How Likely Is It That These Three Items Will Need Replacement When I Do Shocks?

[Scrappycrow]

Y'all,

I'm about to do the shocks on my '13 LTZ with ~200K miles. As per the title, how likely is it that #s 12, 13, and 15 will need to be replaced? If they do not look degraded while inspecting the assembly when it's in the vehicle, will that be an accurate assessment? In my experience with other vehicles, these aren't wear items, but I have no idea how they hold up on GMT 900s.

Yes, I do adhere to the "While you're in there..." philosophy, but I am also frugal and don't care to waste money unnecessarily. I will also be doing the work in a location where I won't be able to run out to a parts store and get the items, I would have to wait for a ride (it would be late enough in the day I might not be able to get them that day, and it'd be an extra 120 miles of driving for the person giving me a ride), so "Just go get them if you need them" isn't helpful.

Note that I am not asking about #14 (the bump stop) or #16 (the mount). Those are definitely wear items on every vehicle I've worked on and I will be replacing them no matter what.

Thanks,
Scrappy

 

[Joseph Garcia]

At 200k miles, your springs have aged. The choice is your, of course, but I changed my springs at 150K, and the new springs lifted my truck by 1/2".

#15 will most likely be worn and should be replaced, as it helps anchor the spring and avoid metal-to-metal contact.

If #12 looks good, reuse it, but it protects the exposed strut shaft and keeps dirt/dust off the strut's shaft, and thus minimizes the degradation of the shaft's seal.

 

[Scrappycrow]

Thanks for the suggestions. It's extra effort, but I guess I can drop the assemblies ahead of time to inspect the items more closely before I order parts.

The trim height* is within specifications and the rake is 1.00° forward as measured at the rocker panels*, so the springs haven't sagged any appreciable amount. Thus, I have already determined I will not be replacing them. Before anyone brings up spring rates, multiple tests have shown that while vehicle suspension springs will sag with usage and aging, undamaged springs (not impacted, not bent, not gouged, not rusted, etc.) do not lose spring rate; even if you disagree with this, the trim height being within spec indicates that the combination of sag and rate still fall within spec.

*As per charm.li: Home >> Chevrolet >> 2013 >> Tahoe 2WD V8-5.3L >> Repair and Diagnosis >> Specifications >> Mechanical Specifications >> Suspension >> System Specifications >> Trim Height Specifications
*No driver or passengers, no 3rd-row seats, full tank of gas.

 

[Joseph Garcia]

Thanks for the suggestions. It's extra effort, but I guess I can drop the assemblies ahead of time to inspect the items more closely before I order parts.

The trim height* is within specifications and the rake is 1.00° forward as measured at the rocker panels*, so the springs haven't sagged any appreciable amount. Thus, I have already determined I will not be replacing them. Before anyone brings up spring rates, multiple tests have shown that while vehicle suspension springs will sag with usage and aging, undamaged springs (not impacted, not bent, not gouged, not rusted, etc.) do not lose spring rate; even if you disagree with this, the trim height being within spec indicates that the combination of sag and rate still fall within spec.

*As per charm.li: Home >> Chevrolet >> 2013 >> Tahoe 2WD V8-5.3L >> Repair and Diagnosis >> Specifications >> Mechanical Specifications >> Suspension >> System Specifications >> Trim Height Specifications
*No driver or passengers, no 3rd-row seats, full tank of gas.

No argument coming from me, though I spent 20+ years in the primary/cast/forged/extruded/coiled metal products and metallurgy industry, and metal fatigue is real and inevitable. It is what it is, and certainly you do what you deem to be appropriate.

 

[OR VietVet]

The only metal that does not fatigue is the 1 oz. and 1.5 oz. double duty shot glasses that bartenders use.

 

[Joseph Garcia]

The only metal that does not fatigue is the 1 oz. and 1.5 oz. double duty shot glasses that bartenders use.

Well said!!!

 

[petethepug]

That’s a fact. Please be aware there may be a mug sliding down the counter your way, compliments of me.

 

[Marky Dissod]

As per the title, how likely is it that #s 12, 13, and 15 will need to be replaced?
If they do not look degraded while inspecting the assembly when it's in the vehicle, will that be an accurate assessment?

If #12, #13, & #15 can be removed and inspected by hand (not merely by eye),
that act alone will likely speak volumes about whether or not to reuse or replace them.

 

[Charlie207]

You should start juicing up the three nuts on top of each strut now, and make your life 2% easier when it's time to dig in.

What are you using to compress the coil springs? I rented two of these AutoZone kits at the same time, and used three compressors spaced evenly. The procedure went fine, but I definitely had my Safety Squints set to max.

 

[Scrappycrow]

You should start juicing up the three nuts on top of each strut now, and make your life 2% easier when it's time to dig in.

What are you using to compress the coil springs? I rented two of these AutoZone kits at the same time, and used three compressors spaced evenly.

Thanks for the suggestion on pre-juicing the nuts -- doing that kind of thing is already a habit of mine. Thankfully, I live in Georgia and the truck has been in Georgia since its original purchase and is essentially corrosion-free.

I am pretty wary of that style of compressor. I have an OTC 6494:

 

[Badge]

Do you have the Autoride Z55 or Z95 (not likely don’t due to year) or more specifically front electronic controlled shocks? Assume you do with an LTZ. If not, disregard this post (sorry). If you do have Z55/95, bite the bullet and buy new GM OEM struts and remake the assembly like mentioned above. Also, the parts diagram above doesn't quite look right for Z55; that top bolt would pass over the stem and there should be an electrical connector shown. IMO, you’re only going to do this job one more time (hopefully) so might as well replace 12, 13 and 15 as they are not expensive parts. If #15 is messed up and you can’t “see” it, you’ll assumably have fitment/alignment issues but wont notice it until breakage. I’d keep your old assembly for parts if needed for an extended while even after you replace them. The OEM boot is better that the replacements (covers more) and you wont likely be able to find new springs for that year. (I tried and tried). IMO absolutely SAVE your springs…I tossed mine after replacing with Duralast prebuilt assembly as that was the closest thing to OEM and I was lazy. Worst mistake ever. They failed multiple times out of the box. And when they did “work” at first (once) the top electrical connectors (the shock stem electrical, not the plastic connector) did not talk with the system so there was no real time dampening happening. Duralast and every look-up system/site will tell you the assembly will work, but it wont. It wont support the dampening, period. Finally got Duralast to fess up on that after they sent me 2 replacements. After taking new assembly’s on/off numerous times trying to determine why the ride was rough, seeing bad struts leaking, I ended up buying new OEM parts and using the Duralast Springs to make my own assembly. Runs good as new now. Key is the OEM shock (#10, make sure it’s the single version that will work) if you want your system to work as designed vs lift, remove dampening, etc. Lastly, agree on the concept of metal fatigue of course, but I also know the steel you’ll buy today is not the same manf. quality from 2013. I think it’s splitting hairs as the rest of the suspension will overcome any very very minor spring lag, assuming they visually inspect fine. I’d still bet on 2013 springs vs new ones as strange as that sounds. Ideal state would be to find new-old stock out there somewhere… Also, buy off Amazon a better coil compressor or find a rental that has the strap/link that goes across the two bars to keep them from flying off. And a thicker screw. Against instructions, i used a dewalt 60v 1” impact gun to tighten, loosing coils (slowly, evenly) and it worked great. Just my 2 cents based off lessons learned from taking the longest, hardest road possible to proactively replacing my front struts on my 2013 Yukon XL Denali 6.2, (Z55, w/rear air level, no Z95)

 

[Scrappycrow]

Thanks for the input, @Badge.

Yep, it's a Z55 setup. That diagram is just a parts diagram from GM Parts Direct, it's not an engineering drawing, so it doesn't have to be exact on the details. When you're on the parts page, the components associated with the numbered items in the picture have the proper configurations.

Also, buy off Amazon a better coil compressor or find a rental that has the strap/link that goes across the two bars to keep them from flying off. And a thicker screw.

I'm quite certain my OTC 6494 coil compressor is more than adequate for this project.

 

[alvocado]

I have the Harbor Freight version of your OTC clam style compressor and they work very well while being much safer than the rod style.

I recommend replacing the strut mounts (#16 here) since they have a rubber bearing which can wear,, especially at 200k miles. There is nothing more annoying than having new struts with a clunk or vibration from a worn mount. You should be fine with the other components in the assembly unless they show visible wear signs.

 

[Scrappycrow]

I recommend replacing the strut mounts (#16 here) since they have a rubber bearing which can wear,, especially at 200k miles. There is nothing more annoying than having new struts with a clunk or vibration from a worn mount. You should be fine with the other components in the assembly unless they show visible wear signs.

Thanks for the input. I did say in the last paragraph that I was going to replace those.