The vague nature of my truck is pissing me off...

[Davetopay]

I would like to toss a 4 inch lift on my 1970 GMC 1500, SO I start poking around under it and notice some things which seem odd....

1. Keep in mind the truck has no suspension lift kit now. It is sitting on 31's and they fit like they are stock.

2. It has 4 inch blocks between the axle and leaf springs(6 leaf packs) in the rear. I don't THINK the factory built them like this, but anything is possible.

3. The front springs are a real puzzler. They look like your standard 2 leaf half ton negative arch springs, until you look twice at the driver's side. It has a THIRD leaf which is only about a foot long! Was that a factory deal or has someone monkeyed with the suspension long before I got the truck?

pic of the rear set up:

Keep in mind, this shot was taken with about a cord of oak firewood in the bed, so it is well compressed.

Sooooo... any ideas on this puzzler?

[Gregs71]

i would guess it already has a lift and the height of the block is the height of the lift.

[Davetopay]

Originally Posted by Gregs71

i would guess it already has a lift and the height of the block is the height of the lift.

If that were the case, it came with 26 inch tires as OEM and looked like a tail dragger low rider.
This is it on 31's unloaded:

loaded with wood:

loaded with car!:

I doubt it has a kit already(in the standard sense) because there is only about 3 inches travel to the bump stops when sitting level a the front axle and the springs have a negative arch.

[msgross]

any pics of the front springs? Looks like stock height to me...

Here are the rear springs from my 1968 1/2 ton, the third leaf was added for 1/5" of lift...

[Davetopay]

I'll have to crawl under there with my phone tomorrow to pop some pics. I am wondering if maybe someone swapped some 3/4ton 2wd springs in the back and lifted it with the 4 inch block to level it.


This leads me to my next though on lifting it...

If I bought a set of 4 inch springs for the front, I could just do a shackle flip on the back.

[72lb4x4]

Look at the shackles in the rear of the front springs. A cheap lift is blocks in the back and shackles in front. A stock shackle is about 4" center to center.

Look at the rear leaves. Notice that some at least aren't tapered, and some are about the same length. It looks like someone has added a couple leaves in back.

I'm not sure what your question is... You know you have a lift since its got blocks in the back. It sits level so its got to be lifted in front. It sits higher than stock.

It probably rides like there's no rear suspension because of the extra leaves... On mine each leaf is about 6" shorter than the one above it, or 3" on each end.

Nice looking truck BTW.

[msgross]

I think that someone replaced the rear springs at some point. Almost looks like they used 3/4 ton front springs on the rear... How does it ride?

If you haul heavy items (like wood) then the rear shackle flip would work with new front springs, Or just replace all four springs with K-20 4" lifted springs...

[Davetopay]

Originally Posted by msgross

I think that someone replaced the rear springs at some point. Almost looks like they used 3/4 ton front springs on the rear... How does it ride?

If you haul heavy items (like wood) then the rear shackle flip would work with new front springs, Or just replace all four springs with K-20 4" lifted springs...

....remember, that is a photo while compressed....


You mean they might have taken leaves from a 3/4 ton front pack and added them to the stock rear pack? I suppose it is possible. This truck has parts of several trucks in it. The tailgate was hugger orange and has higher level trim, the doors are from a 72(vent wing screw holes), the inside is 100% LMC, The manifolds have Corvette casting numbers, the heads appear to be big valve small chamber according to the casting on the end, and the front axle has a disc brake swap. With all the farm land that this county was until the 90's who knows what kind of cobbled up machine someone put together to keep things working!



Oh yeah...the steering box is from a 75.....

[msgross]

do the rear springs have any arch while the bed is empty? Front leaves are flat, rears are usually arched.... that's why I guessed that.

[Davetopay]

Originally Posted by msgross

do the rear springs have any arch while the bed is empty? Front leaves are flat, rears are usually arched.... that's why I guessed that.

Oh yeah...they have a very "normal" arch to them. There is normally at least six inches of compression space between the axle tube and the rubber bump stop when unloaded.

I am wondering if maybe someone took a set of 3/4 ton rear springs from a 4x2 and used blocks to level it.

[msgross]

does it have stock rear shackles?

There is also the fact that nobody aver really knows what GM did back then. GMC also seems to have quirks in parts... could be totally stock... hard to tell.

[Davetopay]

Originally Posted by msgross

does it have stock rear shackles?

There is also the fact that nobody aver really knows what GM did back then. GMC also seems to have quirks in parts... could be totally stock... hard to tell.

Yup. SHackles look as stock as they can be, and the hangers are still attached with rivets.

Like I said...it's a bit of a puzzler.

[powerdriver 1958]

I think thats an extra challenge when working on older trucks,I have replaced 1/2 with 3/4 springs on two trucks in the past.

[GMCMAX]

You say it is a combination of vehicles; are the front axle hangers riveted also? On my 68 converted to 4x4 with the 4x2 frame, I had to put a 4" block in the rear to match the stock height 4x4 front springs to sit level.
Just a thought
Good luck......
Max

[Davetopay]

Originally Posted by GMCMAX

You say it is a combination of vehicles; are the front axle hangers riveted also? On my 68 converted to 4x4 with the 4x2 frame, I had to put a 4" block in the rear to match the stock height 4x4 front springs to sit level.
Just a thought
Good luck......
Max

As far as I can tell, the chassis is NOT a conversion. The front suspension is riveted like factory. It still has the driver's side "capture" at the front hanger and the passenger's side limiter behind the shackle. Not to mention the original mounting of the crossmember for the NP205. Also, the VIN on the frame matches the cab.

I guess what it comes down to, if I want to put a mild lift on it, is I will have to shell some coin out. I have this gut feeling that if I buy a kit iff the shelf, something won't be right.

[71blksuper4x4]

I am with MSGROSS, on the topic. It looks like there are front springs in the back. All stock rear leafs and lifted leafs will have an arch to them. It appears that they had to use 4" lift blocks to level everything back up. I think it's just a matter of pulling the leafs out and installing a new set, or getting you some stock rears and a 4" spring set for the front. I also agree that if you haul stuff, a shackle flip would be the best possible decision if you are wanting to lift it. Trevor