Z71 Springs ??

Tmac

New Member
I was searching for info on the Z71 springs so many people use. What are they off of ? How much stiffer ? Where to get them ? .... I have a new to me 06 TB LS 84K miles, completely stock. I hooked up my 7x14 trailer today that I haul up to 5 dirt bikes or 3 quads on. With just the empty trailer and my 200lbs on the tongue it was way too soft. I had a Ford Edge crossover that rode more like an SUV than this TB does. If I gain lift by stiffer springs that's good. I was contemplating the Lift Meister 2.5" lift level kit if the new springs don't do the trick. Then of course come the shock choices.
 

djthumper

Administrator
OP
OP
T

Tmac

New Member
I was considering stiffer springs front and rear. I read that there were many spring rates available and mine were on the soft side for sure. I think 2 spring rates higher would firm up the ride and handling enough for me.
 

kickass audio

Well-Known Member
I would do like thumper suggested and not get z71 springs unless you are under constant load. I put z71 springs and OEM sized bilstein HD shocks on my rear and they work perfect however I have a great amount of weight that sits in the rear end all the time from my system so the springs can never get fully extended no matter how hard they try from the ~700lbs of weight in the rear. lol. Helper bags can help quite a bit. The z71's are definitely a stiffer spring for the rear and they are somewhat noticeable but are not very harsh to make you hate them. I only can feel the harshness if I hit a hard bump in the road but then again my previous springs and shocks were OEM and they were really shot. The springs sagged a ton, just towing my friends jet ski last summer and having her 2 friends in the back seat with a cooler of beer the mudflaps would scrap on every bump and with the shocks being shot in the rear the truck bounced a lot. I have a little rake in my truck with the z71's but not enough that I would worry about doing the front to center it though I did really like it the other day when I jacked up the truck another 4" off the ground to work under it, that was a pretty cool but stupid height. lol.

If your truck is bouncing around a lot then I suggest getting bilstein HD shocks for the rear.

And since you asked the z71 springs come off chevy tahoe's and avalanche's that have the z71 package. I bought my set from ebay but the guy I bought them from has since sold out of them. They were brand new springs that were pulled off a new tahoe that border patrol purchased and upgraded the springs to something else so they didn't need the z71 springs anymore. Here is a link to someone selling them on ebay: GMC GM 25978750 Rear Suspension Spring | eBay

Again I cannot stress it enough but just z71 springs with an empty rear end of the truck is not smart. On the stock shocks you will top them out on extension and damage them plus you will have about a 1.5-2" lift over good stock springs so you will have a decent amount of rake in the back end if you are okay with that. My rake is about the same if you look at an XL Envoy with how the roof comes up for the 3rd row, its very slight. If you want I made a nice thread about the z71 springs and documented what I did. Sorry I didn't take any pictures during it as I was trying to rush and get it done before it dumped the rain on me and my sisters boyfriend that day we did them. lol. Here is my thread: http://gmtnation.com/f76/suspension-fix-04-envoy-8687/
 

CarbEnvoy

Active Member
I just went through this decision as I was replacing my stock air springs, and am thinking about a lift in the future.

I decided to go with an aftermarket spring made for the Envoy XL, TB EXT. They have a stiffer rate, and heavier design load, but don't change the ride height much compared to the SWB springs. They have a shorter free length. I would order Moog springs for the XL/EXT, check RockAuto. I bought Raybestos, but through more reading since the purchase I've come to believe that springs from Moog, Raybestos, NAPA and possibly others are all made by the same manufacturer as they all have identical specifications.

Those springs, paired with Bilstein HD shocks should work well for towing. I tow a 3300 lb travel trailer with a 300lb tongue weight. I just put the springs in, so I haven't tried towing with them yet, so we'll see how they handle the load in a month or so.
 

The_Roadie

Founding Member
Administrator
What's the mission you see for your truck?

Why do you think you would be better off with replacement springs?

Yes, this is an essay question - there is no one "right" answer.

What height change are you targeting if not a "major lift"?

If you carry variable weight and just want to keep it within 1/2" of stock no matter what you put in the back, you might be well advised to add Airlift1000 bags in the rear coils and adjust the pressure manually (or with a compressor) as required.
 

willbill92

Well-Known Member
I dont really know yet I just started recently hearing a squeak whenever I go over a bump. I was just wondering if there was a different brand that people would suggest other than blistein.
 

The_Roadie

Founding Member
Administrator
Squeaks are often bushings in the control arms or anti-sway bar mounts.

Unless you're lifted, there is no reason IMHO to stray from the well-loved aftermarket heavy duty Bilsteins. If I had to guess, they have 80% market share in the replacement market for our platform here on this enthusiast site. Not sure what the budget-driven market buys.
 

HARDTRAILZ

Moderator
The_Roadie said:
Squeaks are often bushings in the control arms or anti-sway bar mounts.

Unless you're lifted, there is no reason IMHO to stray from the well-loved aftermarket heavy duty Bilsteins. If I had to guess, they have 80% market share in the replacement market for our platform here on this enthusiast site. Not sure what the budget-driven market buys.
Stock height....the bilstein HD are the way to go.
 

Pittdawg

Well-Known Member
CarbEnvoy said:
I just went through this decision as I was replacing my stock air springs, and am thinking about a lift in the future.

I decided to go with an aftermarket spring made for the Envoy XL, TB EXT. They have a stiffer rate, and heavier design load, but don't change the ride height much compared to the SWB springs. They have a shorter free length. I would order Moog springs for the XL/EXT, check RockAuto. I bought Raybestos, but through more reading since the purchase I've come to believe that springs from Moog, Raybestos, NAPA and possibly others are all made by the same manufacturer as they all have identical specifications.

Those springs, paired with Bilstein HD shocks should work well for towing. I tow a 3300 lb travel trailer with a 300lb tongue weight. I just put the springs in, so I haven't tried towing with them yet, so we'll see how they handle the load in a month or so.
Interesting. You say the ride height didn't change "much" from the XL springs, can you be more specific, i.e. completely unnoticeable, 1/2 inch? I was always curious if rear XL springs increased ride height seeing as though the front springs definitely do.
 

smt 59

Well-Known Member
You don't want to run the Z71s alone with a lift as they add about 1.5" of lift. We get them from 07 and later Tahoes and Avalanches. You can actually add bags to the springs in the rear to help with the towing. 2006 Chevrolet Trailblazer 4 WHEEL DRIVE Air Bag Suspension Kits | Air Lift Company
Good day Sir, just purusing the threads as I need to replace the rear springs and came across this, I am looking for a little stiffer ride and have an 1.5 inch lift in the rear with Bilsteins HD's, just how stiff is the ride with the Z71's. I can accept the lift, I do not tow or haul, just a people mover but hate the sag, original springs with height ok. I guess I can get them from the dealer as ordering off of Ebay is in US funds and pricing would be about the same.
 

djthumper

Administrator
With a little weight, maybe 100#, it isn't that bad. When it is almost completely empty it is pretty stiff. When I was hauling a particular trailer it would sag about 3.5 inches with the Z71 maybe 1.5 inches.
 

smt 59

Well-Known Member
So with some people in the back seat it would not be that bad, how bad on a rating 1-10 with 10 being hard rock with it empty would it be?, just me driving? nothing left on Ebay just the dealer now($200 ea.)
 

smt 59

Well-Known Member
Sounds a little rough, good for traction and cornering is guess.
 

BC backroader

Well-Known Member
I'm very happy with the Z71 upgrade on my EXT, along with the BDS 5500 shocks and Marks lift/level. My cargo area is never empty, I always have at least 100 lbs of recovery/camping/repair gear in there. It is noticeably stiffer than stock, which I thought was too soft (possibly bagged from age, with 127,000 km when I got it). I routinely run washboard gravel logging roads in the TB, and can take them at higher speeds than most pickups and Jeeps, but it still gets compliments on the highway ride from my off roading buddies.
 

smt 59

Well-Known Member
Sounds good guy's, looking like I will go with the Z71's, they are alot cheaper in price as well. So since they are an 1.5" longer than stock I may not have to use the rear lift unless I go with the 3" lift on the front from Mark replacing the 1.75". Thank you.
 

tricguy007

Well-Known Member
This might sound stupid but I don't want any lift but a sportier stiffer ride better handling, is it possible to put 2" lowering springs made for a Tahoe in or would it not give me a stock like ride height I do tow with it a couple of motorcycles
 

HARDTRAILZ

Moderator
There are plenty of rear spring options. You might look at what some of the SS guys run since they are into the handling aspect more than anyone running z71s
 

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