Originally Posted by cgoodwin

OK, here's the deal. Both very soft and very hard rides can result from failed accumlators, the suspension should be the finest in the world, no holds barred, it should be firm but smoothe, absorb bumps silently and smoothly, keep a level vehicle regardless of weight and you should be able to run over a brick with just one rear wheel, going around a corner and still cut a diamond in the back seat... OK a bit extreme but not far off.

First you need to know how the system works. You have a belt driven hydralic pump, the pressurized fluid passes through a line to the leveling valve. This valve has an actuating lever attached via an adjustable rod to the sway bar. When the rear of the car is depressed, the valve opens and forces fluid through the accumulators and into the "Shocks" which are actually hydralic rams, these raise the car until the lever is again level and valve closes. The accumulators simply absorb the shocks with compressed gas. Now look at each seperate system.

Leveling. Since the "shocks" are simply rams which raise the vehicle, and fluids do not compress this system is very hard without the accumulators. To check the system, shut the vehicle off, measure from the ground to the wheel arch and write it down. Now place weight in the rear, try opening the trunk and having two people sit on the rear. Measure the didtance again, it should be less with the weight. Now with the weight still in place start the engine and run it at about 1500 rpm for a minute or two...The rear should raise to the original level, if it does not, there is a problem - regardless of the accumulators.

Next raise the vehicle and look at the valve, it has a lever with an adjustable rod connected to it, the other end of the rod connects to an arm attached to the sway bar with a clamp (this clamp can slip lowering the vehicle). Disconnect the rod from the lever on the valve and rotate the lever upward to about 45 degrees. Lower the vehicle to the ground and again run the engine at 1500rpm, as soon as you notice the rear begin to rise, shut the engine down (as not to hyper extend the leveling rams) - OK it it went up then the valve, pump and rams all work. If it did not go up then you need to go into the system more carefully - let me know and I can explain, but since this is rarely the issue I will skip ahead.

The rod can be adjusted by turning the center and shortneing or lengthening the rod. Each two turns shorter raises the vehicle about 1" each two turns longer lowers the vehicle about 1". Keep at it until you get it level and there you go.

Shock absorbtion. Since the leveling system is hydralic and fluids do not compress, if you hit a bump, it will feel like the rear is solid. So the fluid runs into a sphere which is devided by a membrane, on the other side of the membrane is gas presurized to about 1700psi, when the vehicle hits a bump the fluid is forced from the ram and down the line into the oil filled side of the accumulator and from there to the valve, which should be shut because the vehicle is level. The only place which can give is the gas filled side of the accumulator, which it does and just as rapidly the gas expands and forced the ram back to its original position - Just like in a gas filled shock absorber. Get it? the "shock" is actually just a ram which raises or lowers the rear end, the accumulator is actually the "shock"!

If you have a very hard rear end when driving, OR if the rear seems to "wollow" or be very soft on the road then most likely you have bad accumulators but don't take my word for it, test them. The simplest way I know is to unscrew the hose going from the accumulator to the "shock" - BE VERY CAREFUL - the fluid is under a lot of pressure and will spray abut a coffee cup of oil everywhere. With the line off slide a small punch into the end of the accumulator, it should go no more than about 1/2 inch in, if it goes 3 to 4 inches in, the diaphram is gone and the accumulator is worthless and must be replaced.

Do not simply gut the hydramatic system and replace it with springs and shocks, you would be replaceing a remarkable system with a very basic one. Once working you can load the car down and have a level ride, you have a system which works better than just about anything on the road and you have no shocks to go bad.

If you need more info let me know and I will help as much as I can. I have a 1989 560 SEL, looks and runs like new with just under 200k...With hydramatic suspension.

Chris