EVO disabled on Angry Bird truck

jclars

Registered User
I am running the SC power steering with a Jaguar rack. The pressure output is approximately the same at low speed, but I no longer have the ARC to control the EVO at the power steering pump. Is there a way to manually, or automatically adjust this to be a little more firm at higher speeds? Way too sensitive right now.

I have heard of snipping the bypass/relief spring to make it less sensitive, but have yet to pull it apart to even locate such a spring. Does anyone have an exploded view of the SC pump or perhaps a description of how to access this spring (if it exists)?

Thanks,

John L.
 
This shows a spring...
SC_EVO-01.jpg

Have you considered trying different diameter pump pulleys?
 
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I swear Ken, where do you dig these diagrams up? You may have bailed me out again!

Are the mustang pumps of that era the same? I have a very precise article concerning exact length to shorten that spring if they are the same.

Thanks,

John L.

BTW - fuel relay continues to work as intended since the last voodoos were exorcised. In fact has been running great! Now it is down to this sort of tweaking.
 
How does the EVO work? I know what the function of the system is. But, what are the mechanics of the system?
I'm doing the opposite, I'm transplanting an older BBF into my bird and a lot of other stuff and before I travel to far down the wrong road I'm trying to figure out the mechanics of the systems involved, so I can figure how to incorporate them and cut down on the number of failed attempts.
Didn't mean to hijack, but it's relevant to what I am researching now.
Thanks,
MikeH
 
I swear Ken, where do you dig these diagrams up? You may have bailed me out again!

Are the mustang pumps of that era the same? I have a very precise article concerning exact length to shorten that spring if they are the same.

Thanks,

John L.

BTW - fuel relay continues to work as intended since the last voodoos were exorcised. In fact has been running great! Now it is down to this sort of tweaking.

I think the mustang pumps dont have the evo, physically they appear the exact same, I did a supercoupe swap on my buddies '95 v6 mustang we reused his v6 power steering pump and just put the SCs 8 rib pulley on it. I couldn't say if the hydro line is the same threads or not but imagine this would be a pretty easy thing to solve should they be different.
 
Ford only used two main pumps at that time Essex and Windsor got if memory serves CS2. EVA was a add on for upper tier vehicles.

Have tried a non-ARC module, nonSC tbird?
 
Anyone have the same schematic for a Mustang or other non-EVO type Ford pump of that era? If it is just the electronics, I am thinking the spring adjustment should be viable to get the steering to stiffen up a bit.

Otherwise, the suggestion of using one of the non-EVO pumps is a good fall back position and worth a try.

Thanks,

John L.
 
The actual pump unit is the exact same between SC and non-SC 'Birds. I am pretty sure that the non-EVO cars have an adapter fitting that somewhat restricts flow into the HP line. The normal boost of a non-EVO car is much less than the full boost of an EVO car with EVO all the way open.

Edit:

Here, look at the first 4 or 5 pictures on this other forum's thread, and you will see the fitting I mean.
http://www.ford-trucks.com/forums/1069519-how-to-power-steering-pump-replacement.html

Now compare it to the picture KMT linked to:
http://www.sccoa.com/forums/showthre...21#post1069321

I guess you could refer to that fitting as a "fixed orifice", as opposed to the "Electronically Variable Orifice" of the EVO system. The point is, you need SOME kind of orifice, or the feel will be wrong.
 
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Since you are obviously not afraid of wiring, I suggest obtaining the wiring and control module from a 92 or later LX bird with variable assist but no ARC. Wire that in and you should be good to go. Otherwise you can put a manual switch on it, or maybe if you want to be tricky, fab up a speed sensitive switch that is user adjustable. :)
 
Since you are obviously not afraid of wiring, I suggest obtaining the wiring and control module from a 92 or later LX bird with variable assist but no ARC. Wire that in and you should be good to go. Otherwise you can put a manual switch on it, or maybe if you want to be tricky, fab up a speed sensitive switch that is user adjustable. :)

Hmm, certainly not impossible. I think a variable current limiting circuit would be required, which is a bit tricky. I am sure Digi-Key has the goodies you would need. Probably easier to retrofit the later model LX stand-alone ARC box, as long as the speed sensor and other wiring is still around.
 
No more wiring please!!!

I will settle for a little less variability on the pump! The diagram implies a separate flow control valve. Does anyone know the flow rate? I ran across one site that suggests replacing the 3 gpm unit with a 2 gpm unit to get rid of twitchiness. (is that a word?)

It would appear that the default position for the EVO is wide open, so if I could simply replace the flow control fitting, it should do the trick, correct?

Thanks,

John L.
 
Ford tends to default towards safety - more assist rather than less should the controls fail, in which case the spring would push the valve to open and allow full pressure.

"In the event of an electrical malfunction, such as circut open, shorted, or electronic variable orifice (EVO) control module failure, the power steering control valve actuator will provide full power steering assist during such failure modes.

Continued operation under such conditions may cause excessively high power steering fluid temperatures and damage the steering components."
- '96 Ford Service Manual

Just remember that in '96, Ford used an additional(?) electronically controlled valve in the rack itself.
 
The ford racks require ~2gpm flow rate, GM's use ~3gpm from the pump. The EVO on the pump restricts that as speed increases. I have seen that there is a restrictor fitting that holds the flow piston for the non-EVO cars. I have seen aftermarket fittings and shims to set the constant flow rate. I guess that you would have to get the flow rate where slow speed assist is a little harder so that higher speed is not so twitchy. I found out this doing research on various pumps and EVO's.
 
If you get the fitting with the fixed orifice, you simply remove the EVO valve. I think the HP line should screw right into the fixed orifice. Worst case, you can get a HP line from a non-EVO Bird. But I think it's the same.
 
If you get the fitting with the fixed orifice, you simply remove the EVO valve. I think the HP line should screw right into the fixed orifice. Worst case, you can get a HP line from a non-EVO Bird. But I think it's the same.
If I was reading correctly on rock auto, the hoses are the same, and come with the EVO replacement fitting. So, if you have EVO, you remove the adapter. I have seen several companies that make/sell the adapters.
 
If I was reading correctly on rock auto, the hoses are the same, and come with the EVO replacement fitting. So, if you have EVO, you remove the adapter. I have seen several companies that make/sell the adapters.

My understanding is that the pressure hoses do not come with that adapter. There is also an adapter at the rack end that both EVO and non-EVO cars need. Your stock one may be fine, though.
 
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