EVO Steering Bypass Kit From GM

Performance modifications, tips & tricks

Moderators: flyingpolarbear, Eric@PPE, VicC, James B.

JR96CK
Posts: 1519
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

You said you did the EVO kit... I'm wondering if the flow control fitting which comes with that (the one that threads into the back of the pump) has the same flow characteristics as the older non-EVO fitting I used. Curious what it would feel like if you had gone the retrofit route and used a pre-EVO fitting and 96 model pressure hose like I did.

Just a thought... perhaps try robbing a fitting off of a pre-EVO pump and swap that in... the existing high pressure line adapter in the EVO kit (the c-shpaed piece of tubing) should thread right into the older flow control fittings. That would be the only thing I would suggest at this point. Also, did you measure the thickness of the shims you added to the flow control valve? Would be curious what your total clearance is with the 4 shims. Stock clearance on the 99 Tahoe I was working on (GMT400 body) was .024" which was the same as for my 96 pickup.

98Blackss
Posts: 861
Joined: Thu Dec 27, 2007 12:14 pm
Location: Native TEXAN living in Colorado; 1998 K1500 RCSB stepside Escalade and GMT800 AWD conversion

Post by 98Blackss »

I went the retrofit route and used a pre-EVO fitting and 96 model pressure hose. It is still way over assisted. I did not know the GMT800's used EVO? A friend has a 2002 GMT800 truck and it is way over assisted as well, about like mine.

The only benefit I see from the EVO delete kit or retro fit is that I feel confident about pointing my truck down the highway and completely letting go of the steering wheel and knowing it will remain in the same forward heading position as when I let go of it! Absolutely could not even consider that with EVO.

I have noticed that after long trips my pump is whining now. A long time ago I had adjusted the gear with the nut and allen screw. I think I went about a 1/3 turn. That never seemed to do anything, but now with the EVO delete I wonder if that is part of the whining issue? The whining did not start until after the EVO retro fit. If I have to dig into the pump I will tryout the shim kit.

TJ

99bluetahoe
Posts: 634
Joined: Thu Apr 07, 2005 11:19 pm
Location: Fremont, CA 1999 2dr Tahoe 4wd, stock, awaiting engine transplant

Post by 99bluetahoe »

Just did the EVO bypass and threw in a new pump while I was at it.

First impressions are that it is still assisted too much. I haven't tested it too much but at low speed the assist is very similar to what it was before. What I did notice was that I don't have a steering jerk when I press the brakes anymore (hydroboosted). Ever since I installed the hydroboost, the steering would jerk a tad when I applied the brakes. Everything is nice and smooth now and it brakes a little better. I'm not sure if the new pump had anything to do with it or the fact that I now have a constant flow of steering pressure. When I did my hydroboost I installed a acdelco reman unit and it whined since day one. I couldn't stand it anymore so I swapped out the pump for a new acdelco hydroboost unit.

Pump part# 15909826
http://www.amazon.com/ACDelco-15909826- ... 782&sr=8-1
Under a hundred bucks on amazon for a new pump not reman.

I used the fitting that came with the EVO delete kit but I believe the fitting was the same that I removed from the new pump after comparing the two. I didn't use the u-bend that also came with the kit since I have custom SS braided steering lines and just flipped my hose end around.

Ridinlow
Posts: 354
Joined: Thu Mar 24, 2005 6:00 am
Location: Bham, Alabama

Post by Ridinlow »

at100plus wrote:I tried the EVO bypass kit last week after we scanned my computer with my mechanics new scan tool. He found that the EVO was reading fluctuating milliamps. The EVO override did little or nothing. (by the way one of the first things I did last year was replace the EVO sensor under the dash. That did nothing.

Then I read this and I tried 4 shims. This also made practically no difference.

I have a 2002 Tahoe, all front end parts seem tight when checked on the lift by 2 different mechanics. I just put new Bridgestone REVO II AT tires on (stock Tahoe size), and just had the alignment done.

I hate this overassisted 86 Cadillac feel but I love this truck otherwise. I'm spending money throwing parts at this problem and getting annoyed. I've been all over different Tahoe forums, have heard everything from tires to shocks to alignment to people adding an offroad steering stabilizer.

I think next I'll try a different steering pump, after that I'll try a stabilizer or a gear box. I really hope this steering system can be tightened up. Anyone REALLY been successful at getting a tighter controlled feel in their steering? I will say, when I first got the truck last year it had crappy tires, and it was all over the road when windy so the things I've done have improved it, however I am not at all satisfied with this over assist feel.

come on now, surely you like the ease of steering with 1 finger lol
that over assisted 86 cadillac feel is the business!

Whipped383
Posts: 2104
Joined: Mon Mar 01, 2010 9:12 pm
Location: Salt Lake, 97K1500,ECSB, 383,Whipple,0411,Marine, 03K2500,CCSB,8.1&Allison, Whipple in progress

Post by Whipped383 »

I did my conversion the same time I did a hydroboost swap but I used a fitting from an old pump I had sitting around and a 96 hose. I feel the same way it feels way over assisted at highway speeds but feels right when parking etc. It does feel alot better at highway speeds than it did with evo and I thought made the front end feel tighter. I have replaced every single part in my front end and it still feels loose even changed the steering gear.

99bluetahoe
Posts: 634
Joined: Thu Apr 07, 2005 11:19 pm
Location: Fremont, CA 1999 2dr Tahoe 4wd, stock, awaiting engine transplant

Post by 99bluetahoe »

Whipped383 wrote:I did my conversion the same time I did a hydroboost swap but I used a fitting from an old pump I had sitting around and a 96 hose. I feel the same way it feels way over assisted at highway speeds but feels right when parking etc. It does feel alot better at highway speeds than it did with evo and I thought made the front end feel tighter. I have replaced every single part in my front end and it still feels loose even changed the steering gear.
Which steering gear did you put in. I believe the steering gear of a 96 truck is different than the steering gear in trucks that came with EVO.

JR96CK
Posts: 1519
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

99bluetahoe wrote:Which steering gear did you put in. I believe the steering gear of a 96 truck is different than the steering gear in trucks that came with EVO.
Just checked this at Rock Auto...

AC-Delco shows #360517567 for a 99 Tahoe 2wd or 4wd (this would be an EVO-equipped truck).

AC-Delco shows #360517539 for a 96 Tahoe 2wd or 4wd (this would be a non-EVO vehicle).

Now... to figure what is different between the two boxes.

Whipped383
Posts: 2104
Joined: Mon Mar 01, 2010 9:12 pm
Location: Salt Lake, 97K1500,ECSB, 383,Whipple,0411,Marine, 03K2500,CCSB,8.1&Allison, Whipple in progress

Post by Whipped383 »

I just used a stock replacement for a 97 K1500. Id also like to note a friend of mine had a 98 K3500 witch I dont believe had evo but drove like a dream even with a 6 inch lift and 35s on it.

JR96CK
Posts: 1519
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

Whipped383 wrote:I just used a stock replacement for a 97 K1500. Id also like to note a friend of mine had a 98 K3500 witch I dont believe had evo but drove like a dream even with a 6 inch lift and 35s on it.

Stock replacement gearbox or pump? I was referring to the gearbox in the above post. Just want to clarify so as to avoid any confusion.

99bluetahoe
Posts: 634
Joined: Thu Apr 07, 2005 11:19 pm
Location: Fremont, CA 1999 2dr Tahoe 4wd, stock, awaiting engine transplant

Post by 99bluetahoe »

JR96CK wrote:
99bluetahoe wrote:Which steering gear did you put in. I believe the steering gear of a 96 truck is different than the steering gear in trucks that came with EVO.
Just checked this at Rock Auto...

AC-Delco shows #360517567 for a 99 Tahoe 2wd or 4wd (this would be an EVO-equipped truck).

AC-Delco shows #360517539 for a 96 Tahoe 2wd or 4wd (this would be a non-EVO vehicle).

Now... to figure what is different between the two boxes.
There is also the 6.5L Diesel version of the gear box. I believe these were equipped with hydroboost and without EVO.

AC-Delco shows #360517578 for a 98 Tahoe 2wd or 4wd (6.5L Diesel)

The above box is also used in the 98 K2500 Suburbans with the 7.4L. Can anyone confirm if the 97-99 CK2500 Trucks/Suv's were equipped with EVO together with hydroboost? Doesn't James now have a K2500 Suburban? Maybe he can verify.

James B.
Moderator
Posts: 2823
Joined: Thu Apr 03, 1997 4:00 pm
Location: '98GMT400, '98GMT410, '99GMT420, '00GMT420

Post by James B. »

Mine's got EVO.
1998 C2500 Suburban, 7.4L

99bluetahoe
Posts: 634
Joined: Thu Apr 07, 2005 11:19 pm
Location: Fremont, CA 1999 2dr Tahoe 4wd, stock, awaiting engine transplant

Post by 99bluetahoe »

James B. wrote:Mine's got EVO.
1998 C2500 Suburban, 7.4L
Does yours also have hydroboost? I wonder which steering box you have?

Whipped383
Posts: 2104
Joined: Mon Mar 01, 2010 9:12 pm
Location: Salt Lake, 97K1500,ECSB, 383,Whipple,0411,Marine, 03K2500,CCSB,8.1&Allison, Whipple in progress

Post by Whipped383 »

I replaced both the pump and the gear. It has to be in the gear all the trucks Iv drove without evo drive nice and all the ones with felt over assisted.

foreverfalcon40
Posts: 469
Joined: Wed May 06, 2009 10:35 am
Location: NY

Post by foreverfalcon40 »

I bought the fitting from GM ended swapping in a new pump and steering box. I don't know if you guys remember that fiasco! Also thru in a steering stabilizer. Rides like a dream, has a little side to side play. I wish one of you guys would come with a Rack and Pinion for these tanks!

JR96CK
Posts: 1519
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

foreverfalcon40 wrote:I bought the fitting from GM ended swapping in a new pump and steering box. I don't know if you guys remember that fiasco! Also thru in a steering stabilizer. Rides like a dream, has a little side to side play. I wish one of you guys would come with a Rack and Pinion for these tanks!
Someone actually brought that idea up a while back, but no one has ever gone ahead with it on a GMT400 (yet). I'm hell bent and determined to retrofit a rack and pinion on my 96 though, as I love the way the steering feels on the newer trucks which have it.

ThunderTT
Posts: 2845
Joined: Sun Apr 03, 2005 10:27 pm
Location: 97 ECSB 2WD 98 CCLB 2WD 00 Escalade 4x4

Post by ThunderTT »

JR96CK wrote:
foreverfalcon40 wrote:I bought the fitting from GM ended swapping in a new pump and steering box. I don't know if you guys remember that fiasco! Also thru in a steering stabilizer. Rides like a dream, has a little side to side play. I wish one of you guys would come with a Rack and Pinion for these tanks!
Someone actually brought that idea up a while back, but no one has ever gone ahead with it on a GMT400 (yet). I'm hell bent and determined to retrofit a rack and pinion on my 96 though, as I love the way the steering feels on the newer trucks which have it.
im torn with that thought

i think the rack has less feel for the road, too much pump assist perhaps, but just too easy to steer not just 1 finger, but pinky.....

i like a firmer feel......

JR96CK
Posts: 1519
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

VATS Fault Code

Post by JR96CK »

Just wanted to add this into this old thread so it's here for reference:

Something I just discovereed while messing around with EFILive... deleting the solenoid will not trip an MIL or cause any issues at all, but it does show up as a fault code when you scan the VATS module, as that is what controls the EVO solenoid (EFI Live can scan this module, but I've not been able to do so with HP Tuners). I have a screen shot I have been meaning to post about this, but have not had a chance to do so. I plan to measure the resistance of the old EVO solenoid and wire a resistor in place to get rid of the code on my mom's aforementioned Tahoe.

EDIT:

Just looked up my screen shot from EFILive. Here is the info:

DTC = C0503 - Steering Assist Control Solenoid/Motor/Actuator Return Circuit Low (Status HC)

Module: ($C0) Theft Deterrent Control Module (VTD)

Hog
Posts: 5036
Joined: Tue Dec 11, 2001 4:00 pm
Location: 1997 Chev ECSB L31 350 1997 GMC Sierra SLE RCSB, Ontario

Post by Hog »

Interesting info, thanks for posting.

Just a not, obvioulsy this would include the 1998+ GMT400 trucks as they are the fullsize GM trucks that are equipped with VATS.


I did this mod on my ecab 2wd and the steering feel is much improved, I like the predictable feel and dont miss the jumpiness and sense of loss of control when my stock EVO would overassist when turning.

peace
Hog

Chevy 97
Posts: 1076
Joined: Tue Jan 24, 2012 1:19 pm
Location: 97 ECSB K1500 6.3L 4L80E 14 bolt SF Hydro Boost, Headman Ellite Headers, 140 amp alt.

Post by Chevy 97 »

I bypassed that pump. When I changed to Hydro boost, I used a 2003 pump. I suppose when I get the 411 installed, I will have to delete that too. Since I no longer have that pump on my truck.

JMAC1977
Posts: 1
Joined: Sat Jun 01, 2013 4:30 pm
Location: Topeka Kansas

EVO Bypass

Post by JMAC1977 »

I just replaced the EVO control valve on my 1998 C1500. I replaced the valve with a bypass kit and also replaced the power steering pump and flushed the system. I have been bleeding the system but I'm not getting hardly any power assist in the steering. I have bled the system several times the fluid level is not falling anymore.When the system failed I went from a normal operating power steering to no power at all. Does anyone have any input on what my next step should be?

Post Reply