64" spring swap ?
 

Anyone swap them under a 1972 K-10/20.

Re: 64" spring swap ?
 

Check out the link in my sig. Long thread and on a '63 but its basically the same process except I think that DIY and ORU make hangers specifically for the 67 - 72 trucks which might make it easier.

Skip the front axle part.

The rear axle goes pretty easy.

FWIW, most will stay away from the 1/2 ton stuff as they have a tendency to "W" or bend. So Ive been told. I ended up swapping my 1/2 ton springs for 3/4 ton and am still contemplating bags. The 1/2s (while cheap) get onto the overload just a little too easily for my liking.

Re: 64" spring swap ?
 

I've looked through your thread a few times,nice work! I have the same blazer tank just waiting to go in with the springs.The springs that I have are the 3/4 ton 4x4 version. Looking at my front hanger if I move it forward on the lower frame rail rivets. Swapping the back hole for the front. It will move it forward 6.5'' and down 2". Is that about where yours ended up? Also for the rear I'll use a shackle flip compression style two plate design like you used,so I can adjust the height for the rear.How far down did your front shackle end up from the stock hanger? Did you gain any lift from the spring it self? Thanks,Gary

Re: 64" spring swap ?
 

Hey Gary,

I'll try and get some pics off of my computer to show the relationship of the new front hanger vs. where the old one was. I should have taken measurements but was in more of a hurry and trying to make sure that the axle was straight consumed most of my attention..

I do remember clamping the hangers onto the frame and loosely setting everything down onto the axle to estimate what the sag would be several times to mock up the positioning of the hangers before drilling. It was a lot of eyeballing. Not very scientific.

As far as lift, I do not have 4-1/2" blocks anymore and the truck sits with about 3/4" rake. If I had to guess, total lift is around 5".

Re: 64" spring swap ?
 

Your 6-1/2 forward sounds about right. If you look at the larger hole that lines up with the crossmember, you can see it moved forward quite a bit. I think that may have been where the old grease pin may have been centered.

On mine IIRC, the front spring eye moved toward the top of the frame a few inches.

The shackle flip seemed to provide most of the lift. More so than the front eye placement.

Re: 64" spring swap ?
 

the 64" spring center pin is centered .

just do the math and move the hanger that much for each . its how i did it years ago on a not finished project .

also the normal is rear hanger is .5" less that the center pin to eye length . this is to start the shackle on its movement path .

the project i did the swap on was a 77k30 truck . fyi the 20 gal tanks dont fit anymore after this swap . so it would be shorter 16 gal tanks or blazer/burban tank swap in the rear .