Electric power steering conversion... this will be fun :)

M

MWP

New member
So ive decided im going to have a go at this :twisted:

I know other guys have done it into Corollas and Starlets, so why not a GT4?
The other guys have used the EPS unit from a Toyota Yaris (non-ABS), as its the easiest to fit, but they have had issues with the motor overheating.
The Yaris non-ABS unit is fairly easy to use as the EPS control module takes a simple wheel speed sensor input to adjust steering assistance.

This is what a Corolla Alltrac using a Yaris EPS unit conversion looks like:
photo_zpsef98482c.jpg


photo_zps68920aa1.jpg


I'm planning to use a ZRE152 Corolla EPS unit because it has a larger motor that should be more suitable for the heavier steering on a GT4.
The only problem with the ZRE152 EPS is the control module doesn't have a simple wheel speed sensor input, it takes its input via the CAN bus from the engine & ABS ECUs.
Im, hoping that ill be able to program the microcontroller on one of these http://www.crystalfontz.com/product/CFA735YYKKR to take a gearbox speed sensor input, and output packets on the CAN bus that the EPS control module will understand.
By sending the EPS control module variable speeds, ill also be able to modify the level of assistance. So in "race mode" i can have very little assistance, or in "street mode", have high levels of assistance :)

Quite a large project, but i think it'll be worth it.

Now for my first question... does anyone know of a manual steering rack that will fit in place of the normal hydraulic power steering rack?
 
T

Tecker185

Member
I'm also doing this project, but I'm using a different pump. Check out the 2000-2005 ish mr2 spyder. They use an electric pump but its still hydrolic. Just need power, ground, key on power and speed signal. The ecu in built into the pump so its a petty simple install. Here's a picture of my pump got it for $250 shipped.

a5d89d4aa3f4a6ace7eb24704b73d41d.jpg


Here is a quick and dirty install guide
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I plan on doing a write up when I get this thing installed.
 
R

rallygarage

Member
My big dream.
http://easysteer.co.uk/ is the kit I was planning to use. You first have to convert GT4 to a non hydraulic rack this is hopefully faster than OEM. I am using an electric hydraulic pump now. This is in my rally car. Very noisy.
 
M

MWP

New member
Yeah, quite a few people have done the MR2 pump conversion.
Not much different to the original setup other than you have no pump on the engine.

With the full electric power steering you have no hydraulics at all :)
 
M

MWP

New member
rallygarage":2u1oxkr9 said:
My big dream.
http://easysteer.co.uk/ is the kit I was planning to use. You first have to convert GT4 to a non hydraulic rack this is hopefully faster than OEM. I am using an electric hydraulic pump now. This is in my rally car. Very noisy.
Click to expand...

You're very game to use EPS on a rally car.
Have other people done it?
I cant imagine it holding up to the shock inputs & stresses of rally very well?

The ZRE152 EPS module ill hopefully be getting will be coming from a car that's being built for gravel rally.
It'll be getting a normal hydraulic power steering setup instead.
 
M

MWP

New member
Good question, will do some research.
Even if they do though, i bet its not some EPS unit pulled from a Corolla or similar :p
I would hate to see what a WRC level EPS system would be worth!
 
B

bmt

New member
This does sound interesting! What are the pros and cons of electric power steering?

Obviously power gain to the wheels as the motor isn't driving the power steering pump.

On the con side is the lack of feel associated with some units.

Good luck i will be watching
 
M

MWP

New member
There will be a very small power gain due to the removed PS pump idling losses.
Of course when the electric PS is in use, there will be extra draw on the alternator.

Lack of feel ill be able to tune out hopefully.
 
M

MWP

New member
For anyone thats interested, this is what the input shaft & pinion look like in 185 steering racks.

Im manualising the steering rack, so the torsion rod in this shaft needs to be locked up.

IMG_2132.jpg
 
D

deecee

New member
Did you consider using a PS unit from a SW20 MR2? I have seen that conversion used in the past.

I can understand the use of an integrated unit to reduce additional plumbing but will there be enough room under the centre console?
 
M

MWP

New member
Nah, didn't consider the SW20 pump.
I want all the hyd lines gone.

As for room under the dash... ill make room :p
 
D

deecee

New member
I thought removing all hard lines might have been the reason.
There is a decent amount of room under there if you don't want a lot of the air conditioning and air vent stuff. I've saved heaps of room ditching the heater unit for a smaller unit
 
M

MWP

New member
If i cant fit it in with the motor pointing up, it'll end up being like this which will still be ok...

photo_zps9a36d8d4.jpg
 
M

MWP

New member
So this is what ive done with it so far.
Ill now fill as much of the cavity as i can with jbweld.

IMG_2138_s.jpg
 
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