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      11-20-2016, 09:49 PM   #1
fmorelli
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Electronic steering improvements?

Anyone know if it can be done? Heavier feel would be nice, less assist. My turn-in improved, given strut bar, spherical tension strut bearing, M3 lower arm and H&R front swaybar and springs. But it would be nice to dial back the assist.

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      11-21-2016, 02:12 AM   #2
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I have been able to reprogram the assist on my 535. I suppose it could be similar. Mine is an xi that did not have sport automatic transmission as an option. I retrofitted the transmission controller, reflashed the firmware and then changed the steering assist based on speed.


I can put it on my list of things to look into but no promises.
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      11-21-2016, 08:35 AM   #3
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Thanks for the input. Sounds like you have some experience already ;-).

The E89 Z4's criticisms were its un-sportscar-like behavior, in the face of rival cars in-class and a penchant for BMW continuing to soften its cars. We know how to solve these issues in the suspension department, by reaching in the parts bin. The steering is another issue.

My car is vastly improved in steering response, no doubt due to suspension changes noted in my build thread and mostly sorted out by the many that came before me. I highly recommend the AKG spherical bearing for the tension strut. Easy to press-in, really helps with turn-in response, and I noted no real degradation in driving experience or comfort.

My car is M adaptive. I have not noticed any change in steering behavior moving between the modes. It would make a lot of sense to do so. I started digging around (Google searches) without finding much on this subject, BMW-wise. Though I did find a more generic article: Modifying Electric Power Steering. I did read somewhere that BMW steering assist is pulled off when the car's wheels are coming back off center, from a turn. I've also read that, it seems, there have been updates to the software which have caused improvements. My car is a 2011 build.

It would seem that one could program assist, and that it would take table-based coefficients. In our case, we wish these cars to be sports cars not touring saloons with two doors and a drop top. "Fixing" the steering would be a huge win. :-)

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      11-21-2016, 01:58 PM   #4
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I did a bit of looking and it seems there might be a chance to change this.

At the moment, it looks like the amount of assist between comfort and sport mode is nearly identical (with sport having slightly less assist).

It also looks like there is no variation based on speed. I think an ideal set up would be keep assist about where it is for comfort mode, then set decreasing amount of assist the faster the driving speed in sport mode.

I'll do some more work on it and see how far I can get.
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      11-22-2016, 11:43 AM   #5
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I am really interested in this. The steering feeling in my Z4 sDrive 30i is terrible!

What I hate is the EPS always trying to return-to-center and me fighting with it to drive straight!
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      11-22-2016, 03:57 PM   #6
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Quote:
Originally Posted by BBriner View Post
I am really interested in this. The steering feeling in my Z4 sDrive 30i is terrible!

What I hate is the EPS always trying to return-to-center and me fighting with it to drive straight!
I may be incorrect, but I had understood that EPS is programmed to have minimal if any return steer.

When is the last time you had an alignment?

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      11-22-2016, 06:15 PM   #7
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Working on getting my computer updated. At the moment I am unable to get into the modules properly to see what is possible.
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      11-22-2016, 06:21 PM   #8
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Quote:
Originally Posted by fmorelli View Post
I may be incorrect, but I had understood that EPS is programmed to have minimal if any return steer.

When is the last time you had an alignment?

Filippo
I was under the impression it was designed to have the return to center.
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      11-22-2016, 10:16 PM   #9
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I don't know what revisions or model variances there are across the BMW line.

http://blog.caranddriver.com/bmw-det...ring-equation/

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      11-22-2016, 11:47 PM   #10
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That is a helpful article.

Now I know I can use info from the M3/M4 EPS module to see what we might be able to adapt as our own.

I suspect this return to center is indeed part of our version of the programming and they reserved this bit of upgrade for the later M versions getting EPS.

Can you do a bit a of digging on realoem and look over part numbers for the steering rack of the various models and see what we have common?

every bit of info helps.


Jim
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      11-23-2016, 09:44 AM   #11
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Quote:
Originally Posted by fmorelli View Post
I may be incorrect, but I had understood that EPS is programmed to have minimal if any return steer.

When is the last time you had an alignment?

This document explains the return-to-center in the E89.

http://e89.zpost.com/forums/attachme...6&d=1337384167

Before reading this document I found it the hard way. I removed my steering wheel to have the leather changed and in the process I accidentally messed up with the Steering Wheel Angle sensor. In a nut shell on a straight line the car electronics was "thinking" that I was turning left as the Steering Wheel Angle sensor was indicating I was turning left, the EPS then forces right as part of return-to-center, i.e: the EPS was targeting the "ZERO" position of the Steering Wheel Angle Sensor.
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      01-18-2017, 03:28 PM   #12
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So I finally dug into this a bit more and it is more involved than I care to pursue for the small benefit it may have.

it turns out our EPS module does have some "easy" settings that can be changed such as whether the sport button works or not. Not very useful.

The real helpful settings are hidden in obscure hex codes that will take a lot of trial and error along with the driving testing in between to see what affects what.

Too bad.
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      01-20-2017, 04:05 PM   #13
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Bummer ... appreciate your looking into it. I might be happy with no power steering for 95% of my driving. The other trick is to get some adjustable plates and dial in some caster, if I recall.

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      01-20-2017, 04:07 PM   #14
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Bummer ... appreciate your looking into it. I might be happy with no power steering for 95% of my driving. The other trick is to get some adjustable plates and dial in some caster, if I recall.

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