PeachParts Mercedes-Benz Forum - self-levelling height adjustment for w123

PeachParts Mercedes-Benz Forum (http://www.peachparts.com/shopforum/)

- Tech Help (http://www.peachparts.com/shopforum/tech-help/)

- - self-levelling height adjustment for w123 (http://www.peachparts.com/shopforum/tech-help/85061-self-levelling-height-adjustment-w123.html)

Quote:

Originally Posted by cgoodwin (Post 553445)

PS. Has anyone seen a Benz fitted with an aluminum wing, air damn with window screen in the vents, rice rocket exhaust tips, 22" rims, HUGE autometer tach, limo tint, curb feelers, etc. I would really like a pic.

Great thread and great info Mr Goodwin.

As a reward, I may have what you seek.

Go to
http://www.barryboys.co.uk/shedindex/database/?function=show_search_form&table_name=carmain
and in the manufacturer box type 'Mercedes'. Leave everything else as it is and click 'search for record'. You may wish to shield your eyes at this point. This will find some of the more awful 'modified' Mercedes about in the UK.

Russell

I had forgotten this thread existed until I got an email notice about it today. Just after that thread I did write a page on the function of the SLS which can be seen here: http://www.frybrid.com/forum/showthread.php?t=6461

My 560 has AMG 17" Monoblocks, Parelli low profiles, bielstien fronts and H&R springs all around. It does handle mush better than it did in it's original config but does not rattle your filling loose in normal driving, aggressive driveways can be a drag (literally), but the body roll is non-existant now. I rarely drive it anymore as I have sworn off gasoline engines (Except the 911, 4 bmw motorcycles, a Norton Commando and just about anything I can get my hands on).

[quote=Paulwho;553075]Shawnster,
"A rear end which is low in curb weight condition should never be set higher by adjusting the connecting rod of the level controller."
quote]

Hi - I read these and Chris's explanations and caveats - maybe too late - in my neigbourhood (Big Sur - rough mouintainous dirt roads) folks drive mercedes 300TD's like mine (an 82) with the level raised to the max by adjusting the leveling rod, to accomodate 225x70x14 AT tires. I can see you all cringing, but the reason for the practice is the terrain and folks want to drive (bio)diesels without having to haul 3/4 ton trucks around and these old wagons are solid enough for the terrain! I just ordered my tires and realise maybe I should be looking for a different solution to the problem - like if you really want to drive a 300TD on these roads, is there a better way to lift the rear the extra inch for the tires and clearance.

Any thoughts!?
Thanks
:stupid: I guess

The weight of the rear of the vehicle should be supported by the springs, if you want the vehicle to sit higher, change the springs or simply replace them, it is likely that your springs are pretty tired after all these years. Springs can also be reworked to mke them longer or shorter although in this age of parts replacers actual craftspeople ar getting harder to find, we do have a 70 year old spring smith in Seattle who does work for me.

You can carry quite a load in a TD with a good SLS, but you don't want to park with that load for a long time it places a strain on the valve, etc. I moved about 600 lbs of tile on two occasions using my '79 300TD, the SLS was maxed out to maintain level, and I drove very slowly but it performed admirably

There may also be thicker spring pads for the TD if yours is sagging, why don't you check with Fastlane? these go at the top of the spring where it meets the body cup and allows adjustment of ride height without resorting to new springs.
I tried that but I eventually had to order springs made of thicker wire for my 115 which has an air compressor and the battery moved to the trunk (plus the tools I seem to carry around in it, it was almost dragging the ground!)
For any special springs I suggest Coil Spring Specialties, St. Marys KS check them out! http://www.coilsprings.com/index.html

Well those + size tires fit just fine, no need to raise my ride! The Benz has big wheel arches I guess. Thanks for the advise though. I'm sure I'll be back for more.
:)

I have a similar problem in my w124 87 300tdt,i chaNGED THE ACCUMulators and now get a nice ride,but recently after changing them and bleeding the system i find that after returning from cosctco with a heavy load in the back that the shgocks and rear stayed deppressed and that its not bouncing again,could this be the valve??
please help

You can test your system, by applying pressure to the pivot arm which is attaced to the sway bar. Pushing it one way will raise the car, the other way will lower it. You can actually, hook a rod to the pivot bracket, to the outside of the car, and make it into a sort of custom height adjuster. You can set your car's height. I have it on all four corners. I understand this is not really all that common, but atleast you can adjust the rear, how you want it.

CGoodwin:
Can you post a picture of the adjusting rod and lever? What's the proper setting for the rod? there are 3 holes on it. I changed mined after new accumulators and proper bleeding from last position hole towards the rear of the car to the center hole moving towards the front and seemed to soften up suspension more; moved rod to the front hole and seems to ride harder? suspension stays level no matter what. Car was bouncing bronco before new accumulators now rides much better but I think still a little too firm. I also got a lot of cracking noise every time it went over bumps which has diminished a lot after going to hole 1 to the front on the adjusting rod but still there.

Quote:

Originally Posted by cgoodwin (Post 552775)

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

Great explanation, Chris. thanks. This is just what I needed to know.