What did you do to your NBS GMT800 Tahoe/Yukon Today?

[rgosart]

Its the definition of tension. Tension is what a rope sees when it is pulled on.

You are not pulling on the Torsion bar. You are twisting it (Torsional) ( determined by how keys are adjusted) and flexing it (bending due to hitting the jounce stops). The combination of twisting and flexing of the torsion bar is what provides the spring in your suspension. The more you twist the bar by adjusting the keys, the more it wants to rotate the control arm down, thus raising the truck. When you do that, you need to extend the jounce stop so you can maintain the proper amount of flex load on the torsion bar. Conversely, if you take twist out of the torsion bar, your control arm will be able to rotate up further, thus lowering the truck but you will need to shorten your jounce stop to maintain the desired flexing of the torsion bar.

Okay. Wrong word. How does increasing the twist on the torsion bar not change the spring rate of the torsion bar to make the suspension stiffer. By twisting the bar further you are increasing the preload.

My argument is that the "jounce stop" is not the only thing that changes the ride feel.

 

[wjburken]

Okay. Wrong word. How does increasing the twist on the torsion bar not change the spring rate of the torsion bar to make the suspension stiffer. By twisting the bar further you are increasing the preload.

Again, it is a matter of definition. You are correct, twisting the torsion bar increases, or decreases the preload or twist in the torsion bar. The spring rate itself is not affected. Spring rate is a function of material and diameter of the bar only.

 

[Fosscore]

Played musical chairs with Airaid Jr intakes....

View attachment 234725 View attachment 234726

Needs cleaner letters....errr engine bay...sheesh!

 

[rgosart]

Again, it is a matter of definition. You are correct, twisting the torsion bar increases, or decreases the preload or twist in the torsion bar. The spring rate itself is not affected. Spring rate is a function of material and diameter of the bar only.

Alright. I did my research and I understand now. The height change in the front end changes proportionally with the "twist" in the rear so the resting position is the same. Makes sense...

 

[TheAutumnWind]

Please explain how, without increasing tension, the resting position of the front end rises...

You are changing how the bar indexes with the lower control arm.

 

[TheAutumnWind]

Okay. Wrong word. How does increasing the twist on the torsion bar not change the spring rate of the torsion bar to make the suspension stiffer. By twisting the bar further you are increasing the preload.

My argument is that the "jounce stop" is not the only thing that changes the ride feel.

No preload happening here. Think of it more like you are changing the resting position of the lower control arm. Not like compressing a spring.

 

[rgosart]

No preload happening here. Think of it more like you are changing the resting position of the lower control arm. Not like compressing a spring.

Yep! Got it now and edited my initial post. My fault for not fully understanding...

I guess the change in stiffness comes from the load range E tires with stiffer sidewall. I bought small bumpers to add to compensate for the extra distance between the control arm and the jounce stop. I guess it is time to put them on.

 

[TheAutumnWind]

Yep! Got it now and edited my initial post. My fault for not fully understanding...

No problem at all. It's an unfortunately common misconception. Something that I fell victim to in years past.

 

[iamdub]

Alright. I did my research and I understand now. The height change in the front end changes proportionally with the "twist" in the rear so the resting position is the same. Makes sense...

Yaaas. An easier way to imagine it is to picture the T-bar as a solid piece that does NOT bend or twist and it has a lever on each end facing opposite directions. The key is one lever pointing one way, the control arm is the other lever pointing the other way. If you turned one end by lifting the lever, the lever on the opposite end will rotate the opposite direction. You haven't "twisted/wound/flexed" the bar in the middle at all- just rotated it a little.

You turn the key upward a few degrees and the control arm turns downward a few degrees. Since the wheels can't go into the ground, the truck is pushed away from the ground.

 

[TheAutumnWind]

My argument is that the "jounce stop" is not the only thing that changes the ride feel.

I totally agree. The angle of the arms and the amount of uptravel and down travel when you cycle the suspension plays a part as well.

When you take the suspension out of the sweet spot you actually lose overall travel. Less suspension travel is bad for ride quality. This happens because there is a hard limit on how high or low of an angle the arms/balljoints/ axles can achieve.