Author Topic: 6.9 suspension  (Read 2615 times)


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6.9 suspension
« on: 08 August 2006, 01:24 PM »
Hi there, new to the forum but certainly not new to MB(although I am somewhat ignorant to a number of mechanical items).  Just purchased a '78 6.9 L in California,  somewhat of a curious car... black exterior and interior, prior owner had no knowledge of MB, spent over 10K in 1 yr.  Lots of stuff done, engine solid, suspension could use work (he had all of the valves replaced, $ 5,500).  98K miles.  body solid as can be, good 10 footer, just replace grill.  Questions,  we have a '80 450 sel in Canada (our new car is in Nevada).  The ride on the 6.9 is choppy, I suspect that accumulators will need to be replaced.  The 450 in Canada (Calgary) is a sweetheart of a car, one owner (our family) and had engine rebuild 60K ago.  Drives like its new but it has had over the years rust issues.  As it stands it needs two new rocker panels and repairs on the facia of the rear fenders.  It is driven only occasionaly (once every 3-4 months or so) and I am wondering if I just shouldn't make one car out of the two.  The interior on the  450 is immaculate (and I do mean immaculate, you wouldn't know that it wasn't 6 months old) and the 6.9 has issues on the interior (seats are perfect but needs a new dash, the surrounds around the lower inside doors have scuffs and cracks and the console needs to be replaced) to make it perfect.  Firstly, can the shocks and springs on the 450 sel replace the hydro system on the 6.9 (I know that this is the most costly of the 6.9 ownership experience).  Secondly, if I re-do the interiors to make one absolutely perfect will the 450 sel euro lights and steering wheel (its a 1980) fit seamlessly and thirdly, and most importantly, what does it do to the 6.9 engine when I remove the pump for the suspension (can it even be done ?).  Does anyone know of a reputable shop to redo the wood on the 6.9 ?

Lot's of questions,  thank you


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Re: 6.9 suspension
« Reply #1 on: 08 August 2006, 03:55 PM »
Sorry Stevenm,
New rules. No questions answered without photos of your ride/s.  :D :D

Just kidding.  I couldn't make the decision about the interiors, I'm too biased in thinking that all 116's should be saved  8) I'll just answer the part about the lights and steering wheel.  I've seen enough conversions (ie photos) to say that the lights are interchangeable with the same mounts etc. Only differences that I found out from this site are that there's LHD euro and RHD euro, both with differences in anlges of reflection that suit LHD or RHD countries.  There's also been later model lights with remote dimming servos on the back that someone posted somewhere here, so I don't know whether the wiring harness is different for those.

Do your steering wheels look the same?  Being from the same year I would say with certainty that the steering wheels will swap.  Earlier models had 15mm splines with locknut, around 77 they changed to approx 20mm with ring clips though I've never taken a later one off.  Peel the horn pads off to compare the splines.

Good luck with your other q's.
1973 350SE, my first & fave


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Re: 6.9 suspension
« Reply #2 on: 08 August 2006, 09:17 PM »
I would replace the accumulators as necessary and see if you don't love the way the car rides. As suspension parts in this system go, they're individually the least expensive component. If your reluctance to stay with the hydro suspension is caused by the PO spending 5500 on valves, you might look into pricing these components yourself as that sounds way overpriced to me.  With the valves done and only accumulators to be done you might be all right for awhile.  I wonder if the struts have ever been replaced?  They're not cheap, so that's a gamble.

I have had my 6.9 for ten or so years and have been reading about them longer than that and I have never heard of anybody changing to conventional springs and struts.  This is not to say that it can't be done, but the question has come up before and nobody I know has ever followed through with a conversion.  It's possible that this means it would not be economically a good idea.

I had to replace a lower rear control arm a few years back and seem to remember that they are not the same as 450 SELs, so short of getting a wrecked car part, you would be looking at 2200 from MB.  For one side of the rear. Before buying springs. And adapting shocks.  Of course if you have the money, anything can be done.

The pump for the suspension runs off the timing chain.  Off a fixed sprocket.  I think you could leave the sprocket in place so as not to have to re-engineer the length of the chain and fashion some kind of cover for where the pump is supposed to go.  Not being a mechanic, but having seen how this works, this might be the easiest part of a conversion.

Drew Tibcken on the East Coast or Robert (?) Merrick are the top shelf wood restorers in the states.

If you have a notion to mess with the suspension stuff yourself, be aware that the spec for the fluid is several thousand pounds pressure. Not something to be messed with casually.  Never work under the car without all four corners on stands; don't trust the jack that came with the car.
If the lever for the rear suspension valve is detached from the turnbuckle and moved less than a couple of inches to the low position, the car will be low enough to scrape the muffler on the pavement.  If you're under a car that is not supported properly, this would be uhh, disappointing.

I am into my car for the long haul, so I am at the other end of the spectrum from the nay-sayers. There is no reason my car can't be almost as good as the day it came off the showroom floor, that's how solidly built these things are, as I know you are aware.  Few cars that are 28 or so years old can claim the same. You'd just be throwing parts at a worn out platform with almost anything else.  With that bias in mind, I would say fix what you have rather than convert.  Shop for parts. The parts peculiar to 6.9s are not cheap, but you can pay 30% or less of what the dealer charges if you are patient and try to anticipate the next parts needs ahead of time.

I'm new here, too and I think you'll really enjoy this board. Everybody is polite. 


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Re: 6.9 suspension
« Reply #3 on: 08 August 2006, 09:32 PM »
Kenny, I know a guy in the USA (he has previoulsy posted on did change to springs and shocks; I recall this as he also put in a short diff ratio on his 6.9 (3.25 I think) and then did some quarter mile sprints - managed low 14's.  Someone else here might be able to add to this for me.
sigh....sitting back contemplating the next purchase..!


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Re: 6.9 suspension
« Reply #4 on: 08 August 2006, 09:38 PM »
Well, there you are.  It can be done.  14 secs.  WOOF.  That's pretty sprightly!

I wonder what all was involved in changing the suspension over. Do you think it was Jason Schoenfeld?  Seems to me he had some involvement in racing his cars.

I admire people like the drag racer and our own Mr. Alabassi who just go for it.
« Last Edit: 11 August 2006, 10:50 AM by kenny »

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Re: 6.9 suspension
« Reply #5 on: 09 August 2006, 11:41 PM »
Hi there,

My feeling is that a 6.9 is what it is primarily because of a) the engine and b) the suspension.  If you do away with the 6.9 suspension, I think the car will be greatly devalued.  THe M110 cars (600/6.3/6.9) are something of cult cars that really only sell to specialists - and these people are very fussy.

OK that's my 2c worth.

On a more practical level, I have seen in W116 spec sheets that the 6.9 has a slightly shorter wheelbase that other steel spring SEL's.  THis suggests that Kenny is right that the rear control arms are different.

But then given enough money, anything can be done.  My feeling is that it will cost more to do the conversion than to fix up the remianing issues on the 6.9 supension

Ryan in South Africa

'76 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '82 500SEL euro full hydro, '83 500SEL euro full hydro , '81 500SL


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Re: 6.9 suspension
« Reply #6 on: 10 August 2006, 02:07 AM »

Somewhere i remember reading when looking and informing myself about 6.9s' that to change the suspension over would cost about the same as fixing it up. I am failry sure it was on the m-100 site. But then I did a lot of reading. If I find it again i will post it. At least with 6.9 if the suspenison is not working well you have to fix it, and how often do people properly maintain the tradional suspension! That costs money too, but people dont usually do it until it is truely broken. The cost difference for something so unique I am happy to pay for and i know my suspension works.

If one is worried about the costs of a 6.9 I dont think it is a car one should buy and the suspension mosty gives you a warning that it is going to fail.

I would not buy a 6.9 without the suspension and if i did it would only be for wrecking.

Good luck with your car.


78 450 SEL Parting out
78 450 SEL Saving for parts
79 450 SEL 6.9  #5332
77 450 SEL 6.9 Euro # 1696
77 450 SEL 6.9 Euro #1577
78 450 SEL 6.9  # 4172
76 280 S     Manual Parting
80 280 SE  Possible Parts Car
74 350 SLC  Thinking converting to race