Electric Power Steering...

[Jordan]

I've been thinking about this a little lately. There seems to be two different types. One type is an electric pump that hooks to a hydraulic rack. The other is internal into the actual column/steering gear. Lots of examples of people using electric pumps out of MR2s, but the column type intrigues me. They seem to be a lot more common now and may be a neat solution for a 99. They don't seem to be too expensive either...at least used.

Anybody know anything about such contraptions?

Might be something to start pulling out of junkyards if they have arrived yet

[DrewP]

I was led to believe that most of the integral electric assist units had their own controllers to vary the input load since most of those systems are the ones with some sort of variable assist that changes with road speed. For example I think that the current BMW system integrates with engine management, with TCS/ESP, and with the steering controller itself, so you'd essentially have to design your own controller for it to transplant into another car.

There may well be some simpler systems out there though, I believe some of the Saturn Ion and Aura cars may have a dumbed down full electric system.

[Jordan]

Yeah I wondered about that. Universal electric systems have a dumb internal controller, but they are expensive. Since the power rack 99s had a different firewall anyway, it would probably be easiest/cheapest to use an electric pump on a 900 rack. Not sure I'd ever need PS but, just something to think about. I wonder what the amp draw would be... would suck to have the car die trying to get to full lock

[DrewP]

I believe the Saturn systems draw through a 40 amp fuse, the wife's Mini Cooper S with the variable rate electric pump I believe is two 15A control circuits, and one 100A supply circuit straight off the battery that's shared with one or two other things.

I have seen people looking at using the Toyota or whatever systems that's an electric pump feeding a hydraulic rack saying it draws as little as 10-12A though, that seems worth pursuing if it's true, but I find it hard to believe it's that low, especially if you stall it out by travelling the rack to the limits. That pops belt driven P/S pumps too.

One of the guys at work did that on a customer's 9-3 once, the pump was already pretty squawky and he held the steering wheel at full lock for a few seconds at idle - blew the shaft seal out from behind the pulley and I got a nice hydraulic fluid shower. Then he told the customer, "See, you need another power steering pump...."

[Geoff]

Anybody know what the pressure and flow rate requirements of hydraulic power steering systems are? I'm wondering if a 12v oil pump would work.

[Luke]

This is a really common conversion on older rally cars in the UK, they usually use a vauxhall or opel column and one of the rally prep places sells a dummy ecu that plugs in to make the rack work without the need for all sorts of system inputs.

Some of the VW rally guys experimented with electric hydraulic pumps from a Subaru XT or something and I think most found the system to be problematic.

[saabmatt]

Used a Vauxhall Corsa one in my 900 track car

http://www.uksaabs.co.uk/UKS/viewtopic.php?f=35&t=69068

[squaab99t]

Matt, Rockin' build, and all in a car port?
Question on the power steering unit. Does it have any input related to wheel speed? What I'm thinking at low speed it has increase duty and high speed less for better feedback.
It must have some type of strain gauge built in to sense load input (torque) from the steering wheel?
Dennis

[Jordan]

Great project..

Hey this looks familiar...

[saabmatt]

Matt, Rockin' build, and all in a car port?
Question on the power steering unit. Does it have any input related to wheel speed? What I'm thinking at low speed it has increase duty and high speed less for better feedback.
It must have some type of strain gauge built in to sense load input (torque) from the steering wheel?
Dennis

Cheers

Yes wheel and engine speed, mine (at the moment) uses one of these

http://www.ebay.co.uk/itm/CORSA-RALLY-E ... 4ab1178381

and yes it has a built in torque sensor

Turbo engine build and T5 over the winter then it will be hooked up correctly but it works fine with the controller.