Reducing PS pump pressure (1UZ crown pump)

[mullett]

Has anyone attempted this? Aaron mentioned today that there's a bypass valve in the pump (makes sense) and it's probably possible to replace the spring and reduce the overall system pressure...before I go barging in in the quest for better steering feedback, has anyone played with this?

-RM

[mullett]

Edit: according to this:

ToyoDIY.com

It looks like PN 44330A is the spring I'm looking at...so maybe one of these at half the spring rate would be a good start...

On a side note, does anyone know standard MA61 rack pressure and standard crown rack pressure?

-RM

[pandaah]

get a spare spring.. lop a coil or two off... try that?

[CrUZida]

Whats wrong with the steering feedback ?

I find it perfectly acceptable...

[mullett]

There's nothing...the steering in decade is rubbish. There's no feedback, and it loads up in an odd way...

-RM

[CrUZida]

Random, I'd be looking at the rack, (or maybe the pump).
I find Uzzio's a joy to steer.
When I get him back, take it for a drive, see how its different.

[pandaah]

would be keen to see how you go with this, i feel i cant "feel" my rear wheels thru my steering like i could in my skyline.. just feels like too much of a twitch with the steering wheel and the rear wheels go from a small angle to a big angle and i cant really feel it.. my skyline i could almost tell it to go another 5 degrees of angle with the wheel and it would.. talking bout track days btw..

[mullett]

Yeah, I know what you mean. I'll have a play with the spring, a new one is only a few $$ anyway if it comes to it. Wish there was a way I could jury-rig a pressure gauge in there so I could monitor the change!

-RM

[CrUZida]

I've no doubt Enzed or Pirtek will stock all the fittings you'll need!

[pandaah]

i read a good way to measure the tension, place it on a scale, add weight till each coil touches on the compressed spring, minus the original weight of the spring, thats the spring rate.. so you could duplicate it when your done =) ..

and enzed could jig up a hose to fit an oil pressure gauge.. or even rig it up with a blanking plug for future pressure tests..

[shadowR]

I would restrict the line. Take the line that goes from pump to rack and have someone like pirtek remake it with some form of restrictor.

Its fairly experimental and backyard but it will work. Cheap too.

[mullett]

Yeah, adding the fittings wouldn't be difficult, but could be expensive! Also a gauge capable of the pressure

Adding a restrictor probably won't work, it'll reduce volume rather than pressure. So at cruise speed it'll still be lifeless, but turning quickly it'll suddenly load up as the flow rate maxes out...

Also, cruz...do you have the speed-sensitive rack? That could account for it...

-RM

[CrUZida]

Nope, I think the speed sensitive racks were in MZ12's only (MX73's had them, but A61's and normal Z10's didn't)

[Supra967]

Bypass valve? Like a boost T, just link the bypass the return line.

[mullett]

Bypass valve would be messier, but certainly easy to regulate! I think thats what the speed-sensitive PS did. On which note, are the racks interchangeable?