2 Gallon Per Minute Flow Kit - Seems Not Enough Assist At Low Speed (Good Highway Feel)

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m002922

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To address everyone's comments . . .

I live in Virginia - so I see from the 20s to the high 90s. The inadequate assist issue has been popping up while the temperatures have been in the 40s, but it only happens when the vehicle is warm, and doesn't seem to happen all the time. With a little RPM the assist seems to come right up but, obviously, in a parking situation a little RPM isn't always possible.

As a caveat, it was my intention to get rid of the EVO just to simplify things and not have to pay to replace it. I understand that the EVO system can work fine if installed and maintained properly.

That said, had I not already bought the parts (for a 1998 - Cardone 208748 - I'll discuss that below) and then let them sit such that I couldn't return them I would have:

1) Bought a 1996 Pump.
2) Bought a 1996 Line.
3) Put in 2 gallon per minute adapter.

(and this is what I would recommend to anyone looking to get rid of EVO).

That said, I'm not convinced there is any difference between a 1996 and 1998 pump. If you look at Rockauto this is 1996 options from Cardone:

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If you look at 1998 these are the Cardone options:

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It seems that the base pumps are different (2 different part numbers, 20661 v. 20860) - though I've heard some people express skepticism that they really are different (I assume there is some difference).

The second option for 1998 (208748) is the one I bought (that was a mistake - my reservoir was fine . . . and since I wanted to delete EVO I guess I should have bought 208748VB . . . or perhaps the 1996 pump option, which perhaps would have eliminated the need for the speedway adapter . . . this all gets kind of confusing and I don't know what the difference between the 1996 and 1998 pumps are (gpm? something else?).

The 208748VB looks like this:
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The 208748 looks like this:

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I believe the difference is - and should be - the adapter that you can kind of see in the first picture, that isn't in the second (there isn't an adapter underneath the blue cup in the second picture). I believe that adapter will allow you to go directly from the pump to your line (preferably a 1996 for ease of fit) without an adapter.

I ended up essentially getting that adaptor - with reduced 2gpm flow (compared to 2.5gpm, apparently - at least for 1998 - maybe it's less gpm for 1996 without the EVO) - from Speedway.

Regardless, as it is I have a 1998 pump, a 1998 line that I "adjusted" to fit (works, not ideal), and the 2 gpm adapter.

With these parts it's functioning fine (and I think the highway feel is improved - even over when my EVO was functioning properly) . . . except for an occasional issue of inadequate assist at parking speeds after warm.

No one has jumped in this thread to say that their experience was similar to mine (though there probably aren't that many people out there that ended up with this mix of parts), which makes me thing that the issue for me is probably something other than issues with this parts. Especially since the problem is intermittent (that is, I don't have the lack of steering at low speed all the time).

Hopefully this review of this will help someone looking to do this in the future. I kind of stumbled through this thinking I knew what I was doing, parts-wise, without really understanding everything I needed to.
 

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KansasOBS

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Are you sure the twitchy isn't from worn suspension/out of alignment/bad tires?

Did countless V8 swaps over the years, jeeps to jaguars, and just throwing whatever pump was on the shelf onto whatever. Always worked fine. My current obs was the EVO junk, and just connected up the factory 2004 LS pump, and pressure line, all fine there also.

Ive never owned anything new, or ever really owned multiple vehicles that I drove to compare back and forth, so maybe I'm just not as picky. GM did make some things differently through the years, as far as the flow through the valve, and pressures, but never really been an issue that flow kits were needed or whatever. Most of the differences were hydroboost related.
 

m002922

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Are you sure the twitchy isn't from worn suspension/out of alignment/bad tires?

Did countless V8 swaps over the years, jeeps to jaguars, and just throwing whatever pump was on the shelf onto whatever. Always worked fine. My current obs was the EVO junk, and just connected up the factory 2004 LS pump, and pressure line, all fine there also.

Ive never owned anything new, or ever really owned multiple vehicles that I drove to compare back and forth, so maybe I'm just not as picky. GM did make some things differently through the years, as far as the flow through the valve, and pressures, but never really been an issue that flow kits were needed or whatever. Most of the differences were hydroboost related.
The suspension is in excellent condition, as are the tires. I think the twitchy (which, to be clear, I didn't think was dangerous or anything, just not ideal - and of course I had to mess with it . . . ) was a result of the 1998 pump giving more assist, and without the functioning EVO it felt that way.

I, like you, am not particularly picky, but the truck is like a sail, and there were a few times where I got hit by big gusts of wind, reflexively corrected, and scared myself with the amount of correction I got. Obviously I didn't flip the truck or anything, it just felt more dangerous than it need to be. I also didn't think there was great steering feel - in general - on the highway at high speeds.

I think that is what the EVO was for (reduce assist at high speeds) - but maybe I don't understand what it was for exactly.

And honestly, if this is the tradeoff (until I figure out the issue - which - like you I believe is not a design issue - I think if these components were all operating as they should I wouldn't have the intermittent low speed issue, because it is intermittent), I'm OK with it. I do think the highway feel is much better than I remember it - and by that I mean it feels better than when the EVO was working, and MUCH better than when I assume the EVO wasn't working (and when I had it unplugged so I KNOW the EVO wasn't working).
 

KansasOBS

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I suppose a slight brain fart on my part here. Sorry I'm kind of stupid at times. Got to looking at things better, and realize yeah the speedway kit does basically supply the fitting at the back, and the EVO was the twitch. Apologize for wasting your time.

Komet may have been onto something, but just make sure the fluid is up after it sits. Increased turning at slower speeds could be low fluid, and foaming will make it seem higher than it is.
 

m002922

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Yeah, I'm going to keep driving it regularly and see if this kind of just works itself out (or, more accurately, the air works itself out over time). It may be as simple as that and I'm just crying wolf.
 

L31MaxExpress

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I don't know, I have driven my Express with the EVO unplugged for years and it feels much better driving wise than when it was new and had a properly functioning EVO. My Tahoe also steered well without any kind of flow reducing modifications. I went to a non-EVO pump when I put the 8.1L into it. That being said I like the 60s, 70s and 80s GM steering feel. They steer like a 1968 Bonneville.
 

evilunclegrimace

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decrease pulley size of either the drive pulley (if v belt , so probably the water pump or the water pump/crank) relationship to the ps pulley (so the ps pulley could be changed too) if this fixes your concern, you need to increase flow not decrease it. Modify your pressure with your flow control valve, which is where you bolt the hose in .
The flow control port does not affect the line pressure.
 

evilunclegrimace

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Choosing the correct restrictor flow rate is critical to having a steering system with a normal feel. Too much flow results in overly-sensitive steering feel. Too little flow results in stiff and unresponsive steering. A properly matched flow rate between the power steering pump and steering gear improves driver feel, road feedback, and steering sensitivity for the best driving experience.
For more information visit Turn One Steering online at turnonesteering.com.
 

tayto

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please post link of anywhere on that site that talks about flow rate. only thing i could find was pressure.
 
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