Another power steering option

[Joe Campbell]

For my winter upgrades this year I had planned to install an EPAS from a Corolla/Prius, but ended up too busy with work and ran out of time (driving season is too short up here to miss any for nonessential mods!) So rather than cutting and welding on the steering column, I left it as-is and installed an electric power steering pump out of an MR2 pushing fluid to through the power rack. It required adding a PS reservoir of course. One of the other winter upgrades was to machine the rear legs on the front upper control arms a bit so I could get more positive caster. Very pleased with the results - the steering assist level is very moderate and with the 7 degrees of positive caster the on-center feel is very firm. Our 2011 Mustang GT is numb by comparison. Parking lots are no problem with the level of assist, and at 80mph freeway speeds it tracks like an arrow (And at much higher speeds on certain back roads too but I'm not sayin'). Feels like I could set the cruise and take a nap going across I-80 in Wyoming but that would probably be considered bad form.

Very simple to wire as well, just a relay off of the battery to a switch under the dash, and ground. It's a bit noisy but I installed it without any isolators that are probably used in OEM applications. Might play around with that. I'd have to do a little more research on the unit to find out of the MR2 pumps default to a high or low signal in the absence of a speed signal. PPM from my TKO is not right (12 pulses per rev, and the default for the MR2's I think is 4). But it's supposed to modulate the assist based on speed if you have the right signal on that wire....no need for an ECU.

Just another option for those who don't want to cut/weld on their steering shafts.
Attachment 108457

[edwardb]

Nice job explaining the advantages of power steering. I assume you know the Toyota MR2 pump is the same one Fast Freddie uses for the conversion kit he sells. I had that installed on my #7750 build, powering both steering and hydroboost brakes, and worked very well. It's a good option instead of an engine driven pump, although still involves hoses, reservoir, fluid, etc. I don't know any details, but my understanding is there are at least two versions of the MR2 pump. Early versions, like the one Freddie provided for my setup, isn't speed sensitive. Just runs all the time, similar to how an engine driven pump is, which I didn't find to be a problem. Later versions apparently had the capability to be speed sensitive, and that would make sense, e.g. reduce the boost at higher speeds. Will be interesting to see if you can make that work. But still a good setup if you don't.

[CraigS]

Speed sensitive is a great feature. When I was a Lexus tech they started on their top end sedan in early 90s w/ a kind of on/off system. They chose a speed somewhere around 30mph where the assist dropped to a lower level. If you tried to find it you could sometimes feel it but mostly it was not noticed. Later on the assist changed more as a curve than as a point. I wonder what the MR2 does. I hope you can find out.

[WIS89]

Joe-

Nicely done, and a great choice for those of us looking to get some steering assist. I think this might be a great choice for those looking to retrofit a system because of the relative simplicity.

Thanks for sharing, and if you get the speed assist working, please let us know!

Thanks again!

Regards,

Steve

[Railroad]

Great option. Thanks for posting. I am sure this will be a solution for many.

[Sanford]

pump speed controller. Never got around to getting it though
http://www.myraceshop.com/Power_Stee...ontroller.html