126 front end work input and tests - PeachParts Mercedes-Benz Forum

Fisherman · #1 03-31-2004, 03:23 PM

Both of my cars have what seem to be bad bushings etc as I get little noises over bumps and stuff. You know the kind of chatter like a bad shock can make at low speeds. Anyway, I just did the shocks on the 84 and it did not improve the noises so I figure I am in for some suspension work.

Anyone have any input into the most likely causes/bushings and how to test for the problems? I can pull the wheels back and forth and from side to side but they seem okay. Unfortuantely I know they are not though...

Eric Eliel · #2 03-31-2004, 03:27 PM

Please post the mileage on each car.

Fisherman · #3 03-31-2004, 03:43 PM

81 only has 159K on the clock but the PO did nothing to take care of it and I do mean nothing. This one is scary to drive as it seems to kind of get a little loose when you are just about to come to a stop with the brakes applied. This one also has an odd clunk when you release and then hit the brakes at a stop.

The 84 has around 211K but has been fairly well maintained from what I can tell. This car drives very nice and only has the few noises that I mentioned.

kmaysob · #4 03-31-2004, 04:05 PM

sounds like mine. have someone drive it at a slow speed and then slam on the brakes. if the wheel moves back and then springs back into place its just like mine and you need a guide rod mount kit.

Eric Eliel · #5 03-31-2004, 04:12 PM

The noise associated with the brake application you described generally means guide rod mounts (does the car swerve or want to change direction when you apply the brakes?). You can change these yourself without dropping the lca (lower control arm). You won't need a spring compressor. This could also mean lower ball joints too. 159K isn't too bad unless its an east coast or TX/AZ car.

There were some photos posted recently of some really bad lca bushings. If yours look like those, they need replacement. You'll need to get under the car and inspect those for wear. The bushing should be intact and you should be able to see the rubber all the way around without too much cracking.

You need to make a decision as to whether you want to keep the car a long time. A complete overhaul (lca bushings, lower ball joints, guide rod mounts/bushings, idler arm bushings, tie rods and upper control arm bushings + misc) would be most satisfactory but also $. Most of the parts are not that much money, there are just a lot of them. Doing the labor yourself will save you $$.

Sometimes getting a full understanding of the front end, is best done on an alignment bench with someone who knows MB. This way the full condition of the front end can be reviewed including side to side and FtoR movement, Please don't waste any time or effort at the Sears, Firestone, PepBoys etal chains. They know not what they preach!

If you can't locate a good alighment shop call a foreign auto body shop and get a referral.

Fisherman · #6 04-01-2004, 12:51 AM

I have never really done any front end work but I am pretty good at figuring things out. I like to learn too.

When you say guide rod replacment is this the steering knuckle? Sorry I just don't have a reference on my CD to this job.

I kind of perused the parts list the other day and it looks like you can do the job for not too much money.

Eric Eliel · #7 04-01-2004, 01:16 AM

The guide rod attaches to the lca and then diagonally back towards the center rear of the car. The guide rod prevents the lca/spindle connection from moving forward or backward while braking or accelerating. The guide rod mounts attach to the frame of the car at the back of the guide rod. The guide rod bushings attach to the lca right near the ball joint at the front of the guide rod. The guide rod is also known as the strut rod.

There is lots of information on this site about 123/126 front end work, use the search and you'll spend hours reading.

As an overview, you need to figure out what kind of shape the front end is in. What is shot, what is marginal and what can wait. It would be a good idea to spend a little money and let an expert show you what needs attention. This might only cost you $25 or $35. Then you can decide what you want to repair now and what can wait. I'll say this once more......Firestone, Midas, Sears, Goodyear, the local tire store etc can not help you. They don't have the tools, the expertise, the parts availability or knowledge to adequately give you the proper answer. A free front end inspection from one of these folks is worth what you paid. This is a generality and there are exceptions (rare!) imho.

As far as parts go.......use only Lemforder aftermarket front end parts. Lemforder is the OE for many MB front end parts and is sometimes much less than the domestic replacement parts. Fastlane can order these for you (along with other competent suppliers). Some of the aftermarket parts really are not very good and don't last.

Fisherman · #8 04-01-2004, 08:47 AM

Yeah, I have a pretty good indy that can do the inspection for me. I agree with the Midas etc guys. Wouldn't even think about taking it to them.

He will change the oil and then do a full inspection for around $40.00 plus oil and filter so money well spent considering.
He then just gives me a list of everything he finds.

One final question,
Assuming that all bushings are out and you were to sequence the repairs could you make a short list of 1st, 2nd, etc...?

Eric Eliel · #9 04-01-2004, 10:44 AM

Assuming all the bushings and ball joints are toast or near toast? AND you didn't want to do the whole thing at once...........

1) Guide Rod mounts and guide rod bushings. Ball Joints. Lower control arm bushings. Idler arm bushings. Tie Rod ends. IF these are all bad, they should be replaced at one time. The guide rod mounts/bushings, tie rod ends and idler arm bushings can all be replaced without any special tools AND without compressing the spring.

2) Bilstein shocks

3) Upper control arm bushings and sway bar bushings. The upper control arm has a built in ball joint, I don't think I ever had to replace the uca in my prev 300D even w/438,000. New uca bushings were pressed in.

With the kind of mileage you are describing I doubt you need any uca work yet. More likely is tie rod ends, guide rod mounts and bushings, idler arm kit and maybe lca bushings.

Fisherman · #10 04-01-2004, 04:00 PM

The guide rod mounts in the rear are shot. I mean it looks like there might have been at one time a rubber boot on teh front side of the mount but it is totally gone now. The front mounts are so badly worn that the rod allows the lca to rotate so much that it is causing metal to metal contact in the mount as evidenced by shiny metal on the edge of the LCA mount point for the guide rod.

I'd say this is the first thing to tackle. Looks like the repair kit and rear mount kit total about 75.00 per side so not too bad.

I also found the source of the noise in the rear end that sounded like a bad shock. It is the Sway Bar link rocking and a rolling and it makes a rattle sound every time I hit a small bump. that one looks really easy and cheap to repair although I can't tell yet if you need to pull the rotor. if that's the case then it isn't that easy but still doable.

Thanks Eric!

Eric Eliel · #11 04-01-2004, 04:15 PM

Fisherman,

Check your PM mailbox.

ee

Fisherman · #12 04-01-2004, 06:48 PM

Can you pull the Guide rod and both the rear and lca guide rod mounts without removing the springs? It looks like the lower spring plate is in the way of the lower mount.
Thanks again for your help as I build up the courage to take on this project...

Eric Eliel · #13 04-01-2004, 07:23 PM

You may need to disconnect the bottom of the shock absorber to access the guide rod bushing connection but I'd have to get under the car and look for sure. You definitely don't need to compress the springs to renew either of the guide rod ends. I believe the front guide rod bushing is only a nut and washer.

Fisherman · #14 04-01-2004, 07:29 PM

I have been looking and looking on the CD for this job and cannot find it. I did some light reading via the search and it appears that this job is doable but I saw a lot of references to people saying they had a dickens of a time pulling the wheel forward enough to change the bushing. I assume this is the rear mount but by the photos that I have seen I thought this mount was R&R'd from the back of the carrier.
Obviously I am confused... Do you replace this bushing from the front and the back or just the front or just the back or.....duh

Eric Eliel · #15 04-01-2004, 08:55 PM

Lets keep the lingo correct. The guide rod MOUNT attaches to the rear. The guide rod BUSHING attaches to the lca. Unbolt the bushing, disconnect the MOUNT (3 bolts I think?). Drop the mount and slide the rod back to clear the lca. Dropping the mount and clearing the frame is the tough part they are talking about. Once the rear is clear, the rod slides back and out.

Once the rod is out, you can replace the bushing from the front and slide the rod back in (rearward part of bushing gets placed onto rod before installation).

I watched this being done by a buddy while doing something else and was only paying partial attention. But you get the idea?