If anyone is wondering how to align a W116, read on.
1. Check all suspension bushes, especially lower control arms, tie rod ends,
rims, ball joints. Any play here means it will be impossible to accurately
perform an alignment. If anything is worn, damaged or bent, replace it.
2. Although beyond the scope of this post, check that the steering box has
the play adjusted as per the workshop manual and that it is centered. i.e.,
when the steering wheel in the straight ahead position, the steering box is
also in the straight ahead position (Irrespective of the position of the
front wheels). Finally, make sure the pitman arm is fitted correctly to the
spline on the box. The index mark on the pitman arm must match up with
the mark on the spline.
3. You'll need some tools. The most difficult one to get hold of is the
aligner itself. I use a Corghi 6800, it's Mercedes Benz approved, which
means it has all the factory MB settings already in its database. Another
good one to use is a Beissbath for the same reason. If the machine you are
using, or the machine you are watching whilst you pay an operator to do it
not an approved machine, you can still perform the job, but just not as
accurately. Understand that some aligners measure toe from the wheel
centreline to the front of the wheel, others from the rear of the wheel to
the front of the wheel. In other words, you can have a reading that is
either half, or double what it should be depending upon the manufacturers
specification and the set up of the machine. Make sure the aligner knows
what parameters are being measured and if it's not an approved machine, you
have the specifications for them.
What ever you use, make sure it is calibrated (Most are not) and that the
ramps are level. The other thing you'll need is a special tool from Bosch.
This is designed to pre-load the front suspension and you cannot perform the
alignment to MB specs without it. You can see a picture of the Bosch tool
You'll also need a set of 24mm ring spanners and a set of 13mm ring
spanners for the toe adjustment and unfortunately, a pair of vice grips. A
butchers tool but unfortunately necessary for the tie rods as they do not
possess a flat, you have to grip them with the vice grips. I use a rag
around the teeth so as not to mark the tie rod.
4. Now we can begin the alignment. Note, although I am
using a 280 SE for this demonstration, this theory applies to all W116's
(And most other Mercedes-Benz cars too for that matter). On cars with
hydropneumatic or air suspension, it is imperative that the suspension is at
the correct ride hight when measurements are taken. Ensure the car is full of
fuel and laden as per the service bulletin requirements. For the 280 SE, that's
two people with half the payload. I have an assortment of heavy items that I
use to substitute people in the car. Half a dozen car batteries on the front floor
(Do not spill acid!!) and a tool chest in the boot usually does it.
5. Check tyre pressures. It's not necessary to have them at the correct
pressures, but it is essential to have them identical otherwise false
camber readings will occur.
6. Ensure there is no run out in the rims. A good machine will have run out
compensation however this is not necessary if you know your rims are true.
As most alignment machines take the readings from the rim outer, I can't
stress the importance of having this right.
7. Switch on the aligner after making sure the wheel clamps are accurately placed on the rims, the foot brake is locked with the brake clamp and that all sensors are level. Select W116 280SE on the database for the alignner, the machine will ask us to measure some rear suspension parameters. You can see what it will ask us here, the offset between the drive shaft and the suspension wishbone:
Measure the offset and enter the info.
You'll also notice this secondary screen:
This is a reminder for us to place the Bosch special tool on the front wheels as per the diagram.
You can see the tool placed on the wheels here:
Now we are ready to take some readings from the machine, and we will start with the rear:
We have 6 figures on the screen:
Just as it was getting exciting.....I will explain all these figures tomorrow as it's bed time. To be continued. (Please don't post questions till I've finished, we have a lot of info to get through)!