For those with years on a Z71/4x4 and 2" lower strut level spacer only - any CV/Shock/boot/etc issues?

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19TahoeZ71

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Hey y'all,

I've read a ton of articles and watched far too many videos on the subject and have come to the following understandings regarding a 2" Rough Country red bottom strut spacer level kit I have and want to install but haven't yet. None of what I've researched really addresses this specific aspect, but there is a lot of general hypotheses. What I'm looking for is those who have years of experience running a setup like this, and what wear/tear it may have caused or had probability of contributing to regarding the below informational points. I want the look of the spacer, but not at the expense of other mechanical issues potentially caused by it.

1) Adding a bottom strut spacer usually affects ride and suspension quality.
2) It may also add to strain and non-spec load/geometry in suspension when cornering, fully extending, etc.
3) The above may also lead to premature problems with CV boot, strut/spring, and associated suspension components.
4) On the 4x4 models, the axle boot may rub on the bolt head under max compression of the strut assembly/spring. I'd be installing bolt-down (bolt head on top).
5) However, keeping the bottom strut spacer at a 2" or less total level (meaning 1" spacer height) should/does mitigate most if not all of the above points due to it being a minimal increase.

My specific factors are:
1) 2019 Tahoe Z71
2) LT285/60/R18 BFG AT TA/KO2 tires (ride and suspension seems great to me, really not much different, if any, from stock. Gas mileage did suffer a bit.)
3) No "real" off-roading done. This is my around-town vehicle and the one we use for family road trips, often to mountains. We'll often drive along bumpy off-pavement roads and whatnot, but nothing that really flexes the suspension like a true off-road path rock crawling path would. 4x4 mainly gets its use from winter driving when road tripping in the winter.
4) I don't tow and no plans to do so, but if I ever do with something heavy, I'd probably install rear airbags anyway.
5) Regarding vehicle load, the most weight expected is roughly 760 - 850 pounds total cargo/persons (two adults up front (350lbs total), two kids behind, third-row folded down with a medium dog, and usually a Thule XXL roof box with less than 100lbs of luggage etc inside. If we're traveling heavy and camping instead of renting/hotels, will also have a steel tow hitch cargo carrier with less than ~100lbs - 150lbs in load, and the carrier is 70lbs). I'm expecting there may be a little rear sag with the cargo carrier, but not sure without. Maybe there wouldn't be any at all. I've towed a 7k 30' travel trailer with weight distribution/anti sway hitch and the sag leveled out with the front nicely.

Am I way overthinking this with a 2" lower spacer? I'm an engineer so that comes with the trade. I just don't want to cause issues with the steering/suspension by adding this instead of a proper lift kit. Thanks in advance, I appreciate any guidance.
 

jthoske

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I had a 2” spacer on my 2018 Silverado Z71 and hated it. But ultimately I think the issue was the awful Rancho struts that came on it. I took it them all off at 40k miles and put Bilstein 5100s all the way around. Very happy with how it drives now. I have the front strut in its highest 1.85” setting and it’s perfect for me. Plus no more spacer if you’re worried about CV axle angles.
 

Tiki

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2” spacer on my GMT900 for years, no issues. Bilstein replacement struts with 1.25” lift for years, no issues. I find that having large offset/wide heavy wheel & tire package is a bigger killer of front end parts. I’ve replaced wheel bearings on two leveled vehicles after 6+ years of ownership; I can’t wholeheartedly say that their failure was solely attributed to leveling kit as it is very plausible that they were at or near their service life when they began to fail.

Your overthinking it, from an over thinker.
 
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19TahoeZ71

19TahoeZ71

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I had a 2” spacer on my 2018 Silverado Z71 and hated it. But ultimately I think the issue was the awful Rancho struts that came on it. I took it them all off at 40k miles and put Bilstein 5100s all the way around. Very happy with how it drives now. I have the front strut in its highest 1.85” setting and it’s perfect for me. Plus no more spacer if you’re worried about CV axle angles.
Thanks, I'll keep this in mind down the road. I don't know the brand of the red struts used in my 2019 Z71, but they seem fine so far on road driving. If I start doing any real off-roading and flex things out, or if road driving changes, I like the idea of stock gap between the axle and strut bolt with the Bilstein's. I've got 47.5k miles on it now, so probably will change those out by 100k anyway.
 
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19TahoeZ71

19TahoeZ71

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2” spacer on my GMT900 for years, no issues. Bilstein replacement struts with 1.25” lift for years, no issues. I find that having large offset/wide heavy wheel & tire package is a bigger killer of front end parts. I’ve replaced wheel bearings on two leveled vehicles after 6+ years of ownership; I can’t wholeheartedly say that their failure was solely attributed to leveling kit as it is very plausible that they were at or near their service life when they began to fail.

Your overthinking it, from an over thinker.
Thanks for the reply, and the confirmation about over thinking things. I do that to an extreme when I think about my family being in the vehicle with me especially.
 
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19TahoeZ71

19TahoeZ71

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I appreciate the replies, thanks! I didn't notice them until today, but I did go ahead and install the kit yesterday. Pics included. Love the new look. Took a bit longer than expected, but I guess that's to be expected when you're doing things the old-fashioned way and using the factory bottle jack and jack stands. My floor jack wouldn't go high enough, doh!

Some notes for anybody else doing this on their 2019 Z71, and a follow up question:

I did buy beforehand 3” grade 8 bolts to use instead of the grade 5 (metric 8.8) included with the RC kit. Some reviews said that was the length on this model to get. Factory bolts were metric 10.9, which is grade 8 equivalent.

3" was too short.

So, I used the grade 5 bolts since everything was up and taken apart already. Worked fine on install to factory torque, have driven it a few miles.

I also had to put one bolt (inside driver side) inserted up with nut on top because I couldn’t get the 4WD axle out of the way enough without loosening the lower control arm too. Passenger side was fine. All others are inserted down. I’m thinking this should be fine especially since the nuts are nylon locking. Didn’t cut any excess off on that one because it wasn’t extending up much past the nut and the axle still had a little clearance while the front end was jacked up and suspension extended down not connected to the upper control arm. Can’t imagine I’d flex the left side with that much extension in real use to where the axle would actually hit the bolt. The bump stop would probably stop that first anyway.

Lastly, regarding the sway bar, you can't simply re-assemble it while the front end is in the air. Or, at least I couldn't find a way without a special tool. With both sides disconnected, couldn't close the gap that the leveling spacer added by it pushing the lower control arm down, and there was a good 1"+ gap there between the sway bar and lower control arm. I tried using the floor jack to bring the lower control arm up a bit, but it started lifting the vehicle off the jack stand, so that wasn't going to work. I also tried a pry bar in the usual manner, no luck. I think my struts are still very good after 47.5k miles, they didn't want to budge or compress at all. I ended up not attaching the sway bars, putting everything else back together (it mostly was already), re-attaching the wheels and lowering the vehicle down. The weight of the front end closed the gap absolutely perfectly and I was able to get the sway bars re-attached without problem. The extra ground clearance helped that, which was nice. I hand tightened it, drove back and forth a couple hundred feet, then tightened it down fully.

The question:

EDIT: No question anymore. I did contact Rough Country about the grade 5 bolts and what their reasoning was for including those, and the reply was that they found the grade 8 bolts to be overkill. I asked for any use cases or metrics they have to show how the tension on the bolt didn't need more than grade 5 specs, no response yet. That was last week. I already purchased and installed class 10.9 (grade 8) bolts, lock nuts, and washers from McMaster-Carr so the grade 5 are out.

Sizes you'll need for anybody wondering:

M10 x 1.5 x 85mm class 10.9 Bolts
M10 x 1.5 class 10.9 lock nuts (go with the 10mm height, I did 11.5 and they are barely within spec, only one thread showing past any contact points at the end of the nut. I may still replace with 10mm height)
M10 class 10.9 washers (they're slightly larger than M10, but sold as such)
 

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