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Electronic Power Steering?
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Author:  Dan [ Thu Feb 02, 2017 8:03 pm ]
Post subject:  Electronic Power Steering?

I've seen a few folk are converting to electric powered steering (still a hydraulic system). But has anyone tried an electronic power steering system found in a lot (all of?) modern Toyotas?

They seem to only have an rpm and vehicle speed input, along with a switched 12v supply, so relatively easy to wire in, and I assume it will package into the gap under a gt4s dash as there is quite a bit of space under there.

Author:  Davem45r [ Fri Feb 03, 2017 3:51 pm ]
Post subject:  Re: Electronic Power Steering?

The change from the existing mechanically driven hydraulic assist system to an electrically driven version is obviously quite a simple step, you just remove the existing pump and drive mechanism and replace with a suitably positioned and plumbed in electric pump. The rest of the system is entirely unchanged. Hey presto - less parasitic loss.

I believe that there are conversion kits available that work on the 'electronic power steering' system (i.e. all the work is done with an electric motor and no hydraulics involved) but these are aimed at cars with NO power steering at all, and simply splice into the steering column somewhere between the wheel and the rack.

There would seem little point (although I don't see it being impossible to do) in removing all the components of the hydraulic assistance system and then splicing the electric power steering kit into the steering column?

Link to overview of assistance systems: http://www.caranddriver.com/features/electric-vs-hydraulic-steering-a-comprehensive-comparison-test-feature

Link to after market 'electric power steering' systems (aimed at cars which currently have NO assistance system): http://www.ezpowersteering.nl/language/23/2/Home.html

Forum article by someone having the ez system fitted to their Countach (ladyboy!): http://www.ferrarichat.com/forum/lamborghinichat-com-sponsored-cats-exotics/351715-fitting-power-steering-my-countach-qv.html

Just to add I haven't completely read through all those links and have winged my post a bit on stuff I vaguely remember so please feel free to correct if the link material outright contradicts my ramblings :D

Author:  Nibbles [ Sat Feb 04, 2017 1:18 am ]
Post subject:  Re: Electronic Power Steering?

Although you still get steering if hydraulic fluid is removed, I'm not sure how these components would function long term in the absence of fluid. I'm not sure what's involved in removing them and leaving a usable, functioning non pas rack in order to add the fully electric version.

Like Dave, I can see a value in the fairly simple conversion to electric pump, but I'm not sure much more would be gained by going fully electric.

Author:  Dan [ Sun Feb 05, 2017 9:22 am ]
Post subject:  Re: Electronic Power Steering?

Chris, I'm wondering whether the rack could still be left fluid filled to provide lubrication (and cooling?), but with the outlets connected to make it a sealed unit.

The advantage over an electric pump based system would be the space saving (the Saxo etc units that people are using are quite sizeable items), and the removal of fluid filled pipes that seem to have a propensity to leak.

Author:  two_OH_five [ Sun Feb 05, 2017 12:18 pm ]
Post subject:  Re: Electronic Power Steering?

Surely creating a closed loop system doesn't actually solve the problem of leaking as you still have all the pipework, especially if still using a cooler. The only advantage is you remove the pump although that is the most likely component to leak
I also suspect a (small) header tank of some sort would be required otherwise thermal expansion coupled to hydraulic fluid might create alarming system pressure

Personally I also wonder what problems an electric powered column might throw up down the line. I imagine the rack input shaft, gears, UJs etc were designed around a reasonably low torque from a person wrenching the steering wheel. Supplying the mechanical advantage via the steering input will certainly stress all these components considerably more and might lead to increased wear or the worst case failure scenario

Unless I could find a rack that was built to have that level of input torque I would be worried

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