Z55 Oem replacement done- still rough ride?

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Denaliz

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Hey guys,

On my 2011 Yukon Denali -i just wrapped up replacing my z55 front struts, (entire coilover assembly,all parts including springs) as well as my rear shocks last summer. Front is oem ac delco/gm, rear was the Arnott rebuild ones. Confirming this is not a passive conversion but a full z55 replacement of all 4 corners.

I’ve had the front end parts all replaced as well (bushings, end links, inner/outer tie rods, control arms, ball joints.. etc) and upgraded to Eibach sway bars.

I’m not throwing any codes , compressor runs and turns on with no issues that I can see, but the ride is still for shit imo. I’m the original owner and absolutely know what it’s supposed to feel like but I’m baffled here lol..

All 4 tires all new as well. The only thing I can possibly think of is the garage that handled the install of the front ac delco 580-434/ GM# 19300039 the part# has changed over the years ) coilover struts, may not have recalibrated the suspension system in the ecm? I’m going to have it hooked up tomorrow and checked with tech 2.

Anyone have any thoughts or suggestions?
 
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Denaliz

Denaliz

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Typo/ corrected- thx I missed that . The point I was making is it’s not a parts issue an aftermarket or passive- gm replacement ac delco parts were used with correct rpo codes(my phone keyboard hates me.. )
 
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Denaliz

Denaliz

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How did the ride feel before you replaced all the shocks/struts, and for how long?
Felt worse with aging of the suspension system. It wasn’t a daily driver for last 4 years. once the rears were shot I replaced and front struts done a couple months ago when I finished refresh
 

swathdiver

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Hey guys,

On my 2011 Yukon Denali -i just wrapped up replacing my z55 front struts, (entire coilover assembly,all parts including springs) as well as my rear shocks last summer. Front is oem ac delco/gm, rear was the Arnott rebuild ones. Confirming this is not a passive conversion but a full z55 replacement of all 4 corners.

I’ve had the front end parts all replaced as well (bushings, end links, inner/outer tie rods, control arms, ball joints.. etc) and upgraded to Eibach sway bars.

I’m not throwing any codes , compressor runs and turns on with no issues that I can see, but the ride is still for shit imo. I’m the original owner and absolutely know what it’s supposed to feel like but I’m baffled here lol..

All 4 tires all new as well. The only thing I can possibly think of is the garage that handled the install of the front ac delco 580-434/ GM# 19300039 the part# has changed over the years ) coilover struts, may not have recalibrated the suspension system in the ecm? I’m going to have it hooked up tomorrow and checked with tech 2.

Anyone have any thoughts or suggestions?
19300039 is a valid number but it does not come up for a 2011 Yukon Denali. Look at your RPO Sheet for your 6XX and 7XX codes and then plug your VIN in here to verify:


Now, when the struts were replaced, did they replace all of the ancillary parts too? This can definitely contribute to a poor ride as well. Definitely get the Tech-2 on it and let us know.
 

Joseph Garcia

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As @swathdiver suggested, a Tech 2 or equivalent is required to see what is actually going on within the suspension's electronic components. Without that, you are simply groping in the dark. No adjustments or reprogramming are required for the ECM for a simple replacement of Z55 components with new Z55 components. No adjustments or reprogramming are required for the ESCM for a simple replacement of Z55 components with new Z55 components. However, since the coil springs were replaced in the front struts (complete new struts), I would recommend a recalibration of the Auto Level Control (ALC) in the ESCM, as the ride height in the front may have changed with the new coil springs, and a Tech 2 or equivalent is required for this procedure.

Perhaps, you can explain in greater detail what you mean when you say that "ride is still for shit imo", so that we can better understand what you mean by that. What in the suspension's ride characteristics is wrong or missing.

Also, when I replaced my front suspension on my '07, I was advised that GM no longer makes the front coil springs for the Z55 strut assembly, so I had to get alternate front coil springs when I built my front strut assemblies. Perhaps, GM still makes the front coil springs on the '11 model year, even though the '07 and the '11 are both NNBS bodies, though I would think that may be unlikely. So, I wonder about the claim that the front strut assemblies are "oem ac delco/gm".

The Eibach sway bar installation will definitely affect the ride of the truck, but it should not be in a negative way. My Hellwig sway bar installation definitely impacted the ride in my truck, but again, not in a negative way. However, the Hellwig sway bars definitely reduced the amount of second-to-second shock/strut electronic dampening changes required from the ESCM as monitored by my Tech 2 in real time, as the Hellwig sway bars managed much more of the roll prevention while driving.
 
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Denaliz

Denaliz

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The gm coil springs are discontinued so I went with a moog aftermarket designed for my year and make.

Yes the entire coil over assembly with all gm parts we’re used excluding the moog springs and strut mount which was oem aftermarket. My new struts and shocks are actually under warranty from AcDelco and Arnott for the rears.

Usually you’d throw a code I assumed but I’ll make time and have it hooked up to tech 2 to go thru the motions.
 

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