190 suspension after strut replacement - PeachParts Mercedes-Benz Forum

Piotr · #1 08-09-2002, 11:31 AM

I replaced both front struts in a 1985 190 (D) with the original Bilsteins. springs were never removed or compressed during the procedure. car sits (front only) about 2 inches higher than before replacement. This affected the handling (what you would expect after rising the front end of an MB- car wanders all over the road and lost the MB's "solid " feel while at highway speeds). Just looking at the struts makes obvious that they were not meant to be stretched like that (the dust boot is too short to be properly installed). Does anyone have any ideas??

Two mechanics told me (again) that there was nothing wrong with the front suspension.

J.HIDALGO · #2 08-09-2002, 12:43 PM

They are much stiffer than regular Bilsteins. If they are regular Bilsteins just wait a few days for the car to settle down. Otherwise, you can try shorter spring pads.

yal · #3 08-09-2002, 12:44 PM

I was thinking you might have gotten the wrong shocks for that model but you probably checked that already.
C V36-0199
HD V36-0362
or SP V36-0365

Could your older shocks have been Sachs maybe? Check the original rears if you can.

Or the shocks haven't settled yet and combined with the older rear shocks the front looks too high?

Sorry if I am just taking some wild guesses that you've probably already checked

#4 08-09-2002, 02:39 PM

Piotr,

You may want to cut off a coil from the original front springs or install shorter ones such as Eibach to lower the front. Shorter pads also.

Jeff

Piotr · #5 08-09-2002, 04:58 PM

No, no, hmm-possibly, and no way. The struts are exact replacement "standard" Bilsteins. I have already considered the possibility of new struts (replaced 6 weeks ago) not "settling in" although mechs swore that's impossible. I have not considered a possibilty that the original were Sachs. i'll check. Incidentally, I saw a 1985 190E blow by me yesterday. Quite obviously had 4 new shocks, because he was as high as me front AND rear.
I wonder if there is an adjustment of some sorts regulating the vehicle height. I know nobody mentioned it, but...

ronald_m · #6 08-09-2002, 05:50 PM

Just wait for a couple of days depends if you drive it regularly it will settle down.just give it some time.Don't cut the stock springs.

JimSmith · #7 08-09-2002, 07:48 PM

Piotr,

I am with your mechanics on this one. I have never had a shock "settle in" or some other terminology for changing the ride height in a few weeks. In every case I am familiar with the ride height was stable in a few tire rotations as the suspension went from hanging on the lift position to the normal supporting the car position.

The big deal about MB shocks is that they have a volume of trapped Nitrogen gas under high pressure with a sliding piston interface (with "O" ring seals) to separate it from the oil. The point of this feature is to keep the oil in the shock at a high enough pressure to avoid cavitation in the oil as it gets forced through the orifice that provides the damping. Once the shock oil gets warmed up from use, the typical, non-pressurized shock will cavitate, mixing the oil with little air/dissolved gas/oil vapor bubbles. This effectively changes the oil viscosity and other dynamic characteristics and the result is the shock performance will suffer.

In addition, the Nitrogen chamber adds a little length, and an additional spring rate, into the suspension system design. When this gas leaks out, and it will over time, ususally before the oil as Nitrogen is a linear molecule and it is much smaller than oil, or even water, so it leaks as the shock gets old, the shock height and added spring force goes away. The shock damping characteristics also change, but slowly as the gas leaks out so you don't notice it as readily. More of the car's mass is now supported by the coil springs and they collapse a little more, also over time so you don't notice it right off. I would suggest your rear shocks are shot as well, and if you replace them the car will ride at its design attitude and level. The real problem is likely that your old rear shocks are sagging, not your fronts being too tall.

Since most of the trunk load and rear seat load is borne by the rear suspension, if you have a car that is used a lot for hauling kids and junk in the trunk, you should see the rear shocks fail before the fronts.

Good luck, Jim

Piotr · #8 08-10-2002, 12:18 AM

JimSmith- I like your opinion the best. Actually, I considered that issue (rear shocks) before, but my MB mech said they were just fine. Since I put about $600 into her lest week getting a new compressor (remann) and converting to R-134 I have to wait with the rear shock replacement a bit, Or I'm into a possible d-i-v-o-r-c-e symptom so common to the owners of older MBs. ;-P

By the way, how hard is it to change a vacuum pump on these beasties??

sbourg · #9 08-13-2002, 10:50 AM

I haven't replaced our front struts - one reason being similar reports to yours I have read here, with indications that this is normal.

The dust boots not fitting seems suspicious, though, I would quadruple check for correct part on the replacement. Also, you did not indicate that any alignment was done. A raised suspension will change camber, caster, AND toe, so this could account for the handling issues. Also, if the new ride height is removing too much vertical dynamic range, this would cause handling problems when going over bumps.

Finally, raising the rear will shift the cg toward the front, and will likely lower the front ride height a bit. It will also shift the suspension geometry back toward its previous condition. However, when I replaced our rear shocks, any change in ride height was not obvious. It turned out the old shocks were not as badly worn as I had thought (were not the cause of the handling issue of the moment).

Steve

tvpierce · #10 08-13-2002, 11:58 AM

I just did suspension work on my '92 190E. Put everything back together (except sway bar), lowered the car and all was fine. Then I jacked it up again, mounted the sway bar, set it back down, and it sat about 2 inches too high. I manually "bounced" it a couple of times, but that didn't help. So I took the sway bar back off -- and all was fine again.
A co-worker suggested when mounting the sway bar, don't tighten everything up until the wheels are back on the ground and you've "bounced" it a couple of times.

I'm open to suggestions.

I'll try it tonight and give you a full report.

Jeff Pierce

sbourg · #11 08-13-2002, 01:30 PM

This is pretty much always true whenever flex (e.g. rubber) bushings or mounts are involved. This can also be a difficult access issue. Drive-on wood blocks (4-wheels) or a trench may be necessary.

Steve

haasman · #12 08-13-2002, 06:56 PM

Aren't the sway bars supposed to freely pivot in their rubber bushings?

Does this mean that they don't and that they are actually gripping the sway bar?

haasman · #13 08-13-2002, 06:58 PM

tvpierce

I await your results! This is very interesting. It may explain why I have had ride height issues with my other cars ..... Hmmmmm!

tvpierce · #14 08-14-2002, 10:27 AM

Haasman,

Sorry, I'm a slacker. I didn't get to the car last night. But I fully expect to tonight (Wednesday).
Let me preface the following paragraph by saying that it is my THEORY -- I am not stating it as fact. (and I would truly appreciate anyone else's thoughts on the issue)

I don't think it's the friction between the bushings and bar that's creating "spring". (I'm not sure it's physically possible for that kind of friction to create the amount of pressure required to lift the car 1-2 inches.) I think it's that the bar is being held in just the right (or should I say wrong) position so that it's "bowing" -- and that's causing the sway bar to act like a spring between the two control arms.

Again, this is just a therory and I'm open to further suggestions.

I'll keep you posted.

Jeff Pierce

tvpierce · #15 08-14-2002, 09:47 PM

Once again, appologies. I won't be able to get to the sway bar until this weekend. But I will post my findings when I do.

Jeff Pierce