Do you need to change shocks when lowering?

[un1l]

I am in the middle of choosing the right set suspension kit for my w208 avantgarde 230k.
Will i get away with just purchasing the springs, as i am aware that Avantgarde's already sit 10mm lower.
If i was to lower the car 35mm, is it detrimental to the shocks if they are not changed and will this affect the ride in a big way?

 

[Howard]

The car will be like a magic carpet ...

Effectively the shocks will be partially compressed all the time if you just change the springs and they will wear out very quickly ...

The car will be terrible to drive. You need to change them both

 

[un1l]

Ok thanks,
Is it best to buy springs + shocks together.
Or can i buy them separately?
Do you recommend any shocks?

 

[peppernick]

You will accelerate wear in your shocks, but we are still talking 30k miles vs. maybe 70k miles.

You can either change them when they wear out or change them together with your springs. You'll save on labour when you do them all at once, if you can justify the cost of 4 new suitable shocks with the new springs.

What springs are you getting?

They are various cup kits out there (springs + shocks combo). If not Koni, Eibach or H&R shocks are all good. However, they will invariably be stiffer than even the stiffest OEM sport shocks.

 

[cjab98]

The car will be like a magic carpet ...

Effectively the shocks will be partially compressed all the time if you just change the springs and they will wear out very quickly ...

The car will be terrible to drive. You need to change them both

I thought shock absorbers were just filled with a fluid that flows between two chambers, separated by a piston that moves up or down when it is loaded/unloaded?

It shouldn't matter if the shock is compressed a bit, as it cannot create any load. It's the spring that provides the force to bring the car back up to its ride height.
Unless more modern shock absorbers are more complex than that, that's how I always understood it

 

[Howard]

Surely the shocks being half compressed is going to affect the handing ? perhaps detrimentally when you need it most ( an evasive manouvere ? emergency stop ? remember the video they used to show about how much longer it takes a car with faulty shocks to stop )

Changing springs only is not the way to go ... you obviously know more about suspension than me , from reading your other threads , but i can't beleive that it would be ok to drive about in a car with the shocks compressed all the time ...

If it is lowered by 35mm , then the shocks will be squeezed by that amount all the time , why do they make uprated shocks for lowered cars if it is alright ?

The fool that had my car before me just fitted new springs , and not shocks , the car handled appallingly .... soon as i got it , i put new shocks in it ....

What do i know ? Do whatever you think is best ..

 

[Dieselman]

Shorter springs demand shorter dampers to limit the full extension to stop the springs dropping out when under no load.

Most dampers are just straight tubes, in which case where the piston is positioned doesn't matter but a longer damper could bottom out if the spring allows the suspension arm to hit the bump stops hard.

 

[cjab98]

I'm no expert either, just not convinced it will have much effect on the handling .
The way I understand it, the shocks can't be compressed as such, they will just have a piston further down in it's travel than on normal suspension height.


I guess it depends why he wants to lower the car. The way I understand it is this:
If its done purely for looks then keeping original shocks will work, but they will probably wear out faster. Steering geometry will be messed up, and so will the wheel alignment, which will have a detremental effect on handling as well as uneven tyre wear.
If it's to improve the handling, then harder dampers to suit the shorter springs will probably be needed to give a more sporty ride, along with thicker anti roll bars.

Stiffer shocks will also mean the lowered car is less likely to bottom out when driving on uneven surfaces. Speed bumps and the like will be interesting if its already 10mm lower than standard and an extra 35mm ontop of it.

Edit: Dieselman's post makes sense, as the shock absorber stops the spring from travelling too far back when unloaded

 

[andy_k]

standard length shocks may just bottom out when you lower the suspension. If they do then your handling will obviously suffer as you suddenly run out of suspension travel

Most of the other stuff about only using partof their travel isn't really that relevant because under "normal" use a standard shock will never use all of it's travel for at least 99% of the time.

Would I change the shocks? Probably yes and get a pair that are matched to the springs to provide smooth suspension with just the right amount of progressive damping.

Andy

 

[stevesey]

Surely the shocks being half compressed is going to affect the handing ?

The fool that had my car before me just fitted new springs , and not shocks , the car handled appallingly .... soon as i got it , i put new shocks in it ....

What do i know ? Do whatever you think is best ..

Shocks are not "compressed" as such, they just resist movement by limiting the flow of fluid between two chambers. At steady state the fuild equalises and no force is exerted on the suspension.

However lowering normally means stiffer springs to avoid bottoming out and to improve handling (alongside the improvements given by lower ride height). Stiffer springs will re-bound with more force, so need stiffer shocks to control them. So the need for new shocks will depend on how much the spring rate is changing.

P.S. Anyone ever come across anywhere listing MB spring rates? Ops hijacking - should start a separate thread.



Also if you lower using old shocks the piston will now be rubbing on a different bit of tube - which may shorten the life of the seals.

 

[Alps]

the shocks may bottom out !

H&R springs, and Koni yellow shocks - will be a stiffer ride tho, bilstien shocks are a good compramise, and are AMG standard.

 

[andy_k]

The fool that had my car before me just fitted new springs , and not shocks , the car handled appallingly .... soon as i got it , i put new shocks in it ....

What do i know ? Do whatever you think is best ..

then it would probably have handled equally appalingly on standard springs

 

[Howard]

Ok , ok , i'm wrong ....

All i know is that when i put new shocks in it , the car was transformed ...

I don't drive it like an idiot , it was just so much nicer to drive.

Put whatever you think is best in your car .

Best wishes

H

 

[jaymanek]

i would change the shocks too... when old ones suddenly start using a different part of their range constantly they tend to leak soon after...

 

[un1l]

Thanks for the response guys...
I'm not trying to take shortcuts or anything, i was just wondering if it was necessary as on my previous car i just did the shocks and it was fine.
Mind you it was a Ford Fiesta Si.
I do not want to jeopardise my handling (steering) or tracking by not fitting shocks.
And when you mean "dampers" are you still referring to shocks?
So if it is necessary I will be getting them.
I was lookin on another forum and someone had lowered a w208 just on springs and he was wondering how long they would take to settle.
This is why i questioned if it was okay with just springs.
Do you recommend to buy brand new or is it okay to buy used off ebay or anywhere else?

 

[bolide]

I'm no expert either, just not convinced it will have much effect on the handling

That's what makes you "no expert" then

Nick Froome
www.w124.co.uk