Powersteering question?
Discussion
Maybe not the right forum but there does not seem a good fit with any others so here goes...
Currently I have a conventional hydraulic powered powersteering system on my car. The pump is powered from the auxillary belt on the engine as per normal.
Now the thing is that I want switchable assistance; nothing fancy just on or off. A suggestion at present is to remove pump from engine, relocate pipe-work to front of the car and replace pump with an electric pump thereby offering the on/off assistance that I want.
The thing is (assuming this is possible) where am I going to find an electric hydraulic pump?
Removing the pump from the engine is desirable since it removes a certain degree of parasitic loss so I dont want to do the trick of removing the vanes from the pump. Assistance is only required when the car is being moved @ very low speeds (think in and out of pit garage).
Any ideas?
Currently I have a conventional hydraulic powered powersteering system on my car. The pump is powered from the auxillary belt on the engine as per normal.
Now the thing is that I want switchable assistance; nothing fancy just on or off. A suggestion at present is to remove pump from engine, relocate pipe-work to front of the car and replace pump with an electric pump thereby offering the on/off assistance that I want.
The thing is (assuming this is possible) where am I going to find an electric hydraulic pump?
Removing the pump from the engine is desirable since it removes a certain degree of parasitic loss so I dont want to do the trick of removing the vanes from the pump. Assistance is only required when the car is being moved @ very low speeds (think in and out of pit garage).
Any ideas?
Renault Clio 96-onwards has a separate electric PAS pump, I think the specs changed over time but should be a good starting point for your investigation.
I presume you are only wanting to cut assistance at high speed? I think it would probably be best to have the pump activated at all times as it will only need to consume power when you are asking for assistance and so will be more efficient than the on at all times belt driven pump.
I presume you are only wanting to cut assistance at high speed? I think it would probably be best to have the pump activated at all times as it will only need to consume power when you are asking for assistance and so will be more efficient than the on at all times belt driven pump.
jcas said:
You can get electric pumps - Will H fitted one to his V8 Capri in PPC magazine - I think it came from something like a Merc A Class?
Well, Charlie pretty much fitted it for him. 
It was from an A class. Alternatively, I believe Corsa's have electric assistance mounted on the column which people have used for rally cars IIRC.
Or finally, you could use the electromagnetic clutch from an aircon compressor to disconnect the pulley from the pump.
Did think of the air-con clutch idea earlier but I like the "simplicity" of the electric approach. Looks like Merc A-Class could be worth looking at as well as some Vauxhal stuff.
The other question though is; is it likely that all systems run at similar pressures?
egomeister, I'll have to check into the Clio option as well. This question is actually about a v6 Mk1. The original idea was to try and locate a non PAS rack but this seemed pretty much impossible and I was under the impression that all Clio's used engine powered hydraulic pumps.
Edited to add more stuff
The other question though is; is it likely that all systems run at similar pressures?
egomeister, I'll have to check into the Clio option as well. This question is actually about a v6 Mk1. The original idea was to try and locate a non PAS rack but this seemed pretty much impossible and I was under the impression that all Clio's used engine powered hydraulic pumps.
Edited to add more stuff
Edited by GnuBee on Monday 6th November 14:57
Mk2 MR2's have electro-hydraulic power steering - the pump is in the front under the spare wheel. The pump speed is reduced as road speed increases, to increase steering feel at higher speed.
Edit - I *think* they even have a separate control box, that just takes a speed signal input from the instrument cluster...
Edit - I *think* they even have a separate control box, that just takes a speed signal input from the instrument cluster...
Edited by aldi on Monday 6th November 20:56
aldi said:
Mk2 MR2's have electro-hydraulic power steering - the pump is in the front under the spare wheel. The pump speed is reduced as road speed increases, to increase steering feel at higher speed.
Edit - I *think* they even have a separate control box, that just takes a speed signal input from the instrument cluster...
Edit - I *think* they even have a separate control box, that just takes a speed signal input from the instrument cluster...
Correct on all counts!
If you're just going to kill the assistance to a conventonal PAS steering rack, it might feel absolutely horrible. Most of them have the steering column connected to the rack pinion by a thin torsion bar. The amount of wind-up in the torsion bar governs the amount of pressure / flow entering the rack piston for assistance. Without any fluid assistance, the steering feels like it has a load of "play" either side of straight ahead. This is because the torsion bar is nothing like stiff enough to do the actual work of turning the wheels. Once it has reached the limit of its allowable wind-up, there are heavy stops that force the column to turn the pinion. These are a safety measure in the event of the torsion bar shearing. Effectively, with the power off, it would be like driving with a failed PAS pump belt. It might be worth taking the belt off and taking the car for a run to see if you like the feel with no assistance prior to embarking on the project!
egomeister said:
Renault Clio 96-onwards has a separate electric PAS pump, I think the specs changed over time but should be a good starting point for your investigation.
I presume you are only wanting to cut assistance at high speed? I think it would probably be best to have the pump activated at all times as it will only need to consume power when you are asking for assistance and so will be more efficient than the on at all times belt driven pump.
I presume you are only wanting to cut assistance at high speed? I think it would probably be best to have the pump activated at all times as it will only need to consume power when you are asking for assistance and so will be more efficient than the on at all times belt driven pump.
They have direct electric steering with a motor on the steering column.
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