1972 GMC lift kit

[Roadkillerv8]

Hey guys, wondering if it'd be worth it to go with new springs for my lift, or blocks. The guy at les schwab says that if i do lift springs the overload springs will have to go, and i don't really want them to go, however the ride will be nicer. With the block lift the overloads can stay. Will the ride be much worse with blocks? or are there any more pro's or con's to either?

I will either be getting a 4 or 6 inch lift if that makes any difference.

[stomper]

Why do the overloads have to go if you get new springs? Blocks will not change the ride.

[Roadkillerv8]

Originally Posted by stomper

Why do the overloads have to go if you get new springs? Blocks will not change the ride.

I dont really know, he said if i went with the lift springs they would elimiate the overloads, nothing else really. He didnt seem like the brightests of all folks though either.
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[69 MOD]

I think the arch of the lift springs won't allow for the overloads.

My question is if you're going 4/6" are you going to load it to overload spring weight?
Seems like you'll be using it more for a toy than a worker. In which case 3/4 ton springs without OL would be more than fine.

Maybe I'm wrong

[GASoline71]

I assume we're talking about a leaf sprung 4x4 truck. The rear overloads are a thick short spring underneath the spring pack. It will have no effect on the lift kit whatsoever. With the exception of the new U-bolts for the blocks. Not sure but the new U-bolts might be too short with the overloads left in place.

I lifted a 1979 K25 myself with a 4" kit that had blocks in the back and I kept the overload springs in place. The U-bolts were more than long enough. It was a kit from Superlift.

DO NOT use lift blocks on the front leaf springs. You will need new springs with the lift in the arch.

With a 6" kit, I wouldn't use blocks in the back either.

Gary

[57taskforce]

Keep in mind also that the more you lift it the more your steering arm/dragline geometry will suffer. I'd stick with 4", at that height you've got a decent compromise between geometry and lift. At 4" you should be able to clear 35's.

[swamp rat]

With a 43 year old truck its time to think about not just the springs but worn out bushings as well.

Without a pic its not easy to tell what type of overload springs you have weather they are bolted to the top of the spring pack or a heavy leaf added to the bottom of the spring pack using a longer spring pack bolt, the first ones i mention while they work put added stress on the springs.

Either way what you have probably won't work with the new arch of lift springs, there is other options avalable like overload air bags, possibly even some overload springs that will work with a lift spring you buy but you'd have to research that, or a local spring company that can build a set of springs to your spec's..

Rear blocks are least desirable and never use blocks on the front, that said a front spring/rear block kit will do the job but still concider replacing the bushings, after 43 years they are probably frozen solid like mine were.

[special-K]

I just lifted my '72 K2500 4". Overload springs are an extra set of leafs over top of the main pack, as seen on dual rear 1 tons. My truck didn't have those, but I haul everything and anything under the sun w/o needing them. I use this truck, so I retained the stock HD springs. I didn't want 4" blocks, so I went with an add-a-leaf for 2" and used a tapered 2" block for the other 2". The add-a-leaf serves to rejuvenate the original pack (stiffen) while countering the tendency for axle wrap, which is minimal with such a short block. If you have true overload springs you could do fine w/o them.

Another option for the rear is do a shackle-flip and don't touch your springs. But in my mind that's contradictory. To retain overload springs is to say you will be loading it down heavily while raising a truck makes it more top heavy