OEM spring rates?

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Capybarbro

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2018 Tahoe Premier 6.2L RST with Magneride.

I bought the truck with 76K miles on it and from what I remember it rode fine no complaints. Well last month (~113,000 miles on truck now) I took it in for the annual state inspection and they said my shocks are leaking. From that moment on, it "broke the glass" for me and I couldn't focus on anything except for how harsh the ride was.

Last Thursday I replaced all the shocks with OEM. The ones I pulled out were leaking like a sieve and I thought, wow the ride is going to be so much better with fresh OEM magneride shocks. Low and behold, the ride didn't change at all still has stiff and bumpy as it was. So I took out my trusty Foxwell NT510 Elite to recalibrate it. There is a setting in there titled "Suspension System Mode" and mine was originally set to "Sport". After I recalibrated it, it is now defaulted to "Normal" and I can't figure out how to change it again with this scanner.
IMG_2640.jpg

I feel like this may have softened up the ride slightly but not enough for me to rule out placebo. If I didn't know I had switched it from sport to normal I likely wouldn't have felt any difference. On the scanner I can see the live mA going to each shock and they all hover around 0 to -10 mA while stationary and then jump all around to positve numbers with the front being similar and the back being similar. Everything appears to be getting and receiving commands as it should.
IMG_2639.jpg


Before I replaced my shocks I was contemplating bypassing the system and putting in regular gas shocks. My father has a '25 High Country Suburban with 52,000 miles, also with magneride. I took that for a spin before deciding what to do. His ride was soft and nice and I thought, yeah OEM magneride is the way to go.

Lastly, I found this Car and Driver Article that talks about spring rates. Ironically, the Tahoe in this article is SPECed out EXACTLY like mine down to the dealer installed Borla (minus the dealer installed Brembos and mines black). Here's the spring rate quote from the article "Chevy backs off on the suspension’s spring rates, softening the fronts from 610 to 560 pounds and switching the rears from a variable-rate spring (250/445 pounds) to fixed 245-pound units". Visually, my rear springs do not appear to be variable-rate. It looks like the same coil pitch all the way up and down the spring.

I know the High Country is the plush model and the RST is the sporty Tahoe, but how can I get close to that ride quality?
1. How much tuning can be done within the software and what the process?
2. Would going even softer on springs help?
3. Is there more than a ride height calibration?
4. Is there another issue I'm not even considering? I saw there was another fella with a rough ride post talking about throwing the kitchen sink at his front end and I'd rather not do that, my bushings look fine and nothing has play.

Old Shocks-
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Capybarbro

Capybarbro

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I figured it out the spring rates. As I'm sure most of you know, the RPO codes that start with 6 and 7 are your front spring rates (haven't figured out rear yet) maybe someone else will chime in.

My specific codes are 6ZP and 7ZP. I took that information to RockAuto and found out my springs are 560PPI just like in the article I linked.

I found a random '25 Suburban High Country for sale, jacked the VIN off the website and found out it's RPO code is 6WL and 7WL. Again, took to RockAuto, the Burban High Country is rocking 682PPI springs in the front. Way stiffer.

It makes me think the ride difference is all in how magneride is tuned.

I did find softer springs at 515PPI that came with codes 6ZC/7ZC. Does anyone know what set up that would have traditionally come with? My fear with just throwing on softer springs is that magneride won't be tuned for it and it might throw everything off even more.
 
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Capybarbro

Capybarbro

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RPO Code. Spring Rate. Installed Ride Height guide (as per Rock Auto).

Looks like there are only 3 rear spring rates based on packages.
Z95- 243PPI Ride Height 12in
Z85- 256PPI Ride Height 12in
ZW7- 251PPI Ride Height 12in (Smooth Ride Package)

--No Spring rate or installed height listed. Free Height- 12.76in
6XL/7XL, 6B1/7B1, 6PY/7PY, 6SP/7SP, 6WR/7WR, 6HH/7HH, 6HC/7HC, 6XL/7XL

--Spring Rate 119KPI Installed height 17in
6SY/7SY, 6A5/7A5), 6C6/7C6, 6CS/7CS), 6NY/7NY, 6SJ/7SJ, 6ZA/7ZA, 6NR/7NR, 6UU/7UU, 6H2/7H2


--560PPI Ride Height 9.44in
6NT/7NT, 6NC/7NC

--560PPI 9in
6ZN/7ZN

--550PPI Ride Height 9in
6ZD/7ZD

--600PPI 9in
6ZP/7ZP, 6ZS/7ZS, 6ZR/7ZR

--600PPI Ride Height 9.44in
6PA/7PA, 6NU/7NU

--515PPI Ride Height 9.44in
6NB/7NB

--515PPI 9in
6ZC/7ZC, 6YR/7YR

--540PPI 9.4in
6JW/7JW, 6RM/7RM, 6YW/7YW, 6JU/7JU, 6RN/7RN, 6YX/7YX

--612PPI 9.4in
6XM/7XM, 6A9/7A9, 6WN/7WN

--612PPI 9.6in
6ZK/7ZK, 6TJ/7TJ, 6GL/7GL, 6HA/7HA, 6HD/7HD, 6GP/7GP, 6US/7US, 6TD/7TD, 6XU/7XU

--682PPI 9.4in
6A1/7A1, 6C3/7C3, 6CR/7CR, 6NM/7NM, 6WL/7WL

--682PPI 9.6in
6SX/7SX, 6YZ/7YZ. 6ZZ/7ZZ


I tried to make a complete list but the numbers in the rock auto listed started getting wonky. Anyway just go to RockAuto and go to suspension-coil Springs then "CTRL-F" your RPO number if it isn't listed here. I tried to make a comprehensive list...
 
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