Cargo capacity and axle swap questions

[turdmagnet]

I have a stock 1974 K5, 1/2 ton. I replaced the old rear leaf springs with heavy duty springs and put bump stops on too. I loaded in a lot less than 1000 lbs. and the ass end was resting hard on those bump stops. If those bump stops weren't there, I think I might have collapsed the springs. What do I need to do to carry more weight? Do I need to replace the rear axle with a 3/4 ton axle or should I just put on overload springs? Assuming I did want to install the 3/4 ton axle, could I still use the 6 bolt wheels I have or am I forced into an 8 bolt wheel?

 

[Roostertail]

If you are going to always have it loaded like that, then take it to a spring shop and have an add-a-leaf put in. If it's not going to always be loaded, use some air bag helpers, they won't affect the ride when unloaded.

If you want to swap the axle for a FF 14 bolt then you will need to pony up for some 8 lug rims or spend a whole lotta coin making it into a 6 lug. The other option is a 9.5" 14 bolt out of a 3/4 ton van with the 5? or 6 lug pattern.

 

[dremu]

A stronger axle -- while a great idea if you're regularly overloading it like that -- won't help the suspension sitting on the bumpstops. More spring is called for in that instance, whether it's airbags or add-a-leaves or whatever.

And what the HECK are you putting in that's loading it like that? And where on the truck? Might help to center the load over the axle, or farther forward, if you're not already...

-- A

 

[turdmagnet]

Thanks dudes. I think I'll just go with add-a-leaves or overload springs. I didn't have anywhere near 1000 lbs inside that space so I suspect the springs themselves are underperforming.

 

[Avery4jc]

Yeah I'd vote going to some stiffer springs if you're plannign on having that much weight in it fairly often...I've had about 1200lbs in the bed of my K10 that has 8" Superlift springs and a 14ff with no problems...so I vote either helper bags between the frame and spring plate or stiffer springs...

 

[pauly383]

Wow , thats crazy . I have loaded a full load of parts , including two complete axles ( back seat folded up , talgate down ) and still had suspension .

I don't doubt you got what you thought were heavy duty springs , but I don't think the springrate , and load capacity is close to what you need .

I would get new springs made for your aplication , and sell your rears to someone wanting to do 52 fronts with soft springs .

 

[6.2Blazer]

1,000 lbs. is a lot of weight to go in the back of the Blazer, and is probably more than what the cargo capacity is. It may have the same suspension as a "1/2 ton" pickup, but the back of a Blazer weighs a lot more than a pickup. My K5 has a GVWR of 6,250 lbs. but weighed 6,000 lbs. when stock with the exception of a couple hundred pounds of tools, and a full tank of fuel (31 gallons). So in that example if you put an additonal 1,000 lbs. it would be way over capacity.

It also depends on how the weight was loaded. If it's mostly behind the rear axle than I'm not surprised it would do this.