Replacing Front Shocks? DIY-able? at own risk? - PeachParts Mercedes-Benz Forum

pawoSD · #1 04-12-2007, 05:11 PM

I bought a set of Bilstein front shocks for my W126...and I am unsure if I should attempt this on my own or leave it to the dealer. They want $200 to do it. I read that you can DIE with a spring sticking out of your body if you screw it up. I don't want that to happen. Any suggestions?

winmutt · #2 04-12-2007, 05:13 PM

If you do it yourself use the Klann!

tobybul · #3 04-12-2007, 05:19 PM

Quote:

Originally Posted by pawoSD

I bought a set of Bilstein front shocks for my W126...and I am unsure if I should attempt this on my own or leave it to the dealer. They want $200 to do it. I read that you can DIE with a spring sticking out of your body if you screw it up. I don't want that to happen. Any suggestions?

Not familiar with the 126 but on the 123, you don't mess with the springs. Its not a strut so the shock is outside of the spring. I changed mine last summer with Bilsteins from Adsit. One nut at the top and 2 small bolts at the bottom. The tougher ones are the rears as the top end can only be accessed by removing the backseat. But once the backseat is off its a poc.

Just apply WD40 on the bolts a day ahead to help in loosening it.

toomany MBZ · #4 04-12-2007, 05:40 PM

Agree with pawoSD, on the 123, you will need to remove wheels to gain access. Lower onto jack stands under LCA, loosen everything up, jack up, should come right out. You do not have to deal with the spring at all. Just crawled under the SD, looks to be very similar. Those bottom bolts have locktite on them, don't know if WD40 will help or not. Use new locktited bolts on bottom, and new nuts on top. They came with the shocks. Also on the 123, I needed a 12 point 10mm socket, as there is very little room to remove. Just note the oreintation of the spacer under hood. Do one side at a time. Good luck.

dannym · #5 04-12-2007, 06:01 PM

This is absolutely a DIY.
The FSM states "Detach shock absorbers when the vehicle is resting on it's wheels or when the control arm is supported." There is NO mention of compressing or removing the spring.
This is for front and rear.

One bolt is tricky. You have to pull the shock piston down and swivel it out of the way. Then you can remove the second lower mounting bolt and remove the shock.

On new shocks the upper bolt is tightened with suspension loaded, or wheels down.

Torque numbers front:
Lower bolts - 20Nm
Upper bolt - Tighten up to end of threads

Torque numbers rear:
Lower bolts - 45 Nm
Upper bolt - tighten up to thread runout

DO NOT allow the piston rod to rotate when tightening upper bolt.

P.S. I did all 4 of mine this way without touching the springs and I have a spring compressor.

Danny

pjc · #6 04-12-2007, 06:03 PM

No need to pay a dealer $200; this is an easy DIY job. The point about the spring is that when the wheel if off the ground, you don't have the weight of the car compressing the spring, so you have to place an upward force under the lower control arm to keep the spring partially compressed. The best choice would be a hydraulic floor jack, but if you don't have one you could place a jack stand under the LCA and lower the car slightly onto it.

Remove the two nuts holding the top of the shock, then press the center shaft down through the sheet metal hole with a screwdriver, socket+extension, or some other tool. This will allow you to move the shock to a vertical position, which may make removing the two lower bolts easier. Installation is the reverse. Check the condition of the rubber shock stop (you'll see it when you remove the old shock and slide off the protective plastic boot) and replace it if worn.

The dealer will use a special tool that prevents the shaft from turning when fastening the top nuts. You can just use a screwdriver (the top end of the shaft should be slotted), but be careful--the slot can become distorted easily and lose its gripping power.

pawoSD · #7 04-12-2007, 06:23 PM

Thanks a lot guys, I will attempt to do it myself sometime soon, now that I know its not so scary.

I do have a hydraulic jack as well as jackstands. I am nible enough that I could probably do it leaving the wheel on from the looks of it.

Probably won't though. I'll put the control arm on a block of wood on the hydraulic jack.

Hatterasguy · #8 04-12-2007, 08:56 PM

$200!!!!!!!!!

It takes 20 minutes per side if your slow. Un bolt the top of the shock, jack the car up, un bolt the front bolt, compress shock pull towards you, unbolt the inside bolt and its out.

You don't touch the spring on the W126. You won't hurt the lower control arm, the spring will just compress it to the stops. If you hold it up with a jack getting the shock out and back in is going to be real hard. You would have to pop the upper or lower ball joint to be able to lower the control arm enough to get at the spring.

pawoSD · #9 04-13-2007, 01:24 AM

So....taking off the wheel, jacking up the car, with the shock unbolted, is not going to result in the spring launching at warp-10 towards me or something else?

If so, why does it say in the MB documents "SUPPORT LOWER CONTROL ARM WHEN REMOVING SHOCK, SHOCK PROVIDES LIMIT STOP FOR SUSPENSION"

Also, how do you compress the shock to get it out and in? Rent a gorilla to grab the shaft and push it in?

Hatterasguy · #10 04-13-2007, 09:37 AM

I don't know I have done the shocks on two W126's so far this way and havn't had a problem. The lower control arm is attached to the upper and they kind of hold eachother. But if the FSM says you should support the lower control arm then I am probably wrong, I'd support it.

You compress the shocks by grabbing the plastic thing and pulling down. It requires some effort so if your not strong enough go to the gym, more often.

pawoSD · #11 04-13-2007, 09:39 AM

Quote:

Originally Posted by Hatterasguy

I don't know I have done the shocks on two W126's so far this way and havn't had a problem. The lower control arm is attached to the upper and they kind of hold eachother. But if the FSM says you should support the lower control arm then I am probably wrong, I'd support it.

You compress the shocks by grabbing the plastic thing and pulling down. It requires some effort so if your not strong enough go to the gym.

I re-read the rather poorly worded shop manual and it says to unfasten the shocks before raising the car off the suspension, and that the upper control arm stop will hold it. Cool.

I may slightly support it just in case since I am paranoid.

Better safe than sorry!

I'll have no issues compressing the shock. I can bend breaker bars into horseshoes.

softconsult · #12 04-13-2007, 09:48 AM

If so, why does it say in the MB documents "SUPPORT LOWER CONTROL ARM WHEN REMOVING SHOCK, SHOCK PROVIDES LIMIT STOP FOR SUSPENSION"

It means just what it says. The shock limits the downward movement of the control arm. So if you jack up the front end with the shock detached the control arm could pivot downward without limit and the spring could let go. This is why you must jack up or otherwise support the outer end of the control arm.

You will find the whole process easy and un-eventful.

Steve

Brian Carlton · #13 04-13-2007, 09:50 AM

Quote:

Originally Posted by pawoSD

If so, why does it say in the MB documents "SUPPORT LOWER CONTROL ARM WHEN REMOVING SHOCK, SHOCK PROVIDES LIMIT STOP FOR SUSPENSION"

There are actually two stops. If you lift the vehicle, the first stop is the maximum extension of the shock. Go and remove the top nut at this point and you'll have a problem when the nut clears the threads on the shock.

But, if you've already removed the top nut, the suspension will travel down to the lower stop (can't remember where) and you can continue with the removal of the shock.

The spring won't launch in any scenario.

pawoSD · #14 04-13-2007, 11:22 AM

Quote:

Originally Posted by Brian Carlton

There are actually two stops. If you lift the vehicle, the first stop is the maximum extension of the shock. Go and remove the top nut at this point and you'll have a problem when the nut clears the threads on the shock.

But, if you've already removed the top nut, the suspension will travel down to the lower stop (can't remember where) and you can continue with the removal of the shock.

The spring won't launch in any scenario.

Yep, thats what I figured. I am actually about to go out and begin replacing them as soon as I run off the Shop Manual Pages, and have some lunch.

I'll report back later how it went....

pawoSD · #15 04-13-2007, 03:09 PM

All done! Wasn't too hard...I just wish I had had a better 12 point 10mm tool to get the lower nuts on/off, but otherwise it went smoothly. Now I just need to go test drive it!

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