News:

www.W116.org
By the people, for the people!

Main Menu

Engine mounting shore hardness

Started by daantjie, 30 April 2021, 08:28 AM

daantjie

Hi guys

This topic is kind of intriguing to me to be honest, as I recently swapped out engine mountings.  I ended up using the W123 diesel mounts - 1232411613, they felt firmer than the 1232413013 ones which you can get Lemforder still and they are plentiful and cheap. 

The old mounts actually did not feel too bad, slightly compressed but not bad (they were replaced in the late 90's BTW by previous owner).

But I got my hands on the 116 ones for which you get LHS and RHS ones.  Part # 116 241 2913 which is LHS.  I imagine they have different shore hardness then, and that 116 241 2813 (RHS) will be harder.  However the one I got - 116 241 2913 is extremely hard, like hockey puck hard, hmm, is this normal?

Any insights appreciated.

Cheers
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

Daniel, there was a similar thread on this some time back.  I'm going from memory here, always dangerous, but this is my recollection.   At the time the 6.9 mounts were NLA.  As I recall, the consensus was to go ahead and use 450sel mounts anyway, which I did.  Then, by a nice coincidence, the Classic Center announced that the 6.9 mounts were back. I got them and replaced the 450 mounts.  The 6.9 mounts actually were very much harder, along the lines of hockey puck.  As I recall the 450 mounts could be squished a little by hand.  Hope this helps.   :o  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

daantjie

Thanks Dave yup I scoped out that thread as well, however it does not really speak to the "scientific" nature of these mounts.  I am really interested to know if a softer mount is perhaps better as it will then dampen the vibrations better?  If you think about it, a solid steel mount for example will be useless as effectively you might as well mount the engine directly on the frame, so it will rattle your fillings out your head.
On the flipside if the mount is too soft then it will collapse and of course you will get the same result of heavy vibration.  Thus to my mind the answer (as usual) lies somewhere in between :D
The old mounts I took out, which had the correct part number, Benz and Phoenix rubber stamps on them, were still quite nice, but not nearly as hard as the 116 numbered one I scored off ebay, I just got one NOS one for kicks as it was cheap and I wanted to get it in my hand to check.
So I guess the real question is, are the 6.9 mounts, when new also rock hard, and they soften up over time?  Does not make sense to me.  Or maybe they used a softer compound back in the day, and the repop ones you now get from the Classic Centre are of crappier rubber quality.  Hmmm, interesting, at least to me 8)
Daniel
1977 450 SEL 6.9 - Astralsilber

fichtl500

A 123 241 30 13

Looking for mounting for 280, can I use toty parts?

A 123 241 30 13 (LEMFĂ–RDER 10844 02)


I ask because the given info for these dampers is on w126

rumb

I think you need 123 241 15 13 for w116 280se.

The part number you have is for W126.

You should get the original MB one.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

fichtl500

There is a significant difference in price (original MB or LMI), so I asked if it can be used. ;)

s class

I recently fitted Lemfoerder 1232413013 to a 116 280S, fit is perfect and a great result for modest money.


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

fichtl500

Quote from: s class on 22 January 2022, 12:01 PMI recently fitted Lemfoerder 1232413013 to a 116 280S, fit is perfect and a great result for modest money.

Thank you very much, I'm going to order them :)

UTn_boy

The right side mounts are harder on purpose to withstand the torsional twist the engine creates when revved or accelerating.  It's also of vital importance that the engine torque damper shocks are in good condition.  If not, the right side motor mount will collapse in short order.  Shore hardness has nothing to do with how well they absorb vibrations or not.  It has to do with how much they can take when being compressed.  For example, how many pounds (force) does it take to compress the rubber one inch (distance compressed). That is what shore harness is referring to.

The heavier and more powerful the engine is, the harder the rubber needs to be.   
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1979 450sel 516 red/bamboo

PosedgeClk

QuoteShore hardness has nothing to do with how well they absorb vibrations or not.  It has to do with how much they can take when being compressed.
It's a mixture of both. The Shore durometer test is more of a subjective squishiness test than a spring force test. The indenters look like big nails. Shore 00-50 (think almost balls of cotton here) wouldn't transmit any vibrations, but it would be ripped to shreds as soon as the motor moved in any direction unless you had some sort of enchanted damper. Shore 10D or an aluminum bushing would transfer all the vibrations and give the worst ride ever. You might also get resonances with something that hard. I have done a lot of polyurethane bushings for mounts and suspension on various vehicles, and it is amazing what is transmitted based on the hardness and temperature of the elastomer.

Whatever vibrations are not transmitted from the engine are absorbed by the material and to some extent the damper or remain in the engine, whether they are reflected back from the "far end" of the mount or are just not transmitted, e.g. an engine floating in outer space.

QuoteThe heavier and more powerful the engine is, the harder the rubber needs to be.
If you are comparing two mounts of the same dimensions, yes. The mounts also should be physically larger for a larger motor. You aren't going to be able to run a Cummins 6BT school bus motor for very long using something the size of a 300SD mount.
1979 450SEL 6.9

UTn_boy

All engine mounts for W116 cars are the same shape and size.  The only difference is the shore hardness. I did not imply otherwise.  Nor did I imply that the Shore test was in any way related to how springs are tested.  If I mislead any readers it wasn't my intention. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1979 450sel 516 red/bamboo

PosedgeClk

That's not what I am getting at on the Shore hardness test. I'm saying that it is a lot more specific than a simple measurement of force vs. distance which is the classical physics theory for a spring constant (Hooke's Law IIRC). It is like Brinell vs. Rockwell hardness. They are useful measurements for particular engineering applications. Agreed on the mount size being the same. My guess is that there was a lot of trial and error in the original design. They had a fixed chassis so didn't want to change the mount sizes or locations, knew where to start with the rules of thumb, and then went from there. It's kind of like how they used to do sound deadening. Add a little asphalt here in the critical areas, and drive around, and pull out the SPL meter. Take away some here, add a little more here, and repeat the drive.
1979 450SEL 6.9