Replaced Z55 Air ride with KYB Gas adjust and Z-71 springs - ride is too high

sam05

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I removed the Z55 air ride shocks in the back and replaced with the Z71 springs and KYB Gas Adjust shocks. I unplugged the battery and removed the fuse for the air ride. I then reconnected the battery...no messages in DIC!

Since the air ride shocks were completely blown the ride now feels much improved! I was a little bummed that the springs make the back ride almost 2" higher than before. Does anyone have experience running with the Z55 springs (I've read they are softer and I can see that they are shorter.) I'm really tempted to put them back in but will that cause problems with carrying a load in the back or towing? I don't currently tow but may some day. Also, a load in the back would likely be the 6 kids and stuff for a vacation (just a few hundred pounds total.)
 

sam05

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Anyone have experience running on non-air ride shocks with the original equipment Z55 springs? Is it too soft?
 

PNW VietVet

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I recently replaced my stock Z71 springs with new Z71 springs. The height went up by 1.5". After driving with no towing or load hauling for a few months it has settled by 1/2". As easy as they are to change, swap back to the old springs and see what the measurement is.
 

adventurenali92

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I removed the Z55 air ride shocks in the back and replaced with the Z71 springs and KYB Gas Adjust shocks. I unplugged the battery and removed the fuse for the air ride. I then reconnected the battery...no messages in DIC!

Since the air ride shocks were completely blown the ride now feels much improved! I was a little bummed that the springs make the back ride almost 2" higher than before. Does anyone have experience running with the Z55 springs (I've read they are softer and I can see that they are shorter.) I'm really tempted to put them back in but will that cause problems with carrying a load in the back or towing? I don't currently tow but may some day. Also, a load in the back would likely be the 6 kids and stuff for a vacation (just a few hundred pounds total.)
I’ve read that the Z55 springs are too soft to pair with standard shocks and that the back end will have major sag even unloaded with Z55 springs paired with non air ride shocks. From what I’ve read moog makes three different sets of rear coil springs for these rigs at different stiffness levels, and that those are they way to go if you’re deleting auto ride but don’t want to raise the back of the truck up like the Z springs do.
 

sam05

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It's currently riding on Moog 81069 springs. They're specified as the Z-71 option springs. The springs I took off (when I removed the air shocks) had Moog 81871 stickers on them. I'm hoping someone knows if those are the soft ones or the "middle" option between "needs help" and "heavy duty".
 

mwilson62000

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I’ve only ever seen 2 options for Moog springs. 81069 for heavy duty, 81071 for “normal” duty or if you have nivomat shocks. Same with ACDelco shocks. 45H2164 for heavy duty, 45H2165 for normal. I have KYB gas adjust shocks on my Yukon XL. Replaced the factory springs with normal ACDelco springs, but didn’t like the sag when loaded, so swapped them for heavy duty ACDelco springs and it raised the rear about 2”, then settled down to 1.5”. I ended up turning the torsion keys up a couple turns to raise the front just a little. Then got an alignment. Still a little lower in the front but not bad, and good for towing and loading it down.

1st pic is normal springs, 2nd is with z71 springs. Driveway isn’t level so rear looks a little higher than when it’s on level ground.
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sam05

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Thanks Mike and Chase! What you're describing (Mike) is the exact thing I'm experiencing. I'm going to leave well enough alone for now. I haven't done any real highway driving since making the changes. If any problems arise, I'll dig in further. If no problems, I think I just have a little more rake since I don't want to mess with getting an alignment right now. Once I'm done with replacing the back brakes and tracking down some minor noises here and there I'm gonna just drive the thing for a change!

And I wish mine was even half as clean and sharp as yours looks!
 

oh05ext

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so the stiffer springs raise the truck even though they are physically shorter due to less compression I assume? im wanting to lower my yukon 2" in the rear, the avalanche heavy duty springs on rock auto have a higher spring rate but are 1.75in shorter than factory springs.I tow about 4500 lb pontoon often in the nice months.
 

mwilson62000

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The ACDelco heavy duty springs I went with were actually about an inch taller than the normal duty springs. Rated 1300lbs vs 1050lbs I think.
 

oh05ext

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The ACDelco heavy duty springs I went with were actually about an inch taller than the normal duty springs. Rated 1300lbs vs 1050lbs I think.

those were the ones i looked at on roockauto. i guess they just dont compress as much as a stock spring due to the rate. it looks like ill just go with whatever spring i can find and use a helper bad for towing
 

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