Topic: How to align a W116.

[carl888]

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
here.



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)!

[James R]

Umm...wouldn't it be easier to take it to the shop to get checked / repaired ?

[s class]

James, er - Carl is the repair shop as I understand it - are you still in the game Carl?

[koan]

Interesting, keep it going.

koan

[carl888]

Ummm, I was hoping no one would make a post as requested until I'd finshed, but alas!  I'll start a new thread so you can see the procedure in one hit.

With regards to the comments by James and Michel.  I was asked to provice the information, not justify it!  Obviously it is easier to get a shop to do it, but the fact remains, I do not know of any shop that has ever followed the MB procedure regarding a wheel alignment on a W116.  Do you?  When your shop performs an alignment, did you check that the car was prepared as noted?  Even if you don't do any of your own work, wouldn't it be better to at least be informed as to what is involved.......

FYI, I used to be in the alignment industry full time and sold my buiness in March last year.  I kept the equipment for my own use.

Regards,

Carl.

[oscar]

I was good Carl.  I bit my tongue.  James was bad.

This is fascinating stuff, I'm looking forward to the whole procedure.   I find it more intriguing about all the comments you make re the "correct" procedure, correct callibration, mercedes data etc. 

sclass made a comment a while back about wheel alignment and the standard procedure of "misaligning" the fronts to counteract the usual slope of the road that aids rainwater run off.  I found this annoying.  I spend most of my long distance driving in the middle of country roads, on top of the rise, not fighting a slight camber in the road.  I'd expect that if I ask for something, I get it.  It just makes me a bit more wary about who I see to do what.

[carl888]

OK, after that little interuption, lets keep going 

I'll re-post the pics of the screen showing the rear alignment.  A W116 rear is not adjustable.  It's set up at the factory and if it's not right, you either have a bent or distorted suspension component or worn bushes.  Lets have a look at the back of the 280.  We have six figures and they are:





left rear camber.             right rear camber

left rear toe.                  right rear toe

sum of  L+R toe.            thrust angle.



Camber:

Camber is the measurement that refers to the angle of the wheel as you look down on top of it.  Imagine a plan view, if the wheels lean in towards each other, the camber is negative, if the lean out, the camber is positive.   A wheelchair has negative camber, the front of a Bugatti type 35 has positive camber.  Camber is measured in degrees and minutes.  Now remember there are 60 minutes to 1 degree.

Increasing negative camber on cars tends to increase lateral grip at the expense of directional stability and tyre wear.  Positive camber tends to make the car understeer more and respond less to steering wheel inputs.



Toe: 

Toe is a measurement that refers to if the wheels point towards each other at the front of the wheel or back of the wheel.  Have a look at the diagram on the screen.  With the Corghi machine I use, it measures toe IN as a +ve value and toe OUT as a -ve value.  All machines are different and it's important that the operator knows which is which.  Additionally, some machines measure toe from the wheel centre to the front, or from the rear of the wheel to the front of the wheel.  Be careful!

Increasing toe on the rear increases grip at the expense of tyre wear.  Toe out on the rear is very bad, it causes grip reduction (Toe out is often used by drifters to decrease grip at the rear)


Thrust angle:

With any toe difference, the car is going to want to pull away from the side that has the most toe and the thrust angle is displayed in degrees and minutes.  Note, thrust angle affects only the driven axle, in this case, the rear.

So lets have a look at the figures:

Camber:

The 280 has 14 minutes of +ve camber (Or 14/60 of a degree or 1/4 of a degree) on the left and 24 minutes of +ve camber (Or 24/60 of a degree or 1/2 a degree) on the right.  We can see the factory figures are 15 minutes -ve to 1 degree 15 minutes -ve.  How is this so?  Well, with a 116, the camber decreases as the rear suspension raises.  I think the rear of the 280 is too high.  If it were to be about 3 cm lower, I am sure I would get to the factory specification.  I will have a look at the right hight this weekend to check.

Toe:

The left rear shows 3mm of toe in and the right rear shows 1mm of toe in.  We can see the factory figure is 0.20mm to 1.8mm of toe in per side.  The right hand side is within specification and the left is out by 1.2mm.  Personally, I am not that worried by the toe figure as the total toe is therefore 4mm, only 0.40mm out of specification but I would like to see more camber for rear stability reasons.

Thrust angle:

The car will theoretically want to pull 10 minutes to the right (or 1/6 of a degree, this figure is of no consequence and would not manifest itself as a driving issue on the road) 

So there we have the rear, nothing I can do about it because it cannot be adjusted but I am guessing that the rear ride hight should come down a tad and I may have a worn bush causing the increased rear toe on the left hand side.  Having said that, the camber in pretty symmetrical, just 1/4 of a degree difference each side and I am confident the car has no suspension damage.


Now lets have a look at the figures for the front.  As per the rear, we have toe and camber figures, but we have another one here as well, called caster.  Caster is the offset between the top and bottom ball joints as we look at the side of the car.  Have a look at the diagram if you are unsure.  Caster is important, it determines the willingness of the steering to self centre, the more caster, the heavier the steering and the more "feel" through the wheel.  There is also a secondary function used to great effect on racing cars, increasing caster has the effect of increasing negative camber on the outside wheel, the more the wheel in turned, great for grip in tight corners!

So as per the display, the front figures are:




front left caster.        front right caster

front left camber       front right camber.

front left toe            front right toe


Golly, what a mess it is!  Although I will cut the car a bit of slack because I've replaced lower ball joints plus some tie rod ends so I'm not surprised it's a bit messy after re-assembly.  Luckily, all three parameters on the W116 front end are adjustable so lets have a play:

The first figure I want to correct is the caster.  Over 1 degree difference here.....  It is very important to have the caster symmetrical, otherwise the car can pull to one side.  We can see the factory figure as 9 degrees 30 minutes + or - 30 minutes.  The caster is adjusted by this eccentric bolt here:




The next figure I will adjust is camber.  Nearly 40 minutes difference each side, yuk.  The camber adjustment eccentric is here:




Now for once I will disagree with the factory settings.  The reason is that the car will not be a daily driver, and the tyres will be hard before they wear out bearing in mind the mileage I'll be doing.  I am going to run about 30-40 minutes of negative camber on the front.  I am prepared to sacrifice a little straight line stability for a gain in cornering grip.  The factory figure is 0 camber to 20 minutes -ve.  I'm only 10 minutes more, or 1/6 of a degree more than the upper factory tolerance.  I am certainly I'll never notice the stability issue, I run 2 degrees -ve camber on the front of another car and it drives beautifully.

The final figure I will adjust is toe.  Wow, 9mm of toe OUT.  Had I driven the car for 3,000 kms, the inner edges of the front tyres would be down to the canvas with this figure.  The factory figure is 1.0mm to 2.1mm toe IN per side.  Note, we must use our wheel pre-load tool for this measurement.

Toe is adjusted but the tie rod ends, you can see them here, the green/gray coloured rods with a 13mm lock nut on each end:



After we have a good play, we end up with a screen like this, lovely, all nice and symmetrical:



We do a final check of the settings by doing a steering swing, 10 degrees to the left, and 10 degrees to the right.  The allows the machine to acquire the caster data again and at this time we can check Ackerman.  This is the tendency for the inner wheel to turn more that the outer one.  That's because the inside wheel must subscribe a smaller arc that the outer one, so we should see about 15 minutes more on the inner wheel, and luckily we do!  You can see the reading here:



Here is the screen with the before and after figures.  There are some other parameters displayed like king pin and angle and included angle.  These are non adjustable and refer to the angle at which the stub axle meets the upright.  Any accident damage or distortion will show here.  Luckily, the figures are very very close.



One final thing to watch out for.  It is imperative to ensure the ball joints are parallel to the link/steering mechanism.  If they are tilted, you run the risk of snapping them from their housing as the suspension travels.  You canb see how the ball joints are parallel to their mounting surface here:



Well, that's about it.  Now for the test drive.  Wonderful

[carl888]

Whooops, please transpose the pics referring to the camber and caster adjustment.  Note, the front eccentric does camber, the rear one does caster.

Regards,

Carl.

[Mforcer]

Thanks Carl for the great information!

Do you do house calls?

[carl888]

Thanks Carl for the great information!

Do you do house calls?

No probs!  And yes I do, but not for alignments

[kenny]

Remeber that if you are asking someone to align a 6.9, you need to rev the car for a few minutes at about 2k RPM to fully stabize the ride height.  There are some other procedures peculiar to the 6.9 (imagine!) and I will try and dig them up from some notes i had.

One of which is whether or not to put the suspension in 'lock' (first detent) or not.

Sorry this is not more helpful immediately.  Let me go look for that information.

[oscar]

Hi Carl,

Finally got a few q's

Regarding your car, does it have self levelling in the rear?  When you talk about lowering the rear to reduce positive camber, have you done that and how?  I not long ago did my 350 as the rear height was too high and it was simple to adjust the rod connecting the levelling valve and the sway bar. (I think it's the sway bar/roll bar).  Though my method was crude and involved guess work and the car now looks level.  Anyway, if you have conventional suspension at the rear, I was wondering how you'd go about lowering it.

A bit more general here.  If the rear isn't adjustable, why don't manufacturers set the front at a factory spec with fixed tie rod lengths etc that can't be adjusted?  Barring bush and ball joint wear, wouldn't you have perfect alignment all the time?  The vast population has an alignment done and that's that, I doubt many would stipulate different settings for their daily drivers.  Why not just make them fixed?

Lastly, every Ford I've owned has ended up toe out and inner tyre wear at the front. They'd do an alignment, new tyres, and it's happened mostly with supposedly all suspension components in good serviceable condition.  What's the go with Fords and more generally, why do front wheels come out of alignment in the first place if the locknuts on tierods etc havent moved?

[carl888]

Hi Oscar,

No, and that's annoying, I wish that car had self levelling!  I will have to change the springs and the question remains why it's that height in the first place.  BTW, the way you did your car the correct, just make sure is is raked down very slightly as per the WSM.  Don't forget to adjust your headlights.

Unfortunately cars are made to such poor tolerances that toe at least must be adjustable.  As for camber and caster, BMW's for example have never been adjustable on the front for anyhting but toe and this is a real problem as they are often quite assymetric right out of the  factory, especially M3's for some reason.  Decent performace cars like Porsche's and Ferrari's are completely adjustable for all 5 adjustments (Toe, camber, caster on the front and toe and camber on the rear) in addition to adjustable spring perches so you can corner weight them too meaning you can set the car up to hadle how you want.

Fords are notoriously under engineered at the front.  Have a look at the size of the tie rod ends and ball joints compared to a German car, they are just a toy really!  The rubber in the bushes just moves around as they wear.

Regards,

Carl.

[Squiggle Dog]

Excellent write-up! I just finished rebuilding the front and rear suspension and steering on my 300SD. I called the local Mercedes-Benz dealership on the phone to set up an appointment for an alignment. I heard a groan when I told the service advisor the year of the vehicle (1980). Haha.

I understand the rear end isn't adjustable, but I still have to pay for a 4-wheel alignment because the rear wheel camber has to be measured and the fronts set to match, correct?

I've been told that after new parts are installed, it will take about 3 or 4 alignments before it's right due to the parts settling. I asked the service advisor about this, and if there is a warranty so they can dial it in if the parts settle over time, and he said that since I installed the parts myself, I have to pay for another alignment when that happens. Darn.

I asked if the dealership has the spreader bar, and he said it's no longer 1980, and times have changed. He said he is sure their modern machine is equipped to handle it, so I hope he is right.

I also asked if I need to bring in the vehicle with a full tank of fuel and fully laden with weights on the front floor and possibly in the trunk, and he acted like I was crazy and said he never heard anything like that before, and all they are doing is setting the camber and toe.

I go in tomorrow. I centered all eccentric bolts and adjusted the tie rods so I have 1/8" (3mm) of toe in and the steering wheel is perfectly centered going down the road. I'm bringing the Mercedes centering pin for the steering box with me in case they don't have it (the dealership in Washington did not). I was actually worried that they were going to refuse to do the alignment because I had installed the parts myself, saying something like, "We are not an alignment shop." as they've stated when I've asked them to install ball joints or press in bearings, "We are not a machine shop."

[TJ 450]

I reckon they say the “settling” thing, as they don’t have the time to do a proper alignment which requires some care on these cars.

Admittedly, my 6.9 was done once at the local tyre shop after the refurb and it hasn’t been touched since. It’s pretty well spot on and they can compensate for the lack of spreader bar to a point.

Tim