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Help with power steering pressure differences, SR20 > FC

Old 04-27-09, 09:37 AM
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booya
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Lightbulb Help with power steering pressure differences, SR20 > FC

Anyone with experience in PS systems, I could use some help!!

I have an SR20 swap in my FC, with the SR pump connected to the FC rack with braided lines, -an fittings, and a custom reservoir. I filled the system with fluid for the first time this weekend and all hell broke loose, seriously. The SR pump immediately started groaning and the steering wheel had very very minimal effort required, way too light. This was with the car idling and the front wheels elevated.

After 4-5 lock to lock rotations the pump itself took a dump and started leaking oil through the center housing seal. The lines, pump and reservoir were hot to the touch also.

Looking at the FSMs for both cars (RX7 for the rack, SR20 for the pump) here is what Ive found:

SR: MAX pressure - ~1100psi
FC: Pressure @ 1500rpm - ~1180psi

Im pretty sure this is my problem, but for the life of me I cant wrap my head around why its an issue. With the car idling at around a grand the pump went bad in a few minutes, but to me it doesnt make sense. If I was using an FC pump on a 240sx rack I could see this happening, since the Pump would overload the Rack at over 1500rpm, but in my setup I dont see how the rack could cause the pump to go over the max pressure.

Is the pressure created by the pump regulated at the rack? Lets say the SR20 pump was spinning at a constant speed, and the inlet to the rack at the high pressure line was reduced, it would cause the pressure in the line to increase, therefore increasing the pressure inside the pump - this much makes sense, but I dont know enough about power steering systems to know if this caused my problem, or where to start on a solution. Any help at all would be appreciated!!

A note on my setup: The rack Im using was originally a speed-sensing rack, with the two high pressure lines. The guy I purchased the rack and lines from had one high pressure inlet capped, using just the line closest to the low pressure outlet (pic below; blue braided line is high pressure). Was this the correct line to use?




Golden question: Am I better off depowering the rack, or getting a manual rack? What are my options for making this work?! Thanks so much for any help.
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Old 04-29-09, 09:13 AM
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Bummmmmmmmmp, I know people deal with this in LS_ swaps!!
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Old 04-29-09, 09:39 AM
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I got a kit with an adapter for the powered rack, it's adjustable for pressure so you can dial in or out resistance, when it comes in i'll bring it to you and show you...may give you some ideas


I've heard that depowering the rack is favorable over a manual rack, because of the closer ratio, but I dont' know how to do it, or if your rack was damaged with this.
Dave
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Old 04-29-09, 10:22 AM
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Where did you get the kit Dave?
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Old 04-29-09, 02:58 PM
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i got it from hinson, but it isn't listed on their website, you have to call them for it


this might help

http://www.v8rx7forum.com/v8-rx7-tec...lp-me-plz.html

Dave

Last edited by surubasi; 04-29-09 at 03:00 PM.
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Old 04-29-09, 04:33 PM
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Awesome info man, thanks a ton. I posted this over there too for some more replies, hopefully someone with a little more experience can steer (lol) me in the right direction
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Old 05-02-09, 12:24 AM
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hey do you know what size AN fitting those are?
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