Steering issue please help

[Andy93]

Hello guys, on my Mercedes 190e I have this weird issue that is kind of hard to describe, but I will try my best. The steering wheel does not return to center normally after a corner. The front suspension is Mc Pherson.

When I turn my wheel half a turn (180 degrees) it will come back to center, but very reluctantly, and not allways all the way.

When I turn 3/4 of a turn (270 degrees) it wont return at all.

When I turn one whole rotation or more, it will go to full lock by itself. The more speed I have, the faster it turns, just like if it was going to center, but the opposite.

There is no binding of any sort, the steering is not overly heavy while turning while stationary, so the pump is working. There is no jerking, the wheels wont turn by themselves while stationary. Which probably means the steering box is not the issue.

When I am backing up, the steering wheel wants to center itself. Which is sort of like my caster is completely backwards. There is also no pulling to side while going strai even on bumps at speeds of 120kmh or more.

So all of it points to alignment issues. However, the car is freshly aligned,
0 toe
-2,1 degree camber
9,5 degree caster

ALL of the suspension bushings and joints are new. Steering fluid and filter are also new. New brakes up front, new fluid also. All 4 wheel bearings are new. The bushing are polyurethane, the car has been lowered slightly by previous owner, the spring and struts are shorter. I have put on new camber plates on top of struts, but the issue at hand was there before this. The tires are old and worn out, but I cant imagine them causing issue like this. I dont want to put on expensive new tires while the problem is there.

I have not seen anything like this before, can anyone please help?

[RidingOnRailz]

Originally Posted by Andy93

Hello guys, on my Mercedes 190e I have this weird issue that is kind of hard to describe, but I will try my best. The steering wheel does not return to center normally after a corner. The front suspension is Mc Pherson.

When I turn my wheel half a turn (180 degrees) it will come back to center, but very reluctantly, and not allways all the way.

When I turn 3/4 of a turn (270 degrees) it wont return at all.

When I turn one whole rotation or more, it will go to full lock by itself. The more speed I have, the faster it turns, just like if it was going to center, but the opposite.

There is no binding of any sort, the steering is not overly heavy while turning while stationary, so the pump is working. There is no jerking, the wheels wont turn by themselves while stationary. Which probably means the steering box is not the issue.

When I am backing up, the steering wheel wants to center itself. Which is sort of like my caster is completely backwards. There is also no pulling to side while going strai even on bumps at speeds of 120kmh or more.

So all of it points to alignment issues. However, the car is freshly aligned,
0 toe
-2,1 degree camber
9,5 degree caster

ALL of the suspension bushings and joints are new. Steering fluid and filter are also new. New brakes up front, new fluid also. All 4 wheel bearings are new. The bushing are polyurethane, the car has been lowered slightly by previous owner, the spring and struts are shorter. I have put on new camber plates on top of struts, but the issue at hand was there before this. The tires are old and worn out, but I cant imagine them causing issue like this. I dont want to put on expensive new tires while the problem is there.

I have not seen anything like this before, can anyone please help?

The most glaring issue i see is modifications to the car's ride height. New Camber plates, other mods.

Secondarily, are the tires and wheels the original equipment size?

If so, worn out or not, is the correct (vehicle recommended) cold tire pressure being maintained in them?

With 9.5deg of caster, there should be no self-aligning/centering issues of note.

[Andy93]

Originally Posted by RidingOnRailz

The most glaring issue i see is modifications to the car's ride height. New Camber plates, other mods.

Secondarily, are the tires and wheels the original equipment size?

If so, worn out or not, is the correct (vehicle recommended) cold tire pressure being maintained in them?

With 9.5deg of caster, there should be no self-aligning/centering issues of note.

Yeah, the mods obviously have some effect on the car, but it should be ok regardless, if my alignemnt is ok, shouldnt it? Many people modify their cars for track, and I want to use mine in slalom/autocross competituons and on racetracks.

Wheels are a tiny bit smaller, that should also not have such a dramatuc effect. Tire pressures are ok. Tested with 2.0 - 2.6 bars. No significant change.

[RidingOnRailz]

Originally Posted by Andy93

Yeah, the mods obviously have some effect on the car, but it should be ok regardless, if my alignemnt
is ok, shouldnt it? Many people modify their cars for track, and I want to use mine in slalom/autocross
competituons and on racetracks.

Wheels are a tiny bit smaller, that should also not have such a dramatuc effect. Tire pressures are ok.
Tested with 2.0 - 2.6 bars. No significant change.

Unfortunately, such mods as you listed will affect self-aligning torque, and other handling characteristics, of the car.

Facts are, the car's suspension has been modified. From the factory, the steering probably self centered from turns just fine.

[Andy93]

Well that would be a GIANT pain in the butt, to remove all the mods and find out which of them is causing issues, doong alignment after every change, not even talking about the fact that without these mods, the car is not that attractive to me anymore, since I want it for racing. So you might be right, but oh boy do I hope you are not

[RidingOnRailz]

Originally Posted by Andy93

Well that would be a GIANT pain in the butt, to remove all the mods and find out which
of them is causing issues, doong alignment after every change, not even talking about
the fact that without these mods, the car is not that attractive to me anymore, since I
want it for racing. So you might be right, but oh boy do I hope you are not

I'm probably the most boring, OEM individual you'll ever meet regarding cars, and there's a reason for that:

I'm not the one with the engineering degree, and the experience in the design of suspension and other aspects of a vehicle's handling and drivability. Therefore, I don't consider myself to have the authority to make modifications to those, or other components. I wouldn't consider even changing something as benign as the wheel and tire sizes. Something the vast majority of drivers do for looks, and not for any real performance benefit.

I often find that a car handles just fine, as long as factory wheel alignment and OEM tire pressures are maintained, and the vehicle is not pushed to its safe handling limits or beyond.

And you just said it: you performed some of the mods to make it "more attractive" looking. Well, in the automotive world, sometimes, what is done for "looks" doesn't always benefit, and can sometimes negatively impact, the (safe) drivability of a vehicle.

[Andy93]

I meant attractive as in likeability. Every mod I have done was for performance. The alignment I got was custom, also for the best results on track. Many people build their cars, and it is about fun and learning, nobody gets everything right on the first try. And if others can make their 190e handle better, I am sure I can do it too, eventually.

But this problem is just puzzling to me, counterintuitive as hell. Alignment sheet and new joints and parts should all be in my favour, and the steering wheel should be returning to center position, yet the opposite is true.

Anyway, I respect your style, and I really hope thanks to you and folks like you there will be more and more classic and awesome cars saved in pristine and original condition.

But back to the issue, if anyone has any idea, I am open to them. Best from someone with racecar suspension experience . If I ever find out the problem, I will post what I found. Cheers

[RidingOnRailz]

Originally Posted by Andy93

I meant attractive as in likeability. Every mod I have done was for performance. The alignment I got was custom, also for the best results on track. Many people build their cars, and it is about fun and learning, nobody gets everything right on the first try. And if others can make their 190e handle better, I am sure I can do it too, eventually.

But this problem is just puzzling to me, counterintuitive as hell. Alignment sheet and new joints and parts should all be in my favour, and the steering wheel should be returning to center position, yet the opposite is true.

Anyway, I respect your style, and I really hope thanks to you and folks like you there will be more and more classic and awesome cars saved in pristine and original condition.

But back to the issue, if anyone has any idea, I am open to them. Best from someone with racecar suspension experience . If I ever find out the problem, I will post what I found. Cheers

Here's an early Christmas present for ya, I'm not sure what year your 190e is:

Spec screen shows up around halfway through the video:

https://www.youtube.com/watch?v=WANUY-eRY0I

What stuck out to me was the negative camber spec: -0.33 degrees. As I recall you stated you were running -2.01, I presume to tuck the tires in due to the lowering.

Sounds to me like you need to raise that car back up and stand those front wheels back up a bit. At least to -0.5.

You also said the wheels weren't centering that well even before your mods. You need to check your regular load tire pressures, and set them that way, cold, the next morning. Were you running the original wheel & tire sizes before the modifications?

A chronological timeline of everything you did to the car after buying it might clue us in as to when the car lost its self-aligning torque, and what might have caused that.

[CapriRacer]

Just a thought:

Could the lowered suspension have changed where the contact patch is relative to the kingpin inclination angle? If it has moved forward, especially if it has moved ahead, that might affect how strongly the return force is.

[Andy93]

Originally Posted by CapriRacer

Just a thought:

Could the lowered suspension have changed where the contact patch is relative to the kingpin inclination angle? If it has moved forward, especially if it has moved ahead, that might affect how strongly the return force is.

I was going to write that kingpin angle is fixed by the hub assembly, and as I was writing it down, I realized there are different shocks in place. As I said, they were installed by the previous owner, and I do not have original shocks to compare mounting points. I will try to google some images. Other question is if it can have such a dramatic effect.



Thanks for the tip, I will definitely explore this

[RidingOnRailz]

Originally Posted by Andy93

I was going to write that kingpin angle is fixed by the hub assembly, and as I was writing it down, I realized there are different shocks in place. As I said, they were installed by the previous owner, and I do not have original shocks to compare mounting points. I will try to google some images. Other question is if it can have such a dramatic effect.



Thanks for the tip, I will definitely explore this

Ahh yes, the kingpin/SAI angle(both are same thing)!

To quote your original post:

"When I am backing up, the steering wheel wants
to center itself. Which is sort of like my caster is
completely backwards."

This points definitely to something wonky with that SAI.

Left-to-Right SAI unequal by more than 1 degree won't cause a pull going forward, but could cause a pull - or swinging steering wheel - in reverse.


Get that thing to a reputable aligner at your earliest convenience, and have them print a full detailed list of every spec/angle. Then, post a photo of that printout here. Objective, holistic information will help us help you!

It's not just the modifications to that car that's affecting your steering behavior... something might be bent.