb]

Andy I have sent you a pm

[andyburns]

More frustration today.  Lloyd has kindly pointed out the technical difficulties that I will encounter if I go ahead with the power steer conversion.  Very subtle and easy to miss if your not paying a lot of attention.

The early 230's appear to be harder to convert and 'get right' than the latter 250's or 280's.  They had a unique pitman steering box arm and matching idler arm.   Actually it seems that most mercedes of the day have a matching set.  The difference from set to set was the angle that the arms bend toward the ground. 

I currently now have the pitman arm from a 280se W108 power steering unit and the original 230sl mechanical steering box matched idler arm.  With the drag link connected you can see the obvious problem (thanks for putting me on the right track Lloyd). 

Lloyd has indicated that the net result of going ahead with this combination is that you will never get your wheel alignment right as the outer links are traveling different distances due to the height variations in the pickup points. 

I still don't have enough knowledge of the problem to understand the effect on the overall suspension setup.  Looking at the angle of the drag link I now have an appreciation of how bad the situation is. 

If you didn't have the engine out and were doing this conversion you would likely never notice the symptoms and probably plough on with the conversion totally oblivious.  What I need to know is how much of an issue would it cause, and what are the long term symptoms and severity should I choose to forget my past 48 hours of learning.   Sometimes the oblivious route is in hindsight total bliss!

I think the problem could be improved by either obtaining a different pitman arm with a reduced angle or conversely a different idler arm with a more acute angle.  Lloyd has indicated that the correct arms are NLA at the factory so I am left trying to mix and match off other models to get the 'best' possible combination to level out the drag link.  If anyone can help or add any more info to puzzle I would love to here.  It would be good to get an exact list of factory parts that all work together to overcome this.   Even a couple of possibilities ranging from best to worst.

I really dont want to cut my shaft until I sort this issues so its stopped me in my tracks. Chocolate fish to anyone that can suggest a cheap and easy solution 

[GGR]

Did you try to fit your 230 steering box arm on the power steering one to keep the set matched? Size of the nut may be different, but not necessarily the splined area under it. Did you take both arms out of the steering boxes to compare?

[andyburns]

Hi GGR,  I have only just today purchased a pitman arm puller.  I will give that a crack but Lloyd has advised me that the splines on power steer boxes are different from mechanical boxes and cant be swapped.  If you have tried any swaps that turned out to work well please let us know.  I am after confirmed working techniques or part combinations.  I will continue to plug away and post my results over the next couple of days.  I am going to mount back up the original non PS box tomorrow and compare the angles with the PS box.    Cheers Andy

[w113dude]

Hi GGR,  I have only just today purchased a pitman arm puller.  I will give that a crack but Lloyd has advised me that the splines on power steer boxes are different from mechanical boxes and cant be swapped.  If you have tried any swaps that turned out to work well please let us know.  I am after confirmed working techniques or part combinations.  I will continue to plug away and post my results over the next couple of days.  I am going to mount back up the original non PS box tomorrow and compare the angles with the PS box.    Cheers Andy

Lloyd is right They are different.

[GGR]

I have looked on EPC and this is what I found:

The pitman arm p/n on 230SLs RHD started as 111 463 22 01, common to chassis 113.042; 113.043 and 113.044, and was then replaced by 111 463 26 01, common to chassis 113.042; 113.043; 113.044 but also to 111.010; 111.012 and 111.014.

The idler arm (intermediate lever as per EPC denomination) p/n on 230 SLs RHD is 111 460 14 19 and is common to chassis 113,042; 113.043; early 113.044 but also to 108.012; 108.014; 108.015; early 108.016; 111.021; 111.023; 112.021 and 112.023.

This may help you find parts you need. However, I don't understand why common chassis are not the same for the pitman arm and the idler arm, unless fixing points on chassis are different relatively right to left compared to the Pagoda? It can also be that EPC in not giving an exhaustive information (I noted that for other parts) and that all these chassis are in fact compatible.

they do not seem to differentiate the pitman arm between manual and power steering. Replacement of part number seems to be chronological rather than linked to the type of steering.

I'm not sure if this helps or if it brings more confusion.  

[andyburns]

Thanks GGR.  It all is extremely confusing to me.  It would be very easy if I could simply buy the right pitman arm but they are NLA.  Now the confusion comes in knowing exactly what the next best combination for the car is.  I have no doubt I will have to start sourcing new parts but before I do this I want to know exactly what the best combination is.  Until the parts are on the car and you can measure everything up you wont know so unless you have done it before its total trial and error.  Guys like Lloyd who do it for a living would have the luxury of having all sorts of spare parts lying around to mix and mingle and try all the different combinations to get the 'next best result'.  Thanks a million for getting those part numbers for me though.  I wish I had access to EPC would be a fantastic resource.  The pages of the book I posted earlier are total gold.  Factory spec manual that you can slip in your pocket.

[rutger kohler]

Hi Andy, how about getting South Aucklabd Foundry to look at the problem? As you say they are experts in forging and heat treatment so might be able to heat and change to the correct angle then anneal?

[andyburns]

Hi Rodger, really strange you should mention that as I have had them here this afternoon to look at the problem.  You read my mind.  I spent last night getting exact measurements on how far the power steering settings are from the factory mechanical box that the car came out of the factory with.  I used a 'pinned' chalk line to get a datum on exactly where the factory setup was and then swapped out the box for the W108 280se factory box.  Discovered that with the new power steer box from the 280se and the factory 230sl idler arm we are exactly 10mm low on the power steering pitman arm should be.  I then used my new pitman arm puller and swapped over the 20sl mechanical pitman arm to the 280se power steering box.  I thought they would have different splines but in the end turned out to be identical.  So I gave it a crack.  They both appeared to be almost identical when compared side by side once removed.  This was confirmed when I bolted the new configuration into the car and got an almost identical 10mm offset.   See photos for better visualization of what I am on about.  So back to the drawing board.  I have exhausted all my options in terms of parts I have available.  So I called in the big guns.  Barry from South Auckland Forgings has taken the pitman and idler arms away for analysis in the mass spectrometer.    He is going to determine if they are cast iron or have been forged.  If they are cast iron I am buggered but if they have been forged he can heat and bend them and then re heat treat to ensure they retain their original strength.  Will keep you informed how I get on.  I am still interested to talk to a suspension specialist to figure out if I leave it with the 10mm offset  what problems I will end up with.  If it reduces my tread life from 30,0000km to 20,000 I wouldn't give a monkeys.    Another interesting observation is that even the factory mechanical setup seemed to have a slightly different height setup from left to right resulting in the drag link not being on the 100% level.

[rutger kohler]

Hi Andy, i can tell you right now that the part will not be cast iron. Cast iron is strong in static compression but weak in tension and cannot withstand sudden shock loadings, more likely to be a drop forging, heat treated afterwards i would guess. Barry is the right man for this.  i had not appreciated how small the error is, also interesting that the origninal setup has the same built in "error".  As you say experts in suspension geometry can probably predict what the outcome would be if you leave it.

[andyburns]

Rodger,  am still keen to here from anyone who has seen the long term effects of making the change without correcting this problem.  Surely someone out there has seen the consequential physical manifestations.   Lloyd it would be really good if you could describe what you have seen. 

[andyburns]

Barry has come back and the good news is that we can bend the steering arm if done properly.  He is coming over tonight to see the component in place to determine how best to make the bend. For those interested this is his analysis and recomendations:

Hi Burnsy.
The steering arm is a forging, with a chemical composition conforming to AISI5130, a 0.3% Carbon, 1% Chrome alloy steel.
Hardness tests show it has been hardened and tempered to 270 BHN (Brinell Hardness). Depending upon the quenchant speed used by the manufacturer, I would estimate the manufacturer used a final temper temperature of approx. 550-590degC to achieve this hardness.
These results confirm what is usual practice for steering componentry of reliable quality.
It is perfectly possible to alter the shape of such components, something we have considerable experience in.
Usual practice is (after doing tests above to establish existing properties and temperature limits), to carefully heat the product in an accurate heat-treatment oven to min 30degC below manufacturers temper temperature (ie, in this case heat to max 520degC which is a barely-visible dull red in a very dark room).
The part can be pressed to desired new shape whilst at this temp and then allowed to cool.
It is most essential that after cooling the part is Stress-Relieved by re-heating to the same temp for minimum 1 hour per 25mm thickness, to relieve the stresses put in the material by 'warm' pressing.
This last step must not be missed out.
Finally we hardness test the part again to ensure minimal loss of hardness (and hence strength).
 
Barry Robinson
S.A.F.E Ltd

[Benz Dr.]

Interesting research. You can raise or lower the idler arm by adjusting the height on the early example before you turn the nut down.
I seem to remember something about adding or removing a washer under the late idler arm depending on power steering or not.

[andyburns]

Dr Benz,  to be honest I hadn't even considered that or looked closely a the idler setup.  I had thought about altering that side by bending the idler but figured the height it was in relation to the outer link height would have been set perfectly at the factory and therefore I should leave as is and use as my datum. 

I hadn't even pulled it apart as a result so didn't fully appreciate how it hung together.  Got quite a shock when I went out and looked at my spare one.  Quite an unusual setup with the rotation of the arm taken up on the internal thread of the pin.  I can see why they moved the latter version as it makes more sense to have increased turning surface area of the entire bolt shank on a bush for increased wear resistance.  In saying that the 40 year old example of the early setup I took from a W108 isn't showing to much sign of wear.

I understand what your getting at about the adjustment.  It makes me a bit squeamish as you would be reducing the amount of thread the arms turns in.  Two things about this probably need to be considered 1) will decrease the amount of material the pin is turning in which would increase wear and 2) would decrease the amount of thread actually holding the pin in.

In my case I need 10mm adjustment so I would need to reduce the amount of thread available on the pin from 20mm down to 10mm.  I can understand if the factory intended a 1 or 2mm washers for 'fine tuning' but 10mm might be a different matter altogether.  I am really interested in your thoughts on this one Dr Benz.  Have you ever used the idler for adjustment and how far did you take it.



 

[Benz Dr.]

All good questions but it may not matter that much. The heim joints in the steering linkage should allow for some misalignment and I wonder how critical this really is. I know it's best to have everything on an even plane as bump steer issues may result but I usually adjust everything so that the arm will allow full movement to the right without coming anywhere close to locking up. That would not be a very good thing if that were to happen!


I can't recall there being any washers on the early version and all they had was a grease seal above the arm. Looking through my dealers parts book confirms this. It appears that there was only one arm used on 230SL's. This arm with the pin attached can't fall out under normal running conditions. That small amount of height adjustment may not present any adverse driving symptoms at all - or maybe it does but most of it can be adjusted out during a front end alignment.

[GGR]

My '62 W111 Coupe has the same relay arm system. The top nut has gotten loose by a few turns and the consequence was that alignment "opened" on the right wheel (my car is LHD) by quite a bit and the car was wandering on the road. I didn't realize immediately that nut had gotten loose so I readjusted alignment on the right. The car was still wandering and I traced it as being some play in the linkages. At first I thought it was the drag link but it was in fact the nut which was loose. I tightened it, play was gone, but I had to adjust alignment again.

By looking at the system, I don't see how the nut being loose by a little did induce play, as the shaft is turning inside some bushings that I had replaced.

The arm being lower did open the alignment by quite a bit (or was it as a result of the play?).

I also thought you could lower the relay arm a bit, but like you, I was wondering if thread was enough to allow for 10mm. In any case, if you go that route, you will have to make sure there is no play.

Like Dan I think that 10mm difference wouldn't affect the steering geometry very much. It will, but it may well stay within tolerances. The crooked drag link won't look that good though.     

[andyburns]

Cheers fior looking up the parts book for me Dr Benz.  Neither of the early setups I have here have anything but the grease seal  and the crinkle washer.   If I added a spacer I will then have two surfaces to seal as well.  The only way the pin could fall out is if the internal thread stripped.  I know this is extremely unliley but in therory by reducing the contacting thread surfaces by a half would double the possibility of failure.

I see exactly what you mean about ensuring you have 100% travel on the pin when you set it up.  In essence as the arm is turned clockwise its essentially climbing itself upwards as it turn on the thread.  If it got to the end of its travel it wouldn't be good.  Another interesting thought is around the seal at the bottom.  Does that mean that its sealing tolerance is constantly changing as well?  Wouldn't it be interesting to a fly on the wall at the factory tech meeting where they decided to move away from this design.

In any event I think I will just keep on plugging away at my original idea of bending the arm.  I had Barry up last night and he doesnt think it will be a dramma.  He has taken the W108 arm with him to bend.  I will preserve the original setup just in case I have to put it all back.  I am also going to hold off cutting the shaft until I have the bent arm to fit up and compare.

Thanks again for your help Dr Benz

All good questions but it may not matter that much. The heim joints in the steering linkage should allow for some misalignment and I wonder how critical this really is. I know it's best to have everything on an even plane as bump steer issues may result but I usually adjust everything so that the arm will allow full movement to the right without coming anywhere close to locking up. That would not be a very good thing if that were to happen!


was a grease seal above the arm.I can't recall there being any washers on the early version and all they had  Looking through my dealers parts book confirms this. It appears that there was only one arm used on 230SL's. This arm with the pin attached can't fall out under normal running conditions. That small amount of height adjustment may not present any adverse driving symptoms at all - or maybe it does but most of it can be adjusted out during a front end alignment.

[andyburns]

Thanks for your reply to GGR.  I can understand with your scenario where the to top bolt came loose that the pin would no longer be tightly contained in the tube and could effectivley bounce up and down introducing the play that your referring to.  That wouldn't be good.  As Dr Benz suggested as long as I contained the slop with a spaces I might achieve what I am after but its just the saftey aspects I am worried about. 

The drag link arm that can be seen in my photos is off the W108.  I am using this one for the time being as Lloyd suggested they might not be interchangable.  They seem identical but I havn't paid that much attention.  I dont know how that one got that kink in it.  Any length variation in the drag link can be compensated for in the adjustable ball joint in the outter suspension set up I am guessing.

Once again thanks for your input as well.  It all is helping to add to the big picture.

[GGR]

Thanks for your reply to GGR.  I can understand with your scenario where the to top bolt came loose that the pin would no longer be tightly contained in the tube and could effectivley bounce up and down introducing the play that your referring to.  That wouldn't be good.  As Dr Benz suggested as long as I contained the slop with a spaces I might achieve what I am after but its just the saftey aspects I am worried about. 

The drag link arm that can be seen in my photos is off the W108.  I am using this one for the time being as Lloyd suggested they might not be interchangable.  They seem identical but I havn't paid that much attention.  I dont know how that one got that kink in it.  Any length variation in the drag link can be compensated for in the adjustable ball joint in the outter suspension set up I am guessing.

Once again thanks for your input as well.  It all is helping to add to the big picture.

Well, the nut did not come completely loose, just two turns or so.

Drags links are the same, p/n 110 460 02 05, common to many chassis of the w108, 109, 110, 111 and 112 families.

I think link length variations will affect the steering. The connection between the arms and the tie rods is following an arc, and depending on the position, angle is not the same. Therefore transmitted movement won't be the same, depending on angle. I think travel along these arcs are very much coordinated between left and right and the length of the drag link must have been quite precisely calculated. It may not affect much if we are talking of very small length differences.