Rear shocks twisting frame?

[Casey916]

Yay i have questions about that two.. Wouldn't it be better for us to put the shocks all on the same side facing the same way instead of one shock on one side of the axel and one in the other side like they come stock.. when we get a better ride if we've put each stock on the same side of the ankle I called in your truck would not give us a better ride

 

[Schurkey]

Staggered shocks have been used since at least the later-1960s to reduce wheel-hop under acceleration and braking.

Nothin' new there.

 

[Canadian Rust Bucket]

Ok, I tested the relevant components, and have a solution!
After loosening the bolts through the spring eyes and re-hanging the gas tank, the truck now sits about an inch closer to level. I did try taking the shocks out but they had a negligible effect on the height of the frame.
So I believe the people who said it was an issue because of the lack of weight are correct. Once I reattach the bed sometime this summer, I'll torque the spring bolts and maybe do some more adjusting if it's required.
Thanks all for your help and suggestions

 

[Erik the Awful]

Staggered shocks have been used since at least the later-1960s to reduce wheel-hop under acceleration and braking.

Yup. Buy this book and read it. You'll be surprised how often you'll refer back to it.
www.amazon.com/Chassis-Engineering-Building-Performance-Handling/dp/1557880557/

 

[MrPink]

Yup. Buy this book and read it. You'll be surprised how often you'll refer back to it.
www.amazon.com/Chassis-Engineering-Building-Performance-Handling/dp/1557880557/

I have this one and a few others on the shelf in the garage.

 

[Hipster]

Suspension bolts

Ok, I tested the relevant components, and have a solution!
After loosening the bolts through the spring eyes and re-hanging the gas tank, the truck now sits about an inch closer to level. I did try taking the shocks out but they had a negligible effect on the height of the frame.
So I believe the people who said it was an issue because of the lack of weight are correct. Once I reattach the bed sometime this summer, I'll torque the spring bolts and maybe do some more adjusting if it's required.
Thanks all for your help and suggestions

yup... whenever dealing with suspension work the weight of the vehicle needs to be "on" the suspension before torquing down anything that goes through a bushing. If not you can tear up the new bushings. It's an area especially with u-bolts where torque values matter.

I've never seen a full tank of gas change ride height 2.5 inches. That's a considerable amount, and a wavy concrete floor or pavement might give you some idea on the frame but is nowhere near accurate enough for definitive measurements. The frames on these trucks are not as stout as far as torsional twist as one would think. Mild steel ladder type construction.

 

[sewlow]

The frames on these trucks are not as stout as far as torsional twist as one would think.

Ain't that the truth.
In fact, these truck's frames have a problem with what's called 'beam walk'.
An inherent vibration that occurs between 30-40mph (slight) & again between 65-75+mph (pronounced)
GM's aware. ...and they have a 'cure'.
Ballast. Yea. Extra weight.
Their recommendation is to carry a couple of hundred pounds in the box. All the time. WTF?
A more permanent fix is to box the frame.
From the rear cab mount to the shackle mount. Top plates welded to the cross members help, too.
Makes accessing any lines running inside the frame difficult, though.
I've seen some frames that have had trusses added. Alternating vertical & angled steel bars welded inside the leading edges of the frame's C-channel shape.
Easier access to those lines. Less weight than boxing. Easier to fab.

 

[stutaeng]

That's the general trend. Newer stuff is stronger and stiffer, but actually lighter on a unit length basis.

How do they do it? Cross sections are generally thinner, but deeper to make stuff more efficient.

I imagine everything is optimized (using powerful analysis programs and manufacturing technology not available in the 70s-80s,) whereas the older stuff was more-or-less a constant cross-section.

 

[Hipster]

Ain't that the truth.
In fact, these truck's frames have a problem with what's called 'beam walk'.
An inherent vibration that occurs between 30-40mph (slight) & again between 65-75+mph (pronounced)
GM's aware. ...and they have a 'cure'.
Ballast. Yea. Extra weight.
Their recommendation is to carry a couple of hundred pounds in the box. All the time. WTF?
A more permanent fix is to box the frame.
From the rear cab mount to the shackle mount. Top plates welded to the cross members help, too.
Makes accessing any lines running inside the frame difficult, though.
I've seen some frames that have had trusses added. Alternating vertical & angled steel bars welded inside the leading edges of the frame's C-channel shape.
Easier access to those lines. Less weight than boxing. Easier to fab.

Some forethought has to be put into it and a singular reinforcement can transfer loads and particularly vibrations to a different point on the frame and can cause cracks somewhere other than where the reinforcement was installed. Given the choice if I got in one that deep I would box it and go from there.

 

[stutaeng]

I've heard of that vibration thing. I would imagine it affects a certain cab/bed configuration only? Or more so than others?

From my limited knowledge on vibrations in static systems, the major players affecting vibrations are stiffness and mass (weight). There's also excitation cycles, but I don't think you can control that unless you avoid driving a specific speed over a known road conditions cause a specific frequency, LOL.