Hydraulic power steering to Electric power steering

dyezak

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Has anyone successfully converted to electric power steering? This pic is a RHD electric steering rack, but they make LHD electric racks too.

Would be a nice addition to a street car, 1/4mi car, or 1/2mi car.

Get rid of the pump, lines, cooler, resivoir, etc. Would make the VTT shotgun setup so much nicer...

s-l1600.jpg
 
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dyezak

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Highly suggest reading the E89 electric steering section from BMW docs. I have it in my repository. Page 78:

https://drive.google.com/open?id=0By3tH5DDjPZPWW5fZWVudzFYZ2s&disco=AAAACBWDadc

Filippo

Interesting read. And the part numbers don't match the e92 ones but the diagrams are the same. Looks like the motor needs a direct 12v lead from the battery (1 wire), a ground (1 wire), a PT-CAN input (2 wires), and a single link into the Junction Box (one wire). There would be some coding obviously.

Since this is on the Z4 35i I think it should clear the water pump which would be my main concern. This would really clean up some stuff in the engine bay.
 

fmorelli

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As a side note, I've been asking around for a while about coding the hydraulic steering but I've not found anyone that has sorted through that. Obviously programmability would be a benefit of hydraulic steering ...

Some Z4 people (@jts1981) opine for a return to hydraulic steering, wanting to convert back. In my experience the steering has both good feel and responsiveness when using a spherical bearing or monoball in the tension strut. YMMV.

Filippo
 

Lurcher

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Some Z4 people (@jts1981) opine for a return to hydraulic steering, wanting to convert back. In my experience the steering has both good feel and responsiveness when using a spherical bearing or monoball in the tension strut. YMMV.

Filippo

In stock form, the just off-axis feel is not as good as a hydraulic unit. I do enjoy the additional assist feeling when just taking it easy - and that's likely what they were aiming with on the Z....
 

fmorelli

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I was hoping, with the later gen cars having gone to EPS that we would see folks figuring out how to program it, and that retrofitting back to E89. @[email protected] is considering EPS for his upcoming E90 track car build - there are nice things about EPS (some noted on this thread): less parasitic engine drag, less crap hanging on the motor, less weight and lower CoG weight, more space, and hypothetically programmable steering assist.

Filippo
 

fmorelli

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That's a tough question. EPS is not better. On center feel goes to hydraulic, but not that I feel the center is vague in any way with EPS. If I could program the EPS it would be a hands down winner (like the difference between throttle cable and throttle by wire). I think we will get to programmable EPS. Like most advancements in BMW, it's a net positive after all the whining. Look at the crying from the normally aspirated crowd when BMW went turbo. Now we just blow them all off the road ...

Filippo
 

jts1981

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Interesting read. And the part numbers don't match the e92 ones but the diagrams are the same. Looks like the motor needs a direct 12v lead from the battery (1 wire), a ground (1 wire), a PT-CAN input (2 wires), and a single link into the Junction Box (one wire). There would be some coding obviously.

Since this is on the Z4 35i I think it should clear the water pump which would be my main concern. This would really clean up some stuff in the engine bay.

So I did a bunch of research on this and found a few people on e9x non M running M3 steering rack and while it worked mechanically I did not find anyone that could get the programming to work, but I could be wrong. I also looked a the 1M since its n54 with M3 rack. I ultimately decided to walk away thinking the project would need custom linkages, modified subframe possibly, and I did not want to go down the sensor rabbit hole.

One note for you. The e89 is a damn unicorn and while things may look like it will swap on paper the reality maybe that a part is slightly different in shape, size, or clearance.

Tread carefully my friend and good luck. I think if you can figure out how to make the swap work, it can probably go both ways.
 
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dyezak

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So I did a bunch of research on this and found a few people on e9x non M running M3 steering rack and while it worked mechanically I did not find anyone that could get the programming to work, but I could be wrong. I also looked a the 1M since its n54 with M3 rack. I ultimately decided to walk away thinking the project would need custom linkages, modified subframe possibly, and I did not want to go down the sensor rabbit hole.

One note for you. The e89 is a damn unicorn and while things may look like it will swap on paper the reality maybe that a part is slightly different in shape, size, or clearance.

Tread carefully my friend and good luck. I think if you can figure out how to make the swap work, it can probably go both ways.

Head over to our drivetrain/handling section here on SpoolStreet. The M3 servotronic swap has been documented and is fully functional. We have also successfully swapped over the full M3 DCT control systems to the 335i.

And yea, the e89 is similar but not the same. And the cheapest EPS rack I can find used is still $600. Not sure if I want to jump into this head first yet like I did with the DCT conversion project. That taught me that retrofits like this (while possible) can be a money pit.
 
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jts1981

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Head over to our drivetrain/handling section here on SpoolStreet. The M3 servotronic swap has been documented and is fully functional. We have also successfully swapped over the full M3 DCT control systems to the 335i.

And yea, the e89 is similar but not the same. And the cheapest EPS rack I can find used is still $600. Not sure if I want to jump into this head first yet like I did with the DCT conversion project. That taught me that retrofits like this (while possible) can be a money pit.

Dude thanks for the heads up! Thats good to know.

After I get my new turbos installed and dialed in I plan to focus on chassis reinforcement(check out "Cidep" bars) and suspension tuning. Hopefully I can get the chassis stiff and responsive enough, and cross my fingers some one will figure out the how to fine tune the steering.

Good luck with your swap!
 
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E89Revolution

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Just food for thought, in current form the VVT double barrel kits needs to be modified to work on E89's as one of the pulley's hits the rack.

Personally after owning several E92's (non M's), and now owning an E89 I personally prefer the feel of the hydraulic power steering. However if you can program a non M DCT with the GTS flash I'm sure you would be able how to flash the EPS as well. And while all of us E89 owners would be eternally grateful I'm not seeing a good ROI for doing the swap.
 
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fmorelli

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Grateful that we could program the E89, is how I read it. I was just hoping the know-how would come out of people figuring out how to program the current gen BMW hydraulic racks.

Filippo
 

jts1981

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Just food for thought, in current form the VVT double barrel kits needs to be modified to work on E89's as one of the pulley's hits the rack.

Personally after owning several E92's (non M's), and now owning an E89 I personally prefer the feel of the hydraulic power steering. However if you can program a non M DCT with the GTS flash I'm sure you would be able how to flash the EPS as well. And while all of us E89 owners would be eternally grateful I'm not seeing a good ROI for doing the swap.

After speaking to someone that actually did the shotgun for e89, and read about it from someone else on this forum I decided not to go that route. Instead I'm going stage 2 warble 525 lpfp and most likely a new FCP hpfp when my current one kicks.

Back to steering, yes, hydraulic is much more satisfying in general with its better road feedback and assist feeling. I'm hoping suspension and chassis stiffening will translate to better overall road feel and responsiveness. I already upgrade upper/ lower control arms, bushings etc, but yet to play with the actual coil over settings.

I agree the ROI for swap is minimal. Another factor was the balance between steering ratio compared to wheel base. I haven't looked into it enough to determine if the car would actually feel too twitchy.

Grateful that we could program the E89, is how I read it. I was just hoping the know-how would come out of people figuring out how to program the current gen BMW hydraulic racks.

Filippo

Do you mean current BMW electric racks?
 
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