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2011- rehab suspension; Gen II Z71 owners get in here!

DP425

Full Member
Joined
Aug 23, 2011
Messages
142
Location
Michigan
I've got a 2011 with about 80k miles.  Original owner, so I know how it's been treated; that is to say, it's carried some rather heavy loads.  I put a spacer "leveling" kit on the front end shortly after I got the truck, along with 1" blocks in the rear.  Well, I feel the springs may be getting just a little tired, and it's likely not too far away from the point where I need to be looking into shocks.

So, I've started my road to rebuilding my suspension.

I ordered Bilstein 5100 shocks- ride height adjustable for the front and standard for the rear.  Also ordered front and rear MOOG HD springs.  I already have the helwig rear sway-bar installed, so I ordered the front as well.

Now, I supposedly have 2.25" of lift on the front end with the spacers as it is now.  The spacers I have go between the lower shock mount and control arm, and between the shock and upper mount- in other words, they are external to the set-up of the coil-over.  My plan is to use a combination of the ride height shocks (which supposedly add a max of 1.77" lift over stock) and spacers to get proper lift of about 2.25-2.5" over stock.  My only problem here is, I don't know what factory stock ride height is.  So I'll need someone with a low miles, newer, Z71 to give me a hub center to bottom of fender measurement- that will help eliminate any tire and inflation differences.  So, this will take a little trial and error to get the right combination.

I still need to order all control arms/ball joints as well as tie-rod ends.  Going with all MOOG items here as well.

On the back end, I'm looking into Spohn parts.  At the very least, a new panhard bar.



I'm looking for input on:
-Who has had experience with Spohn parts and what value you've found in their available components.
-Who has used the Bilstein Ride Height Adjustable shocks- how they performed and actual noted lift.
-Opinions on the value of the MOOG "problem solver" upper control arms with caster/camber adjusting balljoints.
-Hub centerline to bottom of fender measurements from factory stock low-miles 2011 or newer Z71.
 
I recently installed a Spohn panhard bar and could feel the difference immediately. Extremely well made. Easy install on 09 Z71. Have a combined lift of 4" front and 3" rear. I would suggest tubular drop upper control arms once you hit 2 1/2" or more in front. It will save you the Hassel of bad ball joints and will give your droop a proper amount of space.
 
Cheapazz said:
I recently installed a Spohn panhard bar and could feel the difference immediately. Extremely well made. Easy install on 09 Z71. Have a combined lift of 4" front and 3" rear. I would suggest tubular drop upper control arms once you hit 2 1/2" or more in front. It will save you the Hassel of bad ball joints and will give your droop a proper amount of space.

That's what I was hoping to hear!  I'll be doing a lot of towing this summer, so I'm looking for things to aid in stability for the rear end.  Sounds like that should help a good bit.

My intent on the front is to keep the "lift" between 2.25 and 2.5" over factory.  I just need to find out what factory actually is!  I never recorded the measurements when I put my current leveling kit on, back when the spring were new.  80k miles later, having carried some rather heavy loads, I've got no doubt the springs have taken a little bit of a set to them.  The rear is going to be much worse than the front, but I'd be shocked if the front springs haven't seen it as well.

And given these MOOG springs are supposedly "heavy duty", even on the front, I REALLY need some point of reference to get my measurements from.  Who knows, between the 1.77" the shocks are supposed to give, and the springs themselves, I might hit 2" over stock.  If that's the case, one or two plates on top would get me where I want to be.  But if the springs are a factory new ride height, then I'll have to play around with upper/bottom spacers to get my 2.25-2.5 over factory.  I installed the kit 1 plate short, so it should have given me 2.25" lift.  I had misplaced one of the top plates and could not find it when doing the install originally.  Finally stumbled upon it.  Anyway, I'm fairly happy with the 2.25" look.  Not so sure 2.5 would really be worth it.
 
In prep for my lift kit, and because I'm a nerd, I measured before and after heights.  50k miles and little hauling and towing history (I bought it at 27k).  Front fender flare to ground was 35", rear was 37".  Now all are 45".
 
Well, figured I'd give an update.  I knocked out the rear suspension tonight; didn't take too horribly long; maybe four hours.

I replaced the factory springs from my 2011 Z71 with Moog "heavy duty" springs, PN: 81069.  That is a set of two springs.  I should have taken some side by side photos, but I didn't.  The Moog springs have one extra coil it appears.  Didn't take note of the actual spring steel diameter though.  Difficult part about this was dealing with my previously installed AirLift bags.  They have been in since not too long after I bought the truck brand new.  I ended up resorting to cutting the bottom two coils of the spring off to be able to get the bags out easily, then stuffed them back into the new springs.  Of course, the bags had "settled" into a position on the old springs and you could see where the coils used to lay on the bags; I'm assuming this will eventually adapt itself to the new, tighter spaced coils.

I left my SuspensionMaxx 1" blocks in place, but I replaced the bottom rubber isolator between the spring and block with Moog PN: K160072.  These are sold one per box, so order two.

The shocks I replaced were original, with 80k miles on them.  They actually seem to still be in a great shape, aside cosmetically (if anyone wants free Z71 shocks with 80k miles on them, and will pick them up in Lansing, MI- hit me up asap).  In their place I installed Bilstein PN: 24-187237.  These are not side specific, so two of the same PN gets you the rear shocks you need.

Install was pretty quick and easy (as expected for the rear), once the bags were swapped over.



So, before and after measurements....
BEFORE:
Hitch Height- 17-9/16"
Right Wheel well, centered on axle- 39"
Left wheel well, centered on axle- 38-3/8"

AFTER:
Hitch Height- 18-3/8"
Right Wheel- 39-1/2"
Left Wheel- 39"


I'm now curious if it's entirely normal for an AV to run slightly lopsided.  The right side gained 1/2" and the left gained 5'8", but it's still 1/2" difference from side to side.  Now, some variables I didn't check were tire pressure and how much fuel is in the tank.  I do not believe the tank is full, maybe 1/2 full.  Bedside pockets are likely heavier on the right than left if anything.


All that said, I picked up 13/16" on hitch height.  And I suspect my air bags may work better due to the closer coil spacing as well.  We'll see though.  Obviously, once the front is tackled, if it's running a little low and gains a little height, that is going to drop the hitch a little bit.


If I still end up with more squat than I want, I'll end up swapping the 1" blocks for 1-1/2" blocks.  It will add back some of the rake, but I'm willing to accept that.
 
Hopefully tomorrow (actually today- tuesday), I'll be able to dig into the front end.  For that I have Moog lower ball joints, upper A arms w ball joints, inner and outer tierods, Bilstein adjust a lift 5100 shocks, Moog HD springs and last but not least... AutoZone Duralast Gold CV half-shafts.  I noticed a noise upon sharp turns which seems most likely to be a CV joint.  Lifetime warranty on these Duralast Gold, and I couldn't find a definitively superior product, so this is what will go on.  Then the dealership will be handling my alignment, assuming they can get me in thursday.

I happened upon a really nice dealer who had a 2013 Z71 sitting on their lot with about 28,000 miles and all factory stock- got them to send me over some factory suspension measurements, and I'll base my front "lift" off that.  Aiming for about 2.25" over stock.  I currently have a plate stack set-up above the coil-over assembly, and a spacer where it bolts to the lower A-arm.  I intend on ditching the lower spacer and using two plates up-top.  If Bilstein is right about their shocks adding up to 1.77", and each plate adds 1/4", two plates should have me sitting right where I want to be.  Of course, the question mark is, do these Moog HD springs ride higher than a stock Z71?  After seeing the fairly small height gain on the rear, I'm guessing no, they do not ride higher than stock; my springs had just taken a bit of a set to them from over-loading.

Hopefully it doesn't end up taking some trial and error.
 
Good info here.  

Since this is the thread that brought up the lift height, I measured the drop on my LCA's with the lift.  The Fabtech 6" lift actually drops the LCA's 8", so that explains my 10" height increase.  In the rear I had to use the FT 1" spacer under the FT springs to level the truck.  I kept the struts at factory height.  I guess that means the FT 6" kit is actually an 8" front, 6" rear kit.

I also have a full set of Z71 shocks (in addition to factory rear springs, crossmember, knuckles, rear control arms, etc. that came off the truck from my lift) if anyone wants them.
 
Well, more news!

Tore into the front end today; addressing front ride height-

I'm installing Bilstein 5100 ride height adjustable shocks on the front, with Moog HD springs.  The shocks claim on the highest setting to give 1.77" of lift.  I'm shooting for about 2.5" total.  So I figured max out the shock lift, and retain the two top plates that go between the upper shock mount and the shock tower.

I got one side all put together and lowered the front of the truck back down.  Mind you, driver's side is still running with the "2.25 leveling kit" it's had since shortly after purchase.  Passenger side (newly assembled) now sits at 40" to the bottom of the fender well.  Upper control arm nearly touching the downward movement stop.


So, we can clearly see that the Moog springs give some lift.  PromptCritical had his down at 35" on the front originally, at about 50k mi.  The dealer I spoke to measured it out at 26" on a 2013 with 25k mi.  So even splitting the difference, I'm sitting with 4.5" of lift over stock.  That is a very, very big problem.



I'm going to address this by first removing the top two plates, that are supposed to be good for 1/4" of lift each.  Then I'll see where I'm at- I expect after that I'm going to have to adjust down the shock lift (pre-load).  At that point, my plan of attack will be to go down to the first setting above stock, which advertises .59" of lift.  IF we add 1.77" from the shock and 0.50" from the plates, that is a total of 2.27".  If accurate, we can assume that the springs are good for about 2.25" of lift alone, by themselves.  At least, when brand new.  If that is true, going to .59" of lift on the shock setting puts me at 2.84".  Assuming the suspension settles a little in the first few thousand miles, it wouldn't be unreasonable to end up with a 2.6" lift.  BUT, that is assuming all of these advertisements on lift are accurate.  I'm expecting to see more drop than advertised as I take these lift devices out.  So if I go with 0.59" setting on the shock, and I'm a little short, I can always stack up to three plats on the shock mount.


I'll have more tomorrow.  I sure hope some other people read this and get some use out of it!!
 
What did the front LCA's look like before you did this?  They should be basically horizontal when the truck is sitting on the ground until you mess with leveling kits.  4.5" is way way out of spec and will put very severe angles on the CV joints as well as screw up the camber.  2-2.5" is all you should be able to get without having to replace your UCA's and even then you should only be able to get a max of 4" or so.

I honestly don't see how your suspension could be this messed up after only 80k miles.  Those springs should last a lot longer than that.
 
I also replaced my rear Springs with the same Moog # as you did. I looked around on the interwebs and found that those are the stock replacement for the Z71. They are marketed as HD Springs for the standard vehicles so was a bit confusing at first.
 
PromptCritical said:
What did the front LCA's look like before you did this?  They should be basically horizontal when the truck is sitting on the ground until you mess with leveling kits.  4.5" is way way out of spec and will put very severe angles on the CV joints as well as screw up the camber.  2-2.5" is all you should be able to get without having to replace your UCA's and even then you should only be able to get a max of 4" or so.

I honestly don't see how your suspension could be this messed up after only 80k miles.  Those springs should last a lot longer than that.


I put a leveling kit on shortly after I bought the truck, so I do not recall at what angle the LCAs sat from stock.

I did as I thought I'd have to do- removed the spacer plates and adjusted the shocks down to 0.59" of lift.  Seems to have put me in around 2.5-2.6" above "stock" height.  Which is right where I wanted to be.  Long story short, the Moog front springs will add about 2" in height.

I wouldn't say my suspension is "messed up"  It was just a little bit "tired".  I got the truck back from alignment just a little while ago and there had been a noticeable improvement in the tightness of the front end.  The swaybar I installed on the front made a nice difference as well.  The springs, both front and rear are noticeably more firm.
 
Cheapazz said:
I also replaced my rear Springs with the same Moog # as you did. I looked around on the interwebs and found that those are the stock replacement for the Z71. They are marketed as HD Springs for the standard vehicles so was a bit confusing at first.

I've heard that they are stock replacement Z71 as well.  I'm skeptical on that.  Of course, my springs were a bit tired from doing some heavy lifting, but they certainly didn't look stock replacement. 
 
I have the entire Spohn Off Road kit on my 2011 Z71 4x4. It's an awesome kit, but its meant for serious off roaders . I've had my kit for two and half years now and the only issue I have is that the kit clunks a lot when slowing and during acceleration due to the spherical ends that give you the 28 degree of articulation. They can only be tighten so much before they just start clunking. I've talked to Spohn tech and they said since I don't off road other than two cub scout camping trips a year with my boys, I should have picked the parts with the poly urethane bushing instead for a much quieter ride. They also stated that the off road kit needs to be rebuilt every 1-2 yrs for optimal performance. So instead of rebuilding mine I'm in the process of re ordering the poly urethane kit.

On my truck I have the Rough Country 3.5 inch suspension lift with Bilstein 5100 shocks all the way around. The front shocks are set on the second notch for a 1/2 inch extra clearance for a total of 4 inches. I also have both front and rear Helwig sway bars. Even with the lift my truck handles very well due to Spohn, Bilstein and Helwig. Now I just want more power. :D
 
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