converting self leveling rear
 

On a w140 coupe. Rather than repair the self leveling system, to cure sagging rear, if I convert to bilstein or other standard type shock will ride remain low in rear. Do I also need to respring to establish correct height?

Hi,

I converted my 1984 500 SEL (W126) because of the low rear end. I changed the springs, shocks and accumulators. I also gor rid of a lot of the hydraulic fluid lines and other stuff as well.

The car now sits and rides better that before although the ride improvement is for certain not caused by the conversion but due to old parts being replaced with new parts.

Before the conversion the rear end (beside sitting low) showed all signs of worned out shocks i.e low damping effect.

Good Luck,

Mikael Westerberg
Vanersborg Sweden

If your rear hydro-pneumatic shocks are not leaking then the culprit would be the nitro-cells. Replacing these would be alot cheaper than going a full conversion. From what I have read, if your rear wheels appear to be "squating", this is caused by the rear suspension bushings being worn out.

Actually I repaired low ride. suspension control module (valve) needed to be adjusted. Problem is now the lower shock bush is making low speed rattle/knock. Cannot buy just bush need to buy shock. For price of one shock I could replace all four. Ride is a little to soft anyway. My concern is if I just replace shocks wouldnt car ride low as it did without self level. I would love to think I can just replace with new shocks, disconnect and set control module to full mark. I am sure I could cap line to shocks so they could be refitted if someone wanted.

getting back to the original question re: respringing the car following a conversion from SLS to conventional shocks...

yes, if you delete the SLS you will have to respring the rear end. the spring rates for SLS equpped cars are considerably lower than those for non-SLS equipped cars. this allows the SLS to do the majority of the work in keeping the ride height level.

if you substitute conventional shock but retain the original springs, the car will stll ride low at the rear.

That is what I needed to know. With cost of new springs and labor I suspect it will be cheaper to replace shocks. Many thanks

a better indicator of worn suspension bushings is the feeling that the rear end of the car is steering itself. particularly during squat or dive.

the true test is to jack the car up and attempt to move the rear wheel relative to the body of the car. if the wheel moves in any direction that is not consistent with normal wheel travel during suspension compression and extension you have worn rear suspension bushings.

the crux of the 5-link rear suspension ability to provide zero rear-end steering is the operation of the bushings.

consider that the rear half shaft is of a fixed length and fixed at one end. simple geometry dictates that as the free end moves in its track it must also move in an arc. various systems have been designed to deal with this problem. MB's system has come the closest to eliminating it. the deflection has been reduced to 1/64th of an inch.

the bushings are an active part of the suspension design and the required hardness of each bushing has been calculated. MB did not just throw in any old rubber for the bushings. as such, the bushings are under a considerable amount of strain and WILL wear faster than what most people would consider normal. particularly if the car is driven hard.

the inrtoduction of rigid suspension arms (the custom camber arm that have been sold on bnzsport and 190revolution) look trick, but they could very well transfer the forces that are normally absorbed by the bushing to the mounting points. this could manifest itself as metal fatigue around the mounting points in the future.