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EVO Steering Bypass Kit From GM
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I got it from AutoZone, vato-zone because mostly mexicans work there.

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Hello folks,
I am new here but have read this thread a couple of times. Let me share with you to see if you can help me.

I recently purchased a 1998 Chevy 3500 with big block and hydoboost. It also has the EVO steering system. The truck only has 110K on it. I purchased this truck to pull my travel trailer. I noticed when I was driving it home after I purchased it that the steering felt really off. It appeared to have some play in the steering and was really to easy to react when turning the wheel. At highway speeds(65-70)it is really nerve racking. I bought the old truck knowing I would have to do some work to it to make it road ready. So I have spent the last month or so working on it. One of the first things I did was put new tires on it. Before I did that I checked out the front end to make sure all parts were good. I had to replace the front wheel bearings and brakes. I also put a reman gear box on it as it appeared to have some play in it. Everything else looked and felt good.

I then took it to get the new tires and have the front end aligned. Even though it still felt there was the same play in the steering and it was to easy to steer. I asked the guys doing the front end alignment to check and make sure all was good. When I picked it up, they told me it all looked good except the gear box had some play in it.

So I pulled it back off and returned it to Napa and they warrantee it for me. When I put it back on it did not make a difference in the play, it is still there. BTW, the rag joint is tight.

So this past weekend I decided to hook the trailer up and go camping. I will tell you that is the worst white knuckle ride I have ever been on. It would drive straight down the road but if a big rig past me or I past one it was all I could do to keep it between the lines. With what felt like the play in the steering and the fact that it was to easy to steer just made it almost undrivable. I could almost live with the play if it was not so quick to react when I was trying keep it in the road.

I have not noticed the twitchy feeling that has been talked about in this thread it is just easy steer all of the time.

So in reading this thread it appears that I need to change everything to a 96 model without the EVO system.

I have no leak and everything looks to be sealed up good. So if I keep the same pump and just change the Flow Control fitting to the GM #26009894 and the Flow Control Valve to the GM #7809221 will this be ok?

Look like I will need a pressure hose for the 96 model as well. Gates #353950.

If I change out the gear box again and it is changed out to 96 model without the EVO system I should not have to reshim the Flow Control Valve correct? Does anyone know what the gear box part # is for this? Is it the same as the 1/2 ton

If I do all of this do I just leave the wheel position sensor unplugged under the dash?

I am asking these questions because it appears that what it being talked about most in this thread is the 1/2 ton models. Will this same mod work on the 3500 as well?

If I can not fix this I will be getting rid of this truck and buying something different. I can not pull a 11000 pound trailer with the steering the way it is.......not and enjoy the trip!

Thanks in advance for any help I can get!

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Another thing that can make it worse is not enough caster in the alignment. Most shops are to lazy to adjust it because of the work involved. A buddy of mine was complaining of the same thing on his truck and after a good alignment by someone who knows what they are doing says the truck drives good. I am going to try and get mine aligned before I change my box on mine. There are also frame knockouts on the upper control arms that most places don't like to deal with when they align.

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The guys did tell me is was so far out that they had to knock out the slots to get it right.

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Sounds like your really need to get that EVO crap out of there.

Its a good sign that the truck goes straight down the road. But once disturbed by a passing truck, things get hairly.

Have you tried unplugging the EVO? Just curious as what full assist woudl feel like in a 1 ton?

Good luck.

peace
Hog

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Yes I did unplug it and it made no difference. I think it is at full assist already..

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With it unplugged it should be full assist all the time. I would talk to your parts store and see if they will warranty your gear for a non evo one. That's where I would probably start.

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Do you know if there was both options in 1998? I see folks are changing them out with 1996 models but most of what have been reading on this topic is dealing with 1/2 tons. Is the 1/2 ton and 1 ton gear box the same?

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I would look into it but I just looked up a 97 k1500 and k3500 and it showed the same part number whereas a 94 showed a different part number but all the physical dimensions are the same

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Thanks! Do know if 1997 had the EVO system?

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GSECowboy1 wrote:
Thanks! Do know if 1997 had the EVO system?

Yes they did, all mine do 2wd and 4wd. 1996 didnt, thats why everyone advises the 1996 and older parts, if they dont want to you GM's EVO bypass kit, which is my personal preference.

peace
Hog

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I am going to try the bypass kit first and see what that does. If that don't work, I am going to get the parts store to warrenty the gear box. But when I do that I want to get the right one.(one for non-EVO that will work)

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GSECowboy1 wrote:
I am going to try the bypass kit first and see what that does. If that don't work, I am going to get the parts store to warrenty the gear box. But when I do that I want to get the right one.(one for non-EVO that will work)

So far as getting the correct non-EVO parts, all the 1996 stuff will have you covered.

peace
Hog

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Thanks Man!! it's going to be a week or so before I will get to work on it again but I will keep you posted.

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Gents, rookie to the forum and thread here. This may be a silly question, but has anybody checked to see if a different diameter pulley is available, as in an under drive type setup? Couldn't less rotation result in less pump output without changing valves or adding shims? Would need to buy a slightly shorter serpentine belt, but that sounds much simpler to me. I have a 99 K1500 Sub with 148k, just replaced my PS pump with an AC Delco 99 brand new pump and new hoses. Cleaned the whole EVO valve assembly before transferring it on to the new pump. So far, the steering feels better but still a bit twitchy at highway speeds. I have a brand new steering gearbox from Summit, thinking that would be my next step.

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BDBoss wrote:
Gents, rookie to the forum and thread here. This may be a silly question, but has anybody checked to see if a different diameter pulley is available, as in an under drive type setup? Couldn't less rotation result in less pump output without changing valves or adding shims? Would need to buy a slightly shorter serpentine belt, but that sounds much simpler to me. I have a 99 K1500 Sub with 148k, just replaced my PS pump with an AC Delco 99 brand new pump and new hoses. Cleaned the whole EVO valve assembly before transferring it on to the new pump. So far, the steering feels better but still a bit twitchy at highway speeds. I have a brand new steering gearbox from Summit, thinking that would be my next step.



You want a bigger pulley on the pump? Then that would be a longer belt. March does make an 25% under drive for the crank, dunno about the pump.

Dunno the specifics of the steering hydraulics but logically, with an under drive, there would be less volume but the pressure assist would still be the same and therefore feel the same. Possibly a slow assist at low rpm yet when the engine is sped up, you would't see a difference in power assist from a normal pulley set-up. I don't think t that's a go.

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Yeah, sorry I reversed the belt length. Just wondered if somebody had tried that. My next step is to change out my steering gearbox.

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BDBoss wrote:
Yeah, sorry I reversed the belt length. Just wondered if somebody had tried that. My next step is to change out my steering gearbox.


No prob, I don't recall anything on this specific way to go about it.

Like I said, I believe the assist is pressure regulated so an under-drive would not change anything as it is not affected by RPM.

If it was, parking would be hell and downshifting to pass someone would result in an over-assisted steering. And that's just not the case.

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Cool. I appreciate your response and the info. Lots to filter through on this issue.

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hey y'all. i set up an account to post comments on the topic of the power steering bypass option for chevy trucks.

i have a 1997 k1500 i bought in 97 with 4000 miles on it; it now has 295,400 and i still drive it every week. i have experienced the same things others here have said regarding the feel in the wheel, especially when making long, sweeping left hand turns. the feeling is like hitting a little patch of ice/too much assistance from the power steering pump/twitchy, inconsistent response/wandering at freeway speed from the steering wheel to the tires, or maybe vice versa. sometimes it happens on right turns, but mostly lefts. not at all fun when coming down a mountain road with a load of camping gear and a boat in tow.

i first noticed this condition in 2004 or 2003 and just had it fixed this week (12-10-2015) thanks to member JR96CK for his post on this topic because the thread and following comments was what steered me to the solution that worked. i tried power steering pumps, steering gear boxes, an alignment (which identified a worn pittman arm), front differential service, inspection by my suspension guy and probably some other stuff i have forgotten about.

i was all set to try a new steering wheel sensor and do the EVO bypass when my mechanic said the sensor was a bad idea because it was designed to control the EVO, which we were about to bypass anyway. i agreed and he just did the bypass.

now, i was somewhat expecting the feel of the steering wheel to be super tight or stiff or something remarkable like that. it's not. really, it's not any different feel than before. the difference is that the wandering/ice patch/too much power steering feeling is gone and now instead of spending my time correcting the wander of the truck, i'm actually steering it down the highway.

feels good to have my truck back after 12 years of this BS steering nonsense. here's to another 300 thousand miles. and thanks to this forum and JD96CK whoever he is....


mike

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