I'm new to Blazers and have since learned I have the ZW7 premium ride suspension. I don't intend to go off roading, other than a gravel road or two, so I guess the soft ride package will be a good thing. I also have 4 cupped tires and a nice drone at and above 55 MPH. The suspension feels stiff to me and it corners nicely. Everything looks factory under it, but there are 4 clean-ish Carquest gas-charged shocks. They're probably the stiffest one CQ has to offer a Blazer. The ball joints don't feel bad, using a long prybar under the tire. So, I'm thinking... Could the cupping be caused by a mismatch between the shocks and springs? Assuming the springs are also lighter. Is there an RPO number to ID the springs?
So what can expect by replacing the shocks to ZW7 equivalent, and are the Bil$teins my only ZW7 options? Are softer Blazer shocks available?
BTW... my Blazer is a 2000 LS, 4D, 4WD, AT, it's always been garage kept, my family owned, w/ no kids or pets, originally sold in AZ and it only has 111.5 K miles on the clock. It's looks new in and out.
I've already done the driver side door pins and bushings, the AC and replaced the DS door panel snaps. Eventually I'll be doing an AT fluid & filter change.
TIA,
-Drew from SJ CA




2000 Blazer LS

 

I have the same suspension.

For my front shocks I added 2" longer off road shocks that seem to have worked fine the last several years.

The rear shocks are another story. The rear springs are softer and are designed to work with special self-leveling shocks. You can still find them on Rock Auto. (I recently purchased a replacement pair to install) Look for the RPO code included in the product description.

 

LOL... I did see those ZW7 shocks on RockAuto but thought they were Bilsteins. They're bout $550 to ship what difference will I see/feel? Are there good alternatives for less?
How does this self leveling system work, and how do I know mine is working or to test it?
I had a Cadillac with a self leveling system, and a dash indicator would come on when it was leveling, on start up as I remember. I do see a lift bag of some sort on the rear springs. I need to get under this Blazer and really check things out.
I do appreciate your input.
Thanks,
-Drew from SJ CA.

 

Drew,

When I was working out how to do a suspension lift on my Blazer, I found myself having to go down some rabbit holes to figure out all of this ZW7 stuff. I'm glad to share with you what I learned after putting in so much effort to understand it.

To start with, these are the rear shocks I got for my 1999 Blazer, they are listed as ~ $100 each. This are likely the same as what you would need. This is the description from Rock Auto: (Screen shot below)
ACDELCO 54043 {#12477893} GM Original Equipment
Rear; 4WD; Premium Smooth Ride Chassis Pkg(ZW7), Chassis Pkg(Z85); Code E7,T3T

As for how they work, they self-level by hydraulic/mechanical mechanisms within each shock. This self-leveling provides supplementary support that augments the springs and compensates for any extra load in the back or if there is weight due to a trailer hitched to the back of the truck. (https://www.brakeandfrontend.com/niv...control-units/)

And from this website (https://www.shockwarehouse.com/news/...-decoder.cfm):
"Premium Smooth Ride: indicated by the RPO code ZW7. This suspension uses a conventional suspension in the front, but the rear uses a self-contained, self-leveling Nivomat shock in the rear. ZW7 equipped trucks come with a softer spring in the rear since the Nivomat self-leveling system does some of the work of holding the truck up. Replacing a ZW7 Nivomat unit with a standard shock requires also replacing the spring, otherwise the truck will sag in the rear and have a much harsher ride and potentially dangerous handling."

It is a clever system but it also means that finding parts can be more of a hassle. I've been happy with the system on mine and have actually noted how they will pump up a bit. However, over the winter I realized that my rear end suspension might not have been working correctly and with the shock that are currently installed looking like the stock replacements (if not the originals) I decided it was worth replacing them. I have them but just have not installed them yet.

And for me with a bit of a suspension lift, I had to install shock-mount-extensions so that they would operate in their designed length range.

I hope this helps. Be sure to report back what else you might learn about these suspensions.

Christine

 

Wow... Thanks for the info. Yes, they seem to be a clever design.
What puzzles me is the recommendation to have them upfront, when they are designed to improve load-handling. And nor do I understand why the fronts are 30% more expensive than the rears.
I think I'll eventually get those for the rear, but I'm not sold on the fronts.
Thanks again for your help,
-Drew from SJ CA.

 

As for the front shocks, I'm guessing it is a matter of matching the the damping force the shocks provide to the spring rate in order to get the desired oscillation frequency.

In simple suspension systems, the desire is to have the system just a tad under-damped relative to being critically damped; e.g., when displaced upward by a bump, the front end overshoots one time on its way back down to its equilibrium height but only by a small amount before coming back up to equilibrium. (Damped Harmonic Oscillator) In particular, if the spring rate is low (i.e., soft) then the damping force needs to be correspondingly smaller so that the oscillations are just a bit underdamped. If instead the shock installed provides too much resistance, the suspension system only slowly comes back to equilibrium if at all. This is called being overdamped. An overdamped system will always take longer to come back to equilibrium than a critically damped one. In practice I'm guessing it would be hard to overdamp a front suspension with off-the-shelf parts.

cute student video:

 

I finally got under "Ol-Red" for a closer inspection of brakes stuff. Brakes are fabulous!
I also found that the upper ball joints were replaced. At least I assume so because they are bolted, not riveted, like the lowers. This means it'll just make life a little easier to change them. Less grinding is good!
What's the quality, US made (or close) ball joint these days? I used to go with Moog but now they're also from China.
BTW... At the same time I'm going to change the shocks. I'm leaning towards the KYB-Excel-G's up front, in an attempt to return the ride to somewhat comfortable. Besides the only off-roading this rig will do is flat gravel roads.
For the rear I'm leaning to the Monroe Mono-tube Sensa-track, for the same reason. I hear that on close to normal roads they are surprisingly comfortable.
LOL... Anyone want a set of lightly used real stiff CarQuest (Gabriel) gas-charged "Bruiser-XD" shocks? Just pay postage.

 

I wanted to update everyone interested.... I've changed both the upper & Lower ball-joints, front and back brake pads, anti-swaybar end-links and shocks. I went with the Monroe OESpectrums shocks on all four corners. My objective was to return to the factory ride control and comfort level, with out spending $500 on just the shocks. I think I've met my objectives and I'm happy.
BTW... One of the front shocks was flat, no gas in there, the end-links were all torn up, but the rears shocks seem fine because they still have their gas charge.
Thanks for all your help and explanations,
-Drew from San Jose

 

thanks my friend! I'm a new comer in Blazers/Jimmy and Ive got also the ZW7 RPO code. I'M trying to guess things out