126 guide rod mount replacement

[sixto]

I'm trying to reconcile Roy's DIY with my memory of doing this job on the 87 SDL. As I recall, Step 6 was the most work I've ever done in a single step. Since I didn't remove the spring to remove the spring perch to detach the guide rod forward attachment, I had to pull the wheel/LCA forward for the guide rod to clear the threads on the mount. Is there a quicker way to replace the mount with the guide rod still attached to the LCA?

Thanks,
Sixto
87 300D

[Brian Carlton]

The easiest way to do it is to remove the spring.............the guide rod forward bushing can then be replaced in the process.

If the spring remains in place, the forward bolt on the guide rod cannot be removed. In this case, you must thread the mount to the rod with the rod in place.

If you followed Roy's approach and removed the entire bearing bracket, you might prefer to start the threads into the rod before you secure the bracket to the frame. In this scenario, the LCA won't need to be pulled foward by an ungodly amount in order to start the threads (thereby alleviating the massive twisting moment on the LCA bushing).

Note that I have not attempted this approach because I did the job with the spring removed.

Good luck.

[Hit Man X]

I agree with pulling the spring, it takes all of 10 minutes and honestly I do not believe I would attempt this job with it still in place. Also, I left the rod attached to the guide rod mount and just whacked the thing on the ground a few times and the mount popped right out.

Now the two bushings that hold the bracket to the body... those make me want to swear. Both are easy to remove, one easy to install, the other is very difficult. This is with using a small 15 ton press. That mount to the bracket and the LCA bushing on the W126's front end are probably the worst bits to replace on the front end.

[Brian Carlton]

Originally Posted by Hit Man X

Now the two bushings that hold the bracket to the body... those make me want to swear. Both are easy to remove, one easy to install, the other is very difficult.

KY Liquid............you can use a simple arbor press. Pressing with 15T does nothing but deform the rubber............it doesn't allow the rubber to slide in the aluminum housing.

[pelon]

I left the spring in place and pulled the LCA forward a little with a come-a-long. Threaded the new part on and released the come-a-long.
Hardest part was when one of the hex head bolts stripped out and took a few minutes with an easy out to turn.
Pretty easy job all in all and well worth it. I had constant "clunking" on the right one. The left was still tight.
roberto

[Ryan Z]

I've checked today, and I too must replace the Guide Rod Mount, and the bushing at the LCA.

Using the proper spring compresser, will the spring come out of a SD without unhooking anything else?

Thanks

[brandlj]

OK here is probably a very dumb question. Can the guide mount be replaced without removing the unit from the car? My driver's side is clunking and the rubber cover over the joint is torn and grease is coming out. I have a 1986 300sdl. I looked up under the car and it looks like a royal pain to do this job because the whole assembly has to be removed from the vehicle. Is it because you cannot press the new mount in without it sitting in a vise? It looks like I have access to all bolts that need to be removed with the unit still bolted into the car. I realize that this is probably a dumb question so please ignore my ignorance in advance. The reason I am asking this is that this is the original joint from 1986, the car has never been in salt environment and the entire suspension has no rust on it anywhere. Roy's pictures depicted a severely rusted unit that was replaced.
Thanks
John

[otto huber]

You'll find several posts on using a strap, jack or some other contraption to move the lower control arm forward in order to replace the guide rod mounts. There's a lot of debate on whether or not removing the springs is necessary, but in my experience it was nice to remove the springs and have the unit on a bench to work with.

It wasn't until after I installed the mounts that I figured how the mounts are used to adjust wheel alignment. By turning the mount clockwise(facing the mount), you are pushing the guide rod forward. If you're feeling lucky, you might want to remove the 4 bolts from the back of the mount, and see if the mount will slide out the back while turning clockwise. If the mount doesn't move easily, you risk stripping the threads on the guide rod. Those guide rod threads will also be tested when you install the new mount.

[sixto]

You're doing less than a complete job if you don't replace the bushings at the LCA end of the guide rod.

Sixto
87 300D

[brandlj]

Thank You for the information. It seems like a difficult job doing these and I have no trusted independent Mercedes shop within 100 miles of my location. My closest dealer is in Shreveport and I can only imagine what he would charge for this. I am at a crossroads with my car. It only has 124,000 miles on it and it is beginning to need a bunch of things. My list includes a new A/C compressor, expansion valve and drier ( I have already purchased these items over a year ago, but no time to install), I need to replace my steering box,( it is leaking badly) My transmission is leaking a small amount from the front seal ( tranny will need to come out to fix), a Tree fell on my right front fender making a large dent ( I have another nice used fender, wrong color) Driver's top door panel has a crack, ( the dreaded blue color panel that seem to crack very quickly . The good things are low miles, new master cylinder, front rotors, calipers, upper control arms, brake hoses, front and rear, electric reclining rear seats, the original windshield!! still in good shape, good tires, 25 mpg, uses no oil, new glow plugs last winter. Do I spend some big money on it or sell it and get something else?
Unfortunately the car is not worth much except to us Diesel DieHards. I really believe that there is no better car for Interstate travel, room, ride, safety.
I just have to make up my mind on what I want to do.

[Edward Wyatt]

I use a heavy duty ratchet strap to pull the LCA forward. Before I do this I make sure to have all my tools and supplies ready to minimize the strain on the LCA bushing. The shop I worked at during the '80s showed me this trick, on a lift one can do one side in less than half an hour. I always unbolt the guide rod subframe(forget trying to r&r the mount on the car).

If you are making a living at it, pulling the spring is a complete waste of time and is dangerous even with the correct tools.

[Edward Wyatt]

Having done this job countless times, I can state that you will need the use of a press. Once water gets into the joint and causes rust, a bench vise isn't going to cut the mustard.

I say this for the newbies, who will find themselves unprepared for this.

[vstech]

the 126 and the 123 use similar bushings, but it's mounted in the body of the vehicle differently.
on the 126 it's pretty easy to just drop the entire bushing mount off the body of the car, then unthread it from the guide rod, and unbolt the old bushing and clean out the rust, then bolt in the new one. I did not need any press, or special tools. if the rod mount is cracked or worn badly, you will need to remove the spring. it's easy with the good tools. on a 123, you need the klann tool, or a dremel to clean up the hole, on a 126 the clone tool fits easily through the hole.

no, I don't believe the spring can be removed from the car without unbolting something else, but it's not important to remove the spring, just compress it some to take pressure off the guide rod mount.

the guide rod effects both caster and camber, so unless you are supremely lucky, you will need an alignment after you are done.

[Brian Carlton]

Originally Posted by Edward Wyatt

Having done this job countless times, I can state that you will need the use of a press. Once water gets into the joint and causes rust, a bench vise isn't going to cut the mustard.

I say this for the newbies, who will find themselves unprepared for this.

The housing for the guide rod bushing (sometimes referred to as the carrier) on the W-126 is aluminum. Therefore, the rust is only on the outside of the bushing itself and it doesn't bond itself to the housing. Accordingly, most won't have too much trouble removing the joint on the W-126.

To install a new one without damage, however, does require a thorough cleaning of the bore with some 240 emery paper and a fair amount of elbow grease. This would not be any pleasure if you choose to leave the carrier bolted to the body.

[brandlj]

Thanks to all for the replies. I have decided to tackle this myself. I have just about done everything on all of my cars, so why should this stop me. I was actually thinking of looking for another car, but have come to my senses. Since I will have to take the large crossbeam off that goes across from one guide mount carrier to the other, I will get a better look at the leak in my tranny. Maybe with some wishful thinking the leak is coming from my torque converter drain plug. That would be great! I will drop my pan also and change fluid and filter. As for my steering box, it's leaking and that's all there is to it. I have all winter to change out my A/C components and I will be ready for spring heat and humidity.
There really is no better car for my needs at this time. Wish me luck on my repairs!