C-iii Steering Pump Upgrade

JMC

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May 9, 2017
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For some reason my original thread was deleted, so I am revising it as my DIY and mod section.

Hopefully it will stay long enough for members to enjoy.

Subject, C-III pump to C-II components with mods.

So far I have modded my C-II bracket for clearance of the pressure valve and pressure line. Added a custom adapter plate and used a mountianeer pressure line to allow fitting to my custom heavy duty 2001 Cobra rack and pinion.

Now that components are installed, I am starting on modding my C-III pump. I pulled the pressure spring, spool valve and restrictor, from a 4 cyl for modifying as I want to keep my original pump components for reverting back if needed.

Disassembly was fairly straight forward, and can be done on the bench with pump pulley flat face down to crack the retaining nut to the pressure valve spring.

Once spool valve is slid out you can drive the restrictor out from using a 1/4" socket with an extension and block of wood. The socket needs to be large enough to fit around the protruding tube part of the restrictor, yet small enough to fit inside the bore for the restrictor.

Note, the restrictor has a notch on both sides of the restrictor tube, and looks slotted, but it is not. The notches are the same radius as the center hole of the restrictor. So when enlarging the restrictor hole one will need to enlarge the notches to the same radius as the enlarged hole.

Don't go over bore too much. A little goes a long way.

At this time I have not removed the pressure valve components to my pump, as I never remove anything until I time to work on it. I will be doing a small fastener upgrade to my pump adapter soon, so that will allow time for a quick tare down of the pump's pressure valve assembly, for measurements and comparisons. This way, I can reassemble and have my pump complete, while I am making mods to the valve restrictor, and if need be the spring as well. If I notice any differences in spool valves, I will note them.
 
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JMC

New Member
May 9, 2017
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#2
From further information given about 4 cyl power steering pump, the bleed is larger due to RPM and weight on the front to assist in responsive turning. That means it should have similar characteristics of the Cobra R pump. Can't wait to see.

I also found that the early pump was not used in a hydroboost setup, so the output is restricted to lower the volume to the 4 cyl rack as the only device being driven by pump pressure.

From the above, I can assume drilling out the center to a larger diameter will all be needed in making a mock Cobra R pump, without all the extra cost.
 
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JMC

New Member
May 9, 2017
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#3
I found out that I can drill out the center to 1/8" not much more than original, but makes a huge difference.

As for the low pressure bleed. I found out the standard size is set at a 2.5mm radius.
Moving to 3 mm radius will strengthen low RPM steering responce. Since I have no 2003 to 2004 Cobra R rack, I am not sure how much I will be missing out, outside of a wee stiffer feel.
 
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