W109 300SEL with 3L 6 cylinder. Want help replacing airbag suspension with Hydraulics

[Joker]

Hi

I have a RHD 300SEL (3 litre striaght 6 engine if that matters). The air suspension works good but I want to change it out for hydraulic suspension (IE so I can adjust to run "lowrider" or high). The car is already heavily un-origanal so I am not molesting a concours car or anything.

I would have thought as it currently runs air bags anyway it should be easy to take off the Mercedes ones and replace with aftermarket jobs?

Does any one have any pictures of the bags themselves or the suspension mounting points front and rear with the bags off to give me an idea of what it looks like stripped down?

Also are there any big problems running these cars low? Driveshaft wear etc? This will be a weekend car only (probably 1000 miles a year tops) so not worried unless it will die straight away if run too low.

Any help appreciated

[cth350]

running low to the ground means bumps are kinda bad. Your gas and brake lines are exposed. Worse, the bottom of the radiator and both oil pans are exposed. The can be protected by belly pans. They're easy to fabricate from sheet metal.

The front bellows are directly visible by removing a wheel. On the lower control arm there's a metal cylinder. The can for the air bellows is screwed into a space on the axle.

The rear bellows are roughtly the same, with metal cone mounted on the arms leading from the axle and the can for the bellows is screwed onto the floor of the car.

You can fix the air suspension from one end to the other with 1,000$ worth of parts and some basic mechanical smarts. Or, you can try and retrofit the hydraulics of some other car line in place and pray that you'll get it right.

If you are mechanically inclined, just fix the air suspension. If you can't do that kind of work, go for conventional springs and replace the lower control arms on the front of the car. You should also replace the rear differential.

-CTH

[Joker]

Thanks CHT

that all sounds reasonable. The reason for changing the suspension over is to "customize" the car and not to fix a fault. Sounds like it is very do-able.

I'll take your advice and remove the wheel to take a look for myself.

One other thing. I read on another thread that it can damage the standard airbags if you jack the car up without taking "precautions" What are those precautions? and also what is the pull out lever for under the dash near the steering wheel? the guy who owned it before me told me it makes the suspension pump up faster... is that what it does cos I cant tell the difference with it pulled out or pushed in?

Thanks

[cth350]

the lever controls ride height. the three positions are "normal", "locked" and "high". The locked position has the system hold pressure at whatever position it's at. The high position raises the car a few extra inches, but means it becomes unstable at speed.

If you want to customize the car as a low-rider, then the thing to do is to replace the valves with something else and leave the rest of the system alone. You'll have to read up on how the system functions to figure out the right valve arrangement to employ.

If you're a computer geek, you can build some sort of controller that reacts to pressure and ride height info. Speaking of which, when you take that wheel off, you'll notice a metal rod that connects the lower control arm to the valve. That rod is adjustable. It defines "normal" height.

Another important thing to realize is that the system is always working. Just because the motor isn't running, doesn't mean it's not controlling ride height. When you jack up the front, do so under the axle so that both wheels lift up.

-CTH