Replacing Rear Springs On 95' S350. What Size Spring Mount To Use???
 

I am having the rear springs replaced on my 95' S350. I carry a 200 lbs load woth me at all times in the trunk and the car sags some what now in the rear. Can you tell me what the factory size is for the spring mounts? It could be four different sizes: The mechanic told me they could be like 4/32, 8/32 16/32, 23/32.

What is factory? Also, what should the labor cost to replace to to rear springs?

Thanks!:p

COME ON GUY'S, HELP ME OUT ON THIS ONE PLEASE.......................
 

Replacing Rear Springs On 95' S350. What Size Spring Mount To Use??? :confused:

COME ON GUY'S, HELP ME OUT ON THIS ONE PLEASE.......................
 

Replacing Rear Springs On 95' S350. What Size Spring Mount To Use??? :confused:

COUNT THE LITTLE RUBBER NUBS ON THE MOUNT, CALL YOUR LOCAL DEALERS PARTS DEPT. AND ASK WHICH SIZE APPLIES.

Replacing the springs is not going to change anything, unless you use a higher rate spring or a the same rate spring with greater free length, and selecting a proper spring, assuming alternates are available is going to require some engineering calculations and good data on the alternate springs.

Mercedes uses varying thickness spring isolators to achieve proper ride height depending on the weight of each model, and it can also vary with options.

If you want to raise the rear ride height because you normally carry heavy loads, install thicker isolators, however you will only be able to raise the ride height by the amount that the isolator thickness is increased, so you may not get much out of it depending on what is currently installed and what thicker isolators are available.

For 201 models spring isolators are available in 8, 13, 18, and 23 mm thickenesses, and these may also be used on some other models. I can't make much sense out of the 4/32, 8/32,... spring isolator choices you quoted. You should ask the dealer what it means. I suspect they confused 32nds of an inch with millimeters.

Duke

spring isolators are available in 8, 13, 18, and 23 mm thickenesses,
 

spring isolators are available in 8, 13, 18, and 23 mm thickenesses,

You are correct! What is the factory size??? When you say changing the springs will not help, why? It did not set this low from the factory. What else would couse the sagging if not the springs? I do not understand?

TO CORRECT OR CHANGE THE RIDE HEIGHT ON A BENZ YOU CAN CHANGE THE RUBBER UPPER SPRING MOUNT TO A DIFFERENT THICKNESS. IF YOU ARE UNABLE TO REMOVE THE SPRING MOUNT TO MEASURE WHAT SIZE YOUR VEHICLE IS CURRENTLY USING, YOU CAN COUNT THE LITTLE BLACK RUBBER NUBS THAT ARE HANGING FROM THE MOUNT. THEY ARE SMALL APPROX 1-2mm IN LENGTH, THEY WILL BE IN GROUPS OF 1,2,OR 3 NUBS. EXAMPLE: 2 NUBS EQUALS 8mm (DON'T QUOTE ME ON THAT). OR YOU CAN DO IT THE HARD WAY AND BUY ALL THE SIZES FROM THE DEALER, AND INSTALL WHICH EVER ONE WILL SUIT YOUR NEEDS.

P.S. BEFORE SOMEONE TELLS YOU TO CHANGE YOUR SHOCKS, SPRINGS (and their mounts where applicable) ARE THE ONLY ITEM THAT DETERMINE THE RIDE HEIGHT OF A VEHICLE.

BEFORE SOMEONE TELLS YOU TO CHANGE YOUR SHOCKS, SPRINGS
 

This is the ONLY WAY to tell/correct the ride height, right?

It is my understanding that the correct way to measure ride height for a specific car is to measure the angle of the suspension arms when the car is sitting on its wheels.

Haasman

measure ride height for a specific car
 

If the car is sitting 3" lower than my other "S" class, then what needs to be changed? Why is this so hard??? WHAT can it be besides the springs???

Re: spring isolators are available in 8, 13, 18, and 23 mm thickenesses,
 

I assume from your post that the rear sits low because you carry around 200 pounds of gear. Take it out and the normal ride height should be restored.

All four of those sizes can be used at the plant depending on the weight of the vehicle based on engine, options, wheelbase, etc, so you'll have to inspect or remove them to see what your car has. Their purpose is to achieve the correct ride height for varying curb weight. Ride height must be maintained within a fairly narrow range to achieve desired ride and handling and meet bumper height requirements. Some manufacturers use different length or rate springs to achieve this. MBZ uses the different thickness spring isolators.

Contrary to popular belief, springs rarely "sag" or wear out from use or normal loads. They can be damaged from overloading and can "sag" due to loss of material from corrosion. The spring rate is a function of wire diameter to the fourth power, so it doesn't take too much loss of material from corrosion to cause them to lose rate.

As an example, if your car currently has 13mm isolators the 23mm versions will raise ride high 10mm or about 3/8", which is not much.

Years ago you could buy air bags that would fit inside the springs and they could be inflated to increase ride height or preload the suspension. They were popular with drag racers to counter the torque reaction on solid axle cars by preloading the suspension. In NASCAR/circle track racing it's called "weight jacking" or "wedge". Current GN/Busch cars and Craftsman trucks have adjustable height spring perches with a jackscrew that is easily accessible during a pit stop, so they can quickly change the wedge to improve handling.

Another bygone way to raise the rear was "overload" shocks, which were just shocks with a concentric springs to add to the rate of the OE spring. They were popular with station wagon owners who carried heavy loads.

Duke

Re: measure ride height for a specific car
 

Take everthing out of the trunk and have the ride height checked according to proper MBZ procedure. If it is low, then the rear suspension including the springs should be checked for nonconforming parts and replaced as necessary. If the springs do require replacement discuss the ride height issue and have them install thicker isolators so the car won't sag as much with the your heavy load of gear in the trunk.

You could also investigate aftermarket alternatives such as "overload" springs or overload shocks (with a helper spring as I previously discussed), but I have no idea if such parts are available for the S-class.

Duke

Duke2.6
 

I have a 96' S420 which is a "shock" car like the S350. Putting them side by side, the S350 is 2" lower in the rear? When I take weight out of the trunk, it is 1 1/4 lower than the S420. Plus, the S350 really looks lower (sagging) than the S420. I guess my QUESTION is, will is hurt to order the max size spring mounts which is 23mm? With no load in the trunk, will these make the car sit up too high in the rear? HELP, as I need to get these on order tomorrow. THANKS!

I sense your frustration with this topic. Here' the problem: To my knowledge Mercedes has not made available a specific method to measure and adjust ride heights other than the measurement of suspension arm angles. A lot of us wish we knew an easier empirical way to do it.

That being said, I have adjusted and changed both springs and spring pads in Mercedes and this is what I would do if it were my car:

Get the thickest and second thickest pads. Try the thickest first. If they don't bring it up, you will need rear springs. I went through this with the 300E. Yes, I was told Mercedes springs never wear out etc, but this is untrue. Be there and done that on two cars.

If you do need to replace the springs, keep the original spring pads because they may be exactly what is needed to get it back to where you want it to be.

Hope this helps,

Haasman

Re: Duke2.6
 

It certainly won't hurt to install the 23mm isolators, but it may not help that much. If it currently has 8 mm then the increase in ride height with 23s is only about 3/4", which will not achieve the 1.25" rise you are looking for. If your currently installed isolators are thicker the rise will be less.

Keep in mind that MB did change the ride height spec for some models over the years. They dropped the 201s 10 mm beginning in '89 as I recall. If the S350 sits reasonably level with no load in the trunk then the rear ride height may be normal for that year and model.

I don't know your level of DIY expertise or whether you have any service publications, but your best bet may be to seek out a qualified MB tech who knows how to measure the ride height using the proper MB procedure and can then troubleshoot to find any problems in the rear suspension or springs. Take all the stuff out of the car when this is done, but have the fuel tank at or near full.

Duke