Difference in K10 and K20 Front Springs

[HotRodPC]

My C20's have towed my 18ft Trailer with very little strain on the rear springs. Today I had my trailer with 3 engines on it hooked to my K10 and it was saggin in the ass as if I had a house on it. It was my intent to run rear springs off of one of my C20 frame anyway. So my question is, what will this do to the height of the truck by changing from the K10 rear springs to C20 rear springs?

Is the K10 going to sit much higher in the rear end after I put the C20 spring in the rear?
So if it raises the rear end of the truck, and I want it level, what will I have to do in the front? I'd like to just put K20 front springs on the front of the K10.
Does anyone know the difference between front K10 and K20 springs are? Same Shackles?
Anyone who has a K20 mind taking some pics of your front spring packs, shackles and hangeers?

On this truck I'm going to be keeping the OEM 1/2 ton 3.73 rear and front axles. Just changing springs. I'll be doing springs and axles on the other K10.

Any help with some pics will be appreciated. I actually wouldn't mind some pics of a K30 front spring pack either.

 

[crazy4offroad]

I think the fronts are essentially the same but you do know the rears are going to be 4" longer?
K10 = 52"
K20 = 56"
If the front K20 springs are the same rate as K10s and look low in the front you can use 1" Zero Rate Add-a-leafs to bring it up yet not make it ride harsher.

 

[HotRodPC]

Acuatually !!! aka Actually... I might be able to learn you something about that rear spring dimmensions as far as length. For whatever reason, depending on which RPO code and if heavy duty or not, C10 can have either 52 or 56 inch rear springs. The only other model can have either 52 or 56in springs is K20. So 2wd half ton, and 4x4 3/4 ton can be either from the factory. The rest are pretty much as you'd expect. K10 is 52in rear and C20 is 56in. So being that K20 can be either, I'm moving my K10 springs hangers and installing the C20 rear springs. Just seems to me that the C20 rear springs are going to raise the rear. So how does the front get raised to match in OEM. Is it in the shackles, spring height or what? I'm fairly certain 3/4 ton front K springs can be 2 or 3 springs depending on the RPO codes.

 

[hirschdalechevy]

Acuatually !!! aka Actually... I might be able to learn you something about that rear spring dimmensions as far as length. For whatever reason, depending on which RPO code and if heavy duty or not, C10 can have either 52 or 56 inch rear springs. The only other model can have either 52 or 56in springs is K20. So 2wd half ton, and 4x4 3/4 ton can be either from the factory. The rest are pretty much as you'd expect. K10 is 52in rear and C20 is 56in. So being that K20 can be either, I'm moving my K10 springs hangers and installing the C20 rear springs. Just seems to me that the C20 rear springs are going to raise the rear. So how does the front get raised to match in OEM. Is it in the shackles, spring height or what? I'm fairly certain 3/4 ton front K springs can be 2 or 3 springs depending on the RPO codes.

agree , I have 2 k-20's with 52" rear springs and my k-30 crew cab has 56" rear springs , and my girls k-10 has 52" rear springs as well.

 

[HotRodPC]

agree , I have 2 k-20's with 52" rear springs and my k-30 crew cab has 56" rear springs , and my girls k-10 has 52" rear springs as well.

I found it strange that Only 2wd half ton, and 4wd 3/4 ton could have either or. Are you aware its the same hangers and the frame is already punched for the 56inch springs. So if you wanted, you could grind the hanger rivets, use grade 8 bolts and threadlocker to move your hangers, and install the 56in springs. I'd think they'd be a bit tougher and certainly a smoother ride. I've pretty much made up my mind, I'm putting 56in 3/4 springs on both my K10's.

hirsch, do you by chance have an pics of your front K20 spring packs and hangers?

 

[crazy4offroad]

I found it strange that Only 2wd half ton, and 4wd 3/4 ton could have either or. Are you aware its the same hangers and the frame is already punched for the 56inch springs. So if you wanted, you could grind the hanger rivets, use grade 8 bolts and threadlocker to move your hangers, and install the 56in springs. I'd think they'd be a bit tougher and certainly a smoother ride. I've pretty much made up my mind, I'm putting 56in 3/4 springs on both my K10's.

hirsch, do you by chance have an pics of your front K20 spring packs and hangers?

Maybe on the longbed 1/2 tons, but the shortbeds are only set up for 52s. And yeah the longer springs ride much better.

 

[HotRodPC]

Here is info I posted long ago about spring dimensions. I'm just wondering what decides if a K20 gets 2 leafs or 3 leafs up front. Also if the shackles are taller? Maybe if it has 52in rear springs it has 2 leafs up front like a half ton, and if its 56in maybe its 3 leafs up front? That's what I'm trying to figure out. I want to know what I have to do to the front when I put the 56in rear springs on so it keeps the stance it has now instead of looking like a vato mobile and all jacked up in the back. K20 also has a negative arch in the front springs too right???

http://www.gmsquarebody.com/forum/showthread.php?t=274

 

[sean1960]

I have a question. My 4x4 is setting on a 84 3/4 ton frame' It had 56 inch rear springs and I replaced them with 52 inch springs. I had to drill the holes for the 52's. The question is: How prevalent were the frames with holes punched for both length springs?

 

[Green79Scottsdale]

Hey HotRod, I will take some pics of my K20 tomorrow for you. I wish I would have read this earlier as I was working the truck today.

Now, my K20 is a Camper Special. I was told the spring packs were basically 1-ton springs but with the 3/4-ton driveline. Keep this in mind when you see the pics. Can anyone confirm what I have been told?

 

[crazy4offroad]

Sounds like we got a whole lot of questions, and not a whole lot of answers!

 

[bucket]

In my research I have determined that nothing can really be determined. Front spring pack thickness and leaf quantity changed from year to year and also varied depending on how the truck was optioned. But, the shackles did gain .5 inch in or around '88.

As for the rear springs, they all seem to give about the same ride height, maybe an inch on the heavier springs (unless your replacing badly sagged springs). 2wd's had short rear spring hangers and 4wd's had taller spring hangers. IIRC, 1tons all had the same length spring hangers (a hair taller than the K10/K20 hangers).

 

[HotRodPC]

I have a question. My 4x4 is setting on a 84 3/4 ton frame' It had 56 inch rear springs and I replaced them with 52 inch springs. I had to drill the holes for the 52's. The question is: How prevalent were the frames with holes punched for both length springs?

I sure thought they were punched for both sizes. It appears to me that both of my K10's are. And being that K20 came in both sizes depending on RPO codes if heavy duty or not, you'd surely think K20 is punched for both. Is it possible your spring hangers are aftermarket and different spacing?
I guess maybe I need recheck and measure my K10's to make sure my assumption is correct. It appears to me on my K10's that are 52in now, I will remove the hangers, and use the center set of bolts holes for the front of the hanger instead of the rear of the hanger, then there are holes punched to the rear of the center holes which would now be used for the rear of the hangers. Maybe I need to take a pic.

 

[bucket]

I know my 4x4 Burb had holes for both hanger positions. I swapped from 52's to 56's.

 

[HotRodPC]

Hey HotRod, I will take some pics of my K20 tomorrow for you. I wish I would have read this earlier as I was working the truck today.

Now, my K20 is a Camper Special. I was told the spring packs were basically 1-ton springs but with the 3/4-ton driveline. Keep this in mind when you see the pics. Can anyone confirm what I have been told?

That would be great. I'd appreciate it. It won't matter to me much. As long as I know its 3/4 or even 1 ton and the truck will be level is what is more important to me. I just wand to see the shackles the spring pack and if its negative or positive arched.

 

[hirschdalechevy]

I found it strange that Only 2wd half ton, and 4wd 3/4 ton could have either or. Are you aware its the same hangers and the frame is already punched for the 56inch springs. So if you wanted, you could grind the hanger rivets, use grade 8 bolts and threadlocker to move your hangers, and install the 56in springs. I'd think they'd be a bit tougher and certainly a smoother ride. I've pretty much made up my mind, I'm putting 56in 3/4 springs on both my K10's.

hirsch, do you by chance have an pics of your front K20 spring packs and hangers?

I can take some pic's for you , but all my trucks have lift springs in the front but the hangers are all stock. I can tell you this much , if you buy new , the 56" springs cost a lot more than the 52" ones do.