Mainting "Z" Height with Torsion Key Lift (leveling kit)

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Maxclass

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None of the posts on this forum seem to address maintaining "Z" height when leveling the Tahoe. Not only that, but YouTube ignores this concept too.

Fact: My Tahoe has a disclaimer sticker on the crossmember holding the keys that states when installing aftermarket keys ensure the "Z" height is correct or it could cause the front shocks to come lose, dislodge the break line, causing a crash (paraphrased). However, my leveling kit instructions do not mention checking "Z" height, only measuring the fenders for levelness with back fenders. However, the Haynes manual states affirming "Z" height is within spec. Per Haynes manual it should be 4.7".

My scenario:

Front end was raked downward causing a sag that was extremely cosmetically off putting. Checked the "Z" height before install of new keys and it was way under, liked around 3.5" or less. While cranking the existing factory keys was an option, instead I opted to replace them with aftermarket keys for a slightly higher lift with the intention of leveling the truck's front end with the rear.

Reviewed Rock Auto and found the Southern Truck 1.5"-2.5" leveling kit to be ideal:
https://www.amazon.com/gp/product/B00PYDFEOU/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

Before Keys:
FL = 34 3/8
FR = 35
RL = 38
RR = 38 3/4

After Keys:
FL = 39
FR = 39
RL = 38 1 /2
RR = 38 1/2

"Z" Height was off the charts, around 7".

The above measurements were after installing the 1.5"-2.5 leveling torsion bar key from Southern Truck at the same thread count of 1" of both sides as originally installed. (I marked the torsion bar point before removing the old keys so to keep the same angles as before.)

Main worry: Leveling my truck with the back end, at 38 1/2 would cause my "Z" height to be out of the defined range in the Haynes Manual. How can I keep the truck level while maintaining "Z" height as specified in the manual?

Pictures are of the OEM key compared to the after market keys and the before leveling kit installed. I will post pictures of the after leveling kit once I figure out what I will do. I am very happy with the keys install, but I am anxious about the "Z" height measurement being out of sync with the manual.

IMG_4589.JPG IMG_5116.jpg IMG_5120.jpg
 

Alex33

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This is an interesting question but my question to you is "what is 'z' height?" How is it measured and what are the effects of being out of range (over or under spec)? I imagine that without this info you won't find too many people with the answer you need.
 

Chubbs

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back off a full rotation on the TK bolts, bounce the front suspension a few times and determine the progress made back toward an acceptable Z-height
 
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