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      12-28-2020, 05:48 AM   #1
Neg89
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Exclamation Unique severe handling stability issue

Hello.
I have 2011 35i,

Almost a year i have been tracing down severe handling issue. Spent days on reading every post about suspension and handling.

Issue description.

The faster u go the worse it gets. Say you drove 70+km/h or faster. You snatch the steering wheel fast to one side. Cars front end starts to wiggle left,right left to level where it feels that the shake would never settle down. U can actually see the steering wheel oscilating left,right,left.
If snatch the steering wheel not so hard then the front of car shakes left,right,left and stops after some movements.

Steering feels rubbery,suspension is now stiff as rock, but steering is not. It feels so unstable its nightmare to drive fast. Slow response,then overresponse, then need to compensate, then compensate another way.
None of my cars did it , before had e85 which was not stable car at all, but much more stable than this.
Interesting that all the time i drive`d and tested car with dsc and other stuff completely off. But once testen in normal mode i fell the car is more stable (but far from normal), after switching to sport or sport+ all gets worse.

What has been tested so far=
Alignment done at least 5 times,no change.
Swapped the wheels n tires for test from identical car , no change.
Changed dampers front and rear (same springs), stiff as concrete but no luck, maybe even worse.
Changed front strut bearings, no change
Disconnected font stabilizer , no culprit.
Swapped EPS, no luck.
Changed EPS parameters, no culprit.
Added strut brace, no difference.
Checked steering shaft u joints, seems no play.
Every known bushing,bearing tested in at least 5 shops and by myself.

Setup. Front control arms from m3,sway bars H&R, poly RTABS, new 235/265 tires. Eibach sport springs (- aprox 10mm ), Big brakes front and rear , engine ~500hp.

Help would be very welcome. I have no ideas anymore.
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      01-01-2021, 10:57 PM   #2
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are your tires the same all around? I put on new rear tires of the same brand and i had all kinds of problems. Bad handling abs keeps going off. Lack of power. The car wanted 4 new tires of same tread depth. All problems went away
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      01-02-2021, 03:34 AM   #3
Neg89
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Thank you for your reply. But as mentioend a changed not only tires but also fitted different rims from differnent e89. "And nothing gets better.
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      01-02-2021, 03:36 PM   #4
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Quote:
Originally Posted by Neg89 View Post
Thank you for your reply. But as mentioend a changed not only tires but also fitted different rims from differnent e89. "And nothing gets better.
Have you looked at logging the EPS signals for any clues?

Try loading up INPA and see if there is any usable sensor or load information available. If there is, you could use Test-O to log the event. Maybe find a useful clue. Testo can log just about anything INPA can display.
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      01-04-2021, 01:27 AM   #5
Neg89
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Quote:
Originally Posted by rjahl View Post
Have you looked at logging the EPS signals for any clues?

Try loading up INPA and see if there is any usable sensor or load information available. If there is, you could use Test-O to log the event. Maybe find a useful clue. Testo can log just about anything INPA can display.

No i have not done that. Dou you mean logging while driving? Like input/output signals from different modules?

I have only looked at live data parameters which was availible from Protool app.
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      01-04-2021, 09:39 AM   #6
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With all the work you've done, swapping in a BBK front and rear, m3 control arms, poly bushings etc, is where I would start. Something that is rotating is not rotating correctly. Get it up on the lift and give it some gas, check the rear wheels while they are up in the air for an abnormal movement. Check the wheel bearings.

It could also be that the poly RTABs are just that stiff and transfer every road imperfection into the steering wheel. Without a video, it's hard to tell how bad the problem is.
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      01-04-2021, 10:17 AM   #7
Neg89
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?

With big brakes which are BMW oem but from m4, i have more than 5.000km done. That`s including agressive alpine sessions where standart ones would actually ignite. The same problem was with standart brakes also.

Nothing wrong with brakes. I can check bearings,sure , but i assume that after checking them myself, MOT ,and 5 different shops, they are fine and if they were not some of involved would actually find them being bad.

Poly RTABS just pulled out. They are not stiff at all, will put in new oem e89 rtabs, to rule out next thing.

Everytning is bolted,nothing loose.No control messages,no codes. But steers like shit at speed.

Could it be springs too hard,shocks too hard. There is not much to change , except body itself.


One of the most recent "inteligence" is the fact that , in normal mode stability is much better than in dcsoff or any sort modes. And no, i am not going sideways and not noticing this. For tests i drive in best,plain,super grinder asphalt. So no slinding, no dcs flashing no, abs kicking in. Those all kickin in i can feel instantly,but they are not engaging, because i am riding within limits of traction.



There is that "not connected" feel. Not sharp handling, like some of the steering components is from rubber. In worst situation Left,right,left,right steering wheel movements can be observed ,when at speed and jerk the steering wheel one side or another and let it go on its own.

The situation is better when hard on gas,the harder ,the better.
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      01-04-2021, 11:39 AM   #8
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I wonder of something else besides the end joints has happened to the steering rack??
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      01-04-2021, 12:23 PM   #9
Neg89
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What you men? I disassembled it and get back together 2x. Now it is different rack with original motor. Why? Because tryd many combos ant actually nothing changed. Before that i was about 99% sure it will be rack, but it seems that it is not. Even went to dealer to upgrade modules,but there is nothing upgradable to EPS ,i have been told.

When car is on air, there is not the slightest freeplay anywhere. I doubt there is any binding , because i have done more than 20.000km with this issue. The one who will find the cause will win Nobel for sure.
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      01-04-2021, 12:54 PM   #10
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Quote:
Originally Posted by Neg89 View Post
What you men? I disassembled it and get back together 2x. Now it is different rack with original motor. Why? Because tryd many combos ant actually nothing changed. Before that i was about 99% sure it will be rack, but it seems that it is not. Even went to dealer to upgrade modules,but there is nothing upgradable to EPS ,i have been told.

When car is on air, there is not the slightest freeplay anywhere. I doubt there is any binding , because i have done more than 20.000km with this issue. The one who will find the cause will win Nobel for sure.
Sounds like a great episode for Car Talk with Click and Clack!
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      01-04-2021, 12:57 PM   #11
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Not funny at all.
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      01-04-2021, 01:53 PM   #12
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Quote:
Originally Posted by Neg89 View Post
Not funny at all.
Sorry was not trying to offend you.
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      01-20-2021, 03:11 AM   #13
Neg89
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Owners chime in

Asking for test.

Would be great if few of members will do little test for me.

It is prefferable to test with window down or door open so that you can stand next to car and observe front wheels.

If you turn the steering whell from center position to left/right when the engine is OFF and wheels ar on the ground.

Doy you feel the same that I feel. So the first inch either direction is elastic , I can feel resistance but also feel that something is compressing or wisting, After this inch I feel direct connection to wheels and I can see that the wheels move.
The feel is like you are compressing heavy spring and when coils are compressed together you can feel that there is this direct connection (the more you turn the more wheels react). But this first inch no matter which direction feels non connected directly but with that “compressing spring” feel.


So . Engine OFF, wheels ON ground.


Would be great if I hear from you.
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      02-05-2021, 05:39 AM   #14
Neg89
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After 0 persons responded.I learned that twist mentioned above is torsion bar. Anyway i need person who can solve this mystery.Please chime i or direst me to one .

To be clear.Torsion bar inside EPS. With engine ON, there is no free play if turning the steering and observing front wheel movement.

Last edited by Neg89; 02-09-2021 at 03:33 PM..
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      02-09-2021, 02:23 PM   #15
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Quote:
Originally Posted by Neg89 View Post
Hello.
poly RTABS,.
??


Any video of the issue happening?
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      02-09-2021, 03:30 PM   #16
Neg89
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Quote:
Originally Posted by Lurcher View Post
??Any video of the issue happening?
No video recorded and now it is snow outside,no way to do it 2+months.

I think i described the issue that it is understandable.


So, after sharp steering input to any side ,car starts rocking from one direction to another multiple times, even to level that it continue forever.The wheels are not skidding.The feel and movements of steering wheel is very similar to superbike or naked motorcycle front wheel wobble, but at much slower rate. Like someone turning the st wheel to ride slalom between cones which are set 5meters from each other.

updated info
What has been tested so far=
Alignment done at least 5 times,no change.
Swapped the wheels n tires for test from identical car but other wheels , no change.
Changed dampers front and rear (same springs), stiff as concrete but no luck, maybe even worse.(actually rear dampers changed, front bilstein b6 are customized at suspension shop)
Changed front strut bearings, no change
Disconnected font stabilizer , no positive change.
Swapped EPS, no luck.
Changed EPS parameters, no culprit.
Added strut brace, no difference.
Checked steering shaft u joints, seems no play.
Every known bushing,bearing tested in at least 5 shops and by myself
The front rims are 8.5 with 235 tire, and ET is exactly 29, as OEM 8"is.
(But maybe,maybe the car seemed less bad with 225tire,albeit far from normal.)

Setup. Front control arms from m3,sway bars H&R, poly RTABS changed to OEM not tested yet, new 235/265 tires. Eibach sport springs (- aprox 10mm ), Big brakes front and rear .


I think this must be included as well


One of the most recent "inteligence" is the fact that , in normal mode stability is much better than in dsc off or any sort modes. And no, i am not going sideways and not noticing this.


The car is more stable when hard on gas (less weight on front axle). The feel is that torsion bar inside the EPS is twisting too much,but it is hard to believe.Also i changed the rack with another,and also switched eps motors.The same. It feels that car needs the steering damper. Yesterday i started to think that the happening can bet wheels turning back from turned too quickly and overcompensate themselves, then again overcompensate and so on. I found interesting part on this material page 99.This is very similar to what is happening. https://e89.zpost.com/forums/attachm...6&d=1337384167

Last edited by Neg89; 02-10-2021 at 03:06 AM..
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      02-11-2021, 02:52 PM   #17
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what are poly RTABS?
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      02-11-2021, 03:00 PM   #18
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ABS issue possibly causing a brake on one side to engage?

No codes at all after this happens?

Regardless, 2 months to figure out what to check before you can test. May want bimmer post this board on another dot more technical com forum. Filippo may be some help
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      02-12-2021, 05:15 AM   #19
Neg89
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Quote:
Originally Posted by Lurcher View Post
ABS issue possibly causing a brake on one side to engage?

No codes at all after this happens?

Regardless, 2 months to figure out what to check before you can test. May want bimmer post this board on another dot more technical com forum. Filippo may be some help

No codes. The ABS issue is unlikely to be true. After understanding that in sport and dcs off modes issue is much more dramatic i am concerned about EPS again , Maybe something is wrong with parameters or EPS "motor/module" part and not rack itself. Also thinked about lateral sensors etc. But looked a data, seems normal to me at first sight. Car does not think that i am moving if i am not at least, not tested while driwing yet. So, if the steering is much more stable in NORMAL mode, then there must be some "software" connection between these changes. Maybe EPS active damping is working in NORMAL but not working in DSC off and SPORT. Very confusing. I can not find anythyng about this issue on web and in wehicle description.

Plese refer me in PM to those other two dot com places, as i cant figure which they are.
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      02-13-2021, 06:37 AM   #20
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Has the steering motor been reset. Looks like it's hunting for neutral but can't find it.
From service manual;

"Particularly at high speeds, unintentional jerky movements of the steering wheel
by the driver have a negative effect on vehicle handling stability. So-called
"snatching" of the steering wheel can, under certain circumstances, cause the
vehicle to start rocking, which can lead to snaking and the driver ultimately
losing control of the vehicle if corrective action is not taken quickly enough.
The EPS detects such steering input and operates the electric motor so as to
substantially damp the movements, particularly at high speeds. As a result,
vehicle rocking is prevented."
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      02-13-2021, 09:23 AM   #21
Neg89
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Quote:
Originally Posted by bigendbob View Post
Has the steering motor been reset. Looks like it's hunting for neutral but can't find it.
From service manual;

"Particularly at high speeds, unintentional jerky movements of the steering wheel
by the driver have a negative effect on vehicle handling stability. So-called
"snatching" of the steering wheel can, under certain circumstances, cause the
vehicle to start rocking, which can lead to snaking and the driver ultimately
losing control of the vehicle if corrective action is not taken quickly enough.
The EPS detects such steering input and operates the electric motor so as to
substantially damp the movements, particularly at high speeds. As a result,
vehicle rocking is prevented."
I am not sure about this,but this was on my mind . I cant find clear information about, whether the motor position sensor "self centers" after each car startup using steering angle sensor as reference or it has to be reset and set using programming tools. I am now trying to install ISTA to perform those checks. Alternative software seems too complicate for me, because no instructions what parameter is what and whatnot. I can tell that steering always self centers on slow speeds, but i have never feeled nothing electric like. self centering,dampening,active return to center which is mentioned in manual. I do not know if anyone else have feel that.

E89 is not rocket, few arms,bearings. But form day two i always knew something is not right with steering. Before this got e85, also with EPS. That steered with no complaints.
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      03-01-2021, 09:54 AM   #22
Neg89
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Hi. Tested today. No difference from last time.

I have tried many different EPS parameter change with PROTOOL.

While i can feel there is some difference in steering weight, that unstable thing was still present. Even disabled eps at all and car is not stable as it should (the steering input without eps is limited).

As before, driving in NORMAL is better, than SPORT,SPORT+ OR DSC OFF.

Also when accelerating heavy , the car is more stable. This leads me think there is problem with front end.
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