Shocks/Struts confused!

MPB

Original poster
Member
Feb 26, 2023
27
New York
I have a 2006 Chevy trailblazer which I’m considering installing new shocks and struts in. The RPO code in the glove box says (ZW7) Premium smooth ride suspension, when I looked that up it says it supposed to have Nivomat self leveling monotube shocks, when I look under my truck it has the old Bilstein B4 shocks and struts from the factory, I did a little more research and found out that Nivomat shocks are installed in suburbans and Tahoe‘s but mentions nothing about trailblazers, what’s going on here? Anybody know? I was also thinking about putting in Bilstein 4600s but I’ve heard good and bad. I heard they’re great for stability and handling but ride rougher than OEM? any info on that also would be appreciated. Thanks
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,989
Tampa Bay Area
Welcome to GMT Nation ....

This is an Old Thread, so the product links may not be current...but the information may prove useful:

 

Mooseman

Moderator
Dec 4, 2011
25,671
Ottawa, ON
Although I have no idea of the RPO code, the only premium ride that came on this platform was a rear airbag system that did auto level using a compressor and sensors. The front struts were essentially the same as the regular ones except for possibly different valving for a smoother ride. It's likely that the RPO code ZW7 is also used for the GMT360 however is a different configuration than other platforms.

A lot of times, when the rear system failed on these trucks, they were replaced with regular shocks and springs as replacing the failure prone bags and compressors were expensive. If you look in the rear, look for a left side compartment that you can open where you will likely find the compressor hookup and switch to inflate tires.
 
  • Like
Reactions: MPB

MPB

Original poster
Member
Feb 26, 2023
27
New York
Although I have no idea of the RPO code, the only premium ride that came on this platform was a rear airbag system that did auto level using a compressor and sensors. The front struts were essentially the same as the regular ones except for possibly different valving for a smoother ride. It's likely that the RPO code ZW7 is also used for the GMT360 however is a different configuration than other platforms.

A lot of times, when the rear system failed on these trucks, they were replaced with regular shocks and springs as replacing the failure prone bags and compressors were expensive. If you look in the rear, look for a left side compartment that you can open where you will likely find the compressor hookup and switch to inflate tires.
Thanks for the response, I am aware of the air ride system that comes on some of the trailblazers, mine just has the regular old skinny black Bilstein shocks and struts that came on most of these from the factory, I was just wondering why I have the RPO code (ZW7) for the premium smooth ride package which says comes with Nivomat self leveling premium smooth ride suspension, I guess they’re actually only put on the suburbans and Tahoe’s. Thanks
 
Dec 5, 2011
578
Central Pennsylvania
I think you missed the point....
I have airbags. I know I have airbags. I also know that my rear shocks look nothing like struts. You can't confuse them. There is a difference in "feel" for a rear air-bag suspension vs a rear "sprung" suspension. My rear shocks are shot, completely shot. But with the air-bags, it rides very much like a "sprung" suspension with decent shocks. That's one of the reasons I haven't replaced my rear air-bags. Multiple shock specs are different between air-bag shocks and coil-spring shocks.

It may be helpful to verify which suspension type you have in the rear. Unless you're the original owner, there is always a possibility that something was changed/swapped/retrofitted that you aren't aware of. I'm virtually certain you'll find you have air-bags as I have the same RPO code and I'm convinced it's for "ECAS" or "Electronically Controlled Air Suspension". ECAS 100% only applies to the rear suspension. The rear shocks intended for this suspension are different than those used with coil-spring suspensions. A cursory perusal of RockAuto's shock offerings suggests an inch difference in OAL and total travel in coil-spring shocks vs air-bag shocks.

If you find that you have air-bags under the rear, you'll want air-bag spec shocks. If you have coil-springs under the rear - likely the result of a retrofit - you definitely want coil-spring spec shocks.

I used to be an old-school offroader so I'm still a huge Rancho fan. Rancho actually offers their RS5000 shocks for this platform. They have 2 variants: one for coil-springs, one for air-bags. Different part numbers, different OAL, different stroke, and different damping.

I also recently completely rebuilt my front suspension including upper and lower control arms, and struts. The struts I got were the absolute cheapest that RockAuto carries. The difference was like night and day. New cheap struts beat worn-out top-of-the-line struts hands down.

As for "ZW7 means Nivomat shocks".... no. Not on a GMT360. No such animal exists. ZW7 means Nivomat shocks on the much larger and considerably heavier Yukon/Tahoe platform. The telltale sign for Nivomat shocks is that there is wiring TO THE SHOCK. The "air suspension" portion of a Nivomat shock setup is entirely self-contained within the shock. Nivomat shock suspensions also include lighter coil-springs. The coil-springs take the majority of the weight of the vehicle while the shock is used to level and provide damping.

Our air-bag suspensions are entirely different and do not include coil-springs whatsoever.... unless they've been replaced.
 
  • Like
Reactions: Mooseman

SpitShine_PL

Member
May 26, 2023
41
Poznan, Poland
Sorry for taking a huge backhoe to this.
My 2002 'Burb has ZW7 on the RPO list, it's "Premium Smooth Ride".
There is no evidence of any wiring for the rear shocks, or air lines, or that any air compressor was ever factory installed in the car.
I think ZW7 is the Nivo shocks for the large trucks, like these:
I understand they are self-contained, auto levelling shocks that lift the ass under load about 100 yards of driving from park. Am I correct?
 
  • Like
Reactions: MPB

TollKeeper

Supporting Donor
Member
Dec 3, 2011
8,199
Brighton, CO
Its not a 100 yards, it does take a but more of a drive. But yes, they pump themselves up within 2-4 miles.
 
  • Like
Reactions: Mooseman

MPB

Original poster
Member
Feb 26, 2023
27
New York
This is why I originally thought my TB having the RPO code ZW7 might have Nivomat shocks, turns out my truck just had the skinny Bilstiens that come from the factory, I actually just replaced all four with the same Bilsteins that came on the truck from the factory, also new greaseable end links and sway bar bushings front and rear. Those front bushings were a bitch https://www.monroe.com/technical-re...e-right-replacement-shock-gm-trucks-suvs.html
 
  • Like
Reactions: christo829

Forum Statistics

Threads
23,490
Posts
639,920
Members
18,723
Latest member
RonaldRedd1961

Members Online