Factory Spring Part Numbers & Associated Lift

[teamred250ex]

Installing my 85's this Friday in St. Augustine with some help from Mark, I'll make sure to take some before and after pics and measurements!

[teamred250ex]

   TrailVoy Thread  

this is the link for the thread I started talking about the stiffer factory springs. check it out and let me know what you guys think. I'm trying to figure out if the ball joint angle will be OK or not

[Trail X]

Instead of linking to TV, post the details here too! New springs definitely warrant their own thread here.

[Zero]

Agreed, please make a copy of your TV thread here. Since some of us dont venture over there much anymore because this site has a more organized, concise, info geared to us lifted offroaders.

[Rob93]

I'll be ordering the 85 springs probably in a couple weeks, I have the 82s, hopefully the milder lift wont give me such a harsh ride. I would like to flip my UCAs too but i want to see how the alignment goes for the people who have done it

[Gordinho80]

So I was checking out my RPO codes for my TB... seems as though I have codes that aren't listed yet...

6CC and 7CB... I'm fairly certain I have the lowest spring rate, so it might be worth listing these 2 in the initial post.

[Trail X]

If you have 4WD, you shouldn't have the lowest spring rate. If you can determine for sure what springs you have, I'll put the RPOs in there.

[Gordinho80]

I stupidly ripped the labels off of the springs shortly after getting the truck. I had no idea how useful that information would be now...

[rgraboske]

PM me the VIN. I can look it up in a system I have access through at work

[johnburgelin]

I've got a 2003 TB LTZ and my springs are 6SK and 7SJ, which turn out to be 84 and 83 respectively, what's the reason GM put a lighter spring in one side versus the other? when I replace them should I do the same? like get an 87 and an 86? or just get the same in both sides?

I stupidly ripped the labels off of the springs shortly after getting the truck. I had no idea how useful that information would be now...

you can just find your 6xx and 7xx RPO codes and look up your springs at compnine.com

[Trail X]

I've got a 2003 TB LTZ and my springs are 6SK and 7SJ, which turn out to be 84 and 83 respectively, what's the reason GM put a lighter spring in one side versus the other? when I replace them should I do the same? like get an 87 and an 86? or just get the same in both sides?

As I understand it, GM used a computer measuring device to determine what spring to put at what wheel.

If your particular vehicle had more weight in a particular corner (for whatever reason), the computer would 'up' the spring you have. This was to give proper ride height around the vehicle and to keep it from potentially leaning (which I believe GM had some trouble with in the 90s).

Just replace with the same spring for both sides... the difference is minimal.

[johnburgelin]

I've got a 2003 TB LTZ and my springs are 6SK and 7SJ, which turn out to be 84 and 83 respectively, what's the reason GM put a lighter spring in one side versus the other? when I replace them should I do the same? like get an 87 and an 86? or just get the same in both sides?

As I understand it, GM used a computer measuring device to determine what spring to put at what wheel.

If your particular vehicle had more weight in a particular corner (for whatever reason), the computer would 'up' the spring you have. This was to give proper ride height around the vehicle and to keep it from potentially leaning (which I believe GM had some trouble with in the 90s).

Just replace with the same spring for both sides... the difference is minimal.

Thanks, I'm thinking about going 87's or 88's depending on how my flipped UCA, UHMW shim, turns out :\

[johnburgelin]

Thanks, I'm thinking about going 87's or 88's depending on how my flipped UCA, UHMW shim, turns out :\

Just ordered the 87's should give me some additional lift and capacity for my winch.....now onto new tires

[MrSmithsTB]

I'm going to be firing in the dark with ordering these, since my front springs are not the original that came with the truck. I'll assume they are the same since they are from an Envoy with 4x4. Based on that assumption they are 84 and 83, 87s should net no more than 1" of lift and if they settle too high I can always take out Marks shim. This should leave a slight amount of rake with the Z71 springs I just installed and safely reach the max limit for the half shafts, effectively allowing for 33s with no body lift and leaving the option of adding a steel front bumper without sagging concerns.

Thank you for this thread

[Trail X]

I'm going to be firing in the dark with ordering these, since my front springs are not the original that came with the truck. I'll assume they are the same since they are from an Envoy with 4x4. Based on that assumption they are 84 and 83, 88s should net no more than 1" of lift and if they settle too high I can always take out Marks shim. This should leave a slight amount of rake with the Z71 springs I just installed and safely reach the max limit for the half shafts, effectively allowing for 33s with no body lift and leaving the option of adding a steel front bumper without sagging concerns.

Thank you for this thread

83 to 88 would yield about 1.5" of wheel lift... 1" of strut lift.

[MrSmithsTB]

And that is what I get for not reading thoroughly enough. So I will amend that to say that 86s may be the best choice for me assuming I have 83s, as the tags have been gone for a while now.*Bear with me as I do the math in the thread* That's .96 of wheel lift. If they are 84s, it'll still net .62 of wheel lift. Or 1.16(83s) or .86(84s) if I use 87s. 1.42(83s) or 1.14(84s) with 88s. What to do, what to do.....

[Trail X]

You can probably identify your stock springs by looking up your RPO codes... that's also covered in this thread.

[MrSmithsTB]

You can probably identify your stock springs by looking up your RPO codes... that's also covered in this thread.

And that's what you get for not reading thoroughly enough. The springs are off of an Envoy(picked them up when I ditched the lowering kit), and I do not have access to their RPO codes. My stock springs are supposed to be 83 and 84. Since the Envoy was an 04 w/4x4, I am assuming that they are going to be the same. Right now I sit at 8.25 rear and 6.75 front(fender to top of wheel). That's why I want to try not to exceed 1" of wheel lift. It looked like the back was sitting lower than the front, which is why I got the Z71s. Now I have enough rake to play around and make the front higher, but I don't want to end up where I started. The idea behind it is to create enough lift to run 33s without the want for a body lift, so that I can concentrate on upgrading the weak links in the susp system instead of dumping that cash into a body lift. Looks like it between 87s and 88s, based on cost and versatility.

[Zero]

The 88's are gona be super stiff. You may be happier going with the 87, and using marks shim to keep your pavement drives comfortable.

[MrSmithsTB]

That's what i'm thinking as well. I can always make a thinner shim, but I can't make a spring softer.