How to install new autoride OEM shocks - 2008 LTZ

JohnnieMo

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This is a how to on installing replacement OEM autoride / auto-levelling shocks for an 2007 - 2013 Avalanche LTZ, Yukon Denali, Cadillac EXT or Suburban LTZ.  The steps may also be similar for standard shocks or Arnott replacements.

I decided to swap out my existing shocks after 6 years for a couple of reasons.  Primarily, the rear "airbag" shocks had begun to leak.  This is noticeable because the air compressor for the shocks starts to run more frequently.  Properly setup, the compressor should only run a couple times per week.  I was hearing it almost once a day.  Further the front shocks were squeaking.  I elected to replace all 4 and bought them online for $1000 from shopchevyparts.com

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Rear Shocks

Step 1:
I chose to start with the rear shocks.  Since I was also swapping brakes at the same time, you'll notice that in some pictures.  It is not necessary to jack up the truck to swap the rear shocks, but given that I was installing brakes as well, it was necessary.  So Jack up the truck.  I wanted to keep the suspension "loaded'" so I put the axle stands under the.... axle!  I guess that's why they are called axle stands.



Step 2:
I removed the wheels for easier access.  Obviously this couldn't be done without jacking the truck up.

Step 3:
Remove the sensor for the auto-ride system and the air line.  These are both on the top, back side of the shock.  The electrical connector is your standard GM clip, while the air hose as a small metal clamp.  These remove by hand quite easily.



Step 4:
You can pick which bolt to remove first.  I started with the bottom.  You need a wrench on one side and an impact gun (or another wrench on the other).  It zips off easily.  



Step 5:
Now this is the hardest part.  The top bolt is also secured with a bolt and a nut.  For both the top and bottom, the bolt feeds from the inside while the nut attaches to the outside.  I used a socket on the outside, and then another socket, attached to about an 8" extension to the inside.  This will take some time to figure out, and it's almost impossible to take a good picture of.  For this part you'll be happy you jacked the truck up.  You could also consider removing the spare tire to make this easier. The picture just shows the outside nut.  Note how it is tucked up behind the wheel liner (some elect to remove the wheel liner for this reason)



Step 6:
Now you can pull out the shock.  It might be slightly wedged in.  Work it out.  Here you can see my old versus new.  Part number can vary on this part, but mine are 25979393.



Step 7:
Put the new shock in place.  I elected to start with the top bolt.  Thankfully I had help doing this as two hands is barely enough.  Feed the bolt from the inside.  Leave it a little but loose for now.

Whatever you do, don't do what I did here....



As you can see, I installed the shock on the wrong side of the parking brake cable....  :E:

Try again.



Step 8:  
Now fit the bottom of the shock back into the bracket.  This may require jacking up this side of the truck slightly to make it fit.  Once in place, install the nut. Torque the both the top and buttom nuts to 70 ft-lbs.



Step 9:
Reconnect the air line and electrical line.  Make sure to click them in to place.

Step 10: Do the same steps on the other side.

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Front Shocks

The front shocks are far more work.  Set aside several hours, or perhaps a few days (if you are anything like me)

Step 11:
As with the rears, jack up the vehicle and remove the wheels.  The suspension will hang down and for this one, you require it to.

Step 12:
Remove the lower bolts first.  These are easy to suck out from the bottom.  Just use your impact gun or ratchet.  They come out from underneath how they are shown in the picture:



Step 13:
For the tops, first you need to remove the auto-ride sensor.  It is clipped on to the top nut of the shock (green circle).  Remove it by squeezing the metal clip and then pulling up.  In the picture, mine is already removed.



Step 14:
Remove the top three strut nuts from the inside the engine bay.  To reach these you will probably want a good 12" long extension on your impact gun.  These bolts are red in the previous picture.  Also note there is a brown plastic wire guide stuck to one of the bolts.  Just yank this off.  You won't hurt it.  

Step 15:
With the bolts removed, you can take out the shock by pushing it in at the bottom, lowering it, then pulling it back up and out.  There is no need to remove any other suspension pieces.  This is good news as we already had the bearing puller in hand.  Now this is where it gets tricky....

Step 16:
The next step is to disassemble the strut.  (FYI - strut is the name for when the shock and spring are combined in one assembly)  To do this is VERY VERY dangerous.  Do not simply remove the nuts.  The spring is highly compressed at this point.  You need remove this compression before proceeding.  There are a variety of ways to do this.  For me, the only tool I could get ahold of were these spring compressors.  They are sort of scary.  Attached one on either side of the strut such that they are 180 degrees opposite one another.  



Step 17:
Once installed, you need to tighten each side little by little.  I highly recommend finding a YouTube video on this if you've never done it before.  If you use cheap spring compressors they can break.  I rented heavy duty versions from Auto Value and felt pretty safe.  I tightened each bolt bit by bit using my impact gun.  Eventually the spring becomes loose enough to twist around.  Take it to this point.  In the (blurry) picture you can see how the spring is compressed and is loose at the top.



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At this stage I'm going to review the various parts of the strut assembly, because if you are like me, you have no idea. Here is the diagram I got from GM:



The parts are as follows:
1) Spring
2) Upper Nut - Part# 15815517
3) Lower Nut - Part# 15815519
4) Not sure on the official name, but this is a large metal piece that fastens the strut to the vehicle.  We'll just call it the "Top"
5) Upper Spring Seat - Part # 25940742
6) Reinforcement - Part# 15886466
7) Bump Stop - Part# 15815516
:cool: Dust Boot - Part# 25940741
9) Strut Clip ?? (not sure of it's real name, but they come with the new shock so you don't need a part number)
10) Autoride Shock - Part #19300038 or #20810269
11) Lower Spring Seat, aka isolator - Part# 15808594 (Note that this part is only on some trucks, but adding it doesn't hurt)

Step 18:
Next, to disassemble the strut, remove the upper nut first.  Take care with this as you don't want to spin the whole shaft.  If you do, the shock will spill oil everywhere.  It is for this reason that I put mine upright in the vice.  The lower nut is next.  Take care with it as well.  The strut shaft is keyed so you an hold it with a wrench.  Once they are removed, the whole thing pulls apart.  Here is what you are left with.



The parts I decided to replace were 2, 3, 8, 10, 11.  In my case, every piece could have been re-useable except obviously the shock, however every vehicle is different.  It doesn't hurt to have the new parts and they can be cheap if you buy them online.  I suggest buying the shock, dust boot and isolator at a minimum.

Here are shots of the before and afters:











Step 19:
Now it is time to assemble the strut around the new shock.  As before I did this in the vice.  The first piece here is optional.  The newer trucks likely have this white nylon lower isolator on them, but my truck did not.  I added this piece anyways as I was trying to eliminate noise.  This isolator should help with that.



Step 20:
Now re-assemble the strut as before according to the diagram.  When you get it all fit back together, it needs to be aligned.  I screwed this up COUNTLESS times before I got it right.  Look at my picture below.  The whole strut mounts in at an angle.  It tilts in from the hub towards the middle of the truck.  So first off, ensure the bottom bolting flange is tilted the proper way.  Next, twist the spring and its associated pieces such that the flat part is facing towards the inside of the truck (you can see how the top plate has three straight edges on it).  The three bolts need to be aligned such that one is top centre as shown in the picture. The one in the centre fastens closest to the side of the truck.

EDIT: After the fact it looks like the spring is 180 degrees inverted from stock.  I've elected to leave it as is, but do note that the spring should be twisted 180 degrees from how it is shown here



Step 21:
Once you get this all aligned, you need to tighten down the nuts.  For this, you do the lower nut first and then the upper nut.  For the lower nut I highly suggest you get one of these dog bone wrenches.  If not, you need a through-hole socket.  I had neither at the time so I used an open end wrench.  The down side is I have no idea how much it got torqued down.  You can see in the picture above how the lower but is nestled down below the top plate. The top nut just fits flush to the lower nut.  



Step 22:
To install, if you've done the alignment properly, it is very easy.  You stick the bottom in first, then push the bolts up through the holes in the strut tower.  You'll notice the holes are oblong to give you a little play on the alignment.  



Step 23:
You may need to push down on the wheel hub to sneak the strut in.  I had to literally sit on it.  This part would be easier with some help.  Once you work it in, you put on the nuts.  Torque both top and bottom to 85 ft-lbs.  Re-attach the auto-ride sensor (grey) and that little brown wire guide too.

\

Step 24:
Complete the same steps on the other side of the vehicle.



Step 25:
Put the wheels back on and lower off the jack stands.  Start your truck.  You should see no codes and everything should be fine.....

.... however in my case I had a stabilitrack and TCS light on.  This forum quickly informed me of the problem.  For some reason, when you swap out the rear shocks, a sensor gets disconnected.  This sensor sits up on the right side frame rail, near the top shock bolt, just behind the bump stop.  I managed to find a picture of the little bugger:



It is a mystery of the universe as to why this connector disconnects itself, but don't question it.  Just hook it back up again and move forward.  Codes are gone.

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Ride Review:
Given that I had never driven a new LTZ truck, I had no basis for reference.   My truck was 3 years and 40,000 miles old when I got it.  So the ride was always nice, but nothing like this.  The truck literally feels like it is floating over bumps now.  Also, big bumps are handled far more aggressively.  I don't get tossed about the cab anymore.  I now see why they call it air-ride.  I can't comment as to whether or not it is the 500 adjustments per second making it so magical, or if it is just that the shocks are new.  Either way I am impressed.  It rides like a luxury vehicle now.

I did all 4 shocks mostly because I had a squeak up front and a mild leak from the rear air bags.  Both are gone now.  I'll be able to comment more come summer.


---

If you need any other information about the Auto-Ride LTZ system (Z55 code), then consult this thread.
http://chevyavalanchefanclub.com/cafcna/index.php/topic,131766.new.html#new

This is the best resource on the internet for understanding the system.  My thread here is just intended as a How-to and not a discussion of why.




 

JohnnieMo

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Write-up finally complete.  If anyone sees any errors, let me know.  I'm happy to add insights as well to make this easier for the next guy.
 

DouglasOak

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JohnnieMo said:
Write-up finally complete.  If anyone sees any errors, let me know.  I'm happy to add insights as well to make this easier for the next guy.
Excellent Thread!! Thanks for all the pix and info.

Could you list the part numbers used for reference?

I will be changing out my rears in the spring... time to start saving up now!
 

biggmachz

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JohnnieMo said:
Write-up finally complete.  If anyone sees any errors, let me know.  I'm happy to add insights as well to make this easier for the next guy.

JohnnieMo are you sure you have the spring facing the proper way?
the top of the spring leading edge/end were facing out on my truck when i replaced mine?..
in the pic where you have marked inside and outside, just below the word inside?. the end of the spring should be seen when you look under the wheel well from the outside


looks like #5 in the diagram and the spring have to be turned 180* to be in the original position

excellent work on the write up (y)
 

JohnnieMo

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Here is the parts list as best I know it:

Front:



Also Marioski posted this picture of his new goodies:


1) Spring - ??
2) Upper Nut - Part# 15815517
3) Lower Nut - Part# 15815519
4) Strut Top - ??
5) Upper Spring Seat - Part # 25940742
6) Reinforcement - Part# 15886466
7) Bump Stop - Part# 15815516
:cool: Dust Boot - Part# 25940741
9) Strut Clip - ?? (not sure of it's real name, but they come with the new shock so you don't need a part number)
10) Autoride Shock - Part #19300038 or #20810269
11) Lower Spring Seat, aka isolator - Part# 15808594 (Note that this part is only on some trucks, but adding it doesn't hurt)

Rear:
Compressor -  22941806
Z55 Autoride Shock - 19300071 or 25979393 or 580-451 (AC Delco)
 

JohnnieMo

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biggmachz said:
JohnnieMo are you sure you have the spring facing the proper way?
the top of the spring leading edge/end were facing out on my truck when i replaced mine?..
in the pic where you have marked inside and outside, just below the word inside?. the end of the spring should be seen when you look under the wheel well from the outside


looks like #5 in the diagram and the spring have to be turned 180* to be in the original position

excellent work on the write up (y)
That's a great question.  I literally disassembled and re-assembled 5 times before I got it to work.  So I'm not entirely sure that picture is even the final configuration.  With that being said, by looking at Step 25, it looks consistent.

The upper spring seat is 'keyed' such that you can't put it on wrong however.  It aligns the Top piece with the spring seat and then the boot and spring are oriented from that. It may be possible to invert it 180 degrees, but I'm 70% confident you can't.  I muddled with it quite a bit and was content this was correct.

With all THAT being said, if you turn the spring 180 degrees it is still a spring.  I don't think a spring works better one way than the other.  I'd be happy to be proven wrong though.  And either way, the ride is awesome now  (y)
 

biggmachz

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i'm not trying to criticize your work, i wish i had seen this write up before i changed mine  :E: would have saved me a headache

compare the pics in step 16 and step 24, it probably doesn't make a difference, but in step 16 the original photo the end of the spring is facing out?.

i know what you mean about disassembling and reassembling many times,,,, i put my first one on backwards? spring end facing in?
i got the second one on correctly and noticed i screwed the first one up? i still haven't corrected it yet??. its a hell of a job to install with the front end levelling kit,, 1.5 inch spacer on top of strut, and 3/4 spacer on bottom makes it a Female Dog to install?

i'll take a photo of mine later, it looks like there's more stress on the one thats facing inward, as the dust boot is crooked.. i have to change it when it warms up?..
 

JohnnieMo

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biggmachz said:
i'm not trying to criticize your work, i wish i had seen this write up before i changed mine  :E: would have saved me a headache

compare the pics in step 16 and step 24, it probably doesn't make a difference, but in step 16 the original photo the end of the spring is facing out?.

i know what you mean about disassembling and reassembling many times,,,, i put my first one on backwards? spring end facing in?
i got the second one on correctly and noticed i screwed the first one up? i still haven't corrected it yet??. its a hell of a job to install with the front end levelling kit,, 1.5 inch spacer on top of strut, and 3/4 spacer on bottom makes it a Female Dog to install?

i'll take a photo of mine later, it looks like there's more stress on the one thats facing inward, as the dust boot is crooked.. i have to change it when it warms up?..
Absolutely no offence taken.  I appreciate the feedback.  I do see your point.  It does appear to be rotated 180 degrees.  I'm still not convinced twisting the spring 180 degrees will make any difference on performance.  The sole intent of that upper spring seat is to evenly distribute the force in all 360 degrees.  So I don't think turning it will make any difference.  If I did it again, I would do it the other way though.  (now that you point it out)
 

JohnnieMo

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Thanks guys. I wrote it hoping it would be a sticky, but I don't know how to make it so.
 

willwham1

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(y)
Thanks for all this info...it helped me out. I got my rear shocks from Shopchevyparts.com today and the fronts are coming tomorrow, WITH new springs! My 2008 Avy only has 39k on her but it is 6 years old...I just bought it in Dec and know that after reading your post the ride will be BUTTAH!!!
Thanks again!
 

willwham1

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I have a quick question for anyone that did the install on the front shocks/struts...like I said, I bought new fronts off ebay with the spring and ALL new parts FULLY ASSEMBLED....do I need to do anything before installing or simply skip the spring compressing etc and install?
Thanks.
 

JohnnieMo

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I didn't know you could buy them that way. So long as the part numbers line up and they are the same height I think you'll be fine. Just hope everything is aligned properly or you will need to compress them to spin stuff around.
 

willwham1

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Usually you can't! BUT, I found them on ebay from a wholesaler....I think they are from the Mexican factory directly...they are exactly how they go into the z55 auto ride equipped trucks....look at the part yourself....btw, from what I can tell, they line up EXACTLY...I am haven my mechanic do it but wanted to know how much time it will take and now I know it will be VERY quick since these fronts are FULLY assembled and aligned with all new parts...heres the link
http://www.ebay.com/itm/121218834150?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
 

DouglasOak

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willwham1 said:
Usually you can't! BUT, I found them on ebay from a wholesaler....I think they are tom the Mexican factory directly...they are exactly how they go into the z55 auto ride equipped trucks....look at the part yourself....btw, from what I can tell, they line up EXACTLY...I am haven my mechanic do it but wanted to know how much time it will take and now I know it will be VERY quick since these fronts are FULLY assembled and aligned with all new parts...heres the link
http://www.ebay.com/itm/121218834150?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Thank you for posting the eBay link. I just ordered a pair!!


Not only am I saving a huge amount on the shock itself, but now I can install them myself!!!
(I was gonna leave the fronts to my mechanic as I don't care to see how far I can launch a coil into the stratosphere)
Since they are fully assembled I have no worries dropping them in on a Saturday afternoon.

Also if anyone is looking for the rears the cheapest I have found was at ShopChevyParts.com
http://www.shopchevyparts.com/shocks/absorber-asm-lvlg-shk-black/19300071-p-92263220.html
 

willwham1

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Yes, shopchevyparts.com is the cheapest as JohnnyMo said a bit back....he's the one who had me off on this adventure....yes then I guess you can just drop em in since they are fully assembled and VERY cheap!
 

DouglasOak

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JohnnieMo said:
Wow! $135 for the whole assembly is an incredible price. 
I almost ordered 2 pairs... I could let them sit on a shelf for another 5-6 years for that price!!!
 

JohnnieMo

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DouglasOak said:
I almost ordered 2 pairs... I could let them sit on a shelf for another 5-6 years for that price!!!
Hmmmmm... I think I have a shelf....
 

willwham1

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Well, JohnnieMo was right, what a difference in the ride...my Avy only has 39k on her but is 6 years old now, I bought her in November after a maniac hit my '07 Avy that only had 70k on her and drove like a dream....so the old shocks had lots of life left but were by no means new....now my suspension is like it was off the assembly line...thanks again Johnny, and if anyone is THINKING of doing the shocks...DO IT!!! Not many of those fully assembled fronts left!!

The funny thing is, that friggin code came up about Stablitrak!! haha I told my mechanic how to fix it thanks to the post Johnnie!
 
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