Lift questions????

[kevinr1970]

I cross posted this in the 73-87 forum and will delete which ever thread gives me the least feedback.

I swapped the 2” lift springs from my parts truck (’85 GMC ½ ton swb) to my good truck (’86 GMC ½ ton lwb).

Before I started the swap, when the trucks were parked grill to grill, the hood and bumper of the ’85 parts truck was noticeably higher than the ’86 good truck.
The ’86 had 33x9.5 and the ’85PT had 33x10.5 tires. When off the trucks the tires looked to be almost exactly the same height.
On the ’85PT I measured the distance from the center of the front hub to the edge of the fender (straight up) at 23-1/2”. The distance on the rear was 24-1/2”. On the ’86 it measured 21-3/4 to 22” (little different side to side) and 22-1/2”.


My problem is now that the lift is on my ’86 the ’85PT still sits slightly higher than the ’86? The kicker is that the ’86 is sitting on the 33x10.5’s but the ’85PT is sitting on 31x10.5’s????

The rear of the ’85PT is on jack stands so it will come up some when I mount the axle and set it on tires. It should bring the front down a little bit. I wouldn’t think it would come down more than just about level with the ’86 though. But with a 1” drop because of tire size and a 2” drop in springs the ’85PT should be 3” lower than the ’86.
When I measure the ’85PT it is now about 23-1/4”. The ’86 is about the same. The rear of the ’86 is noticeably higher but it looks like it is jacked up in the back – it slopes down to the front.
I measured the shackles (? the rear mounting brackets for the front springs) at I think 4-1/2” from bolt hole to bolt hole. It was the same on the ’85 parts truck.

WHAT AM I MISSING HERE??????

[Yukon Jack]

Hmm, have you actually measured the tires. Most manufacturers sidewall specs aren't accurate for the true height of the tire. Also, what pressure are they at - higher pressure would make the tire taller.

I assume the 85 doesn't have a small body lift, right?

[kevinr1970]

Originally Posted by Yukon Jack

Hmm, have you actually measured the tires. Most manufacturers sidewall specs aren't accurate for the true height of the tire. Also, what pressure are they at - higher pressure would make the tire taller.

I assume the 85 doesn't have a small body lift, right?

I hadn't thought about a body lift? I'll look closely at that when I get home.
But the initial measurement from hub to fender was 23-1/2 and now is 23-1/4?
I was thinking that maybe the 2" lift in the front was achieved by using a "helper" spring. If this is the case then maybe I need to put my original springs (120k) with the helper back in place of the parts truck springs (240k).

[kevinr1970]

Took some pictures today. Don't know if it will help to answer my questions though?

[kevinr1970]

Also, I was looking at the springs and saw that both sets of springs are two leaf leaf-springs.
The set I put on my '86 (the blue one) have a thick "helper" leaf on the bottom of the pack. Would this helper spring give a 2" lift to otherwise stock springs?

[Zoomad75]

Should give it a little bit. My question is, does the parts truck have an engine in it? The difference in how they sit will differ if one is without an engine. Other difference could be small block vs 6.2 as the 6.2 is a little heavier, it would cause the front end to sit lower. I don't know which truck has what engine, so I may be way off base on that though.

Might just be the perspective of your pics, but the blue truck looks like it has bigger tires on it. Seeing as how both trucks are 1/2 tons, the springs should be the same except for actual use/sagging. I don't know that you are going to gain any lift with stock 1/2 ton springs.

[kevinr1970]

Originally Posted by Zoomad75

My question is, does the parts truck have an engine in it? The difference in how they sit will differ if one is without an engine.

Yes, both trucks still have engines and tranny's in them. Both small blocks, one is a 350 and not sure what the other is?

Originally Posted by Zoomad75

Might just be the perspective of your pics, but the blue truck looks like it has bigger tires on it. Seeing as how both trucks are 1/2 tons, the springs should be the same except for actual use/sagging. I don't know that you are going to gain any lift with stock 1/2 ton springs.

The blue truck has 33's and the red truck has 31's. Which is why I'm puzzled. The red truck has tires that reduce height about 1" plus the springs have been changed out.
The rims/tires on the blue truck were on the red truck to begin with. When those rims/tires were on the red truck I had a different set of 33's on the blue truck and the red trucks hood was noticable higher (wish I would have taken a picture!?!).

My thoughts now are that the springs that came off the red truck and are on the blue truck now are shot.
This weekend I am going to pull the front springs that are on the red truck and put them back on the blue truck but put the helper spring on with it. Hopefully this brings it up level?

[Blue_71]

if im reading this right, the parts truck (red) is swb, right? a swb may just be enough lighter in total weight to make it sit higher then a lwb equally equipped. theres a 78 swb 1/2 ton 4x4 on original springs, wheels and 29" tires in town that sits dern near as high as my 71 k20 with 3" lift and 33s

[kevinr1970]

Originally Posted by Blue_71

if im reading this right, the parts truck (red) is swb, right? a swb may just be enough lighter in total weight to make it sit higher then a lwb equally equipped. theres a 78 swb 1/2 ton 4x4 on original springs, wheels and 29" tires in town that sits dern near as high as my 71 k20 with 3" lift and 33s

Yes, the red one is a swb. I hope thats not the case.
I'll know more by Sunday. I guess if nothing else I end up buying new 2" lift springs?

Boy, this truck that I am not going to throw anymore money at sure is nickel and diming me...

[Zoomad75]

well. I think Blue might be on to something. When I put the 4" lift on my K5, it sat almost as High a DirtyLarry's 78 K10 with the same lift. Differences were Mine was on 33"s, his with Q78 (just about 36") swampers. He even has the longer ORD shackles too. But he's running a Big Block and I've got a small block, so that by itself might have leveled it out.

I'm betting both sets of springs are probably worn out, one might be more than the other. an alternative is to take the better set down to a local spring shop have them re-arched and add another leaf if need be. It should be cheaper than buying new springs.

[kevinr1970]

Would it be worth having used springs re-arched?

To have them rearched I would think it would be better to use the springs that are in better condition. And those are now back on the parts truck. So I would end up swapping both sets again.
If I just buy new springs then I only have to swap one set and will have some piece of mind that I have good parts.

What would new springs cost; $150-$175?
***EDIT - looked up Tuff Country and can get 2" EZ rides for $98 plus shipping.
I am open for suggestions on site supporters for these parts though?

[Zoomad75]

Tuff country springs are pretty good. Nice and soft. haven't heard anything bad about them..

[kevinr1970]

Yeah, they have EZ rides and HD (heavy duty). I'd buy the EZ rides.
I have driven the truck around a little bit. With springs from the PT on there it seems a little bouncier; not as stiff. With the springs that were in there before my kidneys were taking a beating.
This truck just gets driven around, go biking with and use for our annual snow-day (well, about two weeks of ice this year?). It doesn't need to be a heavy duty off-roader.