I had mentioned I got a used EPS motor to take apart and investigate to see if I could find anything that might be an indicator of what's wrong with my EPS. Obviously the issues with each motor may not be the same, but who knows, maybe I would find something to point me in the right direction. Well, I think I did.
Here is the motor I procured from a guy on FB:
Looks like brand new on the outside. I took the cover off the motor to see if there was any filth in there, but it looked perfect, and spins perfectly too. Could not easily disassemble, seems to be pressed together. I removed the screws for the black module box, but that does not seem to come apart easily either. So moved on to popping off the cover, which is also not really intended to be removed, but since I got this to take apart I went after it with some pry tools.
On closer inspection I see on this motor there are four very thin wire leads that are broken. It would make sense to me that these could be a weak link and cause communication problems with the module, and probably other problems as well.
Everything is sealed in some goopy clear stuff, but it sure looks like these broken wires can easily be repaired. I will need to pull my column and pop the cover off the motor to see if there are similar broken wires. Not sure why no one else has ever checked this out, it seems to be a hole in the internet knowledge base. Will have to wait until winter for me to deal with it though, as I drive the car from time to time and don't want some hulk taking up garage space all summer.
In the meantime, I dropped four hundy on these stupid plastic things. What a rip.
Had to remove the bumper cover again to get at them, but that took about two minutes.
So basically the car is all back together, almost 100%. Need to deal with seatbacks but that is low priority. In the meantime I will drive the thing. I did manage to get it to pass inspection, so no danger of getting pulled over other than the usual.
Regarding your EPS motor electronic circuit board and the 4 broken wires.
Having had a good look at the picture you posted…. I would have to say that they aren’t broken but deliberately “clipped” as the likely hood of 4 wires being broken in exactly the same spot on 4 symmetrical corners is 1 to “infinity”…
Looks to be a deliberate act in the manufacturing process. I wouldn’t be pulling my steering rack based upon this.
If you do have the sticky steering issue, then adjust the “lash” (is that the correct term?) of the gears as per the now BMW repair procedure that was product of German forum members investigation and developed fix.
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Well I had not considered it was intentional but yeah it does seem weird. I attributed it to the fact those wires were the longest. But I gotta pull the column anyway. It's not a sticky steering issue, it is a no power steering issue. EPS light comes on and shows codes for power steering reduction due to temperature. I know the steering module senses temperature and shuts down the power steering assist if it overheats. Mine shuts down immediately upon starting the car, even if it is cold. It will then be intermittent. The EPS light stays illuminated. I have not seen anyone with sticky steering say they have the EPS light on the dash.
It wouldn't surprise me if those 4 broke just from vibrations and etc. Given their location they likely see the most stress from vibrations and the flexing/heat expansion of the unit. The "waviness" of the wires nearest the corners, especially on that left side, looks like the result of the areas being fatigued and stressed; especially when compared to the wires more in the middle which are all relatively straight. Perhaps there is some lateral movement from the motor's torque which transfers into this assembly and over time weakens, then breaks, the leads on the edges.
It would be certainly interesting now to follow this up by dissecting a few more failed units to see if they fail in similar ways and perhaps also dissecting a good unit to see if those corner leads are cut.
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I’m going to stay with deliberately disabled/cut. Just not possible to have the same wires break in four corners without having other wires being damaged via the same mechanism you propose.
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Last edited by clarkitect; 07-31-2022 at 05:37 PM.
Not too late to M62 swap it now... They make kits for physical fitment and the wiring is very simple
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Yeah this thread would be a lot cooler if I did that swap. The engine I had for it turned out to be a really good one too but is now in another E38 so would need to find one along with a 6-speed. Kinda bored with the car now so maybe need a new project such as that. Still need to fix the steering though I would convert to hydraulic in an M62 scenario.
I think the biggest issue would be the exhaust, the fabrication of which would need to be farmed out due to the absence of welding skills in me.
A Z4M exhaust would likely work just fine since the S54 made more power than the M62
Not sure how the M exhaust fits on non-M's though...
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Wow, great build thread, someone really drove her into the ground, you've done fantastic work.
I have pretty much the same thing to 2008 Z4MC, https://www.zpost.com/forums/showthread.php?t=1910373
Mine wasn't in anywhere near the condition of yours but I replaced every wearable part anyway.
Thanks
What a save! Great work!
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