2024 Chev 2500 HD Torsion Bar

[BCGM]

Okay I'm going to try and post a couple  of pictures here . Not holding my breath that they will come through . If they don't here's a description.

I was under the new truck checking things out and noticed 2 bolts that seem that they are touching  a big key like piece of metal that is linked to the 2 torsion bars , one bolt for each  key / torsion bar .

 

 

#1  I'm assuming it adjusts the torsion bar ?   

 

#2  Is this for raising  and lowering the front end ?#3  Should those bolts be turned in equally on both sides ? Mine are not . The truck seems to ride great but its been along time since I drove a 3/4 Ton truck .

 

#3  Notice the difference in bolt depth ?

 

#4   Do yours look like this ?

 

#5 Should I get the dealer to check it out ?

 

I'm not that Mechanically inclined . 

Thank You !

 

[asilverblazer]

47 minutes ago, BCGM said:

#1  Yes

#2  Yes

#3  Not necessarily

#3  Yes

#4  Yes

#5  No

No need to be concerned unless there is a significant difference in ride ride side to side on the front.

[Another JR]

Comment on question #2:  Those bolts are for adjusting the spring force on each side of the front suspension. They almost certainly won’t be exactly equal in position. 1/4 inch difference in exposed threads is not unusual.
 

Generally this adjustment is used to achieve a nominal specified height at which alignment is performed. It is not intended to be used to raise or lower the front suspension height for appearance purposes, although some do use it for that despite the problems it causes. Doing so does not change the upper and lower stop heights, plus it messes up the intended suspension arm geometry, so using the torsion bars alone to raise or lower from the nominal specified height is not the best way to change the suspension height. 
 

It’s never been clear to me exactly what conditions GM uses for leveling the truck laterally. I’m sure their shop manual provides it but I don’t have that. The fuel tank is on the left side, and if you are 200 lbs and drive alone with a full tank, the left side has a bunch of extra weigt relative to the right side. I set the truck laterally level (equal front fender heights) and at the original average front fender height with nobody in the truck and approximately 1/2 tank of fuel when I replaced my camper front torsion springs with standard springs. I did not have to re-align the truck after that change and it tracks perfectly on the highway, so I appear to have come close to approximating the original alignment setting conditions. 

Edited May 29, 2024 by Another JR

[64BAwagon]

Been that way on almost every GM truck with IFS that I have owned. 

[asilverblazer]

5 hours ago, Another JR said:

Comment on question #2:  Those bolts are for adjusting the spring force on each side of the front suspension. They almost certainly won’t be exactly equal in position. 1/4 inch difference in exposed threads is not unusual.
 

Generally this adjustment is used to achieve a nominal specified height at which alignment is performed. It is not intended to be used to raise or lower the front suspension height for appearance purposes, although some do use it for that despite the problems it causes. Doing so does not change the upper and lower stop heights, plus it messes up the intended suspension arm geometry, so using the torsion bars alone to raise or lower from the nominal specified height is not the best way to change the suspension height. 
 

It’s never been clear to me exactly what conditions GM uses for leveling the truck laterally. I’m sure their shop manual provides it but I don’t have that. The fuel tank is on the left side, and if you are 200 lbs and drive alone with a full tank, the left side has a bunch of extra weigt relative to the right side. I set the truck laterally level (equal front fender heights) and at the original average front fender height with nobody in the truck and approximately 1/2 tank of fuel when I replaced my camper front torsion springs with standard springs. I did not have to re-align the truck after that change and it tracks perfectly on the highway, so I appear to have come close to approximating the original alignment setting conditions. 

The actual measurement "Z-Trim Height", if I recall correctly, is taken from the bottom of the lower ball joint stud, vertically to the center line of the lower control arm rear mounting bolt. An image search would describe this better.

 

If you do adjust the torsion bar to alter this height, the toe amount in alignment is where the most difference is seen. 

 

As a side note, adjusting the bolts does not really alter the "force" on the torsion bar and it doesn't alter the spring rate either. All it does is change the relative rotation/position of the bar, this change also 'rotates' the lower control arm the same amount. This raises or lower the ride height. If you adjust it so much that you are against the bump stops then it can begin to pre-load the torsion bar and increase spring rate.

[BCGM]

23 hours ago, asilverblazer said:

No need to be concerned unless there is a significant difference in ride ride side to side on the front.

Thank You Silverblazer !   

#1 Hmmm, So I would have to see if it rides different in the passenger seat than the drivers seat ? 

 

#2 Why would it come from the factory like that ?

[BCGM]

Trying to save quotes to everyone . So Thank you 64BAwagon -  Another JR - Asilverblazer  

[asilverblazer]

46 minutes ago, BCGM said:

Thank You Silverblazer !   

#1 Hmmm, So I would have to see if it rides different in the passenger seat than the drivers seat ? 

 

#2 Why would it come from the factory like that ?

...ride HEIGHT side to side...

 

 

\/   \/   \/

[Another JR]

8 hours ago, asilverblazer said:

The actual measurement "Z-Trim Height", if I recall correctly, is taken from the bottom of the lower ball joint stud, vertically to the center line of the lower control arm rear mounting bolt. An image search would describe this better.

 

If you do adjust the torsion bar to alter this height, the toe amount in alignment is where the most difference is seen. 

 

As a side note, adjusting the bolts does not really alter the "force" on the torsion bar and it doesn't alter the spring rate either. All it does is change the relative rotation/position of the bar, this change also 'rotates' the lower control arm the same amount. This raises or lower the ride height. If you adjust it so much that you are against the bump stops then it can begin to pre-load the torsion bar and increase spring rate.

Agreed. I used the wrong terms. 
 

I did my measurements from the fender opening to the center of the wheel to eliminate the tire as a variable. I was just trying to put the suspension height the same as it was prior to my torsion bar replacement. 

[loam_seeker]

#4 Yes, mine looks exactly the same and I was also thinking, "why the heck aren't these threaded in the same depth?!?!?!" First truck with torsion bars, so thanks for posting the question and double thank you to everyone who responded and explained what is going on here!

[Dunn]

they are always different from my experience, all 3 of my HD were like this......trucks always rode fine so I never questioned it, come to find out they arent suppose to be the same

 

 

[BCGM]

11 hours ago, Dunn said:

they are always different from my experience, all 3 of my HD were like this......trucks always rode fine so I never questioned it, come to find out they arent suppose to be the same

 

 

Good to know Dunn !

Thank You