Front tyre wear, outside edge

[television]

Not for different wheels but for different springs there are.
.

Yes, due to the angle changing with the height of the car, I wonder how many cars are corrected after changing the rubber pads,, lowering the car by 1" must almost cancel out any caster angle

 

[wheels-inmotion]

Hello everyone.... I have been watching this thread for some time and i felt the need to introduce my thoughts into this topic.

Apologizes for not going though the normal "newbies" area saying "Hi"....so if i have offended "Hi"

Quick explanation why this topic is of interest to me is that my field is chassis dynamics/calibration.

I hope this "my first post" will be of value to members and not perceived as "all knowing", this is not my intention.

To the topic....
The MB owns a unique platform Geometrically, namely it's aggressive use of the castor angle.

The castor angle is the Geometric/mechanical pneumatic trail designed to force stability at the steering at speed.

Additional traits is the relationship of the castor and camber during a turn and this is the area i feel is generating concern in this thread.

Members are correct to display camber positions because they are relative to the level of wear but in the case of the MB is not the criminal.

The castor/camber position amongst other angles controls where the tyres contact patch is transported during a turn.. Basically the cars weight is moved at the tyre footprint as the steering is turned, this migration can be incorrectly transported and generate wear if the castor is correctly positioned.

In an attempt not to complicate this explanation.
As you turn the inner wheels castor extends as the camber migrates from a negative to positive position "accentuated by the degree of lock".

If the castor is to far advanced the migration will include a camber roll where the tyre scrub radius is inboard of the steering pivotal point, meaning the vehicles weight is now retained by the outer tyre sidewall, "conical deformation".

In severe cases the car once on a full lock it will remain there unless the driver makes deliberate attempts to regain Yaw.

In truth a natural camber cannot transport weight to the sidewall, this crimminal can only be the castor or TOOT "Toe-Out-On-Turns".

I hope this helps.

 

[whitenemesis]

Ok, I've this post 4 times and I still can't follow..

But that's why we need specialists. I don't doubt what he says, how can I? I don't understand it!

But there's the problem he knows his stuff, just not how to explain it in terms a numpty like me can grasp

Or is it just me??

 

[Rory]

In truth a natural camber cannot transport weight to the sidewall, this crimminal can only be the castor or TOOT "Toe-Out-On-Turns".

OK, like whitenemesis, I see words but I've little idea about what you mean! I guess a large book could be written on this subject.

What I want to know please is, are these unique Mercedes characteristics (drifting and excess wear on front tyre edges) correctable, or are they things that, to a certain extent, are "features" of the vehicle, that we just have to live with?

 

[Dieselman]

As per Merc's recommendation you should put front to back ON SAME SIDE OF CAR, so rotational issue does not arise.

I have not seen anywhere that Mercedes says swop diagionally - so DO NOT.

They do, but not in the handbook.

Although the fronts have 4mm in the centres, the NSF outer (kerbside) edge was very worn, and in an effort to correct the drift I swapped the fronts over after its last dealer visit a few weeks ago. The Mercedes bulletin on the camber following issue recommends swapping diagonally, but of course I can't do that due to the staggered setup.

 

[c240yaz]

Hello everyone.... I have been watching this thread for some time and i felt the need to introduce my thoughts into this topic.

Apologizes for not going though the normal "newbies" area saying "Hi"....so if i have offended "Hi"

Quick explanation why this topic is of interest to me is that my field is chassis dynamics/calibration.

I hope this "my first post" will be of value to members and not perceived as "all knowing", this is not my intention.

To the topic....
The MB owns a unique platform Geometrically, namely it's aggressive use of the castor angle.

The castor angle is the Geometric/mechanical pneumatic trail designed to force stability at the steering at speed.

Additional traits is the relationship of the castor and camber during a turn and this is the area i feel is generating concern in this thread.

Members are correct to display camber positions because they are relative to the level of wear but in the case of the MB is not the criminal.

The castor/camber position amongst other angles controls where the tyres contact patch is transported during a turn.. Basically the cars weight is moved at the tyre footprint as the steering is turned, this migration can be incorrectly transported and generate wear if the castor is correctly positioned.

In an attempt not to complicate this explanation.
As you turn the inner wheels castor extends as the camber migrates from a negative to positive position "accentuated by the degree of lock".

If the castor is to far advanced the migration will include a camber roll where the tyre scrub radius is inboard of the steering pivotal point, meaning the vehicles weight is now retained by the outer tyre sidewall, "conical deformation".

In severe cases the car once on a full lock it will remain there unless the driver makes deliberate attempts to regain Yaw.

In truth a natural camber cannot transport weight to the sidewall, this crimminal can only be the castor or TOOT "Toe-Out-On-Turns".

I hope this helps.

Your advice on this is literature and very poor. Aye, thats great college stuff, but from hands on experience, unfortunatly, it does not offer all the solutions in the real world.

Some 30 years workshop experience suggests otherwise.

Suggest you get your hands dirty and enter the real, true world. What about a worn suspension joint, knocking everything out on the N/S/F. ?

Google it, if you have to. Yawn. Good value to literature collectors...poor value to hands on enthusiasts.

 

[Bazzle]

Well, I can't put the fronts on the back as they are different sizes and I can't swap the fronts cross ways because they both wear on their outside edges - unless I removed the tyres from the wheels I guess ??

They are michelin piolet primacy - not sure turning the actual tyres is a good idea even if they are non directional - aren't they worn in one direction already ?

With a lot of MB that get the neg camber wear standard it is normal to swap from side to side but by removing from rim to keep rotational wear and to put wear on opp side.

Yours doesnt sound like neg camber wear as it is on the out side but you can still swap tyres over on rims to get some more life.
I agree with the cornering comment earlier too.

Bazzle

 

[wheels-inmotion]

Your advice on this is literature and very poor. Aye, thats great college stuff, but from hands on experience, unfortunatly, it does not offer all the solutions in the real world.

Some 30 years workshop experience suggests otherwise.

Suggest you get your hands dirty and enter the real, true world. What about a worn suspension joint, knocking everything out on the N/S/F. ?

Google it, if you have to. Yawn. Good value to literature collectors...poor value to hands on enthusiasts.

Extremely rude reply to someone trying to assist a member with a problem!!

Your suggestion to get my "hands dirty" is belayed by the fact i have been "hands on" for over 30 years! As for the worn suspension?.... well "Yes" but wouldn't these simple checks be concluded before this thread evolved?

Answer me this hands on question.... What mechanical realm do most cars live in
1erfect
2:Worn
3:Knackered

I believe the answer is 2.

Anyhoo if you feel the need to swat-up on chassis dynamics or evolutionary Geometric calibration try www.wheels-inmotion.co.uk or www.wheels-inmotion.co.uk/forum..... Or better still just "Google it"!

 

[BlackC55]

Intersting post.

I have an interest in wheel alignment. I do not have any equipment at my workshop to do it though. Need to invest in a 4 poster first.

 

[Dieselman]

I thought your place was a garage not a knocking shop...

 

[c240yaz]

Extremely rude reply to someone trying to assist a member with a problem!!

Your suggestion to get my "hands dirty" is belayed by the fact i have been "hands on" for over 30 years! As for the worn suspension?.... well "Yes" but wouldn't these simple checks be concluded before this thread evolved?

Answer me this hands on question.... What mechanical realm do most cars live in
1erfect
2:Worn
3:Knackered

I believe the answer is 2.

Anyhoo if you feel the need to swat-up on chassis dynamics or evolutionary Geometric calibration try www.wheels-inmotion.co.uk or www.wheels-inmotion.co.uk/forum..... Or better still just "Google it"!

Firstly, when many members come on this forum for some basic advice, some have only basic mechanical knowlege and are looking for a quick fix.

I do not believe that they are looking for a lecture on the advanced fundamentals of steering and suspension geometry, which would totally baffle them. If they wished, they can find that out from Google.

"As for the worn suspension?.... well "Yes" but wouldn't these simple checks be concluded before this thread evolved?" I am sure that I mentioned this in post 44,

For answering your 3 questions, I got the answer wrong, I chose 3, knackered. So what a numpty I am. Please make the questions easier next time.

"swat-up on chassis dynamics or evolutionary Geometric calibration try" That will be too technical for some members, maybe me included. Are these the 2 web sites where you get your info ?

And welcome to the forum !!

 

[wheels-inmotion]

Firstly, when many members come on this forum for some basic advice, some have only basic mechanical knowlege and are looking for a quick fix.

I do not believe that they are looking for a lecture on the advanced fundamentals of steering and suspension geometry, which would totally baffle them. If they wished, they can find that out from Google.

"As for the worn suspension?.... well "Yes" but wouldn't these simple checks be concluded before this thread evolved?" I am sure that I mentioned this in post 44,

For answering your 3 questions, I got the answer wrong, I chose 3, knackered. So what a numpty I am. Please make the questions easier next time.

"swat-up on chassis dynamics or evolutionary Geometric calibration try" That will be too technical for some members, maybe me included. Are these the 2 web sites where you get your info ?

And welcome to the forum !!

Since this members problem is Geometric then the reply is unlikely to be an easy read.. For your information my explanation "was" diluted.

You keep mentioning Google as a source for information.... You are missing the point!!... Google doesn't answer back, hence the reason why car clubs/forums collaboration of knowledge is so vital to members.

As for the 2 web sites..... No i don't get my information there... I wrote the information there, since they are both my sites.

Oh and thanks for the welcome.

 

[Bobby Dazzler]

Welcome to the forum Tony

Are these the 2 web sites where you get your info ?

The clue is in Tony's MBClub logon name - compare it to the web address he posted

 

[jaymanek]

Tony thanks for the detailed response,,, understood parts but not all..

are you saying that wear on the inside edges is normal due to the setup that MB employ (to ensure stability at high speeds)

 

[Dieselman]

wheels in motion
Your forum is really interesting. just spent some time reading Alignment....the big con, time to be wise!.
Do Lexus have a particular problem on the IS range with regard to camber setup and is it adjustable.

I felt sorry for the poster that got ripped at Hi-Q and the 'proper' 4 wheel alignment centre.

So back to Mercs. The front end often has caster/camber bolts to make adjustments with, but what can be done if the rears are out on camber.

There are eccentric bushes available but how well do they work in reality?

Mine are fine, just a generic question. I suppose that could apply to fronts as well if the car is lowered.

Any thoughts on a Visualiner pro32 machine. It appears to be measuring 12 angles, or at least that's what's on the printout.

It would be interesting for a few members here with tyre wear or instability issue to have their cars checked at WIM and post back.

anyone..?

 

[Dieselman]

Tony thanks for the detailed response,,, understood parts but not all..

are you saying that wear on the inside edges is normal due to the setup that MB employ (to ensure stability at high speeds)

That's how I read it as well.
Due to the agressive castor angle, designed to give better straight line stability, the wheel will roll under more at tighter steering angles, thus the weight will be supported on the outside edge of the tyre leading to greater wear as a result.

My only query to that is how much of the time is the wheel at steering angles tight enough for this to be an issue.?
Although I note the O-p says they do mainly town work.

Would one solution to have less castor dialled in?

 

[wheels-inmotion]

wheels in motion
Your forum is really interesting. just spent some time reading Alignment....the big con, time to be wise!.
Do Lexus have a particular problem on the IS range with regard to camber setup and is it adjustable.

I felt sorry for the poster that got ripped at Hi-Q and the 'proper' 4 wheel alignment centre.

So back to Mercs. The front end often has caster/camber bolts to make adjustments with, but what can be done if the rears are out on camber.

There are eccentric bushes available but how well do they work in reality?

Mine are fine, just a generic question. I suppose that could apply to fronts as well if the car is lowered.

Any thoughts on a Visualiner pro32 machine. It appears to be measuring 12 angles, or at least that's what's on the printout.

It would be interesting for a few members here with tyre wear or instability issue to have their cars checked at WIM and post back.

anyone..?

The situation with Lexus is that they wrote the wrong Geometry calibration for the IS200/300/sc in the UK....I re-wrote the calibration for UK owners but this correction was to late for Lexus to confess to without huge liabilities.

Back to Merc
The Y2000+ models do not have front OEM camber/castor adjusters fitted. The aftermarket "corrector" bolts are..... well they are pants in the adjustment range offered compared to the -Y2000 off-set D-cam adjusters.

The lowered position at the rear is not of concern since the cambers position is complementary to handling.... What is of concern is how to balance this at the steer axis.

The 3D visualigner is a superb machine but redundant already?.. I use the Hunter HD system and the "modified car" software side-by-side. This is unique to the UK and delivers over 30 pages or 130 angles, sprung and unsprung.

"Alignment the big con" is a paper i wrote some years ago.... Many members in many forums found this useful, you are welcome to "cut/paste" this paper.

 

[merc07]

How did I mis that slanging match?Anyhow, my problem is not due to suspension wear, unless they fitted worn parts in the factory - it has been like it from new.I have the car booked in with wheels in motion on Friday, I'll report back after. Hope I'm not charged a fortune for the 'pants' aftermarket adjusters Tony ! Cheers, Adam

 

[wheels-inmotion]

How did I mis that slanging match?Anyhow, my problem is not due to suspension wear, unless they fitted worn parts in the factory - it has been like it from new.I have the car booked in with wheels in motion on Friday, I'll report back after. Hope I'm not charged a fortune for the 'pants' aftermarket adjusters Tony ! Cheers, Adam

I didn't design the adjusters.... I would re-design them for sure!!!!

The frustrating thing in the realm of MB calibration is that you are held in the hands of "compromise".... This is not end-of-days but can deny a surgical calibration.

 

[Dieselman]

Any chance of a write up on this, maybe a pic or two as I'm very interested to see how it goes.

I realise WIM is a commercial business so may not want any trade secrets or working prctices to be revealed.