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2007 chevy trailblazer_ls
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Discussion Starter · #1 ·
Got my "new" springs put in Got springs from an 05 ext with 4wd and a V8 engine.(thanks Cuda Jim) . Very easy to put in didn't even have to take off my rear tires. My org. ride height was 34.5 inches on both sides. When the boat was hooked up the back end would drop 1.5 inches and I felt that I was being pushed around in the back by the boat. After I put in the new springs the back went up 7/8 of an inch to 353/8 inches when not loaded. Put on the boat and the truck only drops down 7/8 insdead of 1.5 inches. Towing the boat is a waaaaay better deal. Non towing ride is only slightly firmer. Wife even liked the way it rides unloaded. By the way the shocks are still stock. New spring codes were YHM ,YHL . With both new and old springs my side to side height is dead even. I took some picks but my computer is messed up. Now that I am "Lifted" does this mean I can post in the Off Road section? Jay:woohoo:
 

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Discussion Starter · #3 ·
HA HA I knew that I would get a responce! Seriously though I would be glad to help anyone with rear springs. I have a lot of part numbers and REALATIVE rates. Baseicly I went from the next two Lower rates on Zibby's chart {YUX, YUY) to two of the highest Ext springs. The springs that I put on had about 30k miles on them. On the workbench the free height is the same but the EXT springs have a bigger wire diameter. I would guess that the result is about ~10% firmer. Based on the Z71 being ~20% firmer and giving 1.5 to 2 inches of height on a swb model. This makes a nice mod for someone that tows heavy or wants to get rid of the first 1/2 inch of rear susp travel being too easy. Jay
 

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Got my "new" springs put in Got springs from an 05 ext with 4wd and a V8 engine.(thanks Cuda Jim) . Very easy to put in didn't even have to take off my rear tires. My org. ride height was 34.5 inches on both sides. When the boat was hooked up the back end would drop 1.5 inches and I felt that I was being pushed around in the back by the boat. After I put in the new springs the back went up 7/8 of an inch to 353/8 inches when not loaded. Put on the boat and the truck only drops down 7/8 insdead of 1.5 inches. Towing the boat is a waaaaay better deal. Non towing ride is only slightly firmer. Wife even liked the way it rides unloaded. By the way the shocks are still stock. New spring codes were YHM ,YHL . With both new and old springs my side to side height is dead even. Jay:woohoo:

Nice MOD and thanks for the numbers/RPO's. That sounds exactly what you were looking for these past few months and should work out quite nice for you. And the wife is happy to boot. Good job Jay !!

Just put on the Z71's and they are harsh if one is not used to an off-road suspension . Good for towing or packing some extra freight .Thicker/stiffer for sure. No puns here,please..

PICS...Natch look below :


Quite a jump......
 

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What did you have to unbolt to do your springs? I'm getting ready to install a lift kit, and I've heard conflicting reports of what needs to be removed (just shocks? or did you have to unbolt the track bar, as well?)
 

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Discussion Starter · #6 ·
TB-KSV68 I would guess that my EXT springs are about 1/2 way in thickness between the stock springs and the Z71 in the picture that you posted. I have a measurement of both and if I can find it I will post it up!I have a couple of Questions for you, 1. Are the Z71 springs taller than the stock springs when out of the truck? It's kinda hard to tell fron the pictures. 2. Can you post up the three letter code and number from BOTH of the old springs please? Thanks

PO7r0457 Heres how I put them in. I jacked up the truck with a floor jack at the center of the rear axle, then I put 2 jackstands on the frame in frount of the rear wheels. There is a place on the frame that looks like it's made to put jackstands has a nice little groove. Then i let down the jack a little to take the pressure off and unbolted the bottom of the rear shocks. make a note of how the stock springs are placed so that you can match up the new ones the same way. Drop the jack down until the springs are free and put in the new ones. Very easy. Can I have your code and number from your springs also? Jay
 

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PO7r0457 Heres how I put them in. I jacked up the truck with a floor jack at the center of the rear axle, then I put 2 jackstands on the frame in frount of the rear wheels. There is a place on the frame that looks like it's made to put jackstands has a nice little groove. Then i let down the jack a little to take the pressure off and unbolted the bottom of the rear shocks. make a note of how the stock springs are placed so that you can match up the new ones the same way. Drop the jack down until the springs are free and put in the new ones. Very easy. Can I have your code and number from your springs also? Jay
Thank you for that walk-through.

I am wanting to install my spacer lift... How much room do you think there was between the uncompressed spring and the spring perch?


The Z71 springs are the same physical height (uncompressed) as ours, btw.
 

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TB-KSV68 I would guess that my EXT springs are about 1/2 way in thickness between the stock springs and the Z71 in the picture that you posted. I have a measurement of both and if I can find it I will post it up!I have a couple of Questions for you, 1. Are the Z71 springs taller than the stock springs when out of the truck? It's kinda hard to tell fron the pictures. 2. Can you post up the three letter code and number from BOTH of the old springs please? Thanks Jay
Sure Jay :

1.) If they were longer, I didn't notice much and took no measurements as they were almost identical in length in the non-compressed status. In fact most Stats. on Zibby's list are within 7-10 MM of each other. That's only .30 to .40 Cal. What I noticed most was the over all girth. The Z-71 Avvies were approx. between 9/16"-7/8" larger. Was worried about fuel tank rub. Not to fret. Could slide in my hand up to the wrist for good clearance. :thumbsup:

2.) Stock springs:

YNR----15207739
YNS----15207740

Avalanche Z-71 springs:

MBK----15234633.....Both sides.

Hope that helps.

Mike
 

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Discussion Starter · #9 ·
15207739/40 are the springs used on my 05 4.2l 2wd. They are from the 2nd "wave" of springs. Believe it or not they are what the springs in my 07 convert to as the newer springs that the 07 was built with are not available. As far as spring rate goes they are about in the middle as the part numbers go from 15207736 to 15207742. When I was crawling under a lot of trucks this was a common part/ code for swb models. 15207740 is one or two steps lower than the YUZ code in Zibbys chart. The part number for the YUZ spring is 15948010. 15207740 is the replacement spring for 15948009 (YUY) and 15097376 (YEW). Thanks for the help. I realized that what I was looking for were springs from an EXT so after a while I spent most of my time looking under lwb trucks. What I am trying to do now is complete the info on swb models. Jay
 

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15207739/40 are the springs used on my 05 4.2l 2wd. They are from the 2nd "wave" of springs. Believe it or not they are what the springs in my 07 convert to as the newer springs that the 07 was built with are not available. As far as spring rate goes they are about in the middle as the part numbers go from 15207736 to 15207742. When I was crawling under a lot of trucks this was a common part/ code for swb models. 15207740 is one or two steps lower than the YUZ code in Zibbys chart. The part number for the YUZ spring is 15948010. 15207740 is the replacement spring for 15948009 (YUY) and 15097376 (YEW). Thanks for the help. I realized that what I was looking for were springs from an EXT so after a while I spent most of my time looking under lwb trucks. What I am trying to do now is complete the info on swb models. Jay
Wow Jay,

That is total dedication to end result. Major props on your research, install and happiness. Hopefully, you will compile this into a new list for all of us at trailvoy to use in the future. Just awesome....Mike
 

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Discussion Starter · #11 ·
Thanks Mike. I would gladly post up what I have. What do I do, start a new thread? What I have is about 4 pages on a steno notebook. Probaly 2or3 pages on an 81/2x11 sheet. Is such a post allowed?I would do my best to condense the chart. Could one of the Mods chime in and tell me how something like this is done? Jay
 

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This thread is ancient but it's so hard to find detailed info on all the available springs available for these trucks. It seems like 7 years ago, you guys knew what was up. From a thread on another forum, I was able to find a list of all of the front and rear shocks, with spring rates. It had part numbers for the fronts, but only the three letter codes for the rear springs. Is there a 'master list' somewhere so i can compare all of the options, figure out what my truck has, and pick a nice balanced stiffer set of springs, and have the part numbers to actually order them with?
 

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What a shock! This is JAYBOY. I haven't been on here in many years only to find out that a thread that I started 7 years ago s at the top! I had to change my name old info long gone. What I did then was to look under trucks n the parking lot with the owners permission and write down the 3 digit spring code that I found under the truck and what kind of truck it was. ( 2 or 4 wd 6 or v8 extended or swb). Also the year. Basically there were 3 "waves" of springs based on the year of the truck. Let me do some digging I think I have the info still written down. Jay
 

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Hey JAYBOY aka 78nova
This is what I have for a master list:



I don't know how to convert the three letter codes on the rear springs, into actual numeric part numbers that I can order :undecided Any help would be appreciated!
 

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So I FINALLY got down to the local chevy dealer's parts department to see if they could somehow turn these three letter codes on the rear springs into actual part numbers. He gave it a shot but none of the three letter codes could be looked up on his system.

Does *ANYBODY* know how/where you convert these three letter spring codes that are so popular on this thread, into actual order-able part numbers? It seems like there is some piece of the puzzle I'm missing. :confused:
 

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*ping*

I was never able to find info on rear springs other than a list of part numbers with no specs.

15948005
15948006
15948007
15948008
15948009
15948010
15948011
 

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Ok I found my old info and will gladly share it. These are rear springs. They came in what I would call "waves" where the code letters and part numbers changed to no real reason. This is a lot of info so I will do it in several posts.
First wave 02-03 SWB lowest rate at the top:
P/N. Code. Superseded P/N
15097373. 15207737 YNM

15097374. YDJ. 15207738 YNP
15097375. YEU. 15207739 YNR
15097376. YEW. 15207740 YNS
15097377. YEX. 15207741 YNT
15097378,. YEY. 15058049 YDJ
Possibly used on some 04 trucks. Most of this info I got by actually crawling under people's trucks in store parking lots ( with their permission). There is not a lot of difference between adjacent numbers. A lot of trucks had 2 different numbers on the same truck. Mine included. Next the second wave SWB:
Part number. Code
15207736. YNN
15207737. YNM

15207738. YNP
15207739. YNR
15207740. YNS
15207741. YNT
15207742. YNU
See how the first wave supersedes to the second wave. I have no idea what is still available new. The third and final wave for SWB:
P/N. Code
15948006 YUS
15948007. YUU or YUT
15948008. YUX
15948009. YUY
15948010. YUZ
My own 2007 SWB 6 cylinder 2 wd truck came with YUX and YUY springs in the rear. I don't know what the rates for these springs are just lower or higher compared to each other. Hopefully this will help someone out. On my next post I will list LWB springs.
 

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Ahhhhhhh NOW you post the info!

haha not really mad though, I went with EXT moog rear springs and they feel pretty good. Now that there are rear spring numbers available, I'd probably go with something on that list instead if I were to do it again. But I'm not going to do it again because my truck handles GREAT now.
 
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