How to replace tie rods, center drag link and steering damper on W123

Reading Time: 3 minutes

When your car steering starts to feel floaty and maybe the car is starting to drift to one side so you constantly have to correct when going down a straight road, consider changing the steering linkage components and do a wheel alignment.

I will describe how you replace the tie rods, the center drag link and the steering damper only. I will not describe how to do a wheel alignment, because professional wheel alignment equipment is needed.

Changing the idler arm bushing is also possible if you experience a knocking sound going over bumps, but this procedure will be described later in a separate article.

 Theory

Get the parts needed for this job, they are quite cheap since they are normal wear items on a car.
Parts you should get:

  • Right and left side tie rods
  • Center drag link
  • Steering damper
  • Idler arm bushing (job not described in this article)

You will need a special tool for removing the tie rod ends, this can be picked up quite cheap. Either a tie rod fork or a tie rod press tool will do, the latter will not render the tie rod bushing seal useless, but if you are only changing the parts then this does not matter. Additionally you will need a hammer, a torque wrench, some hex tools and some spanners.

 Practice

Start by raising the front of the car on to jack stands, make sure you block the rear wheels. You will have to be able to remove the front wheels to gain access to the tie rods and also be able to turn the wheels.

Because you are working around the brake rotor, it is important that you wear a dust mask and get a bucket of soapy water and start cleaning the brake rotor and the area around to get rid of all the harmful brake dust before you do any other further work. Think of your health!

When you have cleaned the brake dust, turn the steering wheel all the way left if you are working on the right side, and vica versa.

tie rod tool
Use of tie rod press tool to pop the ends off

Get a small pick and clean road grime from the top of the tie rod so you can get a hex tool inserted in to the top. You will loose the bolt with a spanner, but because the whole tie rod end will rotate you have to counter it with the hex tool. When he bolt is off you will notice the tie rod is still extremely stuck. Hit the side hard a couple of times with a hammer to knock the rusted component loose, this might help to loosen it. Insert the tie rod press remove tool and start tightening until the tie rod pops off, this can sometimes be violent. Be careful and don’t lie under it when this happens, because it can happen quite suddenly and the tool and parts might fall on top of you, ouch!

You have to repeat the process twice on each tie rod for both of the car’s sides.

When you have gotten both off, measure the length by counting the turns the tie rod end can rotate before it comes off, it is important that this is exactly the same for the new tie rod. The new and old tie rod should have exactly the same end so your car will have the same handling properties, so it will not be too much “toe in” or “toe out”. The workshop will do the last alignment with reference to the manufacturer specifications after you take the car there. Tighten the tie rod adjustment screw so it will not rotate when the lengths are right.

w123 steering damper
New vs old steering damper. Old one was leaking and in bad condition

Time to take the steering damper off. This is the easiest procedure, it is held in place with two bolts only.

w123 steering damper bolt
Steering damper bolt on the frame side.

One end is attached to the frame of the car while the other one is attached to the center drag link.

Now it is time to get the center drag link off, the procedure is the same here as with the tie rods. Except you don’t have to adjust anything.

W123 center drag link nut
Unbolting the center drag link nut

The fitting is pretty much straight forward, but remember to use the right torque settings for the tie rod mounting nuts. You should tighten them down only to 41Nm, the tie rods will be stuck in the steering arm and the nuts have plastic inserts in them. Remember throw out the old tie rod ends nuts since thee plastic self tightening mechanism is word. The new tie rods and drag link comes with new nuts and be sure to use these. Loosing control of the car because of some old nuts would be as stupid as driving off a cliff.

Safety warning:
You absolutely have to take the car to a workshop where they will do a new wheel alignment. This must always be done right after changing the lower suspension parts!

Cheers, Robs out 

 

How to replace the rear and front shock absorbers on w123 sedan and coupé

Reading Time: 4 minutes

Changing the shock absorbers is pretty easy and will save you a lot of workshop bills due to the fairly long time it just takes to get it done on all four wheels. I had to change all the four shocks due to wear and age on my coupé. It handled more like a boat than a fast coupé in the corners in the end. I recommend buying high quality shocks from Bilstein, they come in two different options: Heavy duty shocks that give less body roll and the Standard comfort shocks for super smooth highway cruisers. I prefer the Heavy duty ones for using the car on twisty roads. And oh boy what a difference it makes, now it can take corners almost like a modern car down twisty narrow Norwegian roads. Worth the all the effort and money!!

So How do you change these shocks and what equipment do you need?

Parts

  • Firstly buy your new shocks. I really like Bilstein, but it’s up to you and your budget. Always change both shocks on the same axle!

Tools

  • Then you need a special 10mm socket with 12 teeth to loosen the lower fittings on the front chocks, see the image below.
  • Socket tools
  • Spanners
  • Torque wrench
  • Jack stands
  • Jack
special shock absorber tool w123
Front shock absorber loosening tool
Removal procedure

You always have to remove the upper shock mounts with the car on the ground, so wait with raising the car up just yet.

Start with removing the back seats if you plan to change the rear shocks. The back cushion for your asses are removed with just pressing two plastic tabs at the front and just pulling up on the whole cushion. The rear backrest is held in place by three sheet panel bolts on the lower edge. To pull out the backrest just pull upwards and it will come off. Now wiggle it out of the car, easier said than done on the coupé. In the sedan you have some more space to move around.

back seats removed w123
Back seats removed

With the rear seat removed, uncover the holes for the rear shock absorbers by looking behind the soundproofing cover.

plastic rear shock absorber cover w123
Remove the white plastic cover to access the top nuts

Pry open the white plastic covers and you will find the upper mounting on the rear shocks.

rear shock absorber top nuts w123
Top nuts for the rear shock absorbers

To unfasten them, have a adjustable wrench to grip the flat upper part of the shock absorber rod still while rotating the mounting bolts with a 17mm wrench.

removing top nuts shock absorbers w123
Keep the rod from rotating while unfastening the bolts with a wrench

Then open the hood of the car and unbolt the upper front shocks.

removing top nuts shock absorbers w123
Removing top nuts shock absorbers

Now it’s time to jack up the car and place it on jack stands. Find that special socket and a long extension, I mean really long. The socket is for removing the two front nuts on the front shocks. Always star start on the outer one towards the wheel, because you have to angle the whole shock outwards to access the inner one. It is very important that you remove all the rust or dirt that is on this nut to get maximum grip. It is usually very tight and you don’t want to round off this one! Make sure that the socket is sitting all the way down tightly and use your strength to break it loose. I actually had to lift up the suspension arm with the jack so I could gain enough clearance from the wishbone to the outer nut.

lower nut front shock absorber w123
Locate the lower nuts on the front shocks

Pull down the gas piston down to being able to angle the shock outwards to gain access to the inner nut on the lower mounting. If the shock is very stiff, use a pry bar for leverage.

lower nut front shock w123
Compress the shock in order to angle it outwards to access the inner lower nut

When this last nut is removed, you can just remove the old shock. Make note of the placement of all the bushings and shims, but it might be that the new shock has a slightly different mounting arrangements, then you should refer to the instructions provided with the shock.

The rear shocks are easier to remove. After the top nuts have been removed. Then just unbolt the two big bolts in the middle of the trailing arm. Be careful holding the shock when removing the last bolt so you don’t end up with the shock falling on your head while you are lying on the car. You need some ground clearance under the car to be able to withdraw the shock from under the trailing arm.

Fitting procedure

Reassembly is pretty much reverse of the disassembly. Be careful of not rotating the shock absorber rod too much when tightening the top nuts, since it might damage the internal gaskets and the new shock absorber will start leaking. Start with torquing of the lower bolts are done when the car is raised on the jack stands, and only do the last torquing of the upper mounting nuts when the car is resting fully on its suspension on the ground, like when you removed them. The front lower bolts need 19Nm and the upper ones are tightened until the rods are at some height above the hold down plate. Don’t over tighten excessively. This is usually given with the shocks or you can look at how the old ones were before you remove them, given that they are of same type.

top nut front shock w123
The top nut can either be in pairs or like this one with a bolt with plastic inside.

I had to reuse the old dust guard cloth from the old shock and fit it to the new shock before I installed it on the car. So be careful taking it off and not to rip the cloth. The new front shock came though with a new plastic dust cover.

rear shock dust cloth w123
Reuse the old rear dust cloth which does not come with the new shock absorbers

Finally installing the rear shock is reverse order again. Good luck. The rear lower bolts have high torques of 45Nm while the upper mounting is tightened when the car is resting on the ground and to some height of the rod above the hold down plate.

rear shock dust cloth w123
New vs old front shocks

How to replace the upper control arm – Front suspension w123

Reading Time: 3 minutes

Steering start felling loose? Maybe you can hear knocking when going over bumps in the road? Then it’s time to change the upper control arms. These have large rubber bushings that wear down steadily over time and a ball joint holding the knuckle arm in place which can get the typical knocking sound. This part is a common failure in the MOT, but the part is quite cheap and should be changed if it’s old. The failure in the control-arm most often happens in the ball joint, and since you can’t replace the ball joint separately when the part is one forged piece, you have to replace the whole control arm.

old control arm
This control arm might become dangerous due to the deteriorated rubber. 
new control arm
This how it should look like
Preparation

You need only basic DIY tools to do this job

  • Socket tools
  • Ball joint / tie rod fork
  • Torque wrench
  • Jack stands

As for the parts you will need a new control arm and two rubber bushings if you are only doing one side, but I recommend just doing both sides the same time. You might in some cases need a wheel alignment after, but most times you get away with it if you leave the tie-rods be.

The control arms are different for each sides, so be sure you get the right one if you are only changing one side.

Removal Procedure

Secure the rear wheels then Jack the front of the car up and put it on jack stands. Take off the wheels. Then use the jack to raise the front suspension a bit up to change the angle of the sway bar so you can easier loosen the ball joint and nut.

upper control arm loosening ball joint nut
Start loosening the ball joint nut. The ball joint might start rotating, use a hex key and a spanner to counter the rotation.

No start to  pry it off with a tie rod/ ball joint remover fork. This will in most cases ruin the rubber gasket for the ball joint so you can not reuse this part afterwards (make sure you have the correct side control arm before doing this). The ball joint usually sits really hard, so you need to use some muscle to pry it loose. A long fork bar is desirable.

prying off the upper control bar ball joint
Prying off the ball joint, this method will break the rubber gasket and make it unusable. It’s going to be thrown anyway.

Then loosen the nut at the sway bar end and loosen the washers, make sure you note which orientation the different washers have, take pictures if needed.

upper control arm sway bar bolt
Loosening the sway bar bolt

Use the jack to raise or lower the suspension for being able to get the ball joint off the suspension vertical arm. Prepare a zip tie for the knuckle arm which is attached to the lower ball joint and will want to go all over the place unless you secure it to the damper with a zip tie. It is a bit difficult to attain the height needed on the control-arm to get it out of the knuckle arm. You just need to work it off by pushing upwards and using the jack actively.

Securing knuckle with zip tie
Securing knuckle with a zip tie

Now you will need to open your hood and get into the engine compartment for removing the inner control arm attachment bolt.

upper control arm bolt w123
upper control arm bolt location
upper control arm bolt location w123
Slide the bolt out while wiggling the control arm
upper control arm bushing
Old bushings on the left compared with new ones on the right
Fitting Procedure
upper control bar placement
No control arm seen here…

The fitting is kind of fiddly. You are required to use some muscles and ingenuity to be able to push the control arm and the new bushings on to the sway bare in order to get the bolt in. So get ready to sweat!

Prepare the new control arm with the two rubber bushings for the sway bar. Smear the sway bar end with some grease to make it easier for the rubber to slide in.

Place the first bushing before placing the control arm. The hardest part is pushing the the control-arm enough in on the sway bar end so you can fasten the end bolt. The rubber bushings are new and quite wide and stiff compared to the old ones, so you will wrestle this a bit. A helper is nice here, but it is very achievable alone too (I never had a helper on this). In order to squeeze the rubber together far enough so I could get the washers and bolt on, I used a brake caliper separator tool, but for clamping so I could squeeze the control-arm onto the inner bushing, that way I could squeeze enough so the bolt would get on. Worked out perfectly.

Do not tighten the sway bar bolt before fitting the inner bolt from the engine compartment. Then at last place the ball joint through the knuckle arm and then tighten down with a torque wrench.

new control arm w123
New control arm in place! sweet

Cheers!

How to Remove the entire rear Sub frame

Reading Time: 2 minutes

If you like challenges in your life..

Whoa that sounds difficult you could think, I agree it’s not the easiest thing to do in the world. Also doing this without a lift is more tricky, since you have to lower the whole assembly instead of just lifting the car up.

When would you need to do this job?
This is quite a rear job, but changing differential or trailing arms this might be necessary. Also with restoration, body work or mayor overhaul of the car suspension such as replacing those difficult rubber bushings.

Preparation

Set aside time, this is time consuming. Don’t expect to do this on a Friday and be driving again Monday morning unless you are super man. I will rank this maybe even more time consuming than taking out the engine.

Get all the necessary replacement rubber parts, such as sub frame rubber mounts, differential hanger, trailing arms rubber bushings. Rubber seats for the rear springs. New rear springs if needed?

Have at least 3 jacks available. And put your car high up on four big jack stands before starting. The jack stands need to placed in the frame of the car so you can lower the sub frame freely.

No special tools needed other than your large spanners, big sockets and long breaker bars. You will encounter 120Nm bolts here.

Removal Procedure

Step 1:
Remove exhaust system. Check out How to Remove the Exhaust system

Step2:
Remove the propeller drive shaft. Check out How to Remove the Propeller Drive shaft

Step3:
Take off the rear brake Calipers and the sway bar links.

Step4 Lowering the sub frame assembly:

Support the differential with a jack and make sure it can’t slide off. Support also the large sub frame arms with jacks.

jack supporting differential
Jack supporting the differential, note the other two jacks up front supporting the sub frame.
supporting subframe with jacks
Supporting sub frame with jacks, one on each side

Then you have to loosen the two big sub frame tightening bolts. Use a very long breaker bar and lots of force to loosen these bolts.

subframe tightening bolts
Loosen the two big sub frame tightening bolts, then remove the bracket

Then you can take off the sub frame mounting plates by loosening the two bolts to the body.

Next step is to loosen the differential hanger to the differential. If you are replacing this part (you should) then loosen the top four bolts, if not then loosen the two big bolts attached to the differential itself.

differential hanger
Loosen the differential hanger

Now the sub frame is free from the body. Start lowering the whole ting very slowly to release tension on the rear coil springs. Preferably there should be three persons lowering each jack at the same rate, if you are alone you must lower each corner a little bit of a time until the while thing sits on the ground. Use some block of wood to support the assembly while you withdraw the jacks.

Then drag the whole assembly out from the car. Congratulations!

Fitting procedure

Reverse of removal, however don’t forget to place the springs before raising the sub frame. The most difficult part was to align the whole sub frame so the bolts would fit exactly, this is more than a little fiddly.

Cheers, Robs out!