Space age Alignment

[S.Speed]

Hi All,
Do to the deep disapointment of NOT having a Comand unit fitted the other day, I decided to go and visit "Wheels in Motion" in Chesham..
I tell you I have never seen a device such as this Alien looking monster called "Hawkeye"..
You have to see what it does to believe it.
One thing it pointed out was that apparently my rear nearside wheel had the wrong Toe angle..
I never knew the tracking on the rear could be altered.. IT CAN !
This machine is sooo sensitive that it can tell if the car has ever been in an accident and had the chassis straightened.. Because it can never be straightened totally perfectly.

Anyway, once the rear wheel had been adjusted, the fronts were aligned up to the rears.. He also checked the castor and Camber angles and pronounced them OK in my case.
"Wheels in Motion" have in stock the special Mercedes Bolts that you will need if you do need Camber adjustment..
I was particularly impressed that I was welcomed to go and watch this £45000 monster in action and to view the screen and watch the alterations and the effect they had.

I was so surprised to see the front wheel readings altering as he altered the toe in on the rear N/S wheel.

He told me that as MB's go mine wasn't very bad.. Yet on the drive through the lanes it is so very much more sure footed and it just feels planted and safe.. I never realised a large heavy car could handle this well till I owned this Merc.

If any of you out there are less than satisfied with Tyre wear issues or the general handling characteristics of your car then I really do suggest you make an appointment with these people..
http://www.wheels-inmotion.co.uk/
You will need to book with them as they are usually very busy.
Lastly the drive there is sublime.. Its one of the most beautiful parts of the country I have ever seen..
Give them a try and your Mrecedes will love you for it.

 

[LYNALL]

Went there a few weeks ago for wifes c320 and to wheels in motion 4 months ago for my car and both were much better afterwards.



Lynall

 

[Xtractorfan]

It is amazing what some of these machines can do, I remember a bodyshop guy telling me that their new oven could bake paint so hard that you couldnt scratch it with a screwdriver.....A properly straigtened chassis leg on any quality bench will be within manufacturers tolerences.. Tho the car will be weaker as a result..

But it is good that equipment is now getting more sophisticated and can point to the problem areas

How much for a 4 wheel alignment?

 

[LYNALL]

W203 elite £160 incl 2 camber bolts
W210 wheels in motion £145 incl 2 bolts



Lynall

 

[Rory]

Yet on the drive through the lanes it is so very much more sure footed and it just feels planted and safe..

I really must make the effort to get down there. Mine seems much better (a lot of the drift left has gone) now it has Michelin Primacy HP's all round but that "planted" feeling that just isn't there. I have no confidence in the car - it feels like it's on its tippy toes all the time.

 

[michaelj]

If you've got a level surface, a piece of string and a spirit level will do everything that their fancy machine can. Plus you have the re-assurance that's it's not all dependent on some monkey fresh out of mechanics school.
I wouldn't trust it an inch!

 

[turbopete]

If you've got a level surface, a piece of string and a spirit level will do everything that their fancy machine can. Plus you have the re-assurance that's it's not all dependent on some monkey fresh out of mechanics school.
I wouldn't trust it an inch!

problem is that yes you can check the front and rear toein/out and if youre really sensitive, maybe the camber as well, but using that method, you have no way of telling if th rear is aligned correctly with the front. it makes a huge difference, hence why people say their car feels much more planted after 4wheel alignment! everythngruns truewith not only the opposite side, but with the other axle too!

 

[type49]

If you've got a level surface, a piece of string and a spirit level will do everything that their fancy machine can. Plus you have the re-assurance that's it's not all dependent on some monkey fresh out of mechanics school.
I wouldn't trust it an inch!

So how would you measure caster, camber, KPI, set-back & toe-out on turns with a piece of string. Also, bearing in mind how much you can stretch a long piece of string, how can you even measure the wheelbase to within 1/60th of a degree, which is what these machines (& Mercedes tolerances) are capable of

 

[television]

Thanks for all the info on that firm, only 10 miles from my birthplace.

 

[Number_Cruncher]

It can all be done using old fashioned measuring techniques, spirit level, string, feeler blades, straight edge, telescoping clothes props, scientific calculator, etc, etc. The problem is, that it would take ages.

As an example, to get the camber across a 15" rim correct to within 1 minute of arc, you need to be able to measure;

>> tolerance=(pi/180)*(1/60);
>> hypotenuse=15*25.4e-3;
>> shim=hypotenuse*tolerance

shim =

1.1083e-004

>> shim=hypotenuse*sin(tolerance)

shim =

1.1083e-004

to within 0.1mm, i.e., about 4 thou.

However, I suspect 1 minute tolerances are the exception rather than the rule, with 20 and 30 minutes of arc being much more common, relaxing the required accuracy of the measurement significantly.

 

[michaelj]

So how would you measure caster, camber, KPI, set-back & toe-out on turns with a piece of string. Also, bearing in mind how much you can stretch a long piece of string, how can you even measure the wheelbase to within 1/60th of a degree, which is what these machines (& Mercedes tolerances) are capable of

Well, wheelbase is a linear measurement not an angle so I'd do that with a steel tape measure. As for making sure that the two axles are parallel and not displaced axially, I agree it's a bit more difficult than when one end is rigid but it's just a sort of iterative process: you have to go round a few times.
As for the tolerances involved: I know all the tiny fractions of a degree and minutes of arc sound really impressive but this is only a car, it's not the Hubble telescope (and look how they screwed that up!). As long as your toe-in is zero to a couple of mm you're fine and, as for camber...well look at the angle of the road you're driving on before you get too excited with your feeler gauges. I mean the whole lot is pivoting on a load of rubber bushes...it may have a static position which is vaguely repeatable but I'm sure it doesn't spend much time there when you're actually driving it.
I guess I'm just suggesting a sense of proportion before you spend a lot of money. Sorry, didn't mean to provoke such a reaction! There's a link here to a bit in a book about racing cars where they do it with string.

 

[S.Speed]

"As long as your toe-in is zero to a couple of mm you're fine"....

I have a Gunsons Trackrite which did the above very well indeed..
BUT, it did re align my wheels so that the steering wheel is dead straight when travelling straight.

I can assure all of you that I am NOT a person who "imagines" that it drives better after being tracked up properly..

On a previous statement to this thread there was a comment about space age machinery being operated by monkeys..
I agree with that when it comes to certain high street places but these guys invite you to watch and explain the whole relationship of Camber/caster/toe-in etc..
I asked 101 questions and was totally satisfied with the answers and advice given..
After my car was set up, my steering wheel is in the dead straight position when travelling on a straight road..
If you are happy with your tyre wear and handling then obviously it would be a waste of money..
I only had my car a week and wanted it all set up perfectly as a benchmark.
I took a good friend of mine out the other evening on a drive around some well known swoopy country lanes which are a favourite run for the motorcycling people..He commented on how easily it "just does it" without fuss nor drama..
So if I am imagining the handling to be sure footed and good, then so is he.
The tyres so far aren't showing the characteristics of wear on the outer edges of the fronts nor wearing the centres down on the rears, so I intend to regularly take measurements to note any trends..

On a slightly off topic subject (I can cos this is my post) the worst car I ever owned for eating tyres was a Rover 75.. It was a beautiful looking car and very, very comfortable but I only got 9,000 miles from Front AND REARS.. Keep in mind they are front wheel drive!!
I complained on the Forum I was a member of and was told I was lucky to get that much from tyres on that car..

It puts it into perspective that actually tyre wear on our Mercs isn't really that bad at all.

 

[kth286]

I tend to agree with michaelj that the measurements are to some extent a compromise because it depends how your car is used, and not everyone uses their car the same way.

For example if you were a rep with car laden down with heavy samples/equipement, your camber would be constantly more negative with the lower suspension caused by the heavier load.

Compare that with a car that is nearly always driven with only the driver in it.

The light car would be constantly at different camber angles with higher suspension.

Just a couple of examples.

So, if the the firm doing the geometry were in fact as professional as possible the would definately ask how the car was mainly used and set it up accordingly.

In addition, Mercedes specify a spreader bar is inserted between the front wheels to simulate the actual forces as per the situation when driving. (rear drive cars force the front wheels apart on the move, and the compliance of the rubber bushes allow that to happen, but when a car is static the wheels are not in their normal driven state hence the need for a spreader bar when setting the geometry up).

Was that done ?

 

[Number_Cruncher]

>>how the car was mainly used and set it up accordingly.

They would struggle to do this, because they wouldn't know how the suspension geometry changes as the car moves. They would need a kinematics and compliance rig to measure this, and there a very few of those, and they are in research and development labs, like MIRA, not in back street garages.

 

[wheels-inmotion]

>>how the car was mainly used and set it up accordingly.

They would struggle to do this, because they wouldn't know how the suspension geometry changes as the car moves. They would need a kinematics and compliance rig to measure this, and there a very few of those, and they are in research and development labs, like MIRA, not in back street garages.

For the domestic vehicle we do offer a Kinematic image by applying dynamic stages to the suspensions "compression/droop", with today's software this is hardly rocket science.

As said the manufacturers settings are "suggestions" not law since a global driving experience cannot cover all eventualities or driving styles/ environments.

Do we use a spreader rod?.... no, nor do we add the drivers weight, insist on a full tank of fuel or remove the baby seat.... The variables are endless, what we do, do it listen to the complaint and deal with that.

 

[Number_Cruncher]

>>For the domestic vehicle we do offer a Kinematic image by applying dynamic stages to the suspensions "compression/droop", with today's software this is hardly rocket science.

You'll have to explain that.

>>For the domestic vehicle

You only do this for British vehicles?

>>a Kinematic image

What do you mean by this?

>>by applying dynamic stages to the suspensions "compression/droop"

and this?

>>with today's software this is hardly rocket science.

Software alone can't tell you how a loaded suspension is going to move (unless it's design level software, which I very much doubt will be used outside of manufacturers and research institutes).

No, it's not rocket science, but, it's not everyday practice either.

 

[television]

The will be figures where the car just has a full tank and nothing else. This is what MB base their figures on, as the car does have parameters for standing with just a full tank, at least then we all understand the figures.

Loading the car ?? is hardly a practical thing, I know that I have to weigh myself when going on a flight test, but hardly a practical thing to do on a car

 

[S80]

Some interesting points made

As a slight 'aside', will a vehicle correctly set up for a completely level surface tend to 'fall down' a normally-cambered road surface?

I have had several cars which appear to pull to the left slightly on a narrowish B-road, but will pull to the right if I 'go continental' and drive on the right-hand side of the centre line. Usually it's cars with wide-ish section tyres.

If this is the case, can the geometry be deliberately 'biased' at set-up to compensate for this effect?

 

[Number_Cruncher]

>>will a vehicle correctly set up for a completely level surface tend to 'fall down' a normally-cambered road surface?


Yes

As to whether it should be corrected, I don't think there's a technical right or wrong answer. IMO, you shouldn't correct, as correcting for varying camber is something a driver should expect to do.

 

[S80]

So does continually compensating for road camber affect the uniformity of tyre wear? Particularly if most driving is on single-carriageway roads where the camber is always in the same (kerbwards) direction...