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6.9 Ride Quality - how stiff?

Started by raueda1, 09 June 2022, 10:25 AM

raueda1

As posted elsewhere, I rebuilt my struts last summer.  All the spheres were replaced at that time, or 6 months before.  This had the desired effect of no leaks, no weeping and no suspension drop whatever, even after winter storage.  And amazingly, the suspension light never seems to light up unless there was a massive temperature swing. I'm assuming that this is how it's really supposed to be and the system really was returned to "as new" condition.  So far, so good.

So here's the question:   What should the ride quality actually be? 

Prior to rebuild it was soft and floaty, really too much so. I took that to be what the "magic carpet ride" was all about.  The car just floated over bumps and irregularities like they weren't even there.  It was amazing.  Handling wasn't so great though, lots of body roll and some wallowing and even instability when cornering, but it's not a sports car.

After rebuild it's completely different, and I'm not really sure how much I like it.  It was more or less transformed into a modern car.  Much stiffer.  Not harsh, but stiffer than I'd like.  The floaty can't-feel-a-single-bump quality is gone.  On the plus side, less roll and better handling, to be sure.  But don't get me wrong, nobody would ever complain about the new ride quality - unless they had felt it before (which practically nobody has).  But maybe it's worth noting that despite the change, my partner (64 YO female) thinks it's the best highway ride she ever experienced.  Her comparison is recent BMW X1 and my GL550.

So, does anybody have a good handle on what the suspension and ride should be?  Probably none of us was around when these cars were new, so comparisons are probably clouded.  And is there any way to adjust system pressure or something to modify the ride?  I have no idea what that might be, but seems worth asking.  Any comments welcome!  Thanks and cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

daantjie

Dave, I think you may have too much time on your hands  ;D
Daniel
1977 450 SEL 6.9 - Astralsilber

orientrot

For what it's worth, what you describe seems rather similar to the contemporary reviews of the 6.9.

From the ORG library:

"Magnificent Mercedes"
Motor, 9 October 1976:
QuoteIt is a Mercedes policy to sacrifice a modicum of ride refinement in order to achieve good handling. So it is with their hydro-pneumatic system which doesn't soak up the bumps at low speed in the way the Citroen would. But then neither does it roll or pitch so much. Our only real criticism of the 6.9's ride/handling compromise is its poor suppression of the bump-thump from the fat tyres - perhaps a small price to pay for such comfort and such sure-footed handling.

The Newcomers
"Mercedes' Boy-Racer Limousine"
Car, January 1977:
QuoteAt low speeds, the ride can feel slightly firm, in the usual German manner, over rough surfaces; after that it falls into the category of those rides that are sufficiently good for you never to think about them.

I recall similar comments in comparisons with the series II XJ12/Double Six, Rolls Royce Silver Shadow, etc., where reviewers tended to prefer the ride and handling of the XJ.
75 450SEL
80 300SD- ZF8 OM606 superturbo
83 300D- 6-speed M111 Kompressor
84 300D- 5-speed OM617
92 300D- 722.6 OM603 3.5
93 190E 2.6 Sportline LE x2- 6-speed M111 turbo, 3.0 M103
02 C320 Wagon
03 Sprinter 2500
06 E500 4Matic Wagon

raueda1

Yeah Daniel, I've kind of lost my mind. I'm actually having a anxiety-inducing medical treatment that is making me fret over this kind of thing (among a great many others).  It will subside soon enough....

And thanks for the info, orientrot.  Very illuminating indeed.  So I guess I'm actually experiencing something close to what was intended.  Now I have to find something new to fret about.....    Thanks and cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Neil4speed

Quote from: raueda1 on 09 June 2022, 05:27 PMI'm actually having a anxiety-inducing medical treatment that is making me fret over this kind of thing (among a great many others).  It will subside soon enough....


Best of luck sir :)

Randys01

I recently had my spheres renewed when after 11years they  just gave up the ghost almost overnight.

The faster we go the better it feels but there is no doubt about a level of firmness in certain situations....mainly low speed minor one off bumps in the road. However I suspect that  as few of us are running Michelin XWS [modern equiv) one can't be too sure how much of the ride can be attributed to the tyres. I stuck with 14 inch when it came to time to replace and these are new too. Due to the the limited range avail I bought some of the worst tyres I've ever encountered.
I can't help but feel these are part of the problem.

raueda1

Quote from: Randys01 on 09 June 2022, 06:45 PMI recently had my spheres renewed when after 11years they  just gave up the ghost almost overnight.

The faster we go the better it feels but there is no doubt about a level of firmness in certain situations....mainly low speed minor one off bumps in the road. However I suspect that  as few of us are running Michelin XWS [modern equiv) one can't be too sure how much of the ride can be attributed to the tyres. I stuck with 14 inch when it came to time to replace and these are new too. Due to the the limited range avail I bought some of the worst tyres I've ever encountered.
I can't help but feel these are part of the problem.
You make a good point.  I've wondered about the effect of tires as well, but it's very hard to make real comparisons given the many differences in wheel size, pressure, suspension condition etc.  That said, in my case the tires have been a constant and are pretty far from stock - 235/50-15's.  The improvement over the 205/70-14s (?) that came on the car is just ridiculous.  They felt dangerous.

Anyway, what can be changed is tire pressure.  Obviously higher = firmer ride, maybe better handling and longer life.  Factory says 30psi front, 34psi rear.  I'm running 32psi front, 34 rear.  I'm going to try 30 in front and see what it feels like as well as bumping them all up to, say. 34 front / 38 rear.  Obvioulsy this won't make things softer but would make for an interesting comparison.

Also, would optimum inflation vary with tire size?  I'd think the volume of air in the tire would be substantially different between 205/70-14 and 230/50-15, though maybe the sidewall width nets it out.  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0