I've been reading quite a few interesting posts on upgrades removing the camshaft driven servo pump and putting a electro-hydraulic unit in the frunk.

Has anyone ever tried the crazy idea of simplifying one step further and putting the electric steering rack from the 991 in?

There's some diverging opinions about the feel and touch of the EAS but would surely simplify things if the controls are not too complex to sort out.

 

I don't think installing a steering system from another vehiclewould be a simplification. It could be a very expensive experiment.

 

Plus that electric rack probably needs a million sensor inputs from throughout the car in order to function as designed.

 

I'd rather put a cup or MB pump in it and keep the awesome steering feel. Artificial feel of EAS is very real. In the porsche line the 991RS and GT4 are the best yet, but it is nowhere near as good as the 964 or 997 series cars.

Plus beyond controls you're dealing with rack fit.

 

+1

I really like the steering feel of my MB pump conversion.

Thanks!
Andrew

 

It's interesting to see if anyone has ever looked into this.

The motivation would be that you can now take all hydraulics (and the weight) out since the motor acts directly on the rack.

The incoming steering torque comes from a sensor rack in the input pinon and is part of the piece.

There is an external connection and I imagine that this is to transmit the position of the rack and control how the rack assists the driver. However the information available is not very extensive so I'm really just guessing.

 

I wouldn't let you take away my steering feel if you offered to build me a new motor for free. Would completely ruin one of the cars best attributes, in my opinion. The great part about the electric pump assist is that it can actually improve steering feel, and even flip a switch to run it manual if you'd like.

 

Again, just for discussion purposes and to clarify I'm not talking about steer by wire which is something else.

The way the EAS rack works is that it's a mechanic rack directly connected to the steering wheel with a motor assisting electro/mechanically in parallel.

With the motor turned off it should behave as any other mechanic rack or in the same way as if you turn the hydraulic pump off.

 

That sounds not too bad actually. Do you know what's the power draw of the motor when engaged?

It would definitely simplify the conversion.

Thanks!
Andrew

 

Porsche as well as Bosch is claiming a lower power drain than for mechanic/hydraulic or electro/hydraulic.

The logic is the elimination of the conversion loss (el->hyd->mech) and that the power consumption is close to zero when going straight.

A pump weather mechanic or electric will be idling even if there is no steering load.

 

Lots of new cars have electric power assist. There are even aftermarket units used in the hot rod world. While it is certainly possible that a unit could be as good as the stock steering, I would think it would be a long development road, not to mention expensive.

 

I've had a look and you'll get a 991 (or Cayman/boxer since same unit) rack for 600-1000$ If you don't mind a second hand.

There is 6-pins for the connecting cable but not finding any info on this. With this I think the rest could be worked out without spending a fortune.

 

For what it's worth, I unplugged the servo in my Audi to deactivate the electric assist. I know thats mech/hyd with electric assist, but it certainly feels better without it. I'm assuming 991's are not a combo mech/hyd with electric assit like the Audi's, but electric only in the steering rack?

 

This is how they look. The mechanic column from the steering wheel goes on the right side as any mechanical rack and in the same place there is a torque sensor.

The connection to control the assist (increase/decrease off/on) is a can bus.

 

i'm sure Robt964 actually did this (electric pump, not 991 rack), maybe worth a mail?