Manual to Electronic Power Steering Conversion

[RYU]

I have to say, the older I get the more I appreciate the NA2 EPS. It's probably one of the fews things I wish I had on my car 91.

Has anyone taken a good look at the EPS conversion? I was reviewing some old threads but nothing quite stood out.

In my mind, there are two primary areas to address:
1. Hardware installation (the easy part) - Do the holes line up? Same tie rod ends? Same u-joint connection to the steering shaft?
2. Electronic (the hard part) - 12V power and basic "on" wires but how about the EPS translation itself? I know the NSX EPS is speed dependent so there's at least a Vehicle Speed Sensor wire. How about the EPS module? Has anyone looked into what type of signal it needs to receive?

This would be a fun project if I wasn't so busy at work. Just curious if anyone out there has looked into it. It doesn't seem too difficult if enough time was spent to learn the system. The S2000 and Civic guys have these kinds of projects all the time haha! Does anyone have access to a EPS wiring schematic? Maybe [MENTION=15998]d1 guy[/MENTION] has some helpful input on this one.

I know this thread will be derailed by someone saying "but the manual steering is superior because of ____" but it would be nice to stay on topic on this one.

 

[B-E-A-S-T]

I would be interested in this as well...


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[91 X]

Yes it's a bit of a PITA when parking, but there just is no comparison to the feel of the manual steering during spirited driving.... Well worth the work when parking IMO.

Sorry to "derail" your thread.....but don't do it!!!:biggrin:

 

[B2FiNiTY]

I would be interested.

 

[nsxmugen]

RYU, did you ever got any ware with the research what is compatible? It would be a nice project, yea the esp needs vss and rpm signals. The civic unit is little large but there are other models that are smaller and might fit. Would not mind is someone make a retrofit kit as those things are as cheep as $300-500 on salvage yards.


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[Old Guy]

The Civic EPS is a rack mount EPS like the NSX; but, still quite a different cat. Aside from some likely major fit issues, you would likely have a lot of controller integration issues to address such as the assist versus vehicle speed. In the long run, I think it would be a lot simpler to retrofit an NSX electric rack and matching controller into an NSX. As far as I recall, the NSX EPS only requires a VSS (at least on the early ones) and as such the amount of 'electrical' stuff to integrate would be minimal. There is a single connection to the ECU; but, I think that is for the error checking stuff.

As I recall, there are some people who have gone done the EPS to manual rack conversion. They may be able to advise on conversion issues. If the transition from manual to EPS was a drop in fit, then it would seem reasonable that the reverse should also be possible.

An interesting project if I didn't already have EPS.

 

[RYU]

I have already received my refurbished EPS steering rack from @D1_guy from an 02+ car (can't recall the year exactly). Great job as always from Matt and Charles. I have also received my EPS brain but it isn't a newer brain as i'd like - should still work though. As far as hardware, i've got some feelers out for a wire harness. Actually I just need the connectors for a clean install. However the wire harness is integrated into the main harness for the EPS cars so asking someone to cut off the pigtails has proven unsuccessful So once I get comfortable with a method to secure the wires without the pigtails/connectors I can move forward. Joe (forgot his user name) from Florida can get access to about half of the connectors I need but he hasn't gotten back to me... i'll have to figure out a way secure the wires properly.

As far as the wiring.. I have several diagrams from several model years of the NSX. It seems rather straight forward. I won't know which wires are needed but [MENTION=26435]Old Guy[/MENTION] is pretty close to what I studied in the diagrams. As a side note, the steering assist is determined by the VSS. I have a VSS "manipulator" from my old S2000 that could theoretically adjust this variable. I don't think it will be necessary however. We'll see...

I haven't looked at it due to the holidays but I should get back on this horse and finish it up.

 

[stuntman]

I want to do this. Or was considering a racing in-line (steering column) motor that can be turned off to be manual steering, or adjustable for levels of assist.

 

[Old Guy]

I have already received my refurbished EPS steering rack from @D1_guy from an 02+ car (can't recall the year exactly). Great job as always from Matt and Charles. I have also received my EPS brain but it isn't a newer brain as i'd like - should still work though.

You will need to sort out the control unit thing. The early cars used a separate control unit and power unit. At some point during production, definitely by 1997, it changed to a single control unit with no separate power unit. If you are working with an 02+ rack, it would be desirable to be working with a later integrated control / power unit. If you have a later integrated control unit, checking the service manuals for the year that matches your rack and the year that matches the control unit would identify whether there was any changes in the pin outs. If there is no change in the pin assignments then you are probably good to go. When checking, try to get the service manual supplement for the matching model years. I am not sure that the integrated 1997-2005 service manual captures changes during the production run.

Parts numbers on the control units may not necessarily be a sign of changes in the control function. There may have been changes in the part numbers because Honda addressed some issues with the relays in the controllers which might have resulted in a part number change reflecting a parts upgrade. If you go to Kaz's web site, he has a rather lengthy discussion of issues with the controller and may indicate whether there were changes in part numbers during the production. At the least, check to make sure that your controller has the good relays. No point in installing it and then having it flake out.

I assume that you likely have the later integrated control unit, in which case you will also need to acquire the pulse unit. I previously made the comment that the early EPS only requires a VSS which is sort of mostly correct. However, it appears to get speed signals from both the common Vss and the it looks like the AT (perhaps redundancy). The pulse unit seems to fill that duty on the later cars being connected to both the diff and VSS sensors. The two VSS signals on the later controllers are drastically different (50 pulses versus 4 pulses per wheel rotation). That may make fitting your S2000 'manipulator' a challenge.