MB pulling problems, reason/ solution

wheels-inmotion

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With over 30yrs experience within the realm of chassis calibration and Pro-Drive accreditation i feel qualified to offer a voice on this habitual problem some MB's have.

The pull left is "NOT" a design feature intended to save the driver from hitting the barrier in the event he falls asleep. Personally i would prefer to hit the barrier on the right than the tree on the left.

So what's the problem?
The MB has a unique chassis calibration that performs in a executive level as well as a performance level. This remarkable tuning enables the cars to perform beyond expectation but there is a flaw, not in the car but in it's environment namely the road crown.

Some rules
If you have a pull you need to remove any mechanical defects, shocks, coils (front and rear) bushings an so on.

Tyres
The most common reason for a pull is the tyres, this i can explain why in another thread maybe but for now a simple test to see if the reason is the tyres is to move the fronts side-to-side, if the pull stops or changes direction then you have your criminal.

The chassis
The MB chassis is adjustable, the reason for this is over time MB knew the positions would move so we have the opportunity to correct the angles by either adjusting the pre-installed cams or fitting MB adjuster bolts.

The problem
Assuming all the above parameters have been met but the car is still pulling then the chassis needs to be calibrated. The problem is not the actual angles, it's the difference between them? Each angle offers particular forces and it's these forces we need to use to belay the pull.

The forces
Camber: This angle is conically compressive, deforming the tyres sidewall encouraging the tyre to roll into the cars centre. note this angle has many other duties but the conical effect is the one we are interested in now.

Castor: This angle offers directional stability, steering feel, weight and return. note this angle has many other duties but directional stability is the one we are interested in now.

Solution
Having met all the mechanical, pneumatic requirements now is the time to addresses the chassis positions.

Taken from a "non-distressed" chassis the procedure would be.
Camber
NSF: Increase: not recommended
OSF: Decrease: recommended
Castor
NSF: Increase: not recommended
OSF: Decrease: recommended.

I hope this thread adds some insight to this problem for members.
Regards
Tony@ wim
 

Miffy

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thanks for a good write up on our possible pulling issues
 

turbopete

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maybe i need my chasssis calibrated! its me, not the car that has problems with pulling! :Oops::Oops::Oops::Oops::Oops:
 

cleverdicky

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There are still TWO more issues to address.
While its great that adjustments are available (I became aware and came to appreciate recently) this benefit on my car. Which led to my awareness of these other two 'serious' issues.
One is a very limited professional service needed to measure, asses and adjust all these options. Taking advantage of the design features on the car is dependent on the equipment available to do it. While many tyre / garages / dealers are able to measure / adjust simple Toe-in (tracking) few are able do camber, rear or 4 wheel alignment.
The second is the experience / training / Mood? of the operator of the advanced equipment to do it well.

As I found out recently, no point having the services of a 70,000 pound camera assisted state of the art Hunter
http://www.hunter.com/pub/product/alignmentsystems/5384-T/index.htmalignment system if the guy doing it is a jealous knob who doesn't even know which direction a nut should tighten.
I still cant even get them to manage to get the steering wheel in the correct position in a straight line, never mind the tyres. And sadly I know of nowhere else even willing to 'have a go'

If anyone knows the secret passwords or garage 'tek' speak that is needed, i.e. rim ram roo, please advise.
 
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television

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Thank you for the write up,,, the 129 and 230 has never had any problem with the steering
 

dougjoy

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My 210 was pulling quite noticably until recently. All I did was renew my front tyres, renew the inner and outer track rods, renew the drop links and new front shockers. I also changed the power steering fluid. it now only pulls when there is a noticable camber in the road. God knows what bits did it, but it worked.

The most noticable change was with the inner track rods, any steering play disappeared.
 
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wheels-inmotion

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There are still TWO more issues to address.
While its great that adjustments are available (I became aware and came to appreciate recently) this benefit on my car. Which led to my awareness of these other two 'serious' issues.
One is a very limited professional service needed to measure, asses and adjust all these options. Taking advantage of the design features on the car is dependent on the equipment available to do it. While many tyre / garages / dealers are able to measure / adjust simple Toe-in (tracking) few are able do camber, rear or 4 wheel alignment.
The second is the experience / training / Mood? of the operator of the advanced equipment to do it well.

As I found out recently, no point having the services of a 70,000 pound camera assisted state of the art Hunter
http://www.hunter.com/pub/product/alignmentsystems/5384-T/index.htmalignment system if the guy doing it is a jealous knob who doesn't even know which direction a nut should tighten.
I still cant even get them to manage to get the steering wheel in the correct position in a straight line, never mind the tyres. And sadly I know of nowhere else even willing to 'have a go'

If anyone knows the secret passwords or garage 'tek' speak that is needed, i.e. rim ram roo, please advise.

I totally agree and sympathise to your observations, it's crystal clear fast-fit don't understand their own industry when it come to chassis calibration.... A simple test would be to ask the technician "front wheel alignment, what are you aligning the wheels to?" if the answer is anything other than the thrust angle then your in the wrong place.
 
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wheels-inmotion

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Thank you for the write up,,, the 129 and 230 has never had any problem with the steering

Just goes to prove the drift is "not" a design feature then, don't you agree.
 

rf065

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Just goes to prove the drift is "not" a design feature then, don't you agree.

I agree, but would I benefit from your expertise?

My car pulls slightly to the left most of the time, except when on the wrong side of the road when it pulls to the right, so obviously it is following the camber of the road.

It also appears to stop pulling to the left when I remove the summer tyres & fit the winter tyres. Both sets of tyres wear pretty much evenly across the tread, so the alignment must be reasonably close to spec.

The slight pull left is annoying on a long journey though, so in your expert opinion, is it worth a visit or should I just change the tyres?

Russ
 
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wheels-inmotion

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I agree, but would I benefit from your expertise?

My car pulls slightly to the left most of the time, except when on the wrong side of the road when it pulls to the right, so obviously it is following the camber of the road.

It also appears to stop pulling to the left when I remove the summer tyres & fit the winter tyres. Both sets of tyres wear pretty much evenly across the tread, so the alignment must be reasonably close to spec.

The slight pull left is annoying on a long journey though, so in your expert opinion, is it worth a visit or should I just change the tyres?

Russ
Your problem is pneumatic drift, nothing to do with the chassis so there's nothing of value i could calibrate.

Pneumatic drift is very common, maybe i should explain this in another thread.
 

Xtractorfan

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The above write up applies to all modern day cars...
as already mentioned biggest problem is the people who operate these 'magic' computerised tracking machines..

One other very big problem...when fitting new arms and bushings, many people including mechanics fully tighten the bolts whilst the suspension is still hanging...never a good idea as bushes etc need to be centralised and not under strain when the car is back down on its wheels..
 

rf065

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Your problem is pneumatic drift, nothing to do with the chassis so there's nothing of value i could calibrate.

Pneumatic drift is very common, maybe i should explain this in another thread.

Sounds interesting, please do.

Russ
 

MSG2004

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MB C Class 180k Se Auto Avtg Saloon.
Good post!

I had masses of probs with my first W203 iKW27 225/50 R16 96V XL 2004. gators or bushes changed did help. Bt when I had my front tyres changed the tyre fitter took about 30 minsto balance the passever side front tyre with hiden weights. He told me the wheel wheel was diff to balance as it was not 100%. That did the trick andstpped the outside of the tyre wearinf excessively.
Changed to a 2007 W203 last year - Atvg model, much better all round - bit of excessive wearon the o/s edges on both front tyres - will have tyres removed from rims and r-fitted other way round as they are non-directional.
 

S.Speed

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I can thoroughly recommend Wheels in Motion.
When I first bought my car (18000 miles ago) I had them sort out the pull to the left..
I was told that as Mercs go mine wasn't a bad case but it still needed the rear passenger side tracking altering as well as the front.
My drive back from the Wheels in motion workshop was a revelation.
All 4 of my tyres are wearing evenly. I dont have worn shoulders on the front nor do I have worn centres on the rear. All in all I am very satisfied with the set up they did.
P.S They took particular trouble to centre my steering wheel.:D
 
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