Hello, as my signature indicates, I drive a 1990 300ce (with 190k mi). I have lowered the car, but I was trying to save a few bucks when I did it by delaying my shock replacement.

I have been searching for a good DIY page for this, as I'd like to try it myself. I've never done anything like it before, but it seems relatively straight-forward. I will also purchase a Hayne's book for the w124 to assist me. In my searching, I have yet to find a pictorial step-by-step DIY thread, although some people hinted of one existing on these forums. Can somebody point me in the right direction? I looked at the DIY page and didn't see shock replacement for the 124.

Nearly everybody recommends Bilstein Sports for lowered 124's, so I'm gonna use those. My question is, what does the strut do? Again, I'm far from a mechanic. Google searches have resulted in pictures of units that look much like shocks, but I can't figure out what they do exactly...

And a follow-up question would be, how do I know if they need replacing as well?

So, in sum, here's what I'm asking.

1. Could somebody show me a good DIY page for w124 shock replacement?
2. What do the struts do?
3. How do I know whether my struts also need replacing?

Thanks very much!!

Peter

anybody??

The terms 'shocks' and 'struts' are thrown around enough that they're pretty much interchangable at this point. I know somebody will disagree with me, but they do much the same thing. I think of the 'Macphearson Strut' when I think struts, and the plane-jane rear shock absorbers when i hear 'shocks.'

http://www.answers.com/topic/macpherson-strut

Unless i'm mistaken, your w124 has a Macphearson strut up front and plain shocks in the rear. You can replace the rear shocks with little trouble, I think the top nut is in the trunk under the plastic trunk liner and the bottom nut is on the A-arm (duh). Use jack-stands for any suspension job! The new shocks will probably come compressed by some wire, DON'T cut the wire! Take out the old shock by compressing it, get the new one all lined up, THEN cut the wire. And don't ask me why i'm so insistent on this...

I THINK the Macphearson struts should be changed out at a shop beause you will need to be aligned after the job, though I could be wrong. I'm not sure how long shocks/struts last per se, but I'm sure the manufacturer has a mileage recomendation. There is this thing called 'the bounce test' but in my experience shocks are pretty well shot before they fail it, i've heard this is especially the case with biltstein.

I have a pair of sports on the front of mine-very nice. They are 60k old right now and probably ripe for replacement.

If you need a step by step, but a factory CD. I hear they are cheap from benz now..20$?

cheers,
dan r.

Edit: If you're not sure how something works, nothing beats crawling under the car and checking it out...its pretty obvious when you are down there.

about the bounce test not being reliable for bilsteins. long before they fail that your ride quality will be gone. when it starts to feel bouncy they are worn out. i would look for this on average from 80 to 100k miles.

a strut provides the top part of the suspension assembly and bears half the weight of the car at that corner. the top rides in a large bearing that allows it to turn without twisting the shaft in the strut.

they can be changed at home but the spring requires a spring compressor and using a spring compressor is dangerous business. lots of folks do this at home but i personally dont.

agreed the rear shocks are an easy doityourself job.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

If you're going to do the fronts yourself, you should be sure to find the appropriate spring compressor to keep the springs from letting loose. As far as I know, there are only one or two brands that will work on the car, none of the other brands are robust enough to safely secure the springs.

A good way to test the shocks is to find a wavy road, or one with some dips in it, and drive over it at moderate speed. If either end oscillates up and down much, it's probably time to replace them. I think the W124 shocks last a good long time, 200-250k miles, so it may be time to replace yours.

The fronts are not true MacPherson struts because the spring is NOT concentric with the stuts. They are usually referred to as "modified" MacPherson struts.

The struts can be easily changed with the front control arms resting on jackstands so vehicle weight keeps the spring compressed - two bolts on the knuckle and the shaft nut up top. A spring compressor is not neceassry. Alignment should not be necessary after replacement. Always remove the top mounts and carefully inspect them for cracks. Replace if necessary.

High pressure deCarbon struts/shocks can last nearly forever, but some fail early. Failure is usually indicated by a major loss of oil.

If body rebound control is adequate and there is no evidence of oil loss, the OE struts/shocks don't need to be replaced.

Duke

thanks for the detailed explanation about the modified struts. i have often wondered about that and speculated that they may be easier than the true struts.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Struts are shocks and more. In the front, it's design is such that it becomes a more integral part of the suspension, performing a few functions that other suspensions use separate components for, such as a spring support and suspension axis, is the main steering axis, and also incorporates the shock absorber.

As others have indicated, this can be a relatively easy DIY job if you have moderate mechanical ability and some "auto common sense". I changed out struts/shocks on my 1990 300E last year. In his "Mercedes-Benz E-Class Owner's Bible", I believe Stu Ritter indicates useful life as something around 90-100K for the rears and up to 125K for fronts - perhaps longer than the average american equivalent. As Tom indicates, they will wear slowly and loose dampening effect. In the front, worn struts also affect steering angles. If you find oil leaking from one, that is a clear sign of failure. While I believe the German philosophy is to replace no part before it's time, I prefer to replace shocks/struts as pairs to maintain balance in the suspension, and once I get into a particular type of job, I don't want to come back 6 months later to "do the other one!

My 1990 has been mostly a "Garage Queen" (never out in snow & salt and not a daily driver) and now has 98K on it. Last year I noticed the rear felt more soft and bouncy than I thought it should when I had passengers in the rear seat. One rear shock did show a very slight trace of oil where the piston protruded from the shock body. When I replaced the rears, I did the subjective "comparison push test" between the old and new. Both original shocks were slightly easier to compress than the new ones (DUH!) and one of the originals was softer than the other. Result - improved ride/response at the rear.

While the front struts may have theoretically had a few more miles left on them, I had made a couple other minor suspension upgrades, such as "Sport" sway bars and bushings and new 8-hole rims with tires that matched the O.E.M. issue in construction/handling, and wanted to get as close as possible to that "new feel" in the suspension. No signs of leakage on the front struts but they also did feel slightly softer in the compression test. I used the "Comfort" version and have seen it stated that the Bilstein replacements are slightly more firm than the O.E.M.s. Don't know if that is true but now the ride is more firm, balanced, cornering is flatter, and steering response is improved.
OliverB

Thanks for your responses! I used to drive a jeep wrangler, and the shocks were simply a bolt-on sort of thing. These Mercs sure are complicated! I personally have no idea what I'm doing. I'm pretty handy and I like to do things by myself, but this is something I don't want to risk screwing up.

Better left for the professionals. I am, however, almost sure that I need to at least replace the shocks. I have no idea about the struts, though. I'll take the wheels off this weekend and see if I find traces of leaks.

Even if it's not leaking, I lowered my car with H&R springs but didn't replace the shocks. At 190k miles, I'm sure they are due for replacement anyway. I'm not sure if they were replaced by previous owners or not. The car has a good amount of body roll and bounciness.

How many hours should this take a professional mechanic? Is this something I could take to Les Schwab rather than an expensive MB technician (my trustworthy mechanic costs $90/hr!!)?

Thanks again!

As a general rule, I give the job to the person who has seen the most of that type of work. I actually went to a frame and axel shop to get my front set done-they do more of these than my benz mechanic. The shop needed 2 hours, if i recall correctly. Don't shop for mechanic by comparing hourly costs, do it by their experience and honesty! That thang ain't a buick...

Beyond that, get to know the guy that actually works on the car-not his boss, not the 'customer service representative,' not some guy trying to sell you a new car because you walked through the showroom. If they have a problem with you being in the garage talking to the mechanic, move on...

cheers,
dan r.

+1 for Duke explaing the diff types of struts...