Reducing Power Steering flow on 2JZ pumps

[takai]

Right, after my little drive on the weekend which showed that the PS is WAY too light on the cressida im going to have to do something about restricting the flow in the system, because i can steer with my little finger and its twitchy as all hell.

From my reading of this TRSM page off Cygnus:

It seems that there is a spring there which regulates the flow control valve. I assume popping a softer spring in there will assist in reducing the system pressure.

Has anyone done this? And are the springs available off the shelf? Oh and is that the same for the 2JZ pumps, im starting to suspect that diagram is the 7M pump.

[wilbo666]

That diagram is 7Mm, but JZ is same in principle.

Do MX83's have speed proportional power steering on the rack? I'm not a MX83 expert, but I think I recall seeing it on the rack in the past?

If so is it still working? Or it might be possible to use that?

Cheers
Wilbo

[takai]

MX83 isnt PPS, the JZX81 is.

[wilbo666]

Ah OK sweet, I must have seen the remains of a swap at the wreckers eh!



Cheers
Wilbo

[CrUZida]

Get a JZX81 PPS rack and install that.
MX73's also have PPS and the rack may be compatible. If the rack isn't then the ecu will be.
You may even be able to install the MX73 solenoid setup on to the MX83 rack.

[CrUZida]

Oh, and if its twitchy then maybe the dampener needs replacing, or upgrading.
The one with a spring on it (like the 4WD's), that should make everything perfect. ie, get rid of the twitchiness and tighten it up at the same time.

[wagonist]

In the interests of not starting a new thread on this, but is there a way to tell if a car has PPS.

My Caldina isn't listed as having one, but I had trouble placing the front wheels at Wakefield, and I've also caught the system with too low a pressure when suddenly trying to change direction (ie emergency lane change whilst braking) after some straight higher speed running. It's like it gets confused at the lower speed and hasn't compensated, therefore the assistance isn't high enough.

[takai]

Not replacing the rack if i can avoid it, just spent $350 rebuilding the sodding thing during the 2JZ conversion.
Did however use the old dampener, so it might be that, although one would think that it would only affect small bump compliance rather than the one finger turning.

[CrUZida]

Have a look at the rack where the lines connect to it.
If there are 2 wires coming from that area you have PPS.
If not, no PPS.

[CrUZida]

Did however use the old dampener, so it might be that, although one would think that it would only affect small bump compliance rather than the one finger turning.

Yep, I agree the stock one would only affect small bumps, but if you put a heavy duty one in there it will probably make a large difference.

Perhaps adjusting the suspension will make it stiffer, more caster or something.

[Norbie]

Reducing pump flow is not a good way to improve the steering feel; there was an in-depth discussion on this topic over at PF recently.

Get shorter steering arms if you can, this is very effective and gives you quicker ratio steering as well. I wouldn't be surprised if off-the-shelf items are available for the JZX81.

[takai]

Sorry norbs, no shorter steering arms for the X8s, they use an odd steeering arm pattern. I did think of that though.

[c2888]

Take the belt off ya big girl

OR

You'd need a relief valve of the hydralic variety to lower the systems pressure.
Much like a bleed valve, except that you can't bleed to atmosphere for obvious reasons.

OR

Get a bigger diameter pulley made up for the PS pump if there is room.

[CrUZida]

Get a bigger diameter pulley made up for the PS pump if there is room.

That will help at idle (when it doesn't need changing) but no where else in the range.

[takai]

No room on the 2JZ. Maybe i shoudl fit a Boxxer air cartridge to the rack so i can adjust the rebound pressure.