W108 hydropneumatic compensator questions - Page 2 - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #11 of 33 (permalink) Old 02-23-2013, 07:56 AM
BenzWorld Member
 
Date registered: Jan 2009
Vehicle: 1970 280 sel, 1979 300sd, 1988 300sel
Location: Santa Monica, CA
Posts: 273
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
I have the aftermarket compensating spring installed on my w108 so when there is no weight in the trunk I encounter a rear positive camber. I thought about cutting a full coil from the CSpring to correct this. What would happen if I cut a few coils from both rear suspension coils and not touch the compensating spring(axle)? I have expressed in the past that these cars look really good sitting low and I think best if bagged but can a similar affect be reached by just cutting a few coils or purchasing custom made coils so to save the original coils? What would be the best approach so to lower the car and what type of lowering would cause more camber? Would it be best to order a custom made shorter compensating spring if wanting to lower the rear of the car or would it be best to order shorter custom made suspension coils. Which of the two causes more negative camber and is negative camber a final outcome regardless of how you lower the rear? Please advise I need to start working on my car. I know that it seems like I don't understand the rear suspension, I don't...
xaliscomex is offline  
Sponsored Links
Advertisement
 
post #12 of 33 (permalink) Old 02-23-2013, 09:53 AM
BenzWorld Senior Member
 
drew56cus's Avatar
 
Date registered: Oct 2006
Vehicle: 1965 220SE sedan (finnie) with 450SE conversion, 1964 220SE coupe project, 1966 300SE coupe
Location: Brisbane Australia
Posts: 418
Mentioned: 1 Post(s)
Quoted: 32 Post(s)
Hi again,
Have a look at this - it is close enough to the suspension you have to illustrate why camber changes with ride height.
W108 hydropneumatic compensator questions-suspension.jpg
The axles and wheels rotate around a fixed point at the bottom of the diff - so if you raise or lower the car (regardless of what springs you change to do so), the camber of the tyres change.

If you give me about 2 weeks, I will have a definitive answer to your question. My car is sitting too high, so I need to lower it. I have a W111 car, but am using W108 suspension. The W111 is lighter than the W108, so it sits high. Today I bought a W110 190D, with the intention to swap the centre compensator spring over once I get it home. Then I will check how the ride height changes. If it is still high, then I have some choices: reduce the thickness of the rubbers between all the coils and the mounting points, or make the springs shorter. Ideally, you change the rubbers.

A suspension shop quoted me $800 to lower all corners of the car by chopping the springs and re-setting their rates (so the ride is not to harsh). No suppliers have ready-made springs, so they would haveto be custom made - so possibly expensive.
Cheers,
Drew
drew56cus is offline  
post #13 of 33 (permalink) Old 02-23-2013, 11:11 AM
BenzWorld Member
 
Date registered: Jan 2009
Vehicle: 1970 280 sel, 1979 300sd, 1988 300sel
Location: Santa Monica, CA
Posts: 273
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
So I just took a quick look under my w108 and what I see is a Compensating spring holding camber and suspension springs holding up the suspension height..So if I get smaller springs the car should drop while the compensating spring holds the camber upright...I'm sure theres more to all of this but I will leave it to the pros to advise and explain more. Can I then get smaller springs to drop the rear without touching the compensating Spring? How far can the car skeleton drop before it hits the axle or anything else that would prevent it from dropping? Is the compensating spring the limiting factor where by such Comp Spring stops further dropping of the car where then further dropping is only accomplished by then cutting or replacing the Compensating Spring? Please advise. I know there more to this
xaliscomex is offline  
post #14 of 33 (permalink) Old 02-23-2013, 11:51 AM
BenzWorld Senior Member
 
drew56cus's Avatar
 
Date registered: Oct 2006
Vehicle: 1965 220SE sedan (finnie) with 450SE conversion, 1964 220SE coupe project, 1966 300SE coupe
Location: Brisbane Australia
Posts: 418
Mentioned: 1 Post(s)
Quoted: 32 Post(s)
Hi, I think you really need to put some old clothes on, grab a torch and slide under the car and look around. It is not hard to figure out once you see it all. The centre of the diff cannot move - it is fixed. The springs have no impact on this.

All 3 springs act to control the angle of the axles relative to the ground. They are all providing a force to keep the axles horizontal. If any of them are removed, there will be a drop in suspension height.
The big vertical springs are pushing the axles down away from the body - remove that force, and the body will come down relative to the axle, and in doing so, the camber will change.
The compensatng spring is mounted horizontally above the pivot point - it is trying to push the ends of the spring away from each other. As an exercise, think of this spring as a rod of a fixed length. With the axles horizontal (normal car height), the 'rod' will be a certain length. Now if you make that rod longer, the axles must move down so the rod can fit. This will raise the car. And the opposite is true - make the rod shorter, and the car will drop. The compensating spring is just a rod that can have a variable length. A stronger or longer spring will act like a longer rod in normal circumstances (ride height increases), whilst a weaker or shorter spring will act like a shorter rod (ride height decreases). However, if you make the horizontal spring too short or weak, it won't do anything at all, as the big vertical ones will carr all the weight.

I don't know what springs are most influential on the ride height. Given that it is easy to remove the compensator spring, I was going to remove it, go for a slow careful little drive to settle the height, then check the height. Then put the 190D (less strong) comp spring in and see where that gets me.

But once again, you cannot raise or lower the car without getting camber change.
Good luck, Drew
drew56cus is offline  
post #15 of 33 (permalink) Old 02-23-2013, 11:52 AM
Premium Member
 
Date registered: Nov 2012
Posts: 1,241
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
Premium Member
mount the compensator spring without the rubber pads .the 2 main springs are held at the bottom with a adjusting plate , it has 3 positions . also at the top there is a fat rubber pad that come in different thickness .i would not cut any springs because the ends are machined a certain way , it is a lot easier to use a torch and put heat on one coil , the spring will collapse on that coil , lowering the car . you are near the gas tank so be carefull , you need the weight of car on , so reach under .i would do it first at the compensator spring .then drive car around the block and see if you need more .
agillot is offline  
post #16 of 33 (permalink) Old 02-23-2013, 03:02 PM
BenzWorld Member
 
Date registered: Jan 2009
Vehicle: 1970 280 sel, 1979 300sd, 1988 300sel
Location: Santa Monica, CA
Posts: 273
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
Quote:
Originally Posted by drew56cus View Post
Hi, I think you really need to put some old clothes on, grab a torch and slide under the car and look around. It is not hard to figure out once you see it all. The centre of the diff cannot move - it is fixed. The springs have no impact on this.

All 3 springs act to control the angle of the axles relative to the ground. They are all providing a force to keep the axles horizontal. If any of them are removed, there will be a drop in suspension height.
The big vertical springs are pushing the axles down away from the body - remove that force, and the body will come down relative to the axle, and in doing so, the camber will change.
The compensatng spring is mounted horizontally above the pivot point - it is trying to push the ends of the spring away from each other. As an exercise, think of this spring as a rod of a fixed length. With the axles horizontal (normal car height), the 'rod' will be a certain length. Now if you make that rod longer, the axles must move down so the rod can fit. This will raise the car. And the opposite is true - make the rod shorter, and the car will drop. The compensating spring is just a rod that can have a variable length. A stronger or longer spring will act like a longer rod in normal circumstances (ride height increases), whilst a weaker or shorter spring will act like a shorter rod (ride height decreases). However, if you make the horizontal spring too short or weak, it won't do anything at all, as the big vertical ones will carr all the weight.

I don't know what springs are most influential on the ride height. Given that it is easy to remove the compensator spring, I was going to remove it, go for a slow careful little drive to settle the height, then check the height. Then put the 190D (less strong) comp spring in and see where that gets me.

But once again, you cannot raise or lower the car without getting camber change.
Good luck, Drew
makes more sense now, thanks
xaliscomex is offline  
post #17 of 33 (permalink) Old 02-23-2013, 03:06 PM
BenzWorld Member
 
Date registered: Jan 2009
Vehicle: 1970 280 sel, 1979 300sd, 1988 300sel
Location: Santa Monica, CA
Posts: 273
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
Quote:
Originally Posted by agillot View Post
mount the compensator spring without the rubber pads .the 2 main springs are held at the bottom with a adjusting plate , it has 3 positions . also at the top there is a fat rubber pad that come in different thickness .i would not cut any springs because the ends are machined a certain way , it is a lot easier to use a torch and put heat on one coil , the spring will collapse on that coil , lowering the car . you are near the gas tank so be carefull , you need the weight of car on , so reach under .i would do it first at the compensator spring .then drive car around the block and see if you need more .
Will try to see if I can first adjust height at compensator by removing the rubber pads, if any. Again, I hear that there is a weaker or softer spring available but I didn't know that the 190D spring worked, thanks...
xaliscomex is offline  
post #18 of 33 (permalink) Old 02-23-2013, 07:00 PM
Premium Member
 
Date registered: Nov 2012
Posts: 1,241
Mentioned: 0 Post(s)
Quoted: 59 Post(s)
Premium Member
if you remove the compensator spring , the car will really sag down way too far , so this indicate that the easiest way to fix your hight / camber is dealing with that comp spring , it need to be a litle shorter , remove pads , or torch [ dont cut ]
agillot is offline  
post #19 of 33 (permalink) Old 02-23-2013, 09:03 PM
BenzWorld Member
 
Date registered: Jan 2009
Vehicle: 1970 280 sel, 1979 300sd, 1988 300sel
Location: Santa Monica, CA
Posts: 273
Mentioned: 0 Post(s)
Quoted: 10 Post(s)
Very humble question. I thought that when you heat(torch) a spring it crystallizes so then it looses its springing capability? Will this compromise the spring or can it break?
xaliscomex is offline  
post #20 of 33 (permalink) Old 02-24-2013, 02:23 PM
BenzWorld Senior Member
 
drew56cus's Avatar
 
Date registered: Oct 2006
Vehicle: 1965 220SE sedan (finnie) with 450SE conversion, 1964 220SE coupe project, 1966 300SE coupe
Location: Brisbane Australia
Posts: 418
Mentioned: 1 Post(s)
Quoted: 32 Post(s)
I for one don't advocate heating the springs on your own. 1) You could burn the rubbers, fuel tank, under-car body deadening. 2) As you say, heating changes the properties of the spring - so the spring rate changes, and the handling will be affected 3) If you heat it too much, you will need a new spring

Cheers, Drew
drew56cus is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > Vintage Mercedes-Benz

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode



    Posting Rules  
    You may post new threads
    You may post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is On
    HTML code is Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome