Exlex

Hi,

I'm trying to figure out how the power steering computer adjusts the assistance to steering based on speed. The FSM doesn't really cover HOW it works, just how to check IF it works. Searched up some threads but did not really find any more indepth information about this. Anyone have any information regarding this? Maybe even information what parameters that affect it. The idea is to try to adapt this to an electronic pump instead to save place but still keep a good feel in the steering.

With regards, Anton

NZConvertible

Basically the assist decreases as the road-speed increases. A computer-controlled stepper motor in the pump moves a valve that increases and decreases the pressure of the fluid sent to the rack, based on input from the speed sensor in the instrument cluster.

Mazda's Training Manual has a chapter on the power steering , and describes the system is great detail. It's not exactly light reading but it's pretty interesting.

http://208.62.166.66:82/guest/shop_m...aining_manual/

Exlex

Thanks Jason, seems to be great information! I will take a good look at this. Now the hunt for a controllable electronic steeringpump begins, or look into if it's possible to control the flow of a generic electric pump with adjusting the voltage.

Anubis06

look into the citroen saxo electric power steering pump. another member has successfuly done that. im in the process of locating one. look up "post fmic pics here" thread. the explanation how to's is there. if u want more info, PM me.

Exlex

Yes, the saxo electric pump is one of the candidates. However since it has no mean of adjusting the power that means it's constantly aiding wich can lead to a bit strange feel to the steering. So I'm now trying to find a way to adapt a speed-sensing steering so it can mimic the feel of the stock steeringpump.

slpin

iTrader: (9)

what happens if you have a speed sensitive steering and you never plug it in???

TehMonkay

iTrader: (-1)

You hear BEEP...BEEP....BEEP...BEEP as you drive.

TehMonkay

iTrader: (-1)

Also, is the valve internal or external to the pump, perhaps you could adapt the stock valve / stepper motor to the electronic pump?

coldfire

iTrader: (1)

has anyone driven both a vehicle-speed-sensing and engine-speed-sensing PS FC?
the vehicle-speed-sensing is a better system, but i am wondering what the differences are in terms of feel.

the engine-speed-sensing PS in my S5 is ok, but i wish it were a little heavier, especially at higher speeds. it would be nice if there was some way to reduce the level of assist. i don't really want to completely remove the PS at this time.
possibly switching to a vehicle-speed-sensing PS might be an option (either the stock one or from something else). what would be even sweeter would be a very close ratio rack (much lower ratio than stock), but i haven't found one yet.

leffes87rx7

Hi, I know that this Thread is very old (so am I) however, I am in desperate need of a faster and lighter steering on my 87 RX7 turbo ll, heavy modified for track use only. Earlier modified to manual steering 20:1 rack, good for drag racing.
I am running 245/45 ZR 16 competition tires and 13 inch steering wheel (15.5 inch std.) due to my large frame. My 50 years old son and my 25 years old grandson agree that the steering is way to slow and heavy, so please, don’t tell me that manual steering is the best.
I do have a Power Steering Rack, 15.2:1 (I believe) type: A FB05. Koyo Seiko Co Ltd. With 3 ports. I don’t know if it is an ESPS or ECPS rack.
Now my question, as I have no space for a belt driven pump, I am looking for an electrical driven pump like Volvo V50 or any other, I guess, European brand with adjustable speed. If anyone out there have any info or experience with similar rebuilding, please let me know.
Thank you very much.
Leif.

misterstyx69

iTrader: (142)

Look in a Toyota MR2 Pump(electric).No belts or engine pulleys.Just an electric pump connected to the rack.
I actually have the basic setup for this to get installed BUT I haven't done it yet.

(Coldfire?...holy ****..7 years ago?..."hey" Aaron..if yer still kickin!)

bumpstart

use the toyota fluid.....................

bumpstart

oh.. and PS.. top port is the return port via the pipe cooler out front

if you get that wrong .. the kit is edlemann 8861


user on here .. havoc .. using the mr2 pump setup ( IIRC )

bumpstart

by the ratio.. it is GXL which is vehicle speed sensitive , set by a stepper motor on side of the pump

but suspects the earlier system may only be 2 lines

also // another option is to mount the mazda pump.. lower .. in the aircon position

similarly.. cosmo HB.. and luce HC engines,, had a steel bracket
..in vichy versa positions to the alum FC setup

the reason for all the options/// well for proper electric pump control you need ecu control and PWM mapping . else it will be on 100% all the time

the mazda system backs right off after about 30 km/h
.. BUT .. you do not have to plug it in
and you can dial in the power response you want ( permanently)
by setting the stepper motor position on the pump in one spot

bumpstart

PS
you will also need another rackend if swapping back to the power rack

the power rack uses two of the same rackends ( fb01-32-240a ) while the manual rack uses one each of 240.. and 240a
( on the manual rack , one of them is female )

if you do so.. then little heads up about FEQ branded items .. being the right part number.. but utterly fail on any of the critical dimensions

the length and the threads at each end are utterly wrong
.. and there is a rogue batch repeating themselves through suppliers.. including atkins

suggest before you buy// look at the image// the real one is quite long
.. while FEQ part is much shorter , only about 240 mm long ..with an m16x1.0 fine thread at rack end

knowing that it is a track car.. and you may have mods to the ball joint bracket for extra track
and thus require all the rack spacers and custom tie rods etc
then would also suggest you look closer at the subaru rack end and tie rod combo
- as at either end ( rack end thread and tie rod joint taper ) it matches the mazda

but gives considerably more length.. and has a taller tie rod from the pivot
.. exactly what all the spacers and custom tie ends give.. without the expense

note.. you may have to lop a bit off the length of the rack end and thread it more if you have only a minor wide tack change

archaphil

iTrader: (1)

this is the second time I have seen Subaru parts come to the rescue. I am assuming an early 90's legacy rack would do the trick?

bumpstart

parts i tried up where from what is your 00 outback
but thinks these are all retro-compatible
to all legacy stuff and forester right back as far as the early 90's

i tried the rack end thread for fit to the mazda rack
and then measured the tie rod taper and fitted it up into a spare mazda front knuckle

it fits and is little taller off the pivot

overall the length of the rack end with tie rod is a healthy increase on the mazda set
though thinks most will get away with just trimming a few threads from the subaru rack end
( note some generic no brand ones have generous thread lengths )

subaru use a choice of straight or bent tie rod end across the range
and i am told the bent ( curved up ) one is for better steering response

though the one i tried was a straight one
and seemed to clear the knuckle a little better than the aftermarket heim jointed ones that look to be very close to the other furniture at lock

but all up the subie stuff looks a viable candidate for those with the cut shut stretched ball joint for extra track

jjwalker

Holy F dude, I lived there for 6 months in 2003.

Unless you like fishing (or wal-mart), that is the most boring place on earth.

leffes87rx7

Thanks for good info. I wish I could use the original pump, but I have used up all the space with other goodies like W/M pump and tank + intercooler pipes.
The Toyota electrical pump seems to give the users some headache to hock up, running backwards and so on, depending on year model used. I might try the Volvo V50 pump as it seems less complicated. Still don’t know how to control the speed, maybe the “default” speed will do?!

clokker

iTrader: (2)

I'd figure that out first, otherwise you're right where you started after some effort and expense.

leffes87rx7

You are absolutely right, and now there is no water in the lake and the parking lot at Wal-Mart is full,
However I can still drive down to COTA (Circuit Of The Americas) and take my RX7 for a spin. A great track, and I can still hang with some of the big duds…….

leffes87rx7

Yes Sir, I agree and believe you me, I am digging like a mad man......

leffes87rx7

Hmm, my manual rack got two rack ends with the same length and both are males; on top of that the right side is only treaded 12 mm (1/2 inch) in to the tie rod. I guess God is good and look after children and dummies.
The power rack is longer and has the same rack ends.
Also, I noticed that the manual rack got the ball bearing support yoke but the power unit have the old sliding support yoke, I guess that the power unit can take the added friction, or do I have an older model?
Thanks for the input
Leif

jjwalker

Cedar creek can't be as bad as lavon. Used to drive over lavon everyday for work and it is 13ft below full pool so you see miles of lake that is supposed to be there but it isn't.

I know cedar creek is shallow though, are there no usable boat ramps? We only have one usable boat ramp at hubbard.

leffes87rx7

Cedar Creek is only 4 ft below but most ramps have big holes after concrete ends