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!

How to Remove the Propeller Drive shaft + Changing center Bearing

Reading Time: 3 minutes

Propeller drive shaft CPR

Removing the propeller drive shaft (also called the center drive shaft) is necessary when you are removing the engine/transmission, changing the flex disks or removing the differential/ rear subframe.

The procedure is similar to most cars and it is exactly the same for W126 and many Mercedes models. So guide this will work for both. Expect some wrestling and sweat underneath the car since the bolts can be very tightly on.

Theory

I highly recommend to change the center bearing, the center bearing carrier and front and rear flex disks when you remove the drive shaft for whatever reason, simply due to the long time of the job it would be a waste unless you also change these wearing parts with limited life span.

Practice
Removal

Step 1:
Remove the exhaust, check out How to Remove the Exhaust system
Step 2:
Remove the parking brake adjuster cables and springs. You will have to unhook the spring from the adjuster in order to get the cables off. The system is basically an adjusting rod with three cables attached to it and a spring to keep tension on the cable whem the parking brake is released.

Parking brake cable tightener
Remove this assembly to get more access to the drive shaft.

Step 3:
Now on to removing the drive shaft!

Loosen the sleeve nut in the middle of the drive shaft, this is to be able to collapse the drive shaft so it becomes shorter when removing it. Have a helper to apply the brakes so the shaft wont rotate when you try to loosen the sleeve nut. I do not like to apply pressure to the Transmission with the gear in Park due to the possible damage this may cause. Have the car in neutral instead.

sleeve nut drive shaft w123
The Sleeve nut, needs a very large spanner”

Next step is to remove the flex disks, there are one at each side of the drive shaft. The bolts are of a self locking type (the nuts are not completely circular) and they are hard to remove since they are not meant to get loose when you drive. I actually broke my spanner trying to get one stuck bolt off, so here I recommend some long spanners or some form of extension on the spanners to get more torque. Remember simple physics where the torque = force x length, so the longer the better when loosening stuck bolts and nuts. To get the drive shaft off you only have to remove three nuts. The ones that are attached to the drive shaft spider. If you are planning on replacing the flex disk, then you have to remove all 6.

There might be tricky to access a spanner on the side facing the transmission, and you might end up supporting the transmission with a jack and removing the rear transmission mount.

front drive shaft flex disk w123
Front flex disk

Unfortunately you have to remove the three nuts at the differential end as well,  the access here is easier though.

rear flex disk w123
Rear flex disk

Now the drive shaft is hold in place by the center bearing carrier. The center carrier is just hold there by two bolts in the chassis.

drive shaft center bearing carrier
Center bearing carrier

Now you have to collapse the driveshaft by pushing the front side of the shaft in towards the middle to get it loose from the transmission spindle.

The drive shaft can be so corroded onto the flex disk mouting plates that you will not be able to do this easy by hand. I used a long screwdriver to place it between the drive shaft spider and the flex disk and used massive force until it broke loose.

Warning: You might end up damaging the flex disk which i did. It was so corroded that one tab of the flex disk broke off wæstill attached to the spider.

Caution: Be careful when handling the drive shaft so it doesn’t come slamming into the ground or on youself for that matter. The drive shaft needs to be perfectly straight and it is also balanced by the factory to a, so be careful eh?

drive shaft w123
Drive shaft separated
Bearing Replacement

The bearing is most likely stuck in the drive shaft center carrier, always replace this cheap rubber part or your drive shaft will vibrate while driving. Just rip it off or use a knife to cut it so you can access the bearing.

The Bearing is pressed is pressed on the shaft and you need a puller tool like this. Note the placement of the dust caps around the bearing, so you place the the same direction when fitting the new bearing.

puller tool
Bearing puller tool

After pulling out the bearing, insert the new bearing into the new center carrier.

bearing parts w123
Parts distributed, bearing dust caps, center sleeve, new center carrier and bearing, old one to the right.

Remember to insert the inner dust cap before tapping on the  new bearing.

inner bearing dust cap w123
Inner beaing dust cap placement

Use a metal tube to tap on the inner part of the bearing, be careful with the hammering and do this slowly.

tapping on new center bearing driveshaft
Tapping on new center bearing on the drive shaft with a tube
Assembly

Assembly is pretty much the reverse as removal, however you need to spin the drive shaft around a few times after fitting, before tightening the sleeve nut, this is to remove stress on the drive shaft before tightening. The last thing you should do is tightening the sleeve nut!

Always follow the torque specifications on the flex disk bolts!

Cheers, Robs out

How to Remove the Exhaust system

Reading Time: 2 minutes

Removal of the plumbing

Removing the exhaust system may be necessary for a number of reasons. If you are replacing it then obviously you end up removing the old, but often I find the necessity to remove it for gaining access when doing other jobs. This job can be considered a simple one, but often it is not! There are pitfalls and it’s not easy dealing with these heavy tubes under the car.

What do you need?
Jack stands
Blocks of wood
Spanners

Lets get started!

Decide whether to remove the entire exhaust or parts of it. If the exhaust is old I will warn you that trying to separate the tubes will be extremely difficult sometimes. If it is a single tube exhaust like the smaller engines or diesel versions, then you might be able to twist the tube around to loosen it. If you have double tube exhaust systems I will discourage you to even try and simply remove the whole exhaust system from the beginning, talking from frustrating experience.

Jack up your car, it needs to be quite high in the front so you have enough room for the downpipes under the car. Then support the middle and the rear muffler with wooden blocks or even better if you have spare jacks, so you could lower the exhaust fashionably. Then take off the four rubber hangers on your rear muffler.

rear muffler supported with wood
Support rear muffler with wood or similar
middle muffler supported
Middle muffler supported by jack

Depending on your exhaust system it is most likely secured in other ways. In older Mercedes like the W123 it is clamped on at the transmission. Remove these clamps now.

Then the exhaust is only secured at the manifold-downtube. This is your most difficult job until now. The bolts are quite difficult to get to and your spanner will have very little room, a spanner with racketing function comes in handy here.

Exhaust downtube w123
Exhaust downtube attached to manifold

On the M110 engine, each down tube is hold on by two bolts, and they always are rusty due to the heat. Use lots of wd-40 to soak the bolts.

When you have loosened all the bolts, the exhaust will not smash into the ground since you already have supported it. Then just lower the exhaust slowly and wiggle out the downtube from the engine bay. If you have some wooden plates under the car the exhaust should slide out nicely eithout you scrathing it on the ground.  You should now have removed the entire exhaust. Congrats!

Exhaust system 280ce
Entire exhaust system detached

Bonus tip:

If you are persistent to separate the exhaust to eliminate the need to remove the entire thing, you could use a gas torch to heat up the tube at the attachment point so it will loosen up, no promises though.

gas torch on exhaust
Using a gas torch to heat up the tube