Reconstructing Suspension MB 6.9

[laudatioorgani]

First time posting photographs so let us hope this thing will work out!
Here you see the front chassis as it is now, with the standard w116 parts soldered on:



These are the original chassis parts taken out from my 6.9, now useless mostly due to material fatigue caused by temperature during dismantling:



I have to get the original chassis towers for the Hydro suspension (very different geometry to the standard suspension). Any idea where to get them? Second hand would be fine, I guess, but hopefully in the USA.

[NAS_878]

The 6.9 full hydro suspension sounds really great.

Just a quick question... is it possible to install the 6.9 full hydro suspension in 280SE/SEL ?

NAS 878

Yes,

However, it is also possible to dig your own cross-channel tunnel using nothing but common kitchen utensils.

It is also possible to perform a self-vasectomy.

It is possible to pretend to be peter pan using fishhooks:



All of which would be less painful and more rewarding then a 280SE/SEL hydro conversion.
Perhaps an engine swap on a 6.9 chassis? 

Here's a genuine Daimler/Chrysler diesel:



(800cc)

Over here in Malaysia there's only 3 units of 6.9 here. Even I am lucky and rich enough to own one of them I wouldn't want to take out the 6.9 engine and put in a genuine Daimler/Chrysler diesel. That is just not showing respect for a 6.9 IMO. Why want to downgrade such a wonderful car?


Base on the assumption of no chassis modification, if I can obtain all the parts of the 6.9 full hydro suspension... is it possible to do the 6.9 hydro suspension converson in 280SE or 280SEL?

If not, what minimal chassis modification is needed? will the longwheel base chassis easier to convert due to the original parts also from longwheel base?

NAS 878

[s class]

Hi laudatioorgani

OK I see from the photos that your car is a LHD, so I can help you with photos (LHD and RHD have different piping routing).  There are also differences between early and late 6.9's.  Yours looks like an earlier one judging from the brake reservior.  What are the last 4 digits of the VIN - I'm guessing 2000 or lower?  If it is an early one like I suspect, it will be the same as my trusty rusty. 

I'm a bit surprised at the pictures of your suspension towers - I didn't realise they differed between 6.9's and other 116's.  I will put my 280SE and 6.9 side by side today and compare. 

[WGB]

Hi Nicolas,

There may be some geometry differences but I doubt it. THe major difference is the need for spring mounts on the 450.

I have a 450 with standard suspension and a 6.9 with hydraulic suspension and have looked over and photographed both tonight.

Just to clarify a point from the beginning - nomenclature is LH (Left hand) and RH (Right Hand) as viewed from the drivers seat. My Cars are RHD but yours is obviously LHD.

Front suspension
1) Body pressing of upper mount appears to be the same in both cars but on a 450 there is a strengthening plate spot welded to the engine compartment side to support the shock absorber.

Here is a view of the LH underbonnet are showing the 450 mounting



Here is a view of the RH 450 mounting as seen from the underbonnet.



2) The 6.9 has a mounting for the upper end of the front strut spot welded underneath on the wheel-arch side.

Here is the underbonnet view of the 6.9 LH side



Here is the underbonnet view of the RH side



3) Here is a view from under the LH wheelarch showing the upper front suspension and shock absorber of the 450



4) Here is a view under the LH wheelarch showing a 6.9 upper strut mounting.



5) both 450 and 6.9 share the same lower mounting on the lower arm with the same fixing although obviously the spring and it's lower plate are not present.

6) Here is a photo of the RH rear upper shock absorber mounting of the 450 with the rear seat removed.



As far as I remember it is identical to the upper mount of the rear 6.9 strut but there may possibly be some extra reinforcing. As far as I know the lower mount on the suspension arm is the same for both but I am not definite on that and as both cars are sitting on their wheels and I am in respectable clothes I am not going to grovel about tonight - but will on  future occasion.

I can e-mail you better quality versions of these pictures if you wish to show them to your restorer.

Regards

Bill

[laudatioorgani]

Hi Bill,

Thanks a bunch for those highly interesting photographs. You are right: both towers may be very much alike, if not identical. However, we think that the Hydro geometry calls for greater distance between the towers with struts in more parallel position. We took the decision of changing the entire chassis part with the towers because we fear premature material fatigue caused by overheat when taking out the old towers and soldering on the new ones. Changing the entire chassis elements will be quite a job requiring engine and transmission disassembly, but it seems to be the only reliable solution at long term. We shall profit from the occasion to properly repaint the engine compartment and attend some other little issues.

Thank you for the photographs offered. I will print these for the restorer and see if greater detail is needed. Most wholeheartedly gratitude! This will be a long process...

Cheers, NA.

[s class]

We took the decision of changing the entire chassis part with the towers because we fear premature material fatigue caused by overheat when taking out the old towers and soldering on the new ones. Changing the entire chassis elements will be quite a job requiring engine and transmission disassembly, but it seems to be the only reliable solution at long term. We shall profit from the occasion to properly repaint the engine compartment and attend some other little issues.

WELL DONE, WELL DONE.  This man is a hero!.  Glead to hear you are doing it properly.  You will not regret this. 

[laudatioorgani]

Dear S Class,

Thanks you for your kind appreciations. My 6.9 last four chassis digits read 1203, so it is indeed an earlier version (1976). I know there are a few differences between earlier and later versions but did not know about the brake reservoir. I believe the suspension systems had some important differences, the main one consisting in additional bleed valves for specific system instances (aside from different reservoirs and other minor issues). Since we have to remake the whole Hydro again, I am wondering if installing these extra valves would be worth the effort. Did you install them in your "trusty rusty"?

If I read right you have a 6.9 AMG, have you gotten any pictures from this baby? I would love to see it. I promise better pictures from Fritz (so have I named my 6.9) once rendered better looking! Best regards. NA

[s class]

My trusty rusty is a 1976, while the red AMG is a later car (late 1978).  Differences I have noted :

early cars don't have the bleed valves as you mentioned.  I did not fit them to trusty rusty, and it has not been a problem at all. 

early cars have a smaller, simpler oil cooler for the suspension oil below the front bumper

on early and late cars, the three long hydro lines from the front to back of the car run along a different routing under the passenger seat area. 

there are some plumbing differences around the front levelling valve

[WGB]

early cars don't have the bleed valves as you mentioned.  I did not fit them to trusty rusty, and it has not been a problem at all. 

The bleed valves were added in case of collision damage where it might not be possible to start the engine or release the line pressure.

They were added after chassis number 001985 and some people use them for bleeding but that function is not really done by most.

If pressure needs to be released a hydraulic line can always be loosened.

Bill

[laudatioorgani]

Dear Bill,

First of all I ought to apologize for not having replied earlier. Only now I find due time to look and comparatively analyze your photographs of both suspension systems. Thanks a bunch for this! You are probably right: both suspension systems seem to have the same sort of basic chassis mountings (disregarding the extra supports and so forth). I still think the Hydro has chassis mounting towers a bit closer to each other calling for a more parallel geometry. Apart from it, the chassis parts where the struts (and springs, in the case of the standard system) push against seem to be very, very similar.

Considering this I dare to propose the following question: if I ever find a waste w116 and take out precisely the chassis mounting elements so as to be soldered back on my 6.9 with exact Hydro geometry measurements and addition of all necessary extra supports underneath the wheel-arch, should I then be able to install my Hydro back? In such a hypothetical case there would be a space left empty for the lacking springs not present in the Hydro, but who cares.

Quite a thing to have a 450SEL and a 6.9. I have never driven a 450 myself before. I suppose its comparatively smaller engine must still deliver considerable power, right?

And very lastly: I have never driven a w116 with Hydro before either. My enthusiast for having the system reconstructed relies on mere theoretical admiration for its stupendous engineering. But at the end of the day, how different does a standard suspension feel when driving vigorously? If doubtlessly smoother with bumps, has a Hydro better handling conditions on the road?

We shall have quite some discussions with the restorer the upcoming weeks. He is so damned perfectionist. He refuses to solder anything back arguing premature metal fatigue due to high temperature! May be true but alas! I still have to strive for the best possible solution, even if not perfect.

When you ever get the time, could you take one more picture from the 6.9 under-bonnet front suspension area with a wider view, just as you did for the first 450SEL photograph posted here up?

With kindest regards, NA

[WGB]

It is up on the hoist still so I will take better underneath and under-bonnet views and will post them here in this thread later today.

Again if you want any of them in the full 2.5 meg file just let me know and I will e-mail them to you.

One thing I did notice last night while changing the rear suspension bushes  is that the rear spring retainers appear to be still present so the rear chassis structures may not have been modified at all.

I tend to think your restorer may be a bit pedantic about the heated metal parts.

No body part in a 116 is high temper steel and soldering is not that hot - so I cannot see why your old body parts are unusable - and if they are why can't they be used to make patterns for new.

Bill

[laudatioorgani]

Good morning Bill (or good evening should I say in your globe quarters),

I slept thinking over and over about this suspension reconstruction. I concur in your appreciation: the rear structure appears to have remained unaltered. As for the front I believe the differences are by far not as severe as some pretend them to be here.

I agree with you as well about the overreacting position of our restorer. I will have to make a softening persuasion process. From your point of view and paying a look to the old damaged chassis parts I pictured and posted, do you think one could build two new chassis parts using the old ones as patterns? I suppose a skilled technician should have the knick to make such a part correctly. You can not believe how expensive a new 6.9 chassis tower is.

I shall be out this weekend for a well earned rest and will retake the subject next week. I thank you for you offer of higher resolution images which I may need in a later work stage. I remain yours as ever, NA.

[WGB]

Hi Laudatioorgani,

Here are a few photos I collected over the weekend of my car while it was up in the air - I did not take the wheels off so there are some restrictions to the overall panorama.

I did notice an oil leak around the low pressure pipe into the hydraulic pump while taking the pictures that I hadn't noted before and found a poorly fitted hose which was nearly cut through on a sharp edge - so the exercise was a potential expense saver for me.

I replaced the hose with a new length of hydraulic hose and applied two chamfered clips on each end after undoing the fitting on the pump with a 17 mm offset socket and rotating it so the hose couldn't be cut by the sharp edge of the power steering bracket.

Remember my car is RHD.



This is an overall view of hydraulic reservoir and pump



This is a closer view of the pump with the high pressure outlet hose arcing around to the valve on the reservoir



This is a broader view of the LH underbonnet area as you requested but as you can see it gets rather cluttered under there



And this is the RH view



LH front strut



And just in front in the LH wheel arch is the "Central" sphere to the front and more vertically mounted with the LH Front Sphere behind



Here is the RH front strut



But just to be confusing the RH sphere is mounted under the battery tray on it's own bracket - the bracket and sphere can be removed by removing the two nuts that are visible just above and to the right of centre in this picture.

There is also a Levelling valve positioned under the bonnet near the firewall and connected to the front torsion (sway) bar. On a RHD it is on the left hand side mounted on the chassis rail near the rear of the engine - not sure about the LHD.



Here is the rear levelling valve mounted on bracket to the left rear of the diff with an arm connecting it to the rear Torsion (Sway) Bar.



Here is the LH rear strut and sphere



And here is the RH rear strut and sphere.

That is most of the hardware and then we have all the interconnecting pipework.......

Still keen?

If so I will be happy to provide more detail from time to time as required and I'm sure S-class will as well and he can give you LHD specific information as well.

Bill