Can W140 Rear Hydrulic -> Normal Shocks?

[derstar]

The rear hydrulic have some squeeks and maybe time for new suspension.

So here is my question, can it be convert back to regular suspension? since it looks like there is ABS/traction control wires linked with the self level hydrulics...

Please advise...

[Peter Guenther]

Fist of all there are two versions, The first, hydraulic fluid is pumped from a tandem pump with the power steering unit to the rear, the struts (shock look a likes) are tied along with accumulators (a sphere with a rubber diapram filled with nitogen) to this line. The pressure comes thru and is regulated by an axle mounted valve that is attached to the sway bar, and there is constant circulation back to the reservoir mounted in the front fender. The second is almost identical but has valves on the front shocks, and another valve in the rear line and is controlled electrically by a body computer for selective damping via sensors and a drivers switch. The accumulators usually fail, and are a cheap repair, the rest is pretty bulletproof.
There have been those who have converted both systems, but concensus is why? The issues that arrive are as follows the springs were calibrated for residual pressure in the system and must be shimmed or replaced, the pump can not just be drained so the fluid must ciculate, there are some who have replaced the PS pump with one that did not have the tandem function. The shocks can be replaced with standard units is the only good news. I dont think most people would buy the car if they find out it das been modified, it is a great feature. I would find someone who understands the system and have it fixed, any squeeks coming from the struts and shocks can be fixed by getting new bushings. ABS is a stand alone system!

[derstar]

Thanks Peter for the quick prompt informative reply.

We have a 1999 500... so i don't know which version refer to, but the front uses regular strut. Unlike the newer full air bag suspensions, which all 4 is a bag.

Been to shop once, and its the struct/absorber making noise. (Inside the absorber body).

Doesn't sounds like a bushing issue, which i wish... At first we guess air/fluid is trap inside, but now its been half year and it still here. It rides fine and absorb roads beautifully.Not the accumulators too as the rear stood up as high as new.

Since the W140 doesn't have much "used value", i suppose convert back to Standard (With some HD Bilsteins) suspensions are more cost effective. And if we ever do it back to standard, the next buyer might be even more happier... no headachs. But those pumps, hydrulic hoses, censors might not be overided.

So please give some input folks if you have done this conversion. I understand MB from 80s and older are easier to have this operation done since there were no so much traction control censors and computer gadget linked together.

I also went to MB Dealer once and ask the SA, the SA simpily reply it can't be done because he say its rear hydrulic suspensions are linked with traction control computers, one side gets stiffer when it loses control. The whole car dynamic has also something to do with the rear suspension, everything is different.

I hope i'm not imagine too deep, and wrong...

[pcmaher]

I would also stick to the original system. This article describes the system...

http://v12uberalles.com/Adaptive_Damping_System.htm

and this one documents how I changed my creaking strut...

http://v12uberalles.com/Rear_Struts.htm

If you're really set on changing the system, I think Strutmasters.com makes a conversion kit.

[derstar]

wow BINGO PCmaher! Thank You so much...
The best place i could fine is $619 USD...

I guess replacing one is okay? Since if it works, it works, unlike typical struct/absorber which replace a set?

This is way more technical than the mechanic courses i took @ local college

[pcmaher]

Replacing one strut is perfectly acceptable. In fact, the MB technical bulletins from that time state that dealers should stop replacing them in pairs. If they did, MB would not cover the cost of the additional strut.

[Peter Guenther]

I had a defective one, which they changed, and yes I had a devil of a time getting the second one done under warranty.

[pcmaher]

Here is the actual text...

SUBJECT:
All Model 124, 129, 140, 170, 171, 201, 202, 203, 208, 209, 210, 211, 215, 219, 220 & 230

Replacement Procedure of Shock Absorbers and Suspension Struts

It has been noted that shock absorbers and suspension struts are repeatedly being replaced in pairs for no justifiable reason. When a repair requires the replacement of a shock absorber or suspension strut, only replace the damaged part, unless otherwise noted.

Note : There will be increased focus on the compliance with these rules when performing warranty parts inspection. DO NOT replace non-damaged shock absorbers or suspension struts. Warranty claims will be denied in cases where a shock absorber or suspension strut was replaced needlessly.

1) Guideline for Airmatic air suspension struts (Model 211, 219, 220) ABC suspension struts (Model 215 220 230) and ADS suspension struts (Model 129, 140, 210)

Damage to one suspension strut does not justify the simultaneous replacement of the opposite suspension strut. This also applies to complaints of noise, such as thumping. In such cases, thorough diagnostics to determine the responsible suspension strut should be performed by driving each side of the vehicle on a road surface corresponding to the customer complaint. Only the affected suspension strut should be replaced.