Wheel alignment

[Mforcer]

Does anyone have any advice for the wheel alignment after fitting rims with a different offset and width?

My understanding is that it may be necessary to increase toe-in to compensate for the increased offset and a more positive caster to increase straight line stability. Should camber also be changed to handle the increased offset and wider rim?

Did AMG ever release alignment specs for their rims?

Is it possible that most of my steering problems stem from incompetent wheel aligners? I don't assume I can do these adjustments myself

[s class]

Michael,

You certainly could do your own alignment if you had access to a hunter machine.  I always 'work with' the alignment technician if you know what I mean.  Firstly, when going for an aligment its important to make sure they use the right spec.  On the hunter machines here I've found them wanting to use 126 specs - which differ mainly in having different caster.  Once I was told in no uncertain terms my car was a W123, and how dare I dispute their knowledge.  So I go armed with the spec sheet, and make sure that the template they call up is correct.  I have made them enter a template at my preferred tyre shop.  So in amongst the mercedes list they now have 123, 124, 126, 140, Ryan.  Hmmm.  At another shop I discovered that the 116 is not listed on the hunter database, but they did have something called '280' which turned out to have the correct specs. 

The next step is to be present during the alignment, because they generally know less than we do, and will settle for much poorer tolerances than we would.  Also, don't accept the 'its at the limit of adjustment' story.  Just before I rebushed my car, it had nearly 400 000km and it was still possible to get it very very close, though most eccentric adjustments were at the limit. 

During the alignment also make sure the rear is correct.  You can't adjust it - if the thrust angle or cambers are out, you need new bushes at the rear. 

OK a few years ago I tried 15" wheels with 225/60R15.  The wheels had a small offset (ie the wheelsstick out).  The handling was abysmal with strong, erratic pulls to the side.

Later I rebushed the suspension (about 35 000km ago).  I set all the eccentric cranks at the centre of their range.  After that, I went for alignment (with standard wheels) (on the 'Ryan' template), and found that little adjustment was needed from the centre points- very satisfying indeed. 

I then fitted the 16" wheels with 225/55R16 tyres.  Offset is a little larger than standard.  Handling is excellent, with no pulling, no tramlining or other problems.  Remember the alignement was set previously with standard wheels, now I've switched to wider wheels.  I conclude that the 116 chassis is good enough to support wide wheels with no problems, BUT that may only be true when the bushes are in good order.  When I say bushes I'm also including the steering idler arm bush and ball joints. 

Your steering box will not cause problems, unless it has noticeable excess play.  At the time I did this work, my steering box was very worn, but it didn't cause me any problems.  I later fixed the steering box though/

So if you are sure your alignment has been set to the correct spec, I suggest you have a good long look at the front upper and lower control arm bushes.  In my case I could not discern any wear by levering with tyre irons etc, but I suspected they needed changing based on the fact that the adjustments were at the limit (and I knew the alignment had been set correctly).  After replacing everything I was suitably impressed at how much tighter the handling was. 

Finally, I suspect that if your alignement is correct, and your bushes in a good state, wide wheels should work fine (obviously provided the offset is not too dramatically different from standard).

Ryan

[s class]

Perhaps I can specifically answer your question now.  It may be necessary to tweak the alignment settings to cater fow wheels of a different offset (I had to do this on my 107), HOWEVER, my experience is that the standard settings will give you MORE than acceptable handling as is. 

[s class]

Styria,

Thanks for the compliment.  Your vibration is more likely related to tyres/wheels than alignment. In general it is imposisble to get a wheel/tyre combination balanced perfectly both statically and dynamically.  Some small error is quite normal and acceptable.  It becomes a problem (leading to vibration) if the error is excessive, or there is some play in the steering idler arm bush, or the drag link, or the tie rods, or the wheel bearing for instance.

Wheel balancing is actually a complicated subject, and your comments and queries have given me the impetus to write abit about it.  However to do justice to the subject, I wish to start a separate thread with diagrams and explanations.  Give me a few days to get around to it. 

Ryan

PS, as to the '280' specs, I don't have them at hand, but I will scratch around for them in the next few days and post them. 

[Mforcer]

Thanks guys. What you say about not needing to change the alignment seems right to me too. When I first had the rims fitted, no adjustment was made and the car handled superbly. I suspect now, after all other parts of the steering and suspension have been checked and replaced where necessary, the alignment was simply done incorrectly.

Would the rims affect the alignment in such a way as to need original rims fitted during the alignment?

[s class]

Michael, no.

If its the standard hunter type alignment where they check camber, caster and toe-in, you will be fine, because they are static settings. 

As I said, after I rebushed my suspension, I had the alignment set with standard rims.  Then I fixed the steering box, then I fitted the bigger wheels, then I had the alignment checked again, and it was still fine. 

Toe-in and toe-out are two different things.  Toe-in refers to the fact that when the car is stationary, wheels set straight ahead, the front wheels are toed-in slightly - usually 0.5 degress.  In other words they point towards one spot in the centre on the horizon.  The reason for this is to compensate for the way the wheels pull back due to drag and the natural compliance of the suspension during normal driving.  (in other words, if the front wheels were set to 0 degrees toe with the car stationary, when you drove you would find the wheels pointing away from each other due to drag).

Toe-out is a commonly misused term - it is strictly speaking not the opposite of toe-in.  Toe-out referes to the fact that as you turn a corner, the wheels must be toed out with respect to eachother to account for the fact that the outside wheel travels a circle of greater diameter than the inner wheel. 

Toe-out is not set explicitly.  Your car will have a certain toe-out behaviour during cornering that depends on the suspension design and geometry, wheelbase length and the static settings (camber, caster and toe-in).  The maufacturer has designed things so that as long as your car is not bent from an accident, if you set the static camber, caster and toe-in correctly, then you will get the correct toe-out during cornering. 

Now here's the crunch - Toe-out accounts for the different diameters that the inner and outer wheels travel - so if you fit bigger wheels with a different offset, you will be altering the toe-out behavior.  Strictly speaking, this could require changes to the static settings, mainly toe-in and caster to get a more ideal set-up.  In practice, the wheels we can fit to our 116's are not going to differ in offset from the standard wheels sufficiently for it to make any real difference in normal driving situations.  I have heard that in some top track racing formulas they may worry about things like this, but our cars have sufficiently mushy high profile tires (even with 16" rims) and sufficiently mushy suspension bushes that I wouldn't worry about it. 

In any case, I have I think only once seen an alignment rig capable of measuring toe-out anyway. 

To summarise my ramblings :

a) the change in offset in our larger wheels is small enough to have minimal effect on the toe-out behaviour of the car
b) the standard hunter type alignment rigs available to us can't measure toe-out anyway, and so you will get exactly the same set-up with standard rims or the 16"'s

Ryan

PS

If you are really worried about it, I would do the following.  Get the alignment set with the standard settings.  If you find the car skittish, most likely you don't have enough toe-out. You can compensate by dialling in an absolute fraction less static toe-in.  Conversely if the car's handling feels 'dead', you may have too much toe-out.  Likewise you can improve things by dialling in a fration more static toe-in. 

We are working within the tolerance here.  The manufacturer specifies a range of acceptable settings for toe-in, camber and caster.  The adjustements I'm speaking of here are all within the quoted toe-in tolerance.  I think for the 116 the spec if 0.5Degrees +/- 0.5 degrees - ie between 0 degrees and 1 degree.  So When I say increase the static toe-in, I'm suggesting going from the nominal 0.5 degrees to say 0.8 or 0.9 degrees.  Likewise to go for lower toe-in, go to 0.1 or 0.2 degrees. 

This is only worth while if you are paranoid.  My 225/55ZR16 Potenzas have massive grip, which would tend to exaserbate aligment errors.  But I have not found it necessary to mess around with things.  Likewise, styria with his enormous wheels has not reported major problems. 

Ryan

[s class]

OK after a little thinking, here's a more scientific arguement to put your mind at ease.  If you fit wheels of a different offset, they are not likely to deviate from the standard offset by more than +/-10mm due to clearance issues.  OK lets assume you have a worst case scenario and decreased your offset by 10mm each side.  Then you have increased your front track width by 20mm.  The front track of the W116 is somewhere arounf 1650mm IIRC.  So the percentage error you have introduced is (20/1650)*100 = 1.2%.

Now as an example, consider the spec for the caster on our cars which IIRC is 10 degrees +/- 0.5 degrees.  ie a tolerance of 1 degree around a nominal 10 degrees.  That's a percentage tolerance of 10%.  That somewhat puts into perspective the 1.2% error we have introduced from our big wheels.  Our 1.2% error is within the pliability of the bushings and the general state of wear of a 30 year old car.

Ryan

Edit : corrected the calculation - the track error is 1.2%, not 1.7% as originally listed.

[Mforcer]

Thanks Ryan. That has been a huge help and I can now follow up with an alignment with confidence.

[s class]

Michael,

good luck.  The alignment on the 116 is actually a bit complicated to set up if you are not familiar with it.  Unlike many more modern cars, the two eccentric cranks are not an isolated caster setting plus an isolated camber setting.  They strongly interact and influence eachother.  The correct procedure is :

1) get the caster in spec (the rear most eccentric crank)
2) get the camber in spec (front most eccentric crank).  THis will move the caster as well probably pushing it out of spec, though not as bad as it was
3) set the toe-in
4) repeat 1 to 3 above with finer adjustments
5) repeat 4
6) repeat 4......

You get it.  Because they all interact, its an iterative process.  MOstly they get lazy and give up after step 3. 

Now, specifically, on the toe-in (tie rod) adjustments :

Before going for alignment, make sure the steering box is centered on its high point.  THis is important because the assistance characteristic of the box is non-linear.  It has a 'high point' of minimal clearance (and hence best feel) in the centre.  This tapers off progressively to the sides.  Failing to center the box properly can create a tendency for the steering to want to drift slightly one way or the other. 

So, centre the box, then centre the column onto the box, then centre the steering wheel onto the column.

Related to this, it is NOT acceptable for the alignment shop to  remove and refit the steering wheel at a different angle.  If your steering wheel, column, box and pitman arm are all correctly centred, then they must (and will be able to) get your steering centred by adjusting only the tie rod lengths. 

[LordFernwood]

Wow,  what a mine of useful information this trail was for me.   Thanks so much. 

I've been having difficulty getting the tire shop to fix the tendency for my w116 (1980 SD) to pull to the right.  They did an alignment (making some adjustments to Camber and Toe only (the printed report only identifies these changes), and diagnosed my 'pull' as being caused by a seizing right caliper.   (separate story re their quote for each remanuf caliper at $420cdn each -  I bought at $131 each from the local shop). 

I replaced the right side (just ran out of time for the left) and 'Bismark' still pulls to the right. 

So my conclusion is that either a) the steering box needs centering,  or b) they just messed up the alignment.   

More to follow.....

Simon

[oscar]

Take a look at this following excellent thread and you'll be able to make sure you go to a shop with the right equipment and ask for the right specs to be dialed in.

http://forum.w116.org/mechanicals/how-to-align-a-w116/

- Other than that, I assume your tyres aren't unevenly worn??  Simple I know but worth asking.  Your toe might have been cured but uneven treadwear may still cause a pull to the right.  Rotate tyres, front to rear if so and check for a difference.
- Regarding brakes, it seems reman callipers need their pistons excercised to wear in new seals.  Check sclass' eureka-moment post in his thread here http://forum.w116.org/mechanicals/6-9-brake-problems-getting-desperate-here/msg79455/#msg79455
- Lastly regarding steering, I don't know if that would be an issue, I'm just not sure but there's a few good posts on recentering but I'm having probs finding the ones I'm after.  There's some pics in one of my posts but not the best http://forum.w116.org/test-drive/got-a-new-project-pictorial/msg56755/#msg56755

[WGB]

Here is my take Oscar on centering the steering box using a domed bolt.

Steering Box Centralisation

Bill

[oscar]

Thanks Bill.  That was one of the threads I was searching for which shows what needs to be done and the bolt to hold the box centered.

[LordFernwood]

Thanks guys,  I just read through Carls fabulous technical walk through aligning a 116.   I think I may have identied at least one more cause of the pull to the right. In his description he talks of the importance of 'caster', and a mismatched caster will cause pull.  The shop I dealt with didn't do measure or adjust for caster. 

So, two possible causes (centering or caster).  Not sure I like Kal Tire much anymore, but I will take it back there on Tuesday to see what they will fix... 

Anyway, here's there printout..... 

[carl888]

Does anyone have any advice for the wheel alignment after fitting rims with a different offset and width?

My understanding is that it may be necessary to increase toe-in to compensate for the increased offset and a more positive caster to increase straight line stability. Should camber also be changed to handle the increased offset and wider rim?

Did AMG ever release alignment specs for their rims?

Is it possible that most of my steering problems stem from incompetent wheel aligners? I don't assume I can do these adjustments myself

Michel,

Alignment is fixed, it doesn't matter what wheels/tyres/offset you have, or change to, the alignment stays the same.  What steering problem do you have btw?

Regards,

Carl.